Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/08—Silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/063—Titanium; Oxides or hydroxides thereof
• • B01J35/23—
• • B01J35/40—
• • B01J35/615—
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0209—Impregnation involving a reaction between the support and a fluid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0238—Impregnation, coating or precipitation via the gaseous phase-sublimation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/08—Heat treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/08—Heat treatment
  • B01J37/10—Heat treatment in the presence of water, e.g. steam
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D301/00—Preparation of oxiranes
  • C07D301/02—Synthesis of the oxirane ring
  • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
  • C07D301/19—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with organic hydroperoxides

Definitions

• the present invention relates to the preparation of an epoxidation catalyst and to the process of preparing alkylene oxide utilising said catalyst .
• An epoxidation catalyst is understood to be a catalyst which catalyses the manufacture of an epoxy group containing compound.
• a well known process comprises contacting organic hydroperoxide and alkene with a heterogeneous epoxidation catalyst and withdrawing a product stream comprising alkylene oxide and an alcohol.
• Catalysts for the manufacture of an epoxy group containing compound are well known.
• EP 345856 A describes the preparation of an
• epoxidation catalyst comprising impregnating a silicium compound with a stream of gaseous titanium tetrachloride preferably comprising an inert gas.
• a silicium compound preferably comprising an inert gas.
• gaseous titanium tetrachloride preferably comprising an inert gas.
• WO 2004/050233 Al discloses a further improved process for the preparation of an epoxidation catalyst comprising impregnating a silicon containing carrier with a gas stream consisting of titanium halide, wherein the resulting catalyst has improved selectivity even though the carrier has been in contact with the same amount of titanium halide.
• US 6114552 A and US 6383966 Bl teach the use of a high surface area silica support or the like having a surface area greater than 1100 m ⁇ /g in preparing
• the high surface area solid is impregnated with either a solution of a titanium halide in a non-oxygenated hydrocarbon solvent or a gas stream of titanium tetrachloride. It is mentioned that it is desirable to dry the silica support prior to
• US 5932751 A describes the preparation of titanium on silica catalysts in which the silica has been washed prior to the deposition of the titanium component thereon. A solution is used for depositing the titanium component .
• step (b) drying the impregnated silica carrier obtained in step (a) ;
• step (c) calcining the product obtained in step (b) at a temperature of at most 750 °C;
• step (d) silylating the product obtained in step (c) , to give a titanium-based catalyst active in epoxidation
• WO 2004/050241 Al describes an epoxidation catalyst having improved selectivity, which catalyst is prepared by a process comprising:
• step (b) contacting the carrier obtained in step (a) with a gas stream containing titanium halide to obtain an impregnated carrier.
• Catalyst fines are catalyst particles that are typically smaller than 0.6 mm in weight average particle size. Such catalyst fines lead to a steep build-up of pressure drop across the catalyst bed in the commercial reactors. These fines also affect the isolation valves downstream of the reactors by scratching the valve seat surface which prevents complete isolation of the
• the present invention provides a process for the preparation of an epoxidation catalyst, which process comprises :
• step (b) contacting the carrier obtained in step (a) with a gas stream containing titanium halide to obtain an impregnated carrier.
• epoxidation catalyst made in accordance of the process of the present invention in a commercial reactor set up for the epoxidation of propylene to propylene oxide with the performance of a comparative sample of Ti catalyst typically used in the commercial epoxidation of
• the catalyst of the present invention is obtained by drying of a silica gel carrier, and subsequent
• any silica gel carrier having a surface area in the range of from 330 to 450 m 2 /g is suitable for use in the preparation process according to the present invention.
• surface area is determined in accordance with the well known B.E.T. (Brunauer-Emmett- Teller) nitrogen adsorption technique, often simply termed the "B.E.T. method".
• B.E.T. Brunauer-Emmett- Teller
• B.E.T. surface area refers to the surface area of the silica gel carrier prior to
• the silica gel carrier for use in the present invention preferably has a surface area in the range of from 340 to 450 m ⁇ /g, more preferably in the range of from 350 to 450 m ⁇ /g, even more preferably in the range of from 380 to 450 m ⁇ /g and most preferably in the range of from 400 to 450 m 2 /g, according to ASTM D4365-95.
• the silica carrier contains at most 1200 ppm of sodium, more specifically at most 1000 ppm of sodium. Further, the silica carrier preferably comprises at most 500 ppm of aluminium, at most 500 ppm of calcium, at most 200 ppm of potassium, at most 100 ppm of magnesium and at most 100 ppm of iron.
• the silica gel carrier for use in the present invention can in principle be any carrier having a surface area in the range of from 330 to 450 m ⁇ /g and which is derived from a silicon-containing gel.
• silica gels are a solid, amorphous form of hydrous silicon dioxide distinguished from other hydrous silicon dioxides by their microporosity and hydroxylated surface.
• Silica gels usually contain three-dimensional networks of aggregated silica particles of colloidal dimensions. They are typically prepared by acidifying an aqueous sodium silicate solution to a pH of less than 11 by combining it with a strong mineral acid.
• Si (OH) 4 monosilicilic acid
• Si (OH) 4 monosilicilic acid
• the polymer particles aggregate, thereby forming chains and ultimately gel networks.
• Silicate concentration, temperature, pH and the addition of coagulants affect gelling time and final gel
• the resulting hydrogel is typically washed free of electrolytes, dried and
• the silica gel carrier for use in the present invention has a weight average particle size in the range of from 0.2 to 3.0 mm, more preferably in the range of from 0.4 to 2.5 mm and most preferably in the range of from 0.7 to 2.0 mm.
• Silica gel carriers that may be conveniently used in the present invention are commercially available from Grace, PQ Corp. and Kukdong.
• the silica gel carrier may be subjected to a pre-treatment prior to step (a) , said pre-treatment comprising calcining the silica gel carrier and
• Hydrolysis comprises treating the carrier with water or steam.
• the hydrolysis is carried out with steam.
• the hydrolysis treatment may comprise a washing treatment using an aqueous solution of a mineral acid, an aqueous solution of an ammonium salt or a combination thereof. Any water which might still be present after hydrolysis is preferably removed before treating the carrier further. Water is preferably removed by the drying of step (a) .
• the calcination is carried out at a relatively high temperature.
• the preferred carrier pre-treatment prior to step (a) comprises (i) calcining the silica gel carrier at a temperature of at least 400 °C and (ii) hydrolysing the calcined silica gel carrier.
• the hydrolysed calcined silica gel carrier of pre-treatment step (ii) may then be subjected to steps (a) and (b) of the process of the present invention.
• the calcination of pre-treatment step (i) is carried out at a temperature in the range of from 450 to 800 °C, more preferably in the range of from 500 to 700 °C.
• step (a) of the process of the present invention is carried out on calcined and hydrolysed carrier.
• the drying step (a) comprises subjecting silica gel carrier having a surface area in the range of from 330 to 450 m ⁇ /g, preferably in the range of from 340 to 450 m ⁇ /g, more preferably in the range of from 350 to 450 m ⁇ /g, even more preferably in the range of from 380 to 450 m2/g and most preferably in the range of from 400 to 450 m ⁇ /g, to a temperature in the range of from 300 to 450 °C.
• the drying will generally be carried out for a period in the range of from 15 minutes up to 10 hours, more specifically in the range of from 1 to 8 hours, most specifically in the range of from 1 to 5 hours.
• the drying is carried out at a temperature in the range of from 340 to 450 °C, more preferably in the range of from 340 to 430 °C and most preferably in the range of from 360 to 400 °C.
• the atmosphere in which step (a) is performed is not limited and may be air, an oxygen-containing atmosphere, or an inert, oxygen-free, atmosphere.
• step (a) may be conveniently performed in an oxygen-free atmosphere.
• the drying may be conveniently performed in an inert atmosphere comprising one or more of nitrogen, argon and helium.
• Said atmosphere preferably comprises less than 0.1 wt . % of oxygen. Most preferably, said atmosphere is nitrogen.
• silica gel carrier having a surface area in the range of from 340 to 450 m ⁇ /g, preferably in the range of from 350 to 450 m ⁇ /g, more preferably in the range of from 380 to 450 m ⁇ /g and most preferably in the range of from 400 to
• a preferred preparation method further comprises that the drying of step (a) is carried out at a
• step (b) is carried out.
• Such drying ensures that there is no substantial amount of water present during impregnation of the silica gel carrier with titanium halide. This prevents that a substantial amount of the titanium halide reacts with water. Reaction between titanium halide and water makes that titanium compounds are formed which do not contribute to
• the impregnation temperature of step (b) is the temperature of the silica gel carrier before being brought into contact with the gaseous titanium halide.
• the temperature of the carrier increases due to the exothermic nature of the reaction.
• a further preferred embodiment of the process of the present invention comprises supplying an amount of titanium halide in step (b) which is such that the molar ratio of titanium halide added to silicon present in the carrier is in the range of from 0.050 to 0.063.
• the silica gel carrier is contacted with the titanium halide for a period in the range of from 0.1 to 10 hours, more specifically in the range of from 0.5 to 6 hours.
• at least 30 wt . % of the titanium is added during the first 50 % of the impregnation time.
• the time of impregnation is taken to be the time during which the silica gel carrier is in contact with gaseous titanium halide.
• the silica gel carrier is contacted with a similar amount of titanium halide during the full time of the
• Titanium halides which may be conveniently used comprise tri- and tetra-substituted titanium complexes which have in the range of from 1 to 4 halide
• the titanium halide can be either a single titanium halide compound or can be a mixture of titanium halide compounds.
• the titanium halide comprises at least 50 wt. % of titanium tetrachloride, more specifically at least 70 wt. % of titanium tetrachloride.
• the titanium halide is titanium tetrachloride.
• the present invention comprises the use of a gas stream comprising titanium halide in step (b) .
• the gas stream consists of titanium halide, optionally in combination with an inert gas.
• the inert gas preferably is nitrogen.
• selective catalysts may be obtainable with the help of a gas stream solely consisting of titanium halide.
• the preparation is carried out in the absence of a carrier gas.
• limited amounts of further gaseous compounds are allowed to be present during the contact between the silica gel carrier and the gaseous titanium halide.
• the gas in contact with the carrier during impregnation preferably consists for at least 70 wt. % of titanium halide, more specifically at least 80 wt . %, more specifically at least 90 wt . %, most specifically at least 95 wt. %.
• Specific preferred processes have been described in WO 2004/050233 Al .
• Gaseous titanium halide can be prepared in any way known to someone skilled in the art.
• a simple and easy way comprises heating a vessel containing titanium halide to such temperature that gaseous titanium halide is obtained. If inert gas is to be present, the inert gas can be fed over the heated titanium halide.
• the impregnated carrier may be further treated before being used as a catalyst.
• the impregnated carrier will be calcined, subsequently hydrolysed and optionally
• the present invention provides a process further comprising:
• step (e) contacting the carrier obtained in step (d) with a silylating agent.
• impregnated carrier generally comprises subjecting the impregnated carrier to a temperature of at least 500 °C, more specifically at least 600 °C.
• the calcination is carried out at a temperature of at least 650 °C. From a practical point of view, it is preferred that the calcination temperature applied is at most 1000
• Hydrolysis of the impregnated and calcined carrier can remove remaining Ti-halide bonds.
• the hydrolysis of the impregnated carrier in step (d) generally will be more severe than the optional hydrolysis of the carrier before impregnation in pre-treatment step (i) .
• this hydrolysis of the impregnated carrier is suitably carried out with steam at a temperature in the range of from 150 to 400 °C.
• the hydrolysed impregnated carrier is subsequently silylated in step (e) .
• Silylation can be carried out by contacting the hydrolysed impregnated carrier with a silylating agent, preferably at a temperature of in the range of from 100 to 425 °C.
• Suitable silylating agents include organosilanes such as tetra-substituted silanes with C1-C3 hydrocarbyl
• a very suitable silylating agent is hexamethyldisilazane (HMDS) .
• silylating agents are, for instance, described in US 3829392 A and US 3923843 A which are referred to in US 6011162 A and in EP 734764 A.
• the amount of titanium (as metallic titanium) will normally be in the range of from 0.1 to 10 wt . %, suitably in the range of from 1 to 5 wt. %, and most preferably in the range of from 3 to 5 wt . %, based on total weight of the catalyst.
• titanium or a titanium compound, such as a salt or an oxide is the only metal and/or metal compound present.
• alkylene oxides such as propylene oxide
• hydroperoxide such as hydrogen peroxide or an organic hydroperoxide as the source of oxygen.
• the hydroperoxide can be hydrogen peroxide or any organic hydroperoxide such as tert-butyl hydroperoxide, cumene hydroperoxide and ethylbenzene hydroperoxide.
• the alkene will generally be propylene which gives as alkylene oxide, propylene oxide.
• Propylene for use in the epoxidation reaction may be conveniently prepared by propane dehydrogenation or by olefin metathesis as described in WO 2005/049534 Al and WO 2006/052688 A2. Such processes to prepare propylene may be conveniently integrated with the process to prepare propylene oxide.
• WO 2011/118823 Al describes an integrated process for preparing propylene oxide from propylene, wherein the propylene is first prepared in a propane dehydrogenation step. Processes for preparing propylene oxide which integrate epoxidation with propylene preparation via olefin metathesis reaction may also be conveniently employed.
• the catalyst prepared according to the present invention has been found to give especially good results in epoxidation processes.
• the present invention further relates to a process for the preparation of alkylene oxide which process comprises contacting a hydroperoxide and alkene with a heterogeneous epoxidation catalyst and withdrawing a product stream comprising alkylene oxide and an alcohol and/or water, in which process the catalyst is prepared according to the present invention.
• the hydroperoxide may be conveniently selected from hydrogen peroxide and organic hydroperoxides such as tert-butyl hydroperoxide, cumene hydroperoxide and ethylbenzene hydroperoxide.
• a specific organic hydroperoxide is ethylbenzene hydroperoxide, in which case the alcohol obtained is 1- phenylethanol .
• the 1-phenylethanol usually is converted further by dehydration to obtain styrene.
• Another method for producing propylene oxide is the co-production of propylene oxide and methyl tert-butyl ether (MTBE) starting from isobutane and propene .
• MTBE methyl tert-butyl ether
• This process is well known in the art and involves similar reaction steps as the styrene/propylene oxide production process described in the previous paragraph.
• tert-butyl hydroperoxide is reacted with propene forming propylene oxide and tert-butanol .
• Tert-butanol is subsequently etherified into MTBE.
• a further method comprises the manufacture of propylene oxide with the help of cumene. In this process, cumene is reacted with oxygen or air to form cumene hydroperoxide.
• Cumene hydroperoxide thus obtained is reacted with propene in the presence of an epoxidation catalyst to yield propylene oxide and 2-phenyl propanol.
• the latter can be converted into cumene with the help of a heterogeneous catalyst and hydrogen.
• Specific suitable processes are described for example in WO 02/48126 A.
• reaction conditions include temperatures in the range of from 50 to 140 °C, preferably in the range of from 75 to
• the silica gel carrier used in the examples had a surface area of 429 m ⁇ /g and a weight average particle size of about 1 mm. Substantially all particles had a particle size between 0.6 and 2.0 mm.
• the dried silica gel carriers thus obtained were contacted with a gas stream consisting of titanium tetrachloride.
• the gas stream was obtained by heating titanium tetrachloride to 200 °C with the help of an electrical heating system.
• the silica carrier was impregnated with the titanium tetrachloride gas stream.
• the impregnated catalysts thus obtained were
• catalysts were silylated at 185 °C for 2 hours by being contacted with 18 grams of hexamethyldisilazane per hour in a nitrogen flow of 1.4 Nl per hour.
• the catalytic performance of the titanium catalyst samples was measured by testing the catalyst in a process for epoxidation of 1-octene.
• Example 1 The afore-mentioned catalyst composition of Example 1 was prepared on a multi-ton scale and loaded in a commercial reactor set up for the epoxidation of
• Figures 1 and 2 compare the performance of this catalyst composition after carrier drying at 380 °C (Catalyst Sample G) with a sample of a titanium- containing catalyst typically used in the commercial epoxidation of propylene (Catalyst Sample H)
• MGR merry-go-round
• the fresh catalyst is loaded in the 4 MGR position and then it moved as it is ages from 4 th to 1 st MGR position, wherein it sees the fresh feed.
• FIG 1 gives the plot of tonnes of PO made per Kg of catalyst used. As seen from the plot, Catalyst Sample
• FIG 2 gives the intrinsic activity of Catalyst Sample G and comparative Catalyst Sample H. It is apparent that the intrinsic activity of Catalyst Sample G is higher in comparison to comparative Catalyst Sample H.
• Catalyst Sample H deactivates slowly in comparison to catalyst sample G.

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• 2016
  • 2016-11-07 CN CN201680065121.1A patent/CN108349918A/zh active Pending
  • 2016-11-07 WO PCT/EP2016/076872 patent/WO2017080962A1/en active Application Filing

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