ES2877670T3 - Regeneration procedure of a titanium zeolite catalyst for the epoxidation of propylene - Google Patents

Abstract

A process for the regeneration of a catalyst comprising a zeolite containing titanium of MWW framework structure as a catalytically active material, comprising (i) a step comprising (a) continuously preparing propylene oxide comprising (a1) introducing a stream of feed comprising propene, hydrogen peroxide or a hydrogen peroxide source and an organic solvent in a reactor containing a catalyst comprising the MWW framework titanium-containing zeolite as a catalytically active material; (a2) subjecting the feed stream according to (a1) in the reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent; (a3) removing a product stream comprising the propylene oxide and the organic solvent from the reactor; (b) stopping the introduction of the feed stream into the reactor; (c) washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, wherein the washing is carried out for 2 to 12 hours ; step (i) further comprising repeating the sequence of steps (a) to (c) n times and n is an integer in the range of 1 to 10; The procedure for regeneration further comprises (ii) a step that comprises the calcination of the catalyst obtained from (c) after having repeated the sequence of steps (a) to (c) n times, where the calcination is carried out at a catalyst temperature in the range of 0 to 600°C, using a gas stream comprising oxygen in the reactor containing the catalyst; where the sequence of steps (i) to (ii) is optionally repeated m times and m is an integer and is at least 1, where in each repetition of the sequence of steps (i) to (ii), n is equal or different.

Description

DESCRIPTION

Regeneration procedure of a titanium zeolite catalyst for propylene epoxidation

The present invention relates to a process for the regeneration of a catalyst comprising a zeolite containing titanium as catalytically active material, to a regenerated catalyst and to a continuous process for the preparation of propylene oxide.

In recent years, various titanium-containing zeolites have been developed that are useful for catalyzing organic reactions such as the conversion of olefins to epoxides. For example, WO 98/55229 A1 discloses the production and further the use of a zeolite containing titanium for the epoxidation of olefins.

Titanium-containing zeolites are of great industrial interest and, in this context, economic and environmental considerations are of significant relevance. An efficient regeneration of such zeolites for their subsequent reuse in the catalysis of organic reactions would be much more preferable than their replacement with fresh catalyst.

The publication EP 1 221 442 A1 discloses the regeneration of a titanium zeolite catalyst used in the epoxidation of olefins with hydrogen peroxide, the process that comprises carrying out the epoxidation reaction, where the regeneration of the spent catalyst is carried out with peroxide of hydrogen in the presence of olefin, whereby the epoxidation reaction continues and where regeneration is achieved by reversing the direction of feeding of hydrogen peroxide. Hydrogen peroxide is also a valuable starting material and as such is difficult to handle due to its tendency to spontaneously decompose.

WO 2005/000827 A1 discloses the regeneration of a titanium silicalite catalyst following a procedure for the continuous epoxidation of propene with hydrogen peroxide. The catalyst is periodically regenerated with a methanol solvent at a temperature of at least 100 ° C. Methanol is a valuable organic compound that requires costly and time-consuming recovery. After regeneration, the epoxidation must be restarted at a higher temperature compared to the new catalyst in WO 2005/000827 A1.

Document WO 2007/013739 A1 discloses the regeneration of a titanium-containing molecular sieve catalyst in which, after a pre-treatment of the spent catalyst with water or alcohol, the thus pre-treated catalyst is contacted with a mixture comprising peroxide hydrogen, water and alcohol. Therefore, this process includes two mandatory and subsequent steps in which the spent catalyst is contacted with two different solutions. Furthermore, the fine-tuning of the mixture comprising hydrogen peroxide, water and alcohol is required.

Document WO 2015/010994 A1 describes a process for the regeneration of a catalyst, where the regeneration process comprises the separation cycle, washing with an aqueous liquid system and calcination.

Therefore, an object of the present invention was to provide a simple and cost-effective process for the regeneration of a catalyst comprising a zeolite containing titanium as a catalytically active material used in the epoxidation of olefins. Another object of the present invention was to provide a regenerated catalyst comprising a titanium-containing zeolite as a catalytically active material that can be easily reused in olefin epoxidation.

Therefore, the present invention relates to a process for the regeneration of a catalyst comprising a zeolite containing titanium of MWW framework structure as catalytically active material, comprising

(i) a stage comprising

(a) continuously preparing propylene oxide comprising

(a1) introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into a reactor containing a catalyst comprising the MWW framework titanium-containing zeolite as a catalytically active material;

(a2) subjecting the feed stream according to (a1) in the reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent;

(a3) withdrawing a product stream comprising the propylene oxide and the organic solvent from the reactor;

(b) stopping the introduction of the feed stream into the reactor;

(c) washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, wherein the washing is carried out for 2 to 12 hours ; step (i) further comprises repeating the sequence of steps (a) to (c) n times, and n is an integer in the range of 1 to 10; the procedure for regeneration further comprises

(ii) a step that comprises the calcination of the catalyst obtained from (c) after having repeated the sequence of steps (a) to (c) n times, wherein the calcination is carried out at a catalyst temperature in the range of 300 at 600 ° C using a gas stream comprising oxygen in the reactor containing the catalyst; where the sequence of steps (i) to (ii) is optionally repeated m times and m is an integer and is at least 1, where in each repetition of the sequence of steps (i) to (ii), n is equal or different.

Surprisingly, according to the process according to the present invention, the regeneration of a catalyst comprising a zeolite containing titanium as a catalytically active material used in an olefin epoxidation can be achieved by washing the catalyst with an aqueous liquid system according to step (c) of step (i) at least once without subsequent calcination, wherein after said washing, the catalyst exhibits the same or at least substantially the same catalytic activity as the respective new catalyst already without a calcination step, and wherein the results Regeneration can even be improved by calcining the catalyst according to step (ii) after one or more additional washing steps.

Stage (i)

Step (i) of the present procedure comprises

(a) continuously preparing propylene oxide comprising

(a1) introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into a reactor containing a catalyst comprising the MWW framework titanium-containing zeolite as a catalytically active material;

(a2) subjecting the feed stream according to (a1) in the reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent;

(a3) withdrawing a product stream comprising the propylene oxide and the organic solvent from the reactor;

(b) stopping the introduction of the feed stream into the reactor;

(c) washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, wherein the washing is carried out for 2 to 12 hours ;

step (i) further comprising repeating the sequence of steps (a) to (c) n times and n is an integer in the range of 1 to 10.

Stage (a1)

The feed stream according to (a1) comprises propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent.

Source of hydrogen peroxide or hydrogen peroxide

Both hydrogen peroxide and a source of hydrogen peroxide can be used as an epoxidation agent in the feed vapor according to (a1).

In case hydrogen peroxide is used, it is preferred that the hydrogen peroxide is an aqueous solution of hydrogen peroxide, wherein the solution preferably comprises 30 to 50% by weight of hydrogen peroxide with respect to the total amount of water. .

It is also possible that hydrogen peroxide is formed in situ in the reaction mixture from hydrogen and oxygen in the presence of a suitable catalyst or catalyst system, for example in the presence of a titanium-containing zeolite that additionally contains one or more metals. noble metals, or a zeolite containing titanium and an additional catalyst containing one or more noble metals, for example supported on a suitable support such as charcoal or a suitable inorganic oxide or a mixture of inorganic oxides.

For the preparation of hydrogen peroxide in the feed stream according to (a1) the anthraquinone process can be used. This procedure is based on the catalytic hydrogenation of an anthraquinone compound to form the corresponding anthrahydroquinone compound, subsequent reaction of it with oxygen to form hydrogen peroxide and subsequent extraction of the hydrogen peroxide formed. The cycle is completed by rehydrogenation of the newly formed anthraquinone compound in oxidation. An overview of the anthraquinone process is given in "Ullmann's Encyclopedia of Industrial Chemistry", 5th edition, volume 13, pages 447-456. Alternatively, hydrogen peroxide can be obtained by anodic oxidation of sulfuric acid with simultaneous evolution of hydrogen at the cathode to produce peroxodisulfuric acid. Hydrolysis of peroxodisulfuric acid forms first peroxosulfuric acid and then hydrogen peroxide and sulfuric acid, which is thus recovered. In a further alternative, hydrogen peroxide can be obtained directly from the elements hydrogen and oxygen.

Preferably, hydrogen peroxide is used in the feed stream according to (a1).

Organic solvent

The organic solvents to be used in (a1) are in principle all solvents known for this purpose. Preference is given to organic solvents such as alcohols, nitriles and mixtures thereof, optionally also water. Preferably, the organic solvent is selected from the group consisting of methanol and acetonitrile. Most preferably, the organic solvent is acetonitrile.

Feed flow according to (a1)

Generally, the feed stream according to (a1) can be prepared according to any conceivable method. Thus, the feed stream in (a1) can be prepared by mixing a stream comprising the propene, a stream comprising the hydrogen peroxide or the hydrogen peroxide source, and a stream comprising the organic solvent, which comprises a sequential mixing, that is, mixing a stream comprising the propene with a stream comprising the organic solvent and mixing the resulting stream with a stream comprising the hydrogen peroxide or the hydrogen peroxide source.

Generally, the feed stream according to (a1) is not restricted with respect to the molar ratio of propene and hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the hydrogen peroxide source. Preferably, the propene is present in a molar excess in the feed stream according to (a1) with respect to the hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the hydrogen peroxide source. Preferably, the molar ratio of propene and hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the source of hydrogen peroxide in the feed stream according to (a1) is 1 to 1.6, more preferably 1.1 to 1.55, more preferably 1.2 to 1.5, more preferably 1.40 to 1.45.

Generally, the feed stream according to (a1) comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent is not restricted with respect to the other components comprised by the feed stream. Thus, the feed stream according to (a1) may further comprise at least one additional component, for example at least one salt comprising potassium.

Salt containing potassium

With regard to the chemical nature of the at least one potassium salt, there are no specific restrictions. Preferably, the at least one potassium salt is selected from the group consisting of at least one inorganic potassium salt, at least one organic potassium salt, and combinations of at least one inorganic potassium salt and at least one organic potassium salt.

Preferred potassium-comprising inorganic salts include, but are not limited to, potassium halides such as potassium chloride or potassium bromide, potassium nitrate, potassium sulfate, hydrogenated potassium sulfate, potassium hydroxide, potassium perchlorate. potassium, phosphorous-comprising potassium salts such as dihydrogen potassium phosphate or hydrogenated dipotassium phosphate or potassium phosphate or potassium pyrophosphates such as monobasic potassium pyrophosphate or dibasic potassium pyrophosphate or tribasic potassium pyrophosphate or potassium tetraphosphate, or potassium tetraphosphate potassium etidronate such as monobasic potassium etidronate or dibasic potassium etidronate, tribasic potassium etidronate or tetrabasic potassium etidronate, potassium cyanate, potassium oxides such as potassium oxide (K ² O) or potassium superoxide (KO ² ) or potassium peroxide (K ² O ² ).

Preferred potassium-comprising organic salts include, but are not limited to, potassium carbonate (K ² CO ³ ), potassium hydrogenated carbonate, potassium salts of saturated aliphatic carboxylic acids such as monocarboxylic acids preferably having 1 to 6, more preferably 1 to 5, more preferably 1 to 4, more preferably 1 to 3 carbon atoms such as formic acid, acetic acid, propionic acid, dicarboxylic acids preferably having 2 to 6, more preferably of 2 to 4 carbon atoms such as oxalic acid, malonic acid, succinic acid, tartaric acid, tricarboxylic acids, preferably 6 to 10 carbon atoms such as citric acid or isocytric acid or propane-1,2,3-tricarboxylic acid, or tetracarboxylic acids. Preferably, the organic potassium salt is selected from the group consisting of potassium salts of saturated aliphatic monocarboxylic acids, preferably having 1, 2, 3, 4, 5 or 6 carbon atoms, potassium carbonate and potassium hydrogen carbonate. More preferably, the organic potassium salt is selected from the group consisting of potassium formate, potassium acetate, potassium propionate, potassium carbonate, and potassium hydrogen carbonate. More preferably, the organic potassium salt is selected from the group consisting of potassium formate, potassium acetate, potassium carbonate, and potassium hydrogen carbonate.

Therefore, the salt comprising potassium is preferably selected from the group consisting of at least one inorganic potassium salt selected from the group consisting of potassium hydroxide, potassium halides, potassium nitrate, potassium sulfate, potassium hydrogenated sulfate. , potassium perchlorate, potassium dihydrogen phosphate or dipotassium. hydrogenated dipotassium phosphate or potassium phosphate or potassium pyrophosphates such as monobasic potassium pyrophosphate or dibasic potassium pyrophosphate or tribasic potassium pyrophosphate or tetrabasic potassium pyrophosphate, or potassium etidronates such as potassium dibasic or potassium etidronate monobasic etidronate Tribasic potassium etidronate or tetrabasic potassium etidronate, at least one selected organic potassium salt from the group consisting of potassium salts of saturated aliphatic monocarboxylic acids preferably having 1, 2, 3, 4, 5 or 6 carbon atoms, potassium carbonate and potassium hydrogen carbonate, and a combination of at least one of the al least one of the inorganic potassium salts and at least one of the at least one of the organic potassium salts.

More preferably, the salt comprising potassium is selected from the group consisting of at least one inorganic potassium salt selected from the group consisting of dihydrogen potassium phosphate or hydrogenated dipotassium phosphate or potassium phosphate, potassium hydroxide, potassium halides, nitrate potassium, potassium sulfate, potassium hydrogenated phosphate, potassium perchlorate, at least one organic potassium salt selected from the group consisting of potassium formate, potassium acetate, potassium propionate, potassium carbonate and potassium hydrogen carbonate, and a combination of at least one of the at least one of the inorganic potassium salts and at least one of the at least one organic potassium salts.

Especially preferably the salt comprising potassium is dihydrogen potassium phosphate, hydrogenated dipotassium phosphate or potassium formate. Therefore, if a single potassium salt is used, the salt comprising potassium is most preferably dihydrogen potassium phosphate, hydrogenated dipotassium phosphate or potassium formate. If two or more salts comprising potassium are employed, a potassium salt is dihydrogen potassium phosphate, hydrogenated dipotassium phosphate or potassium formate.

Regarding the concentration of the salt comprising potassium in the feed stream, there are no specific restrictions. Preferably, the concentration of the potassium-comprising salt in the feed stream is at least 10%, preferably in the range of 10 to 100%, preferably 20 to 100%, more preferably 30 to 100%, more preferably of 40 to 100%. % of the solubility limit of the salt comprising potassium in the feed stream. The term "solubility limit of the at least one potassium salt in the liquid feed stream", as used in the context of the present invention, refers to the saturation concentration of the salt comprising potassium in the liquid stream. feed, where adding more salt comprising potassium does not increase the concentration of the salt comprising potassium as solute in the mixture and the salt comprising potassium would begin to precipitate. The solubility limit of the potassium-containing salt in the feed stream will depend on the composition of the mixture and conditions such as temperature and pressure at which the feed stream is provided. Determining the solubility limit of the salt comprising potassium in the mixture is an easy and straightforward task for those skilled in the art who are familiar with said conditions and said composition of a given mixture. A simple procedure to evaluate whether the amount of salt comprising potassium added is above the solubility limit is to pass the feed stream before subjecting it to the epoxidation conditions in (a2) through a filter and measure the drop. pressure through the filter. If the pressure drop across the filter increases with time in the stream and the potassium-containing salt is in the filter when it is switched off, the amount of potassium-containing salt that is added is already above the solubility limit.

Preferably in (a1), the molar ratio of potassium comprised in the salt comprising potassium to hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the source of hydrogen peroxide comprised in the feed stream is in the range of 10x10-6: 1 to 1500x10-6: 1, preferably 20x10-6: 1 to 1300x10-6: 1, more preferably 30x10-6: 1 to 1000x10-6: 1. The molar amount of potassium comprised in the potassium-comprising salt refers to the total molar amount of potassium comprised in all the potassium-comprising salts employed in (a1), if two or more potassium-comprising salts are employed.

More preferably in (a1), the molar ratio of potassium to hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the source of hydrogen peroxide in the feed stream is in the range of 10x10-6: 1 to 5000x10 -6: 1, preferably 15x10-6: 1 to 2500x10-6: 1, more preferably 20x10-6: 1 to 1500x10-6: 1, more preferably 25x10-6: 1 to 1300x10-6: 1, more preferably 30x10-6: 1 to 1000x10-6: 1.

Preferably, the feed stream according to (a1) is free of dihydrogen ammonium phosphate. More preferably, the feed stream according to (a1) is free of ammonium phosphate, hydrogenated ammonium phosphate and dihydrogen ammonium phosphate. More preferably, the feed stream according to (a1) is free of ammonium carbonate, ammonium hydrogenated carbonate, ammonium dihydrogen phosphate, ammonium hydrogenated phosphate, ammonium phosphate, ammonium hydrogenated pyrophosphate, ammonium pyrophosphate, ammonium chloride, ammonium nitrate and ammonium acetate. More preferably, the feed stream according to (a1) is free of ammonium salt. The term "free from", as used in this context, refers to a concentration of a respective compound of at most 2 ppm by weight, preferably at most 1 ppm by weight, based on the total weight of the feed stream.

Preferably, the feed stream according to (a1) contains sodium in a molar ratio of sodium to hydrogen peroxide or an equivalent of hydrogen peroxide resulting from the hydrogen peroxide source in the range of 1x10-6: 1 to 250x10 -6: 1, preferably 5x10-6: 1 to 50x10-6: 1. Preferably, the mixture, preferably the feed stream according to (a1) does not comprise dissolved sodium dihydrogen phosphate (NaH2PO4), more preferably neither dissolved sodium dihydrogen phosphate nor dissolved disodium hydrogenated phosphate (Na2HPO4), more preferably nor sodium dihydrogen phosphate dissolved neither dissolved disodium hydrogen phosphate nor dissolved sodium phosphate (Na3PO4).

In case the feed stream according to (a1) further comprises at least one salt comprising potassium, the liquid feed stream is preferably prepared by combining at least four individual streams. Preferably, an aqueous stream comprising at least one dissolved salt comprising potassium is combined with the stream comprising propene, or with the stream comprising hydrogen peroxide or the source of hydrogen peroxide, or with the stream comprising the organic solvent, or with a mixed stream of two or three of these streams, preferably with the stream comprising the hydrogen peroxide or the hydrogen peroxide source, or with the stream comprising the organic solvent, or with a mixed stream of the same.

The propene-comprising stream may further comprise propane, wherein preferably at least 98% by weight, more preferably at least 99% by weight, more preferably at least 99.5% by weight, more preferably at least 99.9% by weight of the stream consists in propene and propane. Preferably, the weight ratio of propene to propane in the stream is at least 7: 3. For example, commercially available propene can be employed which can be a polymer grade propene or a chemical grade propene. Typically, polymer grade propene has a propene content in the range of 99 to 99.8% by weight and a propane content in the range of 0.2 to 1% by weight. Chemical grade propene typically has a propene content in the range of 92 to 98% by weight and a propane content in the range of 2 to 8% by weight. Preferably, a stream is employed which has a propene content in the range of 99 to 99.8% by weight and a propane content in the range of 0.2 to 1% by weight.

The stream comprising hydrogen peroxide or the source of hydrogen peroxide can be prepared according to all conceivable methods. It is conceivable to obtain the stream comprising hydrogen peroxide by converting sulfuric acid to peroxodisulfuric acid by anodic oxidation with simultaneous evolution of hydrogen at the cathode. The hydrolysis of the peroxodisulfuric acid then leads through the peroxomonosulfuric acid to hydrogen peroxide and sulfuric acid, which is obtained again. The preparation of hydrogen peroxide from the elements is also conceivable. Depending on the specific preparation process, the stream comprising hydrogen peroxide may be, for example, an aqueous stream or an aqueous / methanolic stream of hydrogen peroxide, preferably an aqueous stream of hydrogen peroxide. In case an aqueous hydrogen peroxide feed is employed, the content of the stream with respect to hydrogen peroxide is usually in the range of 3 to 85% by weight, preferably 25 to 75% by weight, more preferably of 30 to 50% by weight, such as 30 to 40% by weight or 35 to 45% by weight or 40 to 50% by weight. Preferably, at least 25% by weight, more preferably at least 30% by weight, more preferably at least 35% by weight of the stream comprising hydrogen peroxide consists of water and hydrogen peroxide. Preferred ranges are 30 to 80% by weight or 35 to 75% by weight or 40 to 70% by weight.

To provide sufficient stability of the hydrogen peroxide during extraction with water, preferably essentially pure water, usually suitable stabilizing agents are added to the water, preferably essentially the pure water used. In particular, strong inorganic acids and / or chelating agents should be mentioned. According to preferred extraction procedures, small amounts of nitrates and / or phosphates and pyrophosphates, respectively, are added as stabilizing agents, either as acids or as sodium salts. These stabilizing agents are normally added in amounts such that the crude hydrogen peroxide aqueous solution contains from 50 to 400 ppm by weight of sodium cations, from 100 to 700 ppm by weight of phosphorus calculated as phosphate (PO ⁴ 3-), and from 50 to 400 ppm by weight of nitrate anions, calculated in each case with respect to the hydrogen peroxide contained in the crude aqueous hydrogen peroxide solution. Preferred ranges are, for example, 50 to 200 ppm by weight or 50 to 100 ppm by weight of sodium cations, 100 to 500 ppm by weight or 100 to 300 ppm by weight of phosphorus and 50 to 200 ppm by weight or 50 to 100 ppm by weight of nitrate. Furthermore, it is conceivable that other stabilizing agents such as stannites such as sodium stannite (Na ² SnO ² ) and / or organic phosphonic acids are used, in particular organic diphosphonic acids such as etidronic acid. Preferably, the aqueous hydrogen peroxide stream comprises sodium with a molar ratio of sodium to hydrogen peroxide in the range of 1x10-6: 1 to 250x10-6: 1, more preferably 5x10-6: 1 to 50x10 -6: 1.

Generally, the molar ratio of water to organic solvent in the feed stream provided in (a1) is not subject to any specific restriction. Preferably, in particular in case the organic solvent is acetonitrile, the molar ratio of water to organic solvent is at most 1: 4, more preferably in the range of 1:50 to 1: 4, preferably 1:15 at 1: 4.1, more preferably 1:10 to 1: 4.2.

Catalyst according to (a1)

Generally, a zeolite containing titanium used as a catalytically active material could have a type of zeolitic framework structure according to the following three letter codes: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, CDO, CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU, LEV, LIO, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MMFI, MFS, MON, MOR, MSO, MTF, MTN, MTT, MTW, MWW, NAB, NAT, NEES, NON, NPO, OBW, OFF, OSI, OSO, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN SFO, SGT, SOD, SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET , VFI, VNI, VSV, WEI, WEN, YUG, ZON or a mixed structure of two or more of these framework structures. With regard to three letter codes and their definitions, reference is made to the "Atlas of Zeolite Framework Types", 5th edition, Elsevier, London, England (2001).

According to the present invention, the titanium-containing zeolite used as catalytically active material is of MWW-type framework structure. Preferably, the titanium-containing zeolite is a "TiMWW".

Preferably, in particular in case the titanium-containing zeolite is TiMWW, the titanium-containing zeolite comprises one or more of Al, B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn, Pb, Pd, Pt, Au, Cd, preferably one or more of B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni , Zn, Ga, Ge, In, Sn, Pb, Pd, Pt, Au, Cd, more preferably Zn.

The term "MWW framework titanium zeolite", as used in the context of the present invention, also referred to as "TiMWW", refers to a MWW framework zeolite containing titanium as an isomorphic substitution element in the framework. zeolitic. Preferably, the zeolitic structure is essentially free of aluminum and consists essentially of silicon, titanium, and oxygen. Preferably at least 99% by weight, more preferably at least 99.5% by weight, more preferably at least 99.9% by weight of the zeolitic structure consists of silicon, titanium and oxygen. Optionally, the MWW framework structure titanium zeolite can comprise extra-structural titanium which is to be understood as all titanium species that are not part of the MWW zeolitic structure. The preparation of TiMWW catalysts is described, for example, in US 2007043226 A1, in particular in Examples 3 and 5 thereof.

The titanium content of the MWW frame structure titanium zeolite is not subject to specific restrictions. Preferably, the titanium zeolite of MWW type framework structure comprised in the catalyst in (a1) contains titanium, calculated as elemental titanium, in an amount in the range of 0.1 to 5% by weight, more preferably 0.2 to 4% by weight , more preferably 0.5 to 3% by weight, more preferably 1 to 2% by weight, based on the total weight of the MWW frame structure titanium zeolite. Therefore, the present invention relates to the process described above, in which the titanium zeolite of MWW type framework structure comprised in the catalyst in (a1) contains titanium, calculated as elemental titanium, in an amount in the range of 0.1 to 5% by weight, preferably 1 to 2% by weight, of silicon, based on the total weight of the MWW type framework titanium zeolite.

In addition to titanium, the MWW-type framework titanium zeolite may comprise at least one additional element other than titanium, silicon, and oxygen. In general, it is conceivable that this at least one additional element is an isomorphic replacement element that forms part of the MWW zeolitic framework structure. Preferably, this at least one additional element is not an isomorphic replacement element. Such an additional element which is not an isomorphic substitution element can be applied to the zeolite by, for example, a spray process, a wet impregnation process such as a damp process or any other suitable process. Preferably, the at least one additional element is selected from the group consisting of Al, B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Ga, Ge, In, Sn , Pb, Pd, Pt, Au, Cd and a combination of two or more, preferably from the group consisting of B, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, Ga , Ge, In, Sn, Pb, Pd, Pt, Au, Cd combination of two or more. More preferably, the MWW frame structure titanium zeolite contains zinc as an additional element in addition to titanium, silicon and oxygen. More preferably, the MWW type framework titanium zeolite contains zinc as the only additional element in addition to titanium, silicon and oxygen. More preferably, the titanium zeolite of MWW type framework structure contains zinc as the only additional element in addition to titanium, silicon and oxygen where at least 99% by weight, more preferably at least 99.5% by weight, more preferably at least 99.9% by Weight of the zeolitic framework structure consist of silicon, titanium and oxygen. More preferably, in case the MWW type framework titanium zeolite contains zinc as the only additional element, at least 99% by weight, more preferably at least 99.5% by weight, more preferably at least 99.9% by weight of the zeolite MWW-type frame structure titanium consists of zinc, titanium, silicon and oxygen; This MWW frame structure titanium zeolite containing zinc as the only additional element is also called "ZnTiMWW".

ZnTiMWW Catalyst

The zinc content of the MWW framework structure titanium zeolite is not subject to specific restrictions. Preferably, the m Ww framework structure titanium zeolite comprised in the catalyst in (a1) contains zinc, calculated as elemental zinc, in an amount in the range of 0.1 to 5% by weight, more preferably 0.2 to 4% by weight. weight, more preferably 0.5 to 3% by weight, more preferably 1 to 2% by weight, based on the total weight of the MWW frame structure titanium zeolite. Therefore, the present invention relates to the process described above, in which the titanium zeolite of MWW framework structure comprised in the catalyst in (a1) contains zinc, calculated as elemental zinc, in an amount in the range of 0.1 to 5% by weight, preferably 1 to 2% by weight, based on the total weight of the MWW frame structure titanium zeolite.

Therefore, it is preferred that the titanium-containing zeolite which is comprised in the catalyst in (a1) and has a MWW framework structure, comprises zinc and contains titanium, calculated as elemental titanium, in an amount in the range of 0.1 to 5% by weight, preferably 1 to 2% by weight, based on the total weight of the zeolite containing titanium, and containing zinc, calculated as elemental zinc, in an amount in the range of 0.1 to 5% by weight, preferably 1 to 2% by weight, based on the total weight of the titanium-containing zeolite.

The catalyst according to (a1), which comprises the MWW type framework titanium zeolite, may consist of the MWW type framework titanium zeolite, preferably consist of TiMWW or ZnTiMWW as described. In such cases, the catalyst may be the MWW type framework titanium zeolite in the form of a zeolitic powder which can be molded, for example, as a granulate, a microsphere such as a microsphere obtained by spray drying or by spray granulation, a molded body having, for example, the shape of a pellet, a tablet, a cylinder, a wheel, a star or a sphere.

Preferably, the catalyst according to (a1), which comprises the titanium zeolite of the MWW type framework structure, preferably the TiMWW or the ZnTiMWW, is prepared as a molding comprising the titanium zeolite of the MWW type framework structure, preferably the TiMWW or ZnTiMWW, by suitably mixing the MWW-type framework titanium zeolite with at least one binder and / or with at least one binder precursor, and optionally at least one pore-forming agent and / or at least one plasticizer. The molded parts can be shaped into all conceivable geometries, such as strands, for example, with rectangular, triangular, hexagonal, quadratic, oval or circular cross section, stars, tablets, spheres, hollow cylinders and the like. Examples of such binders are metal oxides, such as, for example, SiO ² , AhO3, TiO ² , ZrO ² or MgO or clays or mixtures of two or more of these oxides or mixed oxides of at least two of Si, Al, Ti , Zr, and Mg, and SiO ² is preferred. Pore-forming agents such as meso-pore-forming agents include polymeric vinyl compounds, such as polyalkylene oxides such as polyethylene oxides, polystyrene, polyacrylates, polymethacrylates, polyolefins, polyamides, and polyesters. Adhesion agents include organic polymers, particularly hydrophilic, such as carbohydrates such as cellulose, cellulose derivatives, such as methylcellulose, and starch, such as potato starch, wallpaper plaster, polyacrylates, polymethacrylates, polyvinyl alcohol, polyvinylpyrrolidone, polyisobutene, or polytetrahydrofuran. The use of water, alcohols or glycols or mixtures thereof, such as mixtures of water and alcohol, or water and glycol, such as water and methanol, or water and ethanol, or water and propanol, or water and propylene glycol, can be Mention as gluing agents. Preferably, the catalyst according to (a1) is used as a molding having the form of an extrudate, preferably an extrudate having a length preferably 1 to 10 mm, more preferably 1 to 7 mm, more preferably 1 to 5 mm, and a diameter preferably 0.1 to 5 mm, more preferably 0.2 to 4 mm, more preferably 0.5 to 2 mm. In particular, as regards the preferred catalyst according to (a1) comprising the ZnTiMWW, it is preferred to employ this catalyst in the form of a micropowder or in the form of a molded part, wherein the molded part preferably contains said micropowder.

Said catalyst according to (a1) in the form of a micropowder, comprising ZnTiMWW, is preferably characterized by the following characteristics and, including combinations of embodiments according to the given dependencies:

One embodiment (1) refers to a micropowder, the particles of which have a Dv10 value of at least 2 microns, and said micropowder comprises mesopores having an average pore diameter (4V / A) in the range of 2 to 50 nm. determined by Hg porosimetry according to DIN 66133, and comprising, based on the weight of the micropowder, at least 95% by weight of an aluminum-free microporous zeolitic material of MWW type structure containing titanium and zinc (ZnTiMWW). It is understood that the Dv10 value is determined according to Reference Example 8 of WO 2013/117536.

A preferred embodiment (2) of realization of embodiment (1) refers to said micropowder having a DV10 value in the range of 2 to 5.5 microns, preferably 3 to 5.5 microns.

A preferred embodiment (3) of concretization of embodiment (1) or (2) refers to said micropowder having a Dv50 value in the range of 7 to 25 microns and optionally a Dv90 value in the range of 26 at 85 microns. It is understood that the Dv50 and Dv90 values are determined according to Reference Example 8 of WO 2013/117536.

A preferred embodiment (4) that specifies any of the embodiments (1) to (3) refers to said micropowder, wherein the mesopores have an average pore diameter (4V / A) in the range of 10 to 50 nm, preferably 15 to 40 nm, more preferably 20 to 30 nm, determined by Hg porosimetry according to DIN 66133.

A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said micropowder further comprising macropores having an average pore diameter (4V / A) in the range of more than 50 nm, and said macropores preferably have an average pore diameter in the range of 0.05 to 3 microns, determined by Hg porosimetry according to DIN 66133.

A preferred embodiment (6) that specifies any of the embodiments (1) to (5) refers to said micropowder, wherein the micropores of the ZnTiMWW have an average pore diameter in the range of 1.0 to 1.2 nanometers. determined by nitrogen adsorption according to DIN 66135.

A preferred embodiment (7) that specifies any of the embodiments (1) to (6) refers to said micropowder comprising, based on the weight of the micropowder, at least 99% by weight, preferably at least 99.7% by weight of the ZnTiMWW.

A preferred embodiment (8) that specifies any of the embodiments (1) to (7) refers to said micropowder, wherein the ZnTiMWW contains zinc in an amount of 1.0 to 2.0% by weight, preferably 1.2 to 1.9% by weight, calculated as Zn and based on the weight of the ZnTiMWW.

A preferred embodiment (9) that specifies any of the embodiments (1) to (8) refers to said micropowder, wherein the ZnTiMWW contains titanium in an amount of 1.0 to 2.0% by weight, preferably 1.2 to 1.8% by weight, calculated as Ti and based on the weight of the ZnTiMWW.

A preferred embodiment (10) that specifies any of the embodiments (1) to (9) refers to said micropowder having, as determined by X-ray diffraction analysis (XRD), of at least (80 / - 10)%, preferably at least (85 / - 10)%. It is understood that crystallinity is determined according to Reference Example 10 of WO 2013/117536.

A preferred embodiment (11) that specifies any of the embodiments (1) to (10) refers to said micropowder comprising, based on the total weight of the micropowder and calculated as an element, less than 0.001% by weight, preferably less than 0.0001% by weight of a noble metal, preferably selected from the group consisting of gold, silver, platinum, palladium, iridium, ruthenium, osmium and a mixture of two or more thereof, more preferably selected from the group consisting in gold, platinum, gold, and a mixture of two or more of them.

A preferred embodiment (12) that specifies any of the embodiments (1) to (11) refers to said micropowder comprising, based on the total weight of the micropowder and calculated as an element, less than 0.1% by weight, preferably less than 0.01% by weight of boron.

A preferred embodiment (13) embodying any of the embodiments (1) to (12) refers to said micropowder having a bulk density in the range of 80 to 100 g / ml.

A preferred embodiment (14) that embodies any of the embodiments (1) to (13) refers to said micropowder which is a spray powder, preferably obtainable or obtained by spray drying.

Furthermore, said catalyst according to (a1) in the form of a molded part, comprising ZnTiMWW, is preferably characterized by the following characteristics and embodiments, including combinations according to the given dependencies:

An embodiment (1) refers to said molded part comprising a microporous zeolitic material without aluminum of MWW type structure containing titanium and zinc (ZnTiMWW), and said molded part preferably comprises a micropowder comprising, based on the weight of the micropowder, at least 95% by weight of an aluminum-free microporous zeolitic material of MWW type structure containing titanium and zinc (ZnTiMWW), and said molding more preferably comprises the micropowder according to any of the micropowder embodiments from 1 to 14 as described above, and the molding preferably further comprises at least one binder, preferably a silica binder.

A preferred embodiment (2) that specifies embodiment (1) refers to said molding comprising mesopores having an average pore diameter in the range of 4 to 40 nm, preferably 20 to 30 nm determined by Hg porosimetry according to DIN 66133.

3. The molding of embodiment 1 or 2, having a crystallinity, determined by XRD analysis, of at least (55 / - 10)%, preferably in the range of ((55 to 75) / - 10) %. It is understood that crystallinity is determined according to Reference Example 10 of WO 2013/117536.

A preferred embodiment (4) to realize any of the embodiments (1) to (3) refers to said molding comprising the micro-powder in an amount in the range of 70 to 80% by weight and the binder of silica in an amount of 30 to 20% by weight, the micropowder together with the silica binder constituting at least 99% by weight of the molded part, wherein the molded part has a concentration of silanol groups with respect to the number Total Si atoms of at most 6%, preferably at most 3%, as determined according to 29Si MAS NMR. It is understood that the concentration of the silanol groups is determined according to Reference Example 3 of WO 2013/117536.

A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said molded part which is a strand having a circular cross section and a diameter in the range of 1.5 to 1.7 mm. and having a crush strength of at least 5 N, preferably in the range of 5 to 20 N, more preferably in the range of 12 to 20 N, the crush strength is determined by the Z2 crush strength testing machine .5 / TS1S according to the procedure described in Reference Example 2 of WO 2013/117536.

A preferred embodiment (6) that specifies any of the embodiments (1) to (5) refers to said molded part, the 29Si-NMR spectrum of said molded part comprises six peaks in the following peak position 1 to -98 / - x ppm,

peak 2 at -104 / - x ppm,

peak 3 at -110 / - x ppm,

peak 4 at -113 / - x ppm,

peak 5 at -115 / - x ppm,

peak 6 at -118 / - x ppm,

and x at either peak is 1.5, preferably 1.0, more preferably 0.5,

where Q is defined as

Q = 100 * {[a1 a2] / [a4 a5 a6]} / a3

is at most 2.5, preferably at most 1.6, preferably at most 1.4, and [a ¹ + a ² ] is the sum of the peak areas of peaks 1 and 2, and [a4 a5 a6] is the sum of the areas peak of peaks 4, 5 and 6, and a3 is the peak area of peak 3. It is understood that these 29Si-NMR characteristics are determined according to Reference Example 4 of WO 2013/117536.

A preferred embodiment (7) that embodies any of the embodiments (1) to (6) refers to said molded part having a water absorption in the range of 3 to 8% by weight, preferably 4 to 7% by weight. It is understood that the water absorption is determined according to Reference Example 6 of WO 2013/117536.

A preferred embodiment (8) embodying any of the embodiments (1) to (7) refers to said molded part, and the infrared spectrum of said molded part comprises a band in the region of (3700 3750) / - 20 cm_1 and a band in the region of (3670 - 3690) / - 20 cm_1, where the intensity ratio of the band in the region of (3700-3750) / - 20 cm_1 with respect to the band in the region of (3670 - 3690) / - 20 cm_1 is at most 1.5, preferably at most 1.4. These IR characteristics are understood to be determined according to Reference Example 5 of WO 2013/117536.

Furthermore, a preferred process for the preparation of said catalyst according to (a1) in the form of a micropowder and / or molding, which comprises the ZnTiMWW, is characterized by the following characteristics and embodiments, which include the combinations of embodiments according to the given dependencies:

An embodiment (1) refers to said process comprising

(a) providing a suspension containing an aluminum-free microporous zeolitic material of MWW type structure containing titanium and zinc (ZnTiMWW);

(b) subjecting the suspension provided in (a) to spray drying to obtain a micropowder;

(c) optionally calcining the micropowder obtained in (b), wherein the micropowder obtained in (b) or (c), preferably in (c), is preferably the micropowder according to any of said micropowder embodiments 1 to 14 as described above.

A preferred embodiment (2) that specifies embodiment (1) refers to said process, wherein the suspension provided in (a) has a solids content in the range of 5 to 25% by weight, preferably of 10 to 20% by weight, and the suspension is preferably an aqueous suspension.

A preferred embodiment (3) that specifies embodiment (1) or (2) refers to said process, wherein the ZnTiMWW according to (a) contains zinc in an amount of 1.0 to 2.0% by weight, preferably of 1.2 to 1.9% by weight, calculated as Zn, and titanium in an amount of 1.0 to 2.0% by weight, preferably 1.2 to 1.8% by weight, calculated as Ti and based on the weight of ZnTiMWW.

A preferred embodiment (4) that specifies any of the embodiments (1) to (3) refers to said process, wherein in (b) a spray apparatus is used, preferably a spray tower to dry by spraying the suspension, and said apparatus has at least one spray nozzle, preferably at least one two-component nozzle, and said nozzle has a diameter in the range of 3.5 to 4.5 mm.

A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said process, wherein in (b) a spraying apparatus is used, preferably a spraying tower for spray drying the suspension, and said apparatus operates with a nozzle gas having a temperature in the range of 20 to 50 ° C, preferably 20 to 30 ° C, and a drying gas having a temperature in the range 250 to 350 ° C, preferably 275 to 325 ° C, and said nozzle gas is preferably an inert gas, more preferably technical nitrogen, and said drying gas is preferably an inert gas, more preferably technical nitrogen.

A preferred embodiment (6) that specifies any of the embodiments (1) to (5) refers to said process, wherein in (c) the micropowder is calcined at a temperature in the range of 600 to 700 ° C for a duration in the range of 0.5 to 6 h.

A preferred embodiment (7) that specifies any of the embodiments (1) to (6) refers to said process that further comprises

(d) shaping the micropowder obtained in (b) or (c) to obtain a molded part;

(e) optionally drying and / or calcining the molding obtained in (d).

A preferred embodiment (8) that specifies embodiment (7) refers to said process, wherein the molding according to (d) comprises

(aa) mixing the micropowder with a binder or a binder precursor, preferably a silica binder or a silica binder precursor, wherein the weight ratio of the ZnTiMWW contained in the micropowder to the silica contained in or resulting of the silica binder is in the range of 3: 7 to 1: 4, to obtain a mixture;

(bb) molding the mixture obtained in (aa) to obtain the molding, and said molding preferably comprises subjecting the mixture obtained in (aa) to extrusion from which strands are preferably obtained having a diameter preferably in the range of 1.0 to 2.0 mm, more preferably 1.5 to 1.7 mm.

A preferred embodiment (9) that specifies embodiment (8) refers to said process, wherein in (aa), a carbohydrate and / or water is added as adhesion agent.

A preferred embodiment (10) that specifies embodiment (8) or (9) refers to said procedure, wherein the mixing in (aa) is carried out for a time in the range of 15 to 60 min. , preferably 30 to 55 min, more preferably 40 to 50 min.

A preferred embodiment (11) that specifies any of the embodiments (7) to (10) refers to said process, wherein in (d), no mesopore-forming agent selected from the group consisting of polyalkylene oxides such as polyethylene oxides, polystyrene, polyacrylates, polymethacrylates, polyolefins, polyamides and polyesters are added.

A preferred embodiment (12) that specifies any of the embodiments (7) to (11) refers to said process, wherein in (e) the molding is dried at a temperature in the range of 100 to 150 ° C for a duration in the range of 10 to 20 h and calcine at a temperature in the range of 500 to 600 ° C for a time in the range of 0.5 to 2 h.

A preferred embodiment (13) that specifies any of the embodiments (7) to (12) refers to said process that further comprises

(f) subjecting the molding obtained in (d) or (e), preferably in (e), to a treatment with water;

(g) optionally drying and / or calcining the molding treated with water, wherein the molding obtained in (f) or (g), preferably in (g), is preferably the molding according to any of said embodiments of molded parts 1 to 8 as described above.

A preferred embodiment (14) that specifies embodiment (13) refers to said process, wherein in (f), the water treatment comprises treating the molded part with liquid water in an autoclave under autogenous pressure at a temperature in the range of 100 to 200 ° C, preferably 125 to 175 ° C, more preferably 140 to 150 ° C for a period of 2 to 24 hours, preferably 6 to 10 h.

A preferred embodiment (15) that specifies embodiment (13) or (14) refers to said process, wherein in (f) the weight ratio of the molded part with respect to water is in the range of 0.02 to 0.08, preferably 0.03 to 0.07, more preferably 0.04 to 0.06.

A preferred embodiment (16) that specifies any of the embodiments (13) to (15) refers to said process, wherein in (g) the molding treated with water is dried at a temperature in the range of 100 to 150 ° C for a time in the range of 10 to 20 h and calcined at a temperature in the range of 400 to 500 ° C for a time in the range of 1 to 3 h.

A preferred embodiment (17) that specifies any of the embodiments (7) to (16) refers to said process, where the molded part is not subjected to vaporization.

Regarding said preferred process for the preparation of said catalyst according to (a1) in the form of a micropowder and / or molded part comprising the ZnTiMWW, described above by means of embodiments 1 to 17, the ZnTiMWW on the basis of which the suspension in embodiment 1. (a), can be prepared according to all conceivable procedures. For example, it is possible to prepare an aluminum-free microporous zeolitic material of MWW type structure containing titanium (TiMWW) and subject the TiMWW to a suitable treatment to obtain the ZnTiMWW. Furthermore, it is possible to prepare an aluminum-free zeolitic material of the MWW (MWW) type structure and subject the MWW to a suitable treatment to obtain the ZnTiMWW where, for example, both Zn and Ti are suitably incorporated into the MWW. Furthermore, it is conceivable to prepare aluminum-free zeolitic material of the MWW-type structure wherein, during the synthesis of the MWW-type structure, Ti is introduced and the resulting material is subjected to a suitable treatment to incorporate Zn, or Zn and the resulting material are introduced. it is subjected to a suitable treatment to incorporate Ti, or both Zn and Ti are introduced. As conceivable procedures for the preparation of TiMWW, the procedures described, for example, in US 6,114,551, or in Wu et al., "Hydrothermal Synthesis of a novel Titanosilicate with MWW Topology", Chemistry Letters (2000), pp. . 774-775. Preferably, an aluminum-free zeolitic material of MWW type structure containing Ti (TiMWW) is prepared in a first stage, and in a second stage the TiMWW is subjected to a suitable treatment to obtain the ZnTiMWW. More preferably, the ZnTiMWW is prepared according to a process comprising

(I) preparing an aluminum-free zeolitic material of MWW type structure containing boron (B-MWW);

(II) remove the boron from the B-MWW to obtain an aluminum-free zeolitic material of the MWW (MWW) type structure;

(III) incorporating titanium (Ti) into the MWW to obtain an aluminum-free zeolitic material of MWW type structure containing Ti (TiMWW);

(IV) preferably acid treat TiMWW;

(V) subjecting the TiMWW to zinc (Zn) impregnation to obtain the ZnTiMWW.

Preferably, in step (I), the B-MWW is prepared by a process whose preferred steps and conditions are defined by the following embodiments 1 to 28 and the respective dependencies as indicated:

An embodiment (1) refers to said process for preparing an aluminum-free boron-containing zeolitic material containing the MWW framework structure (B-MWW), comprising

(a) hydrothermally synthesize a B-MWW precursor from a synthesis mixture containing water, a silicon source, a boron source and a MWW template compound obtaining the B-MWW precursor in its mother liquors , and the mother liquors have a pH greater than 9;

(b) adjusting the pH of the mother liquor obtained in (a) and containing the B-MWW precursor to a value in the range of 6 to 9;

(c) separating the B-MWW precursor from the pH adjusted mother liquor obtained in (b) by filtration in a filtration device.

A preferred embodiment (2) that specifies embodiment (1) refers to said process wherein in (a) at least 95% by weight, preferably at least 99% by weight, more preferably at least the 99.9% by weight of the synthesis mixture consists of water, the silicon source, the boron source, and the template compound.

A preferred embodiment (3) that specifies embodiment (1) or (2) refers to said process, wherein in (a) the source of silicon is selected from the group consisting of fumed silica, colloidal silica and a mixture of them; the silicon source is preferably colloidal silica, more preferably ammonia stabilized silica, the boron source is selected from the group consisting of boric acid, borates, boron oxide, and a mixture of two or more thereof; the boron source is preferably boric acid and the MWW template compound is selected from the group consisting of piperidine, hexamethylene imine, N, N, N, N ', N', N'-hexamethyl-1,5-pentanediammonium ion, 1,4-bis (N-methylpyrrolidinium) butane, octyltrimethylammonium hydroxide, heptyltrimethylammonium hydroxide, hexyltrimethylammonium hydroxide, N, N, N-trimethyl-1-adamantyl-ammonium hydroxide, and a mixture of two or more thereof , and the MWW template compound is preferably piperidine.

A preferred embodiment (4) that specifies any of the embodiments (1) to (3) refers to said procedure, wherein in (a) the synthesis mixture contains the boron source calculated as elemental boron, with With respect to the source of silicon, calculated as elemental silicon, in a molar ratio in the range of 0.4: 1 to 2.0: 1, preferably 0.6: 1 to 1.9: 1, more preferably 0.9: 1 to 1.4: 1, the water relative to the silicon source, calculated as elemental silicon, in a molar ratio in the range of 1: 1 to 30: 1, preferably 3: 1 to 25: 1, more preferably 6: 1 to 20: 1 ; and the template compound with respect to the silicon source, calculated as Elemental silicon, in a molar ratio in the range of 0.4: 1 to 2.0: 1, preferably 0.6: 1 to 1.9: 1, more preferably 0.9: 1 to 1.4: 1. A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said process, wherein in (a), the hydrothermal synthesis is carried out at a temperature in the range of 160 to less than 180 ° C, preferably 170 to 175 ° C, for a period of time in the range of 1 to 72 hours, preferably 6 to 60 hours, more preferably 12 to 50 hours.

A preferred embodiment (6) that specifies any of the embodiments (1) to (5) refers to said process, wherein in (a), the hydrothermal synthesis is carried out at least partially with stirring.

A preferred embodiment (7) that specifies any of the embodiments (1) to (6) refers to said process, wherein in (a), the synthesis mixture additionally contains a seed material, preferably a material zeolitic comprising the MWW framework, more preferably a boron-containing zeolitic material comprising the MWW framework.

A preferred embodiment (8) that specifies the embodiment of embodiment (7) refers to said process, wherein the synthesis mixture contains the seed material, with respect to the silicon source, in a weight ratio in the range from 0.01: 1 to 1: 1, preferably from 0.02: 1 to 0.5: 1, more preferably from 0.03: 1 to 0.1: 1, calculated as the amount of seed material in kg with respect to the silicon content in the silicon source calculated as silicon dioxide in kg.

A preferred embodiment (9) that specifies any of the embodiments (1) to (8) refers to said process, wherein the pH of the mother liquor obtained in (a) is greater than 10, preferably in the range 10.5 to 12, more preferably 11 to 11.5.

A preferred embodiment (10) that specifies any of the embodiments (1) to (9) refers to said procedure, wherein in (b), the pH of the mother liquor obtained in (a) is adjusted to a Value in the range 6.5 to 8.5, preferably 7 to 8.

A preferred embodiment (11) that specifies any of the embodiments (1) to (10) refers to said procedure, wherein in (b), the pH is adjusted by a procedure comprising

(aa) adding an acid to the mother liquor obtained in (a) containing the precursor B-MWW, wherein the addition is preferably carried out at least partially with stirring.

A preferred embodiment (12) that specifies the embodiment of embodiment (11) refers to said process, wherein in (aa), the addition is carried out at a temperature in the range of 20 to 70 ° C, preferably 30 to 65 ° C, more preferably 40 to 60 ° C.

A preferred embodiment (13) that specifies the embodiment of embodiment (11) or (12) refers to said process, wherein in (aa), the acid is an inorganic acid, preferably an aqueous solution containing inorganic acid.

A preferred embodiment (14) that specifies the embodiment of embodiment (13) refers to said process, wherein the inorganic acid is selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, acid nitric and a mixture of two or more thereof, the inorganic acid is preferably nitric acid.

A preferred embodiment (15) embodying any of the embodiments (11) to (14) refers to said method, and the method further comprises

(bb) stir the mother liquor to which the acid was added according to (aa), wherein during (bb) no acid is added to the mother liquor.

A preferred embodiment (16) that specifies embodiment (15) refers to said process, wherein in (bb), the stirring is carried out at a temperature in the range of 20 to 70 ° C, preferably 25 to 65 ° C, more preferably 30 to 60 ° C.

A preferred embodiment (17) that specifies any of the embodiments (1) to (16) refers to said procedure, where in (b), the size of the particles contained in the mother liquor, expressed by the respective Dv10, Dv50 and Dv90 values, increases by at least 2%, preferably by at least 3%, more preferably by at least 4.5% with respect to Dv10, by at least 2%, preferably by at least 3% , more preferably by at least 4.5% with respect to Dv50, and by at least 5%, preferably by at least 6%, more preferably by at least 7% with respect to Dv90.

A preferred embodiment (18) that specifies any of the embodiments (1) to (17) refers to said process, wherein the pH-adjusted mother liquor obtained in (b) has a solids content in the range 1 to 10% by weight, preferably 4 to 9% by weight, more preferably 7 to 8% by weight, based on the total weight of the pH-adjusted mother liquor obtained in (b).

A preferred embodiment (19) that specifies any of the embodiments (1) to (18) refers to said process, wherein the pH-adjusted mother liquor obtained from (b) has a resistance to filtration in the range 10 to 50 mPa * s / m2, preferably 15 to 45 mPa * s / m2, more preferably 20 to 40 mPa * s / m2.

A preferred embodiment (20) that specifies any of the embodiments (1) to (19) refers to said process, which further comprises (d) washing the B-MWW precursor obtained from (c), preferably the filter cake obtained from (c), wherein the washing is preferably carried out using water as the washing agent.

A preferred embodiment (21) that specifies embodiment (20) refers to said process, where in (d), the filter cake obtained from (c) has a resistance to washing in the range of 10 to 50 mPa * s / m2, preferably 15 to 45 mPa * s / m2, more preferably 20 to 40 mPa * s / m2.

A preferred embodiment (22) that specifies the embodiment of embodiment (20) or (21) refers to said procedure, wherein the washing is carried out until the conductivity of the filtrate is at most 300 microSiemens / cm, preferably at most 250 microSiemens / cm, more preferably at most 200 microSiemens / cm.

A preferred embodiment (23) that specifies any of the embodiments (1) to (22) refers to said process that further comprises

(e) drying the WW precursor obtained from (c), preferably from (d), at a temperature in the range of 20 to 50 ° C, preferably 20 to 40 ° C, more preferably 20 to 30 ° C, wherein the drying is preferably carried out by subjecting the B-MWW to a gas stream, preferably a nitrogen stream.

A preferred embodiment (24) that specifies any of the embodiments (1) to (23) refers to said process, wherein the residual moisture of the B-MWW precursor obtained from (c), preferably from (d ), more preferably from (e), is in the range of 80 to 90% by weight, preferably 80 to 85% by weight. A preferred embodiment (25) that specifies any of the embodiments (1) to (24) refers to said process that further comprises

(f) preparing a suspension, preferably an aqueous suspension, containing the B-MWW precursor obtained from (c), preferably from (d), more preferably from (e), and having a solids content in the range of 10 to 20% by weight, preferably 12 to 18% by weight, more preferably 14 to 16% by weight;

(g) spray drying the suspension obtained from (f) containing the B-MWW precursor, obtaining a spray powder;

(h) calcining the spray powder obtained from (g) containing the B-MWW precursor, preferably at a temperature in the range of 500 to 700 ° C, more preferably 550 to 650 ° C, more preferably 575 at 625 ° C for a period of time in the range of 1 to 24 h, preferably 2 to 18 h, more preferably 6 to 12 h, obtaining a spray powder of which at least 99% by weight, more preferably at least minus 99.5% by weight of the B-MWW.

A preferred embodiment (26) that specifies embodiment (25) refers to said process, wherein in (h), the calcination is carried out continuously, preferably in a rotary calciner, preferably with a yield in the range of 0.5 to 20 kg of spray powder per hour.

A preferred embodiment (27) that specifies the embodiment of embodiment (25) or (26) refers to said process, wherein the degree of crystallinity of the B-MWW contained in the spray powder n obtained from (h) is at least (75 ± 5)%, preferably at least (80 ± 5)%, as determined by XRD.

A preferred embodiment (28) that specifies any of the embodiments (25) to (27) refers to said procedure, wherein the BET specific surface area of the B-MWW contained in the spray powder obtained from ( h) is at least 300 m2 / g, preferably in the range of 300 to 500 m2 / g, as determined according to DIN 66131.

Preferably, step (II) is carried out by means of a process whose preferred steps and conditions are defined by the following embodiments 1 to 7 and the respective dependencies as indicated:

An embodiment (1) refers to said process for the preparation of a zeolitic material, comprising

(a) providing the boron-containing zeolitic material of MWW type structure (B-MWW) obtained according to step (I);

(b) removing the boron from the B-MWW by treating the B-MWW with a liquid solvent system thus obtaining a B-MWW (MWW) without boron;

wherein the liquid solvent system is selected from the group consisting of water, monohydric alcohols, polyhydric alcohols, and mixtures of two or more thereof, and wherein said liquid solvent system does not contain an organic or inorganic acid or a salt. thereof, and the acid is selected from the group of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid and tartaric acid.

A preferred embodiment (2) that specifies embodiment (1) refers to said process, wherein the liquid solvent system does not contain an organic or inorganic acid, or a salt thereof.

A preferred embodiment (3) that specifies the embodiment of embodiment (1) or (2) refers to said process, wherein the liquid solvent system is selected from the group consisting of water, methanol, ethanol, propanol, ethane-1,2-diol, propane-1,2-diol, propane-1,3-diol, propane-1,2,3-triol, and mixtures of two or more thereof, preferably water.

A preferred embodiment (4) that specifies any of the embodiments (1) to (3) refers to said process, wherein the treatment according to (b) is carried out at a temperature in the range of 50 to 125 ° C.

A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said procedure, wherein the treatment according to (b) is carried out for a time in the range of 6 to 20 h.

A preferred embodiment (6) that specifies any of the embodiments (1) to (5) refers to said procedure, wherein the treatment according to (b) is carried out in at least 2 separate steps, wherein between at least 2 treatment stages the MWW is dried, preferably at a temperature in the range of 100 to 150 ° C. A preferred embodiment (7) that specifies any of the embodiments (1) to (6) refers to said method, which further comprises

(c) subsequently treating the MWW obtained in (b) by a process comprising

(c.1) separating the MWW from the liquid solvent system;

(c.2) preferably drying the separated MWW, preferably by spray drying;

(c.3) optionally calcining the MWW obtained from (c.1) or (c.2), preferably at temperatures in the range of 500 to 700 ° C.

As regards step (III), a suitable starting mixture, preferably an aqueous mixture, containing the MWW and a precursor containing Ti, and preferably containing at least one agent, is subjected to hydrothermal crystallization under autogenous pressure. suitable micropore former. It may be conceivable to use at least one suitable planting material. As a suitable Ti-containing precursor, there may be mentioned by way of example tetraalkyl orthotitanates such as tetrabutyl orthotitanate. As a suitable micropore-forming agent there may be mentioned, by way of example, piperidine, hexamethyleneimine or mixtures of piperidine and hexamethyleneimine. Preferably, the crystallization time is in the range of 4 to 8 days, more preferably 4 to 6 days. During hydrothermal synthesis, the crystallization mixture can be agitated. The temperatures applied during crystallization are preferably in the range of 160 to 200 ° C, more preferably 160 to 180 ° C. After hydrothermal synthesis, the obtained TiMWW crystalline zeolitic material is preferably suitably separated from the mother liquor. All procedures for separating TiMWW from its mother liquor are conceivable. These processes include, for example, filtration, ultrafiltration, diafiltration and centrifugation processes or, for example, spray drying processes and spray granulation processes. A combination of two or more of these procedures can be applied. According to the present invention, TiMWW is preferably separated from its mother liquor by filtration to obtain a filter cake which is preferably washed, preferably with water. Subsequently, the filter cake, optionally further processed to obtain a suitable suspension, is subjected to spray drying or ultrafiltration. Before separating the TiMWW from its mother liquor, it is possible to increase the TiMWW content of the mother liquor by concentrating the suspension. If washing is applied, it is preferred to continue the washing procedure until the wash water has a conductivity of less than 1,000 microSiemens / cm, more preferably less than 900 microSiemens / cm, more preferably less than 800 microSiemens / cm, plus preferably less than 700 microSiemens / cm. After separation of the TiMWW from its mother liquor, preferably by filtration, and after washing, the washed filter cake containing the TiMWW is preferably subjected to pre-drying, for example by subjecting the filter cake to a gas stream. suitable, preferably a stream of nitrogen, for a time preferably in the range of 4 to 10 h, more preferably 5 to 8 h. Subsequently, the pre-dried filter cake is preferably dried at temperatures in the range of 100 to 300 ° C, more preferably 150 to 275 ° C, more preferably 200 to 250 ° C in a suitable atmosphere such as technical nitrogen, air or lean air, preferably in lean air or air. Said drying can be carried out, for example, by spray drying. After drying, the TiMWW can be calcined at temperatures in the range of 500 to 700 ° C, more preferably 550 to 675 ° C, more preferably 600 to 675 ° C in a suitable atmosphere such as technical nitrogen, air, or poor air. Preferably, a calcination according to (III) is not carried out.

Preferably, steps (III) and (IV) are carried out by a process whose preferred steps and conditions are defined by the following embodiments 1 to 27 and the respective dependencies as indicated:

An embodiment (1) refers to said process for the preparation of a titanium-containing zeolitic material having a MWW framework structure comprising

(a) providing the MWW boron-free crystalline zeolitic material obtained according to step (II);

(b) incorporating titanium into the zeolitic material provided in (a) comprising

(b.1) preparing an aqueous synthesis mixture containing the zeolitic material provided in (i), a MWW template compound and a titanium source, wherein the molar ratio of the MWW template compound to Si, calculated as SiO ² and contained in the zeolitic material provided in (a) is in the range of 0.5: 1 to 1.4: 1;

(b.2) hydrothermally synthesize a zeolitic material containing titanium having a MWW framework structure from the aqueous synthesis mixture prepared in (b.1), obtaining a mother liquor comprising the zeolitic material containing titanium containing it has a MWW framework structure;

(c) spray drying the mother liquor obtained from (b.2) comprising the titanium-containing zeolitic material having a MWW framework structure.

A preferred embodiment (2) that specifies embodiment (1) refers to said process for the preparation of a zeolitic material containing titanium having a MWW framework structure, wherein in (b.1), the compound MWW template is selected from the group consisting of piperidine, hexamethyleneimine, N, N, N, N ', N' ion, N'-hexamethyl-1,5-pentanediammonium, 1,4-bis (N-methylpyrrolidinium) butane, Octyltrimethylammonium hydroxide, heptyltrimethylammonium hydroxide, hexyltrimethylammonium hydroxide, and a mixture of two or more thereof, and the MWW template compound is preferably piperidine.

A preferred embodiment (3) that specifies embodiment (1) or (2) refers to said process for the preparation of a zeolitic material containing titanium having a MWW framework structure, wherein in (b.1 ), the titanium source is selected from the group consisting of tetrabutyl orthotitanate, tetraisopropyl orthotitanate, tetra-ethyl orthotitanate, titanium dioxide, titanium tetrachloride, titanium tert-butoxide, and a mixture of two or more of the themselves; the titanium source is preferably tetrabutyl orthotitanate.

A preferred embodiment (4) that specifies any of the embodiments (1) to (3) refers to said process for the preparation of a zeolitic material containing titanium having a MWW framework structure, where in the mixture of Aqueous synthesis in (b.1), the molar ratio of Ti, calculated as TiO ² and contained in the titanium source, in relation to Si, calculated as SiO ² and contained in the zeolitic material that has a B2O3: SiO2 molar ratio of at most 0.02: 1, it is in the range of 0.005: 1 to 0.1: 1, preferably 0.01: 1 to 0.08: 1, more preferably 0.02: 1 to 0.06: 1.

A preferred embodiment (5) that specifies any of the embodiments (1) to (4) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in the mixture of aqueous synthesis in (b.1), the molar ratio of H ² O with respect to Si, calculated as SiO ² and contained in the zeolitic material that has a molar ratio B ² O ³ : SiO ² of at most 0.02: 1 , is in the range of 8: 1 to 20: 1, preferably 10: 1 to 18: 1, more preferably 12: 1 to 16: 1.

A preferred embodiment (26) that specifies any of the embodiments (1) to (5) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in the mixture For aqueous synthesis in (b. 1), the molar ratio of the MWW template compound to Si, calculated as SiO ² and contained in the zeolitic material provided in (i), is in the range of 0.5: 1 to 1.7: 1 , preferably 0.8: 1 to 1.5: 1, more preferably 1.0: 1 to 1.3: 1.

A preferred embodiment (7) that specifies any of the embodiments (1) to (6) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (b .2), the hydrothermal synthesis is carried out at a temperature in the range of 80 to 250 ° C, preferably 120 to 200 ° C, more preferably 160 to 180 ° C. A preferred embodiment (8) that specifies any of the embodiments (1) to (7) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (b .2), the hydrothermal synthesis is carried out for a period in the range of 10 to 100 h, more preferably 20 to 80 h, more preferably 40 to 60 h.

A preferred embodiment (9) that specifies any of the embodiments (1) to (8) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (b .2), the hydrothermal synthesis is carried out in a closed system under autogenous pressure.

A preferred embodiment (10) that specifies any of the embodiments (1) to (9) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where neither during ( b.2) neither after (b.2) nor before (c), the zeolitic material containing titanium and having a MWW framework structure is separated from its mother liquor.

A preferred embodiment (11) that specifies any of the embodiments (1) to (10) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, wherein the liquor mother subjected to (c) comprising the zeolitic material containing titanium and having a MWW framework structure has a solids content, optionally after concentration or dilution, in the range of 5 to 25% by weight, more preferably 10 to 20% by weight, based on the total weight of the mother liquor comprising the titanium-containing zeolite material.

A preferred embodiment (12) that specifies any of the embodiments (1) to (11) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, wherein during the Spray drying in (c), the inlet temperature of the drying gas is in the range of 200 to 350 ° C and the outlet temperature of the drying gas is in the range of 70 to 190 ° C. A preferred embodiment (13) that specifies any of the embodiments (1) to (12) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, wherein the material zeolitic having a MWW framework structure obtained from (c) has a Si content in the range of 30 to 40% by weight, calculated as elemental Si, a total organic carbon (TOC) content in the range of 0 to 14% by weight, and a Ti content of 2.1 to 2.8% by weight, calculated as elemental titanium, in each case based on the total weight of the zeolitic material.

A preferred embodiment (14) that specifies any of the embodiments (1) to (13) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, which further comprises

(d) treating the zeolitic material containing titanium and having a MWW framework structure obtained from (iii) with an aqueous solution having a pH of at most 5.

A preferred embodiment (15), which specifies embodiment (14) refers to said process for the preparation of a zeolitic material containing titanium and having a framework structure m Ww, where after (c) and Before (d), the zeolitic material containing spray dried titanium and having a MWW framework structure obtained from (c) is not subjected to calcination.

A preferred embodiment (16) that specifies embodiment (14) or (15) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (d), the weight ratio of the aqueous solution to the zeolitic material containing titanium and having a MWW framework structure is in the range of 10: 1 to 30: 1, preferably 15: 1 to 25: 1, more preferably of 18: 1 to 22: 1.

A preferred embodiment (17) that specifies any of the embodiments (14) to (16) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (d ), the aqueous solution comprises an inorganic acid, preferably selected from the group consisting of phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, and a mixture of two or more thereof, and the aqueous solution preferably comprises nitric acid.

A preferred embodiment (18) that specifies any of the embodiments (14) to (17) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (d ), the aqueous solution has a pH in the range of 0 to 5, preferably 0 to 3, more preferably 0 to 2.

A preferred embodiment (19) that specifies any of the embodiments (14) to (18) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in (d ), the zeolitic material containing titanium and having a framework structure of MWW is treated with the aqueous solution at a temperature in the range of 50 to 175 ° C, preferably 70 to 125 ° C, more preferably 95 to 105 ° C.

A preferred embodiment (20) that specifies any of the embodiments (14) to (19) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, where in ( d), the zeolitic material containing titanium and having a MWW framework structure is treated with the aqueous solution for a period in the range of 0.1 to 6 h, preferably 0.3 to 2 h, more preferably 0.5 to 1.5 h.

A preferred embodiment (21) that specifies any of the embodiments (14) to (20) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, wherein the treatment according to (d) is carried out in a closed system under autogenous pressure.

A preferred embodiment (22) that specifies any of the embodiments (14) to (21) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, further comprising

(e) separating the titanium-containing zeolitic material having a MWW framework structure obtained from (d) from the aqueous solution, optionally followed by washing the separated titanium-containing zeolitic material having a MWW structure.

A preferred embodiment (23) that specifies embodiment (22) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, wherein (e) comprises drying the zeolitic material containing titanium, separated and optionally washed, having a MWW framework structure.

A preferred embodiment (24) that specifies any of the embodiments (14) to (23) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, which further comprises

(f) preparing a suspension, preferably an aqueous suspension containing the titanium-containing zeolitic material and having a MWW framework structure obtained from (d), preferably from (e), and said suspension has a solids content preferably in the range 5 to 25% by weight, more preferably 10 to 20% by weight, based on the total weight of the suspension, and the suspension is subjected to spray drying.

A preferred embodiment (25) that specifies embodiment (24) refers to said process for the preparation of a zeolitic material containing titanium and having a framework structure m Ww, wherein, during spray drying, the inlet temperature of the drying gas is in the range of 200 to 330 ° C and the outlet temperature of the drying gas is in the range of 120 to 180 ° C.

A preferred embodiment (26) that specifies any of the embodiments (14) to (25) refers to said process for the preparation of a zeolitic material containing titanium and having a MWW framework structure, which further comprises

(g) calcining the zeolitic material containing titanium and having a MWW framework structure obtained from (d), preferably from (e), more preferably from (f), wherein the calcination is preferably carried out at a temperature in the range range 400 to 800 ° C, more preferably 600 to 700 ° C.

A preferred embodiment (27) that specifies embodiment (26) refers to said process for the preparation of a zeolitic material containing titanium and having a framework structure m Ww, where in (vii), the calcination is carried out in continuous mode, preferably with a speed in the range of 0.2 to 2.0 kg of zeolitic material per hour, more preferably 0.5 to 1.5 kg of zeolitic material per hour.

According to step (V), the TiMWW preferably obtained according to step (IV) is subjected to a suitable treatment with Zn to obtain the ZnTiMWW used for the preparation of the suspension according to (a). Generally, as regards (V), there are no specific restrictions as long as the preferred ZnTiMWW, defined above, can be obtained with the preferred content of Zn and Ti. Most preferably, step (V) comprises at least one suitable impregnation step, more preferably at least one wet impregnation step. With regard to this impregnation step, it is preferred to contact TiMWW preferably as obtained according to (IV) and contacted with at least one suitable Zn-containing precursor in at least one suitable solvent (wet impregnation), of the most preferably water. As a suitable Zn-containing precursor, water-soluble salts of Zn are especially preferred, and zinc acetate dihydrate is especially preferred. It is further preferred to prepare a solution of the Zn-containing precursor, preferably an aqueous solution, and to suspend the TiMWW in this solution. More preferably, the impregnation is carried out at elevated temperatures, relative to room temperature, preferably in the range of 75 to 125 ° C, more preferably 85 to 115 ° C, for a time preferably in the range of 3.5 to 5 hrs, more preferably 3 to 6 hrs. It is preferred to stir the suspension during impregnation. After impregnation, the obtained ZnTiMWW is preferably suitably separated from the suspension. All procedures for separating ZnTiMWW from suspension are conceivable. Especially preferably, the separation is carried out by means of filtration, ultrafiltration, diafiltration or centrifugation procedures. A combination of two or more of these procedures can be applied. According to the present invention, the ZnTiMWW is preferably separated from the suspension by filtration to obtain a filter cake which is preferably washed, preferably with water. If washing is applied, it may be preferred to continue the washing procedure until the wash water has a conductivity of less than 1000 microSiemens / cm, more preferably less than 900 microSiemens / cm, more preferably less than 800 microSiemens / cm , more preferably less than 700 microSiemens / cm. Subsequently, the preferably washed filter cake is subjected to a pre-drying, for example by subjecting the filter cake to a suitable gas stream, preferably a nitrogen stream, for a time preferably in the range of 5 to 15 h, more preferably from 8 to 12.

If TiMWW or ZnTiMWW is used as the catalytically active material according to the present invention, it is preferred that the organic solvent is acetonitrile.

Generally, the preferred ZnTiMWW catalyst can be prepared according to the specific teachings as disclosed in WO 2013/117536 A2, which is attached herein in its entirety by reference.

Stage (a2)

According to (a2), the feed stream according to (a1) is subjected in the reactor to epoxidation conditions in the presence of the catalyst, and a reaction mixture comprising the propylene oxide and the organic solvent is obtained.

The reactor employed in (a2) can be operated in an isothermal or adiabatic manner, where it is preferred that the reactor in (a2) is an isothermally operated reactor.

Conveniently, the conversion rate of the starting materials can be controlled by adjusting the temperature, pressure, WHSV of the starting materials, and the like. By way of example, the reaction temperature can be adjusted so that at least 90% of the epoxidation agent is converted. The amounts of starting material present in the reaction mixture before and after the epoxidation reaction can be analyzed by any suitable technique, eg, chromatography.

Generally, the continuous epoxidation reaction in (a2) can be carried out in any suitable vessel or reactor. Preferably, the reaction in (a2) is carried out in at least one continuously operated reactor such as a tube reactor or a tube bundle reactor which preferably contains at least one cooling jacket surrounding at least one tube, wherein the temperature of the reaction mixture is isothermally controlled using a heat transfer medium, preferably by passing the heat transfer medium through a reactor jacket. If the reaction in (a2) is carried out in such a reactor containing at least one cooling jacket, the term "epoxidation reaction temperature" as used herein is defined as the temperature of the medium of heat transfer before controlling the temperature of the reaction mixture, preferably as the temperature of the heat-carrying medium at the inlet of the isothermal reactor jacket.

Preferably, the at least one of the reactors in which the reaction according to (a2) is carried out is a tube reactor or a tube bundle reactor.

The catalyst comprising the titanium-containing zeolite can be employed in all conceivable forms described above, including a powder, a micropowder, preferably a spray powder, as a molding comprising a powder, or as a molding comprising a micropowder. , preferably a spray powder. Preferably, the catalyst comprising the titanium zeolite is used as a molding comprising a powder or a micropowder, preferably a spray powder, more preferably as a molding comprising a micropowder, preferably a spray powder.

The catalyst used in step (a2) of the present invention can be placed in the reactor in all conceivable ways. Preferably the catalyst is arranged as a fluidized bed or as a fixed bed, more preferably as a fixed bed.

Preferably, the epoxidation conditions in (a2) comprise an epoxidation reaction temperature in the range of 20 to 100 ° C, more preferably 25 to 80 ° C, more preferably 25 to 60 ° C, more preferably 30 to 60 ° C.

Preferably, the epoxidation conditions in (a2) comprise an epoxidation reaction pressure in the range of 5 to 100 bar, more preferably 10 to 32 bar, more preferably 15 to 25 bar, wherein the epoxidation reaction pressure It is defined as the pressure at the outlet of the isothermal reactor.

Therefore, the epoxidation conditions in (a2) preferably comprise an epoxidation reaction temperature in the range of 20 to 100 ° C and an epoxidation reaction pressure in the range of 5 to 100 bar, more preferably a reaction temperature of epoxidation in the range of 25 to 60 ° C and an epoxidation reaction pressure in the range of 10 to 32 bar, more preferably an epoxidation reaction temperature in the range of 30 to 60 ° C and a reaction pressure of epoxidation in the range of 15 to 25 bar.

The term "epoxidation conditions" as used in this context of the present invention refers to an epoxidation reaction in step (a2) wherein at least 98%, preferably at least 99%, more preferably at least 99.9% of the total reaction time, the reaction temperature and pressure are in the ranges defined above. The term "overall reaction time" as used in this context of the present invention refers to reaction time; A given catalyst bed is used before it is discarded or subjected to regeneration. In particular at the beginning of an epoxidation reaction in (a2) when the catalyst is fresh, that is to say at the beginning of the epoxidation reaction in (a2), the reaction temperature or pressure or both may be outside the ranges mentioned above during a short period of time. Preferably, the flow rate of the heat transfer medium is chosen so that the temperature difference between its inlet temperature and its outlet temperature is at most 3 K, more preferably at most 2 K, more preferably at most 1 K.

Preferably, the epoxidation reaction according to step (a2) of the present invention is carried out at essentially constant epoxidation agent conversion, preferably hydrogen peroxide conversion. Preferably, to determine the hydrogen peroxide conversion, the molar flow rate of hydrogen peroxide in the effluent stream withdrawn in (a3), referred to herein as m0ut, is compared to the molar flow rate of hydrogen peroxide in the feed stream. provided in (a1), referred to herein as min, and where the hydrogen peroxide conversion is defined as 100 x (1-m0ut / min). Preferably, the inlet temperature of the heat transfer medium described above is adjusted in the preferred ranges mentioned above to keep the hydrogen peroxide conversion essentially constant in the range of 80 to 100%, more preferably 90 to 100%, plus preferably 95 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, more preferably 99.9 to 100%. The term "epoxidation conditions comprise", as used in this context of the present invention, refers to an epoxidation reaction in step (a2) wherein at least 98%, preferably at least 99%, plus preferably at least 99.9% of the total reaction time, the hydrogen peroxide conversion is in the ranges defined above. The term "overall reaction time", as used in this context of the present invention, refers to the reaction time that a given catalyst bed is used before it is discarded or subjected to regeneration. In particular at the beginning of an epoxidation reaction in (a2) when the catalyst is fresh, i.e. at the beginning of the epoxidation reaction in (a2), the hydrogen peroxide conversion may be outside the aforementioned ranges for a short time. time frame. Preferably, the reaction temperature is not kept constant during the reaction, but is adjusted continuously or stepwise to allow a constant hydrogen peroxide conversion. Generally, due to a certain deactivation of the catalyst, the reaction temperature increases continuously or in stages. Preferably, the reaction temperature is increased continuously or stepwise by at most 1 K / d (Kelvin / day), more preferably by less than 1 K / d.

Preferably, the reaction mixture which is present in the reactor in (a2) is liquid under the epoxidation conditions. Preferably, the reaction mixture consists of a single liquid phase, two liquid phases, or three or more liquid phases. Preferably, the reaction mixture in the reactor in (a2) consists of a single liquid phase or two liquid phases, more preferably a single liquid phase.

Generally, the reactor used in step (a2) of the present invention can be arranged horizontally or vertically. Preferably the reactor is arranged vertically. In the preferably vertically arranged reactor, the feed stream provided in (a1) may pass in up-flow mode or in down-flow mode, and the up-flow mode is preferred. Preferably, compared to the flow direction of the feed stream, the heat transfer medium passes through the jacket in co-current mode.

Generally, the epoxidation reaction in (a2) can be carried out in one or more reactors, where these reactors can be arranged in parallel or in series. Preferably, the reaction in (a2) is carried out in one reactor or in at least two reactors, preferably two reactors, which are arranged in series, and a suitable intermediate treatment can be carried out between two reactors arranged in series. If the reaction is carried out in two reactors arranged in series, it is preferred that the first reactor operates as described above, that is, as an isothermally operated reactor, and the second reactor, that is, the downstream reactor operates as a adiabatic or essentially adiabatic reactor. The term "reactor", as used herein, also encompasses two or more reactors arranged in parallel in which a past feed stream is divided into two or more sub-streams, each sub-stream being passed into a reactor and effluent streams drawn from the reactors are combined to obtain the total effluent stream. Thus, the epoxidation reaction can be carried out in at least one first reactor such as two or more first reactors, for example 2, 3, 4 first reactors, which are arranged in parallel and which are preferably isothermal reactors, and in at least one second reactor such as two or more second reactors, for example 2, 3, 4 second reactors, which are arranged in parallel and which are preferably adiabatic or essentially adiabatic reactors.

If the epoxidation reaction according to (a2) is carried out in two reactors arranged in series, it is preferred that in the first reactor, which is preferably an isothermally operated reactor, the hydrogen peroxide conversion is kept essentially constant over a range of 80 to 99%, preferably 85 to 98%, more preferably 90 to 97%, and in the second reactor which is preferably designed as an adiabatic or essentially adiabatic reactor, the total hydrogen peroxide conversion, i.e. the peroxide conversion of hydrogen, taking into account the conversion in the first and second reactors, is brought to a value of more than 99%, preferably at least 99.5%, more preferably at least 99.9%.

Stage (a3)

According to step (a3), a product stream comprising the propylene oxide and the organic solvent is withdrawn from the reactor. Such a product stream typically undergoes at least one fine-tuning step to isolate the propylene oxide from the product stream. Furthermore, the organic solvent, which normally comprises by-products of the epoxidation reaction, is preferably subjected to one or more fine-tuning steps to allow recirculation of the organic solvent, preferably acetonitrile, preferably after one or more purification steps in step (a1). A preferred sequence of set-up steps is described in Reference Example 2 and Figures 1 and 2 below.

Stage (b)

According to (b), the introduction of the feed stream into the reactor according to (a1) is stopped.

Preferably, step (b) further comprises separating the reaction mixture comprising propylene oxide and the organic solvent from the catalyst comprising the titanium-containing zeolite as catalytically active material. This separation of the spent catalyst reaction mixture comprising a titanium-containing zeolite can be accomplished in any suitable way, such as pumping, draining, decanting, filtering, and the like. Optionally, (b) further comprises drying the catalyst prior to performing the wash in (c), wherein preferably the catalyst is not dried prior to performing the wash in (c). If drying is carried out, it is preferred that said drying includes contacting the catalyst with a gas stream comprising nitrogen, preferably at a temperature of said gas stream in the range of 40 to 200 ° C, more preferably in the range of 55 to 150 ° C, more preferably in the range of 70 to 100 ° C. Such separation can be further achieved by purging the reactor with the organic solvent, preferably acetonitrile.

Therefore, in a preferred embodiment, the reactor is purged to rid itself of hydrogen peroxide, propylene and propylene oxide by replacing the feed stream according to (a1) with a stream consisting essentially of the organic solvent, preferably acetonitrile until that the reactor is essentially free of hydrogen peroxide, propylene and propylene oxide and, optionally, depressurizing and emptying the reactor. For example, a stream consisting essentially of the organic solvent, preferably acetonitrile, contains at least 60% by weight, preferably at least 70% by weight, more preferably at least 75% by weight, more preferably at least 80% by weight of the organic solvent, and optionally contains at least one other liquid, preferably comprising water. Therefore, it is preferred that at least 95% by weight, more preferably at least 98% by weight, more preferably at least 99% by weight of the stream consisting essentially of the organic solvent, preferably acetonitrile, consists of in the organic solvent, preferably acetonitrile and water, where at least 60% by weight, preferably at least 70% by weight, more preferably at least 75% by weight, more preferably at least 80% by weight of the stream consists of the solvent organic, preferably acetonitrile. Said purging is preferably carried out at a temperature of said stream consisting essentially of the organic solvent, preferably acetonitrile, in the range of 20 to 90 ° C, more preferably in the range of 25 to 80 ° C, more preferably in the range range 30 to 70 ° C.

In an alternative preferred embodiment, the present method further comprises preparing the feed stream in (a1) by mixing a stream comprising the propene, a stream comprising the hydrogen peroxide or hydrogen peroxide source and a stream comprising the organic solvent, wherein step (b) comprises

(b1) stopping the stream comprising the hydrogen peroxide or the hydrogen peroxide source;

(b2) stopping the stream comprising the propene and the stream comprising the organic solvent;

(b3) optionally depressurize and empty the reactor,

wherein step (b2) preferably ends at least 30 minutes, more preferably at least 60 minutes, after step (b1).

Stage (c)

According to step (c), the catalyst is washed with an aqueous liquid system.

The possible components of the aqueous liquid system according to (c) and the respective amounts thereof, as described below, are to be understood as with respect to the aqueous liquid system employed in (c) before addition to the catalyst comprising a zeolite that contains titanium.

The aqueous liquid system according to (c) contains at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water based on the total weight of the system watery liquid.

The water used in (c) can be obtained from any suitable source. Preferably, the water used in (c) is demineralized or condensed water.

Preferably, the aqueous liquid system according to (c) contains methanol only in minor amounts, while preferably it is free or at least essentially free of methanol. Preferably, the aqueous liquid system according to (c) contains at most 5% by weight, more preferably 1% by weight, more preferably 0.1% by weight, more preferably 0.01% by weight, more preferably 0.001% by weight, more preferably 0.0001% by weight of methanol, based on the total weight of the aqueous liquid system.

Preferably, the aqueous liquid system according to (c) contains hydrogen peroxide only in minor amounts, while preferably it is free or at least essentially free of methanol. Preferably, the aqueous liquid system according to (c) contains at most 0.1% by weight, preferably 0.01% by weight, more preferably 0.001% by weight, more preferably 0.0001% by weight of hydrogen peroxide, based on the total weight of the liquid system aqueous.

Preferably, the aqueous liquid system according to (c) has a pH value of 4 to 10, preferably 7 to 9, as determined with a pH electrode.

In a particularly preferred manner, the aqueous liquid system according to (c) consists of water.

The washing in (c) is carried out in the reactor containing the catalyst.

Thus, the washing in (c) is carried out in the reactor containing the catalyst, wherein the aqueous liquid system according to (c) contains at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water, based on the total weight of the aqueous liquid system.

The washing in (c) can be carried out in batch mode or in continuous mode. In case the washing is carried out in batch mode, the catalyst is contacted one or more times with a specific amount of the aqueous liquid system. Therefore, washing can be performed by immersing the catalyst in the aqueous liquid system. During the wash it is possible to subject the aqueous liquid system together with the catalyst to agitation. It is conceivable that when the washing in (c) is carried out in batch mode, the aqueous liquid system can be replaced one or more times.

In case the washing is carried out in continuous mode, the catalyst is continuously contacted with a stream of the aqueous liquid system. In case the reactor comprising the catalyst is arranged vertically and the washing is carried out in the reactor or the washing is carried out outside the reactor in any other suitable container, arranged vertically, the washing can be carried out in flow mode up or down, preferably in down flow mode. Preferably, the washing in (c) is carried out in continuous mode. More preferably, the washing in (c) is carried out continuously in the reactor containing the catalyst.

Therefore, the washing in (c) is preferably carried out continuously in the reactor containing the catalyst, wherein the aqueous liquid system according to (c) contains at least 95% by weight, preferably at least 99% by weight , more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water, based on the total weight of the aqueous liquid system.

Preferably, the continuous mode scrubbing is performed in a tube reactor or tube bundle reactor with the aqueous liquid system having a liquid hourly space velocity (LHSV) in the range of 1 to 20 m / h, more preferably 5 to 15 m / h, more preferably 5 to 10 m / h. The liquid hourly space velocity LHSV in (c) is defined as the volumetric flow rate of the aqueous liquid system in cubic meters per hour divided by the total cross section in square meters of the empty reactor tube or the empty tubes of the reactor, in the case that a tube bundle reactor is used, wherein the tube has a constant diameter throughout its length and the tubes have constant diameters throughout its length, respectively.

Therefore, the washing in (c) is preferably carried out continuously in a tube reactor or a tube bundle reactor containing the catalyst, wherein the aqueous liquid system contains at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water, based on the total weight of the aqueous liquid system, and is performed with the aqueous liquid system having an LHSV in the range from 1 to 20 m / h, more preferably 5 to 15 m / h, more preferably 5 to 10 m / h.

The washing in (c) can be carried out at any temperature of the aqueous liquid system. Preferably, the washing in (c) is carried out at a temperature of the aqueous liquid system in the range of 30 to 90 ° C, preferably 40 ° C. up to 80 ° C.

The washing in (c) is carried out for 2 to 12 hours, preferably 2.5 to 9 hours, more preferably 3 to 6 hours.

Therefore, the washing in (c) is preferably carried out at a temperature of the aqueous liquid system in the range of 30 to 90 ° C for 2.5 to 9 hours, more preferably at a temperature of the aqueous liquid system in the range of 40 at 80 ° C for 3 to 6 hours.

Therefore, the washing in (c) is preferably carried out continuously in a tube reactor or a tube bundle reactor containing the catalyst, wherein the aqueous liquid system contains at least 95% by weight, preferably at least 99% by weight, more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water, based on the total weight of the aqueous liquid system, and is performed with the aqueous liquid system having an LHSV in the range of 5 to 15 m / h at a temperature of the aqueous liquid system in the range of 30 to 90 ° C for 2.5 to 9 hours, more preferably 5 to 10 m / h at a temperature of the aqueous liquid system in the range 40 to 80 ° C for 3 to 6 hours.

According to the present method, the wash in (c) is typically controlled by the total organic carbon concentration of the aqueous liquid system after it has been contacted with the catalyst, and the wash in (c) is preferably performed until achieved a specific total organic carbon concentration in the aqueous liquid system after it has been in contact with the catalyst. Since the total organic carbon concentration passes through a maximum during the wash in (c), the specific concentration that is reached preferably refers to the value reached after passing the maximum.

Preferably, the washing in (c) is carried out until the total organic carbon concentration of the aqueous liquid system after having been in contact with the catalyst is 25% or less, preferably 20% or less, preferably 15% or less, preferably 10% or less, more preferably 5% or less, more preferably 4% or less, more preferably 3% or less, more preferably 2% or less, more preferably 1% or less of the maximum concentration of organic carbon total detected during washing in (c), where the total volume of the aqueous liquid system is equal to or greater than the internal volume of the reactor. It is understood that the total organic carbon concentration is determined according to DIN EN 1484.

The time at which step (b) is carried out and the introduction of the feed stream into the reactor is stopped to allow washing in (c) is preferably chosen based on the decrease in selectivity with respect to formation of propylene oxide in (a2) with respect to the average selectivity of the reaction in (a2) during the first 100 hours of performance of step (a). The selectivity with respect to the formation of propylene oxide in (a2) in the context of the present process is understood as the selectivity with respect to the formation of propylene oxide in (a2) based on hydrogen peroxide and is calculated as shown in Comparative Example 1. Thus, step (b) can be carried out, for example, when the selectivity with respect to propylene oxide formation in (a2) has decreased by 15% or less, or by 10% or less, or 6% or less with respect to the average selectivity of the reaction in (a2) during the first 100 hours of performance of step (a). Preferably step (b) is carried out when the selectivity with respect to propylene oxide formation in (a2) has decreased by 4% or less, preferably by 3% or less, more preferably by 2% or less with respect to the average selectivity of the reaction in (a2) during the first 100 h of carrying out step (a).

Step (i) further comprises repeating the sequence of steps (a) to (c) n times and n is an integer in the range from 1 to 10. Therefore, the sequence of steps (a) to (c ) is repeated at least once before step (ii) is carried out. The integer n is in the range of 1 to 10 and therefore is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. More preferably, n is in the range of 1 to 6 and therefore it is 1, 2, 3, 4, 5 or 6. More preferably, n is in the range of 1 to 4 and therefore 1, 2, 3 or 4.

According to the present process, the catalyst obtained from (b) is preferably washed only with an aqueous liquid system containing at least 95% by weight, more preferably at least 99% by weight, more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water based on the total weight of the aqueous liquid system. This washing is preferably carried out continuously. Therefore, it is preferred that the catalyst is treated without any other liquid system between step (b) and step (ii) except the aqueous liquid system containing at least 95% by weight, more preferably at least 99% by weight. , more preferably at least 99.9% by weight, more preferably at least 99.99% by weight of water based on the total weight of the aqueous liquid system. Therefore, preferably, no pre-treatment or post-treatment is carried out with a different aqueous liquid system, preferably with any different liquid system, wherein purging of the reactor with the organic solvent, preferably acetonitrile in (b) is not excluded. by this preferred embodiment.

According to the present process, the catalyst obtained from (b) is preferably not treated with a gas stream consisting of or, preferably, comprising ozone.

Optionally, (c) further comprises drying the washed catalyst. If drying is carried out, it is preferred that said drying includes contacting the catalyst with a gas stream comprising nitrogen, preferably at a temperature of said gas stream in the range of 40 to 200 ° C, more preferably in the range of 55 to 150 ° C, more preferably in the range of 70 to 100 ° C. According to the present invention, it is preferred that said drying is not carried out after a washing step (c) after which no calcination is carried out; that is, it is carried out after the same washing step (c), after which step (ii) is carried out.

Stage (ii)

The present process for regeneration further comprises

(ii) a step that comprises calcining the catalyst obtained from (c) after having repeated the sequence of steps (a) to (c) n times.

Calcination in (ii) is carried out at a catalyst bed temperature in the range of 300 to 600 ° C, preferably 350 to 550 ° C, more preferably 400 to 500 ° C.

The calcination in (ii) can be carried out in a static surrounding gas atmosphere or in a gas stream with which the catalyst is contacted. Preferably, the calcination in (ii) is carried out in a gas stream. Bliss The gas stream comprises oxygen, preferably oxygen and nitrogen. Generally, said gas stream comprising oxygen, preferably oxygen and nitrogen is not restricted with respect to the source used for oxygen, preferably oxygen and nitrogen. Preferably air, lean air or a mixture thereof is used as the source, more preferably air or lean air. Therefore, the calcination in (ii) is preferably carried out in a gas stream comprising oxygen, preferably oxygen and nitrogen, wherein the gas stream comprising oxygen, preferably oxygen and nitrogen, is preferably air, lean air or a mixing them, more preferably air or lean air.

Therefore, the calcination in (ii) is carried out at a catalyst bed temperature in the range of 300 to 600 ° C, preferably 350 to 550 ° C, more preferably 400 to 500 ° C in a gas stream. comprising oxygen, preferably oxygen and nitrogen, wherein the gas stream comprising oxygen, preferably oxygen and nitrogen, is preferably air, lean air or a mixture thereof, more preferably air or lean air.

The calcination in (ii) can be carried out for any time necessary to achieve sufficient calcination of the catalyst in the present process for regeneration of a catalyst. Preferably, the calcination in (ii) is carried out for 1 to 15 hours, preferably 2 to 10 hours, more preferably 3 to 7 hours.

Therefore, the calcination in (ii) is preferably carried out at a catalyst bed temperature in the range of 300 to 600 ° C for 1 to 15 hours, more preferably 350 to 550 ° C for 2 to 10 hours, more preferably at 400 to 500 ° C for 3 to 7 hours in a gas stream comprising oxygen, preferably oxygen and nitrogen, wherein the gas stream comprising oxygen, preferably oxygen and nitrogen, is preferably air, lean air or a mixture of the same, more preferably air or lean air.

Calcination in (ii) is carried out in the reactor containing the catalyst.

The sequence of steps (i) and (ii) of the present process for the regeneration of a catalyst can be repeated m times before the catalyst is discarded, and m is an integer and is at least 1, where in each repetition of the sequence of steps (i) and (ii), n is the same or different. Thus, the sequence of steps (i) and (ii) is repeated at least once, where in each repetition of the sequence of steps (i) and (ii), n is the same or different. Preferably, m is in the range of 1 to 10 and therefore is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. More preferably, m is in the range of 1 to 6 and therefore therefore it is 1, 2, 3, 4, 5 or 6. More preferably, m is in the range of 1 to 4 and is therefore 1, 2, 3 or 4.

Preferably m is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 while n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, more preferably 1 , 2, 3, 4, 5 or 6, more preferably 1, 2, 3 or 4. More preferably, m is 1, 2, 3, 4, 5 or 6 while n is 1, 2, 3, 4, 5 , 6, 7, 8, 9 or 10, more preferably 1, 2, 3, 4, 5 or 6, more preferably 1, 2, 3 or 4. More preferably, m is 1, 2, 3 or 4 while n is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, more preferably 1, 2, 3, 4, 5 or 6, more preferably 1, 2, 3 or 4.

A regenerated catalyst according to the process of the invention.

The regeneration product is a regenerated catalyst comprising a zeolite containing titanium as catalytically active material, obtainable or obtained by a process according to the present invention and as described above; said regenerated catalyst itself is not covered by the present invention.

It is preferred that the catalyst regenerated according to the process of the present invention exhibits in a process for the preparation of propylene oxide a differential conversion temperature of not more than 5 K, preferably not more than 2 K, more preferably not more than 1 K, wherein the differential conversion temperature is defined as the absolute difference between

(A1) the temperature at which a predetermined conversion of hydrogen peroxide is achieved in said process for the preparation of propylene oxide wherein the regenerated catalyst is used as a catalyst, and

(B1) the temperature at which said predetermined conversion of hydrogen peroxide is achieved in said process for the preparation of propylene oxide wherein the respective new catalyst is used as a catalyst under otherwise identical epoxidation reaction conditions.

After a certain operating time, a decrease in the catalytic activity of a catalyst comprising a zeolite containing titanium as a catalytically active material is observed in an epoxidation reaction. The reduced catalytic activity is directly related to a reduced conversion rate for at least one of the starting materials, i.e. the olefin and / or the epoxidation agent, where the reduced conversion rate can be compensated for by increasing the reaction temperature. general. This implies that with the continuous operation of the catalyst a gradual increase of the reaction temperature with respect to the initial temperature is required, which makes the epoxidation process more and more ineffective.

However, by subjecting a catalyst, comprising a titanium-containing zeolite spent in an epoxidation reaction, to the regeneration process of the present invention, its catalytic activity can be restored. initial. Initial catalytic activity refers here to the catalytic activity of a freshly prepared catalyst. Since catalytic activity is conveniently directly related to reaction temperature under otherwise identical reaction conditions, the efficiency of a regeneration of a spent catalyst can be derived from the reaction temperature required to maintain a set conversion rate. In the present case, the regenerated catalyst according to the present invention favorably exhibits, in the process for the preparation of an olefin oxide, a conversion temperature which deviates by a maximum of 5 K, preferably by a maximum of 2 K, more preferably by a maximum of 1 K of the conversion temperature of the fresh catalyst under otherwise identical epoxidation conditions.

It is further preferred that a catalyst regenerated according to the process of the present invention exhibits in a process for the preparation of propylene oxide, a differential selectivity of at most 1, where the differential selectivity is defined as the absolute difference in percentage points between

(A2) the selectivity based on hydrogen peroxide in said process for the preparation of propylene oxide wherein the regenerated catalyst is used as the catalyst, and

(B2) The hydrogen peroxide-based selectivity in said process for the preparation of propylene oxide in which the respective new catalyst is used as a catalyst under otherwise identical epoxidation reaction conditions, wherein the selectivity based on the Hydrogen peroxide is defined as moles of propylene oxide produced, divided by moles of hydrogen peroxide consumed x 100.

The quality of the catalyst comprising a titanium-containing zeolite, regenerated according to the process of the present invention, can also be quantified by comparing the selectivity of the regenerated catalyst with the selectivity of the fresh catalyst under otherwise identical epoxidation conditions. After prolonged use a decrease in catalyst selectivity is also typically observed. In the present case, favorably, after having been subjected to the regeneration process of the present invention, a catalyst comprising a zeolite containing titanium has a selectivity that deviates by a maximum of 1 percentage point from the selectivity of the new catalyst. under otherwise identical epoxidation reaction conditions.

The continuous process for the preparation of propylene oxide.

According to the present invention, it is preferred that the epoxidation reaction is carried out in more than one reactor, for example, in at least two reactors, three reactors or four reactors, and that such reactors operate in parallel. According to this process design, it is preferred that during regeneration of the catalyst in a given reactor the epoxidation reaction is carried out in one or more of the remaining reactors. Therefore, propylene oxide can be prepared continuously, and regeneration of the invention can be carried out simultaneously. It may be preferred that, according to this process design, the epoxidation reaction in the at least two reactors is started sequentially with a suitable delay between the respective starts.

The present invention further relates to a continuous process for the preparation of propylene oxide, comprising

(i ') a stage comprising

(a ') continuously preparing propylene oxide in a first reactor comprising

(a1 ') introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into the first reactor containing a catalyst comprising a zeolite containing titanium of MWW framework structure as catalytically active material ;

(a2 ') subjecting the feed stream according to (a1') in the first reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent;

(a3 ') withdrawing a product stream comprising propylene oxide and organic solvent from the first reactor;

(b ') stopping the introduction of the feed stream to the first reactor;

(c ') washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, where the washing is carried out for 2 to 12 hours;

step (i ') further comprises repeating the sequence of steps (a') to (c ') n' times, and n 'is an integer in the range of 1 to 10; and the process comprises the preparation of propylene oxide which further comprises

(ii ') a step that comprises the calcination of the catalyst obtained from (c') after having repeated the sequence of steps (a ') to (c') n 'times, where the calcination is carried out at a temperature of catalyst in the range of 300 to 600 ° C using a gas stream comprising oxygen in the reactor containing the catalyst, where the sequence of steps (i ') to (ii') is optionally repeated m 'times, and m' is an integer and is at least 1, where in each repetition of the sequence of steps (i ') to (ii '), n' is the same or different;

the process for the preparation of propylene oxide which further comprises

(i ") a stage comprising

(a ") continuously preparing propylene oxide in a second reactor comprising

(a1 ") introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into the second reactor containing a catalyst comprising a zeolite containing titanium of MWW framework structure as catalytically active material ;

(a2 ") subjecting the feed stream according to (a1") in the second reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent;

(a3 ") withdrawing a product stream comprising the propylene oxide and the organic solvent from the second reactor;

(b ") stopping the introduction of the feed stream to the second reactor;

(c ") washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, wherein the washing is carried out for 2 to 12 hours;

step (i ") further comprises repeating the sequence of steps (a") to (c ") n" times and n "is an integer in the range of 1 to 10; the process for preparing propylene oxide comprises, further

(ii ") a step that comprises the calcination of the catalyst obtained from (c") after having repeated the sequence of steps (a ") to (c") n "times, wherein the calcination is carried out at a temperature of catalyst in the range of 300 to 600 ° C using a gas stream comprising oxygen in the reactor containing the catalyst; wherein the sequence of steps (i ") to (ii") is optionally repeated m "times, and m "is an integer and is at least 1, where in each repetition of the sequence of steps (i") to (ii "), n" is the same or different;

wherein during at least one sequence of steps (b ') and (c') or at least one sequence of steps (b '), (c') and (ii '), propylene oxide is prepared according to (a ") .

The present invention is further illustrated by the following figures, reference examples, examples, and comparative examples.

Description of the figures

Figure 1 shows a block diagram of the procedure according to Reference Example 2. In Figure 1, the letters and numbers have the following meanings:

A epoxidation unit A

B epoxidation unit B

C distillation unit

D distillation unit

E distillation unit

F part stream distillation unit

G mixer-decanter unit

H acetonitrile recovery unit

I acetonitrile recycling unit

(1) - (20) streams according to a specifically preferred procedure as described in the examples

S0, S01, S02, S1, S2, S3, S4, S4b, S5, L1, L2, TL1, TL2, TL2, BL2

currents according to a preferred procedure as described in the general description and examples

Figure 2 shows a block diagram of the partial stream distillation F of the unit of Figure 1 in detail. In figure 2, the letters and numbers have the following meanings:

F1 first fractionation unit of part-stream distillation unit F.

F2 second fractionation unit of part-stream distillation unit F.

(13), (13a), (14), (15), (15a), (15b), (15c), (16), (19), (20)

currents according to a specifically preferred procedure as described in the examples

S1, S2, S3, S4, S4a, S4b, S4c, S5, TL2

currents according to a preferred procedure as described in the general description and examples

Examples

Reference Example 1: Preparation of a molding containing ZnTiMWW spray powder

The catalyst in molding form was prepared as described in WO 2013/117536 A2, in Example 5, in particular in Examples 5.1 -5.6, on pages 83-99. The characterization procedures of said molded part referred to in said Examples 5.1-5.6 are described in Reference Examples 2-10 on pages 66-71 of WO 2013/117536 A2. The characteristic properties of the catalyst are shown in figures 20-27 of document WO 2013/117536 A2 and the respective description of said figures on page 104 of document WO 2013/117536 A2.

Reference Example 2: Epoxidation Reaction Setup

Regarding abbreviations, reference is made to the schemes according to Figures 1 and 2, generally described in the section "Description of the Figures". All pressures given are absolute pressures.

1.1 Preparation of the SO stream (step (a))

a) Epoxidation in a main epoxidation reactor (epoxidation unit A)

Main reactor A was a vertically mounted tube bundle reactor with 5 tubes (tube length: 12m, tube internal diameter: 38mm), each tube was equipped with an axially positioned multipoint thermocouple with 10 measurement points equally spaced, enclosed in a suitable thermowell with a diameter of 18 mm. Each tube was loaded with 17.5 kg of the ZnTiMWW catalyst moldings prepared according to Reference Example 1 (post-treated moldings). The free space that remained was finally filled with soapstone spheres (3 mm diameter). The heat of reaction was removed by circulating a thermostatted heat transfer medium (water / glycol mixture) on the shell side in co-current with the feed. The flow rate of the heat carrier medium was adjusted so that the temperature difference between the inlet and the outlet did not exceed 1 ° C. The reaction temperature referred to below was defined as the temperature of the heat transfer medium entering the reactor shell. At the outlet of the reactor, the pressure was controlled by means of a pressure regulator and was kept constant at 20 bars.

The reactor was fed from below with a single-phase liquid stream (1). Stream (1) was prepared by mixing four streams (2), (3), (3a) and (4). The temperature of stream (1) was not actively controlled, but was generally in the range of 20 to 40 ° C:

- The stream (2) with a flow rate of 85 kg / h. At least 99.5% by weight of stream (2) consisted of acetonitrile, propene, and water. This stream (2) came from the bottom of the acetonitrile recycle distillation unit (I).

- Stream (3) with a flow rate of 15 kg / h was an aqueous hydrogen peroxide solution with a hydrogen peroxide concentration of 40% by weight (Solvay "crude / wash" grade with a TOC (total organic carbon ) in the range of 100 to 400 mg / kg The aqueous hydrogen peroxide solution was supplied from a storage tank, which allowed for continuous feeding, and was fed by a suitable metering pump.

- Stream (3a) was an aqueous stream comprising dissolved potassium formates. The additional stream was supplied from a storage tank, which allowed for continuous feeding, and was fed using a suitable metering pump. The concentration of potassium formates was 2.5% by weight, the feed rate of the stream (S3a) was 370 g / h. Stream (3a) was thoroughly mixed with stream (3) before the combined stream was mixed with the stream resulting from mixing streams (2) and (4).

- Stream (4) was a make-up stream of pure acetonitrile (chemical grade, from Ineos, purity approximately 99.9%, containing between 70-180 ppm by weight of propionitrile, 5-20 ppm by weight of acetamide and less than 100 ppm by weight of water as impurities). Enough fresh acetonitrile was added to compensate for the losses in the procedure. Under regular conditions, an average of 100 to 150 g / h of make-up acetonitrile was added.

The outlet stream (5) leaving epoxidation unit A was sampled every 20 minutes to determine the hydrogen peroxide concentration using the titanyl sulfate procedure and to calculate the hydrogen peroxide conversion. The hydrogen peroxide conversion was defined as 100 x (1-m0ut / min) where min is the molar flow rate of H ² O ² in the reactor feed and m0ut is the molar flow rate of H ² O ² at the outlet of the reactor . Based on the respectively obtained hydrogen peroxide conversion values, the inlet temperature of the heat transfer medium was adjusted to keep the hydrogen peroxide conversion essentially constant in the range of 90 to 92%. The inlet temperature of the heat transfer medium was set at 30 ° C at the beginning of a given cycle with a fresh batch of epoxidation catalyst and was increased, if necessary, to maintain the hydrogen peroxide conversion in the mentioned range. . The required temperature rise was typically less than 1 K / d.

The outlet stream (5) leaving the epoxidation unit A was passed through a heat exchange unit. The stream leaving the heat exchange unit (stream (6), S0) was fed to the Epoxidation Unit B.

b) Epoxidation in a finishing reactor (Epoxidation Unit B)

Finishing reactor B was an adiabatically operated fixed bed reactor. In this context, the term "adiabatic" refers to a mode of operation according to which no active cooling is performed and according to which the finishing reactor is adequately insulated to minimize heat losses. Finishing reactor B had a length of 4 m and a diameter of 100 mm. The reactor was filled with 9 kg of the same epoxidation catalyst that was used in the main epoxidation reactor A. The reserve space was filled with steatite spheres (3mm diameter). The operating pressure of the finishing reactor B was 10 bar, which was kept constant by a suitable pressure regulator at the outlet of the reactor. The output from Finish Reactor B was sampled every 20 minutes to determine the hydrogen peroxide concentration using the titanyl sulfate procedure.

The effluent from finishing reactor B, stream (6), was depressurized in a flash drum (flash drum), and both liquid and gas from this drum were fed to a low-boiling compound separation column ( distillation unit C).

Stream (6) (stream S0) averaged an acetonitrile content of 69 to 70% by weight, a propylene oxide content of 9-11% by weight such as 9.8% by weight, a water content of 17 % by weight, a propene content of about 3% by weight, a propane content of about 0.05% by weight, a hydrogen peroxide content of about 250 ppm by weight, a propene glycol content of about 0.1% by weight and an oxygen content of about 150 ppm by weight.

1.2 Separation of propylene oxide from stream S0 to obtain stream S1 (step (b))

a) Separation of low-boiling point compounds from stream (6) (stream S0) to obtain stream (8) (stream S01)

Stream (6) was sent to a light kettle separation column (distillation unit C) operated at 1.1 bar. The distillation column had a length of 8.5 m, a diameter of 170 mm and was equipped with 40 bubble trays, an evaporator at the bottom and a condenser at the top. The column was operated as a mixed wash / distillation tower. As a scrubbing agent, part of the bottoms stream from distillation unit D (stream 11, about 20-30 kg / h) was removed, cooled to 10 ° C, and fed to the top of the column. Liquid and gaseous inlet streams were introduced into the column at different points. The feed point of the liquid portion of stream (6) was above bubble tray 37; the gaseous portion of stream (6) was introduced into the column above bubble tray 28 (counted from above). The gaseous stream (7) leaving the cooling media at the top of the column contained mainly propene, propane (which was contained as an impurity in the polymer grade propene used), oxygen formed as a by-product, and small amounts from other light boilers. (acetonitrile (1-2% by volume), propionaldehyde (around 200 ppm by volume), acetone (around 100 ppm by volume, H ² (around 400 ppm by volume), CO ² (around 400 ppm by volume) ) and acetaldehyde (about 100 ppm by volume)) and was essentially free of propylene oxide (less than 300 ppm by volume) .This overhead stream was sent to the torch for removal. from the light boiler (stream (8), ie stream S01,) having a temperature of 70 ° C, had a propene content of 100 to 200 ppm by weight.

b) Separation of propylene oxide from stream (8) (stream S01) to obtain stream S02

Stream S01 obtained according to section 1.2 a) above was introduced into a distillation column (distillation unit D) to separate propylene oxide from stream S01. The column had a height of 50 m and a diameter of 220 mm and was equipped with a packing (Sulzer BX64) with a total packing length of 27.5 m divided into 8 beds with a length of 3060 mm each and two beds with a length of 1530 mm each one. Intermediate flow distributors were installed between each bed. The column was operated at a maximum pressure of 750 mbar. The feed point for stream S01 was located below the fourth packing bed, counted from above. The stream from the top of the column was condensed and partially returned to the column as reflux (reflux ratio approximately 5: 1). The remainder (stream (9)), which had a flow rate of 10.1 kg / hr, was taken as the top product and consisted essentially of propylene oxide with a purity of more than 99.9% by weight. The bottoms evaporator was operated such that the propylene oxide concentration in the bottoms stream was below 100 ppm by weight. The resulting bottoms stream temperature was approximately 69 ° C. The current S02 was then divided in two. Most of this (stream (10), with a flow rate of about 85 kg / h) was sent to the next distillation column (distillation unit E). The remainder (stream (11), 20-30 kg / h) was cooled and recirculated to the top of the light kettle separation column (distillation unit C) as a scrubbing agent as described above in section 1.2 a). This S02 stream had an acetonitrile content of approximately 80% by weight, a propylene oxide content of less than 100 ppm by weight, a water content of approximately 20% by weight, a propene glycol content of approximately 0.1% in weight and a hydroxypropanol content of about 0.1% by weight.

c) Separation of low-boiling point compounds from stream (10) (stream S02) to obtain stream (13) (stream S1)

The S02 stream obtained according to section 1.2 b) above was introduced into a low-boiling compound separation column (distillation unit E). This low-boiling compound separation column had a height of 8 m and a nominal diameter of 150 mm and was equipped with 35 bubble trays. The column was operated at a pressure greater than 2 bar and the S02 stream was introduced above bubble tray number 7 (counted from the bottom). The top stream obtained (stream (12), flow rate about 1 kg / h) exited the column at a temperature of 40 to 45 ° C and did not condense as the column was operated without internal reflux current. . In addition to acetonitrile (6500 ppm by volume), this overhead stream contained mainly nitrogen which was used to maintain the column operating pressure at 2 bar) and small amounts from kettles of low-boiling compounds (acetaldehyde (900 ppm by volume), oxygen (300 ppm by volume) and propionaldehyde (320 ppm by volume). This overhead stream was sent to the torch for removal. The sump evaporator was operated by feeding it a constant amount ( 5 kg / h) of saturated steam at a pressure of 16 bar. The bottom temperature of the column was 100 ° C. The bottoms stream, stream S1, consisted mainly of acetonitrile and water, and the rest are compounds of high boiling point This S1 stream had an acetonitrile content of about 80% by weight and a water content of about 20% by weight.

1.3 Division of the current S1 into the currents S2 and S3 (step (c))

Stage (c), the current S1, flow rate 86 kg / h, obtained according to section 1.2 c) above, was divided into two streams, streams S2 (current (13a according to Figure 1) and S3 (current 14 according to Figure 1) Stream S2 had a flow rate of 84 kg / h and stream S3 had a flow rate of 2 kg / h. Stream S3, 2.3% of stream S1, was subjected to a partial stream F distillation unit (partial stream distillation columns).

1.4 Partial flow distillation of flow S1 (step (d))

The first fractionation unit, that is, the first distillation column, F1, had a height of 9.5 m and a diameter of 85 mm and was equipped with 6.5 meters of Rombopak 9M packing with a metallic structure installed in three identical beds. Above the first bed of the structured packing, counted from above, stream S3 ((stream 14)) was introduced into the first distillation column. The temperature of the S3 stream was 60 ± 3 ° C. The first distillation column was operated at a higher pressure of approximately 1.4 bar and a bottom temperature of 92 ± 5 ° C. Reflux was not applied. The amount of steam fed to the bottom evaporator of the first fractionating unit was controlled in such a way that the acetonitrile concentration in the bottoms was in the range of 10 to 25% by weight. The tail stream S4b (stream (15b), approximately 3% of stream S3) was removed. This stream consisted mainly of water (72-85% by weight) and acetonitrile (10-24% by weight). The sum of all analyzed high-boiling components (27 components) ranged from 2-10% by weight. The upper stream, vapor fraction stream S4a (stream 15a), which had a temperature of 85 ± 3 ° C, did not condense and passed to the bottom of the second fractionating unit, that is, the second distillation column, F2 . S4a entered F2 below the last bed of the structured packing, counted from above. F2 had a height of 9.5 m and a diameter of 85 mm and was equipped with 6.5 m of Rombopak 9M packing with metal frame, installed in 3 identical beds. The second distillation column was operated at a higher pressure of about 1.25 bar and a bottom temperature of 85 ± 5 ° C. The upper stream, the vapor fraction stream S4c (stream (15c), maximum 1% of stream S4a), was completely condensed by an external upper condenser (not shown in Figure 2) and applied essentially by complete to use the condensed liquid stream as reflux to the second distillation column. The liquid bottoms stream S4 (stream 15) was removed and proceeded to the next stage (recycle of stream S4). Stream S4 had an acetonitrile content of about 80% by weight and a water content of about 20% by weight.

1.5 Recycling of current S4 (stage (4))

a) Preparation of a liquid stream S5

Stream S4 (stream 15 according to FIG. 1 and FIG. 2) was mixed with stream S2 (stream (13a) according to FIG. 1 and FIG. 2). Thus, stream s 4 was pumped back into the acetonitrile solvent stream from the bulk process. Mixing took place at a point downstream from where stream S3 deviated from stream S1. This combined stream having a flow rate of 86 kg / h was mixed with a liquid stream P (called stream (20) in Figure 1 and Figure 2) to obtain a stream S5. Stream P was a fresh propene stream containing propane (polymer grade, purity> 96% by weight, liquefied under pressure, feed rate: 10.9 kg / hr). To obtain the current S5, the combined current of S2 and S4 was additionally mixed with two other currents: the first of these currents is the current (16) according to Figure 1, and said current is obtained from the upper part of the unit. distillation H. The second of these streams is stream (19) according to Figure 1, and said stream is obtained from the acetonitrile recovery unit I. Both streams (16) and (19) are described in detail below.

b) Adjustment of the temperature of the current S5 and separation of the liquid phases L1 and L2

Stream S5 having a flow rate of 130 kg / h ± 10 kg / h was then fed to a mixer-decanter unit operated at 18 bar and a temperature in the range of 15 ± 5 ° C. The sedimentation tank had a volume of 5.3 liters. Two liquid phases L1 and L2 were obtained, an aqueous phase L2 and an organic phase L1. The upper organic phase L1 was removed from the settling tank as stream (17), the lower aqueous phase L2 was removed from the settling tank as stream (18). Stream (17) had a flow rate in the range of 110 kg / h ± 11 kg / h. Stream (17) was then passed to acetonitrile recycle unit I, stream (18) was passed to acetonitrile recovery unit H from which the above-mentioned stream (16) was obtained. The stream (17) thus obtained had an acetonitrile content of approximately 45-51% by weight, a propene content of approximately 49-55% by weight and a water content of approximately 2 to 5% by weight.

The stream (18) thus obtained had an acetonitrile content of approximately 19-21% by weight, a water content of approximately 79-81% by weight and a propene content of less than 0.5% by weight.

c) Recovery of acetonitrile (recovery unit of acetonitrile H)

To recycle as much solvent as possible and to minimize acetonitrile losses, stream (18) was introduced into a distillation column from which stream (16), also called stream TL2, was obtained as an overhead stream which, at in turn, it was recycled into the solvent stream as described above. For this purpose, a distillation column with a height of 9.5 m and a diameter of 100 mm, equipped with 50 bubble trays, was used. The column was operated at a higher pressure of 1.5 bar with a reflux ratio of 1: 4. Stream (18) was fed to column above bubble tray 26 (counted from the bottom). The bottoms temperature was approximately 113 ° C, and the bottoms product consists mainly of water containing high-boiling by-products. A typical composition of the bottoms stream was as follows (wt% in parentheses): water (> 99.0), propeneglycol (0.5), acetonitrile (0.001 maximum), dipropylene glycol (0.06), acetamide (0.01), acetic acid ( 0.03), TOC (2.4)). After optionally dosing and analyzing, this stream was discarded. The overhead product (stream (16) = stream TL2) had the following typical composition ranges (wt% in parentheses): acetonitrile (75-80), water (15-20), low-boiling compounds (for example, propene, 1). As described above, stream (16) is recycled to the feed stream which is passed to the mixer-decanter unit.

d) Recycling of acetonitrile (recycling unit of acetonitrile I)

For the recycling of acetonitrile, the stream (17) obtained from the mixer-decanter unit G was introduced into a distillation column with a height of 10 m and a nominal diameter of 200 mm, equipped with 40 bubble trays. The column was operated at a higher pressure of 18 bar with a reflux ratio of 1: 4. Stream (17) was fed to the column above bubble tray 26 (counted from the top). The top product (stream (19)), also called TL1 stream, containing mainly propene (about 97% by volume) with small amounts of propane (about 1-3% by volume) was returned to the feed of the mixing unit- decanter G as described above. Therefore, the excess propene was removed from the vapor (17) and recycled. The bottoms stream (stream (2), also called stream BL1), had a temperature in the range of 106 to 110 ° C. The precise operating parameters of the column, such as the energy input into the sump, are adjusted in such a way that the amount of propene returned to the reactor with stream (2) is in a range such that the molar ratio of propene to peroxide hydrogen in stream (1) is about 1: 1.43. For the above-mentioned feed rate of 15 kg / h of aqueous hydrogen peroxide, this means that the conditions had to be adjusted so that the flow rate of propene in stream (2) was about 9.7 kg / h. Before feeding stream (2) to main epoxidation reactor A, acetonitrile (stream (4), chemical grade, from Ineos, purity about 99.9%, containing between 70-180 ppm by weight of propionitrile, 5-20 ppm by weight of acetamide and <100 ppm by weight of water as impurities) was optionally added to compensate for possible solvent losses.

The exact amount of acetonitrile further added required depended on losses in the outlet streams and by-products, but also on the number of samples taken for analysis. A typical amount of acetonitrile added further for the process design described above may be in the range of 100 to 150 g / hr.

Comparative Example 1a: One-time ZnTiMWW Catalyst Regeneration

Partial regeneration of the ZnTiMWW catalyst was performed based on the epoxidation reaction setup as described in Reference Example 2 above. The reactor was charged with the ZnTiMWW catalyst according to Reference Example 1. The epoxidation reaction was operated continuously until the selectivity with respect to the formation of propylene oxide in (a2) based on hydrogen peroxide decreased by 2% with with respect to the average selectivity with respect to the formation of propylene oxide in (a2) based on hydrogen peroxide during the first 1000 h of performance of step (a). The reaction was then stopped and the reactor purged free of H ² O ² , propylene, and propylene oxide. After decompression and emptying, the reactor was washed at 70 ° C with demineralized water from top to bottom with an LHSV (liquid hourly space velocity) of approximately 7 m / h (the LHSV is based on the cross section of the tubes empty) for at least 3 hours. After this time, the aqueous liquid system exiting the reactor had a total organic carbon concentration lower than 0.1% of the maximum value detected and the total volume of the aqueous liquid system obtained from the reactor in the washing procedure was greater than the volume of the reactor. The reactor was then emptied and restarted. Continuous operation according to Reference Example 2 was resumed and was carried out for about 1500 h until the reaction temperature again reached the value it had before regeneration.

Comparative example 1b: continuous operation according to reference example 2 without regeneration

As a comparative example, the procedure according to reference example 2 was carried out for 2500 h without regenerating the catalyst.

Results of example 1a and comparative example 1b

The results of Comparative Example 1a and Comparative Example 1b are discussed below and shown in Table 1. The inlet temperature of the heat transfer medium of epoxidation unit A in both Comparative Example 1b and Comparative Example 1b was adjusted during continuous operation according to Reference Example 2 to keep the hydrogen peroxide conversion essentially constant in the range of 90 to 92% (see Reference Example 2, section 1.1 a). The resulting temperature of the heat transfer medium (cooling water) of the epoxidation unit A after a total operating time of 2500 h is shown in Table 1 for both Comparative Example 1b and Comparative Example 1a. Furthermore, the deactivation rate is given as the ratio between the temperature difference of the heat transfer medium at the inlet at the end of the experiment and the beginning of the experiment divided by the total operating time of 2500 h, expressed in ° C / day. Furthermore, the S selectivity of the hydrogen peroxide based epoxidation reaction after the total run time of 2500 h is given in Table 1. The S /% selectivity = (n (PO) / n (H ² O ² ) ) x 100 where n (PO) is the molar amount of propylene oxide detected directly downstream of unit B and n (H ² O ² ) is the molar amount of hydrogen peroxide converted in the epoxidation reaction.

Table 1

As clearly shown in Table 1, the procedure according to Comparative Example 1a allows the epoxidation unit A to be operated after a total operating time of 2500 h at a significantly lower temperature of the cooling water; that is, the catalyst exhibits a significantly better performance than in Comparative Example 1. Furthermore, also the deactivation rate (delta (T) / delta (t)) differs for the two experiments and is significantly lower with respect to Comparative Example 1a . Furthermore, the process according to the present invention provides, after a total operating time of 2500 h, a selectivity significantly higher than that of Comparative Example 1b.

The regenerated catalyst of Comparative Example 1a exhibited a differential conversion temperature of 1 K, where the differential conversion temperature is defined as the absolute difference between (A1) the temperature at which the 90-degree hydrogen peroxide conversion was achieved. 92% when regenerated catalyst is used as catalyst, and (B1) the temperature at which said determined hydrogen peroxide conversion was achieved when the respective fresh catalyst was used under otherwise identical epoxidation reaction conditions. Furthermore, the regenerated catalyst of Comparative Example 1a exhibited a differential selectivity of 0.3 percentage points where the differential selectivity is defined as the absolute difference in percentage points between (A2) the selectivity based on hydrogen peroxide in the epoxidation process in the which the regenerated catalyst is used as the catalyst, and (B2) the hydrogen peroxide-based selectivity in said epoxidation process wherein the respective new catalyst is used as the catalyst under otherwise identical epoxidation reaction conditions.

Example 2.1: Regeneration of the ZnTiMWW catalyst according to the invention including three washing stages

Partial regeneration of the ZnTiMWW catalyst was performed based on the epoxidation reaction setup as described in Reference Example 2 above.

Epoxidation

Partial regeneration of the ZnTiMWW catalyst was performed based on the epoxidation reaction setup as described in Reference Example 2 above. The main reactor was charged with the ZnTiMWW catalyst according to Reference Example 1. The epoxidation reaction was run continuously for approximately 1300 hours up to the "epoxidation reaction temperature", defined as the temperature of the heat transfer medium at the inlet. of the jacket of the main reactor whose starting value at the beginning of the epoxidation reaction was 30 ° C, had reached a value of 50 ° C. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

First stage of washing

Subsequently, the reaction tubes were filled from below with water at a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Epoxidation

Continuous operation according to Reference Example 2 was resumed and was carried out for about 1400 h until the reaction temperature reached 50 ° C again. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

Second stage of washing

Subsequently, the reaction tubes were filled from below with water at a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Epoxidation

Continuous operation according to Reference Example 2 was resumed and was carried out for about 1200 h until the reaction temperature again reached the value of 50 ° C. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

The residual amounts of acetonitrile and water were removed from the reactor by passing nitrogen through the catalyst bed at a nitrogen temperature of 70 ° C.

Third washing stage

Subsequently, the reaction tubes were filled from below with water at a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Calcination stage

Then, nitrogen was passed through the catalyst bed for about 60 hours at an initial nitrogen temperature of 70 ° C, where this temperature was raised to a value of 100 ° C at 10 K / h. Subsequently, the catalyst was calcined by passing a gaseous mixture of air and nitrogen through the catalyst bed at a flow rate of 0.58 kg / s. The temperature of said mixture was further raised continuously at 10 K / h from its initial value of 100 ° C to a final value of 450 ° C and then was kept essentially constant at a value of 450 ° C for 6 hours. At the beginning of the calcination, the gas mixture passed to the reactor had an oxygen content of 4% by volume. Once 450 ° C was reached, said oxygen content was adjusted to a value of 21% by volume. After calcination at 450 ° C, the reactor was cooled to a temperature of about 30 ° C.

Epoxidation

Continuous operation was resumed according to Reference Example 2 and was carried out for about 1000 h.

Example 2.2: Regeneration of the ZnTiMWW catalyst according to the invention including two washing stages

Partial regeneration of the ZnTiMWW catalyst was performed based on the epoxidation reaction setup as described in Reference Example 2 above.

Epoxidation

The main reactor was charged with the ZnTiMWW catalyst according to Reference Example 1. The epoxidation reaction was run continuously for approximately 1200 hours until the "epoxidation reaction temperature", defined as the temperature of the heat transfer medium at the inlet. of the jacket of the main reactor whose starting value at the beginning of the epoxidation reaction was 30 ° C, had reached a value of 50 ° C. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

First stage of washing

Subsequently, the reaction tubes were filled from below with water having a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Epoxidation

Continuous operation according to Reference Example 2 was resumed and was carried out for about 1300 h until the reaction temperature again reached the value of 50 ° C. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

The residual amounts of acetonitrile and water were removed from the reactor by passing nitrogen through the catalyst bed at a nitrogen temperature of 70 ° C.

Second stage of washing

Subsequently, the reaction tubes were filled from below with water having a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Calcination stage

Then, nitrogen was passed through the catalyst bed for about 60 hours at an initial nitrogen temperature of 70 ° C, where this temperature was raised to a value of 100 ° C at 10 K / h. Subsequently, the catalyst was calcined by passing a gaseous mixture of air and nitrogen through the catalyst bed at a flow rate of 0.58 kg / s. The temperature of said mixture was further continuously raised to 10 K / h from its value initial 100 ° C to a final value of 450 ° C and then held essentially constant at 450 ° C for 6 hours. At the beginning of the calcination, the gas mixture passed to the reactor had an oxygen content of 4% by volume. Once 450 ° C was reached, said oxygen content was adjusted to a value of 21% by volume. After calcination at 450 ° C, the reactor was cooled to a temperature of about 30 ° C.

Epoxidation

Continuous operation was resumed according to Reference Example 2 and was carried out for about 1000 h.

Comparative Example 2: Regeneration of the ZnTiMWW catalyst including a washing step

Epoxidation

Regeneration of the ZnTiMWW catalyst was performed based on the epoxidation reaction setup as described in Reference Example 2 above. The main reactor was charged with the ZnTiMWW catalyst according to Reference Example 1. The epoxidation reaction was operated continuously for approximately 2200 hours up to the "epoxidation reaction temperature", defined as the temperature of the heat transfer medium at the inlet. of the jacket of the main reactor whose starting value at the beginning of the epoxidation reaction was 30 ° C, had reached a value of 50 ° C. At that time, the epoxidation reaction was stopped by stopping the flow of hydrogen peroxide; Acetonitrile and propene flows were continued until epoxidation in the tubes was complete. The reactor was then purged to free H ² O ² , propylene, and propylene oxide by passing a mixture of acetonitrile and water through the reactor (80% by weight acetonitrile, 20% by weight water) where the temperature of this mixture was 50 ° C, followed by draining most of the acetonitrile and water mixture from the reactor.

The residual amounts of acetonitrile and water were removed from the reactor by passing nitrogen through the catalyst bed at a nitrogen temperature of 70 ° C.

Washing stage

Subsequently, the reaction tubes were filled from the bottom with water at a temperature of 70 ° C, and then water at a temperature of 70 ° C was passed from the top down through the tubes for about 6 h. The water wash was stopped once the conductivity of the flowing water was below 200 microSiemens. The water was then drained from the reactor.

Calcination stage

Then, nitrogen was passed through the catalyst bed for about 60 hours at an initial nitrogen temperature of 70 ° C, where this temperature was raised to a value of 100 ° C at 10 K / h. Subsequently, the catalyst was calcined by passing a gaseous mixture of air and nitrogen through the catalyst bed at a flow rate of 0.58 kg / s. The temperature of said mixture was further raised continuously at 10 K / h from its initial value of 100 ° C to a final value of 450 ° C and then was kept essentially constant at a value of 450 ° C for 6 hours. At the beginning of the calcination, the gas mixture passed to the reactor had an oxygen content of 4% by volume. Once 450 ° C was reached, said oxygen content was adjusted to a value of 21% by volume. After calcination at 450 ° C, the reactor was cooled to a temperature of about 30 ° C.

Epoxidation

Continuous operation was resumed according to Reference Example 2 and was carried out for about 1000 h.

Results of Examples 2.1 and 2.2 and Comparative Example 2

The results of Examples 2.1 and 2.2 and Comparative Example 2 are discussed below and shown in Table 2 below. The inlet temperature of the heat transfer medium from epoxidation unit A in both Examples 2.1 and 2.2 and Comparative Example 2 was adjusted during continuous operation according to Reference Example 2 to maintain the hydrogen peroxide conversion essentially constant at about 96%. The selectivity S of the hydrogen peroxide based epoxidation reaction as given in Table 2 is defined as (n (PO) / n (H ² O ² )) x 100 where n (PO) is the molar amount of oxide of propylene detected directly downstream of unit B and n (H ² O ² ) is the molar amount of hydrogen peroxide converted in the epoxidation reaction.

Table 2

As clearly shown in Table 2, a process according to the invention where one washing step (example 2.2) and two washing steps (example 2.1) are carried out without a subsequent calcination step leads to a slight improvement, although however existing, in the selectivity (1000 hours after calcination) compared to a common procedure (comparative example 2) according to which a calcination is carried out directly after the (only) washing step. This remarkable result is achieved, although the total epoxidation time up to the calcination stage is longer (more than 300 hours compared to example 2.2) or even significantly longer (more than 1700 hours compared to example 2.1). Therefore, it is convincingly shown that the inventive concept of a partial regeneration according to step (i) which avoids a calcination step after each washing step and therefore represents a significantly less complex procedure, unexpectedly leads to even improved results with respect to the most important parameter of a process, in particular on an industrial scale, that is the selectivity with respect to the valuable product.

Cited literature

- WO 98/55229 A1

- EP 1221 442 A1

- WO 2005/000827 A1

- WO 2007/013739 A1

- Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume 13, pp. 447-456

- Atlas of Zeolite Framework Types, 5th edition, Elsevier, London, England (2001)

- US 2007043226 A1

- US 6,114,551

- Wu et al., "Hydrothermal Synthesis of a novel Titanosilicate with MWW Topology", Chemistry Letters (2000), pp. 774 775

- WO 2013/117536 A2

- WO 2015/010994 A1

Claims (15)

1. A process for the regeneration of a catalyst comprising a zeolite containing titanium of MWW framework structure as catalytically active material, comprising (i) a stage comprising (a) continuously preparing propylene oxide comprising (a1) introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into a reactor containing a catalyst comprising the MWW framework titanium-containing zeolite as a catalytically active material; (a2) subjecting the feed stream according to (a1) in the reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent; (a3) withdrawing a product stream comprising the propylene oxide and the organic solvent from the reactor; (b) stopping the introduction of the feed stream into the reactor; (c) washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, wherein the washing is carried out for 2 to 12 hours ; step (i) further comprising repeating the sequence of steps (a) to (c) n times and n is an integer in the range of 1 to 10; the procedure for regeneration further comprises (ii) a step that comprises the calcination of the catalyst obtained from (c) after having repeated the sequence of steps (a) to (c) n times, wherein the calcination is carried out at a catalyst temperature in the range of 300 to 600 ° C, using a gas stream comprising oxygen in the reactor containing the catalyst; where the sequence of steps (i) to (ii) is optionally repeated m times and m is an integer and is at least 1, where in each repetition of the sequence of steps (i) to (ii), n is equal or different. 2. The process of claim 1, wherein the organic solvent is methanol or acetonitrile, preferably acetonitrile. The process of claim 1 or 2, wherein at least 99% by weight, preferably at least 99.5% by weight, more preferably at least 99.9% by weight of the framework structure of the titanium-containing zeolite, of the MWW framework structure, it consists of silicon, titanium and oxygen. 4. The process of any of claims 1 to 3, wherein the MWW framework titanium-containing zeolite comprises Zn. The process of any one of claims 1 to 4, wherein the catalyst comprising a zeolite containing titanium of MWW framework structure is present in the reactor as a fixed bed catalyst. 6. The process of any of claims 1 to 5, wherein the aqueous liquid system according to (c) contains at least 99.9% by weight of water, based on the total weight of the aqueous liquid system. 7. The process of any of claims 1 to 6, wherein according to (c), the catalyst washing is carried out in the reactor containing the catalyst in continuous mode. The method of claim 7, wherein the reactor according to (a) is a tube reactor or a tube bundle reactor and the washing according to (c) is carried out with the aqueous liquid system at an hourly space velocity of the liquid. (LHSV) in the range 1 to 20 m / h, preferably 5 to 10 m / h. The process of any of claims 1 to 8, wherein the washing according to (c) is carried out at a temperature of the aqueous liquid system in the range of 30 to 90 ° C, preferably 40 to 80 ° C. 10. The process of any of claims 1 to 9, wherein the washing according to (c) is carried out until the total organic carbon concentration of the aqueous liquid system after having been in contact with the catalyst is a maximum of 5%, preferably at most 1% of the maximum total organic carbon concentration detected during the wash in (c). The process of any of claims 1 to 10, wherein the sequence of steps (b) and (c) is carried out when the selectivity of the epoxidation reaction according to (a2) has decreased by 4% or less, preferably by 3% or less, more preferably 2% or less, with respect to the average selectivity of the epoxidation reaction according to (a2) during the first 100 h of performance of step (a), wherein the selectivity of the Epoxidation reaction is defined as the molar amount of propylene oxide obtained in (a2) in relation to the molar amount of hydrogen peroxide converted in (a2). 12. The method of any of claims 1 to 11, wherein n is in the range of 1 to 6, more preferably 1 to 4. The process of any of claims 1 to 12, wherein the calcination according to step (ii) is carried out at a catalyst temperature in the range of 350 to 550 ° C, preferably 400 to 500 ° C, preferably using a gas stream comprising oxygen and nitrogen, wherein the gas stream is preferably air or lean air. The method of any of claims 1 to 13, wherein the sequence of steps (i) to (ii) is repeated m times and m is an integer in the range of 1 to 6, more preferably 1 to 4 . 15. A continuous process for the preparation of propylene oxide, comprising (i ') a stage comprising (a ') continuously preparing propylene oxide in a first reactor comprising (a1 ') introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into the first reactor containing a catalyst comprising a zeolite containing titanium of MWW framework as catalytically active material ; (a2 ') subjecting the feed stream according to (a1') in the first reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent; (a3 ') withdrawing a product stream comprising propylene oxide and organic solvent from the first reactor; (b ') stop the introduction of the feed stream into the first reactor; (c ') washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, where the washing is carried out for 2 to 12 hours; step (i ') further comprising repeating the sequence of steps (a') to (c ') n' times, and n 'is an integer in the range of 1 to 10; the process that comprises the preparation of propylene oxide that further comprises (ii ') a step that comprises the calcination of the catalyst obtained from (c') after having repeated the sequence of steps (a ') to (c') n 'times, wherein the calcination is carried out at a catalyst temperature in the range of 300 to 600 ° C using a gas stream comprising oxygen in the reactor containing the catalyst; where the sequence of steps (i ') to (ii') is optionally repeated m 'times and m' is an integer and is at least 1, where in each repetition of the sequence of steps (i ') to (ii '), n' is the same or different; the process for the preparation of propylene oxide which further comprises (i ") a stage comprising (a ") continuously preparing propylene oxide in a second reactor comprising (a1 ") introducing a feed stream comprising propene, hydrogen peroxide or a source of hydrogen peroxide and an organic solvent into the second reactor containing a catalyst comprising a zeolite containing titanium of MWW framework as catalytically active material ; (a2 ") subjecting the feed stream according to (a1") in the second reactor to epoxidation conditions in the presence of the catalyst, obtaining a reaction mixture comprising the propylene oxide and the organic solvent; (a3 ") withdrawing a product stream comprising the propylene oxide and the organic solvent from the second reactor; (b ") stopping the introduction of the feed stream into the second reactor; (c ") washing the catalyst in the reactor containing the catalyst with an aqueous liquid system containing at least 95% by weight of water, based on the total weight of the aqueous liquid system, where the washing is carried out for 2 to 12 hours; step (i ") further comprising repeating the sequence of steps (a") to (c ") n" times, and n "is an integer in the range of 1 to 10; the process comprising the preparation of oxide propylene which further comprises (ii ") a step that comprises the calcination of the catalyst obtained from (c") after having repeated the sequence of steps (a ") to (c") n "times, wherein the calcination is carried out at a temperature of catalyst in the range of 300 to 600 ° C using a gas stream comprising oxygen in the reactor containing the catalyst; wherein the sequence of steps (i ") to (ii") is optionally repeated m "times, and m "is an integer and is at least 1, where in each repetition of the sequence of steps (i") to (ii "), n" is the same or different; wherein during at least one sequence of steps (b ') and (c') or at least one sequence of steps (b '), (c') and (ii '), propylene oxide is prepared according to (a ") .