CS263194B1

CS263194B1 - Catalyst for the preparation of alkylene oxides and / or isomers thereof

Info

Publication number: CS263194B1
Application number: CS8610071A
Authority: CS
Inventors: Antonin Ing Mikestik; Milan Ing Csc Polievka; Milan Ing Csc Dimun
Original assignee: Antonin Ing Mikestik; Polievka Milan; Dimun Milan
Priority date: 1986-12-29
Filing date: 1986-12-29
Publication date: 1989-04-14
Also published as: CS1007186A1

Abstract

Katalyzátor pre technologický postup, ktorý je založený na schopnosti rozkladu niektorých látok za svýšenej teploty. < Podstatou riešenia je synergická zmes iontové aktívneho zeolitu, ktorý je vo formě molekulového šita a bázickej látky zo skupiny alkalických soli karboxylových alebo minerálnych kyselin, ktoré majú hodnotu pH v 0,1 molárnom vodnom roztoku 8 až 13, pričom ich koncentrácia vztiahnuté na zeolit je v rozmedzí 0,1 až 50 % hmot.Catalyst for a technological process, which is based on the ability to decompose certain substances at elevated temperatures. < The essence of the solution is a synergistic mixture of ionic active zeolite, which is in the form of a molecular sieve, and a basic substance from the group of alkaline salts of carboxylic or mineral acids, which have a pH value in a 0.1 molar aqueous solution of 8 to 13, while their concentration relative to the zeolite is in the range of 0.1 to 50% by weight.

Description

263194 2

The present invention relates to a catalyst suitable for the preparation of alkylene oxides and / or isomers thereof by waste-free technology based on the ability to decompose some of the substances at elevated temperature.

With the enhancement of acetoxylation of alkenes, propylene oxide is a new progressive process that rests! replacing expensive palladium catalyst with other elements and their compounds, such as tellurium and selenium, titanium, manganese, tin, me3, lithium, potassium, and i. or an electrochemical acyloxylation process has opened the way to utilize the products of this oxy-esterification reaction. Thus, from propylene and acetic acid, oxygen is formed to form a mixture of the acetocypropanols, i.e. 1-acetoxy-2-propanol and 2-acetoxy-1-propanol otherwise called propylene glycol monoacetates / hydroxyesters / and 1,2-diacetoxypropane otherwise propylene glycol diacetate (diester). The reaction may also be conducted in such a way that the main product is either hydroxyesters or diesters.

A method for preparing propylene oxide based on Brownstein (U.S. Pat. 4,012,423, Ger. 2 412 136] to the deacyloxylation reaction of vicinal hydroxy esters according to the reaction scheme: R 1 -CC-R 4

OH

Catalyst]

250-600 ° C

Ro R

1 / C— C / v /

The general principle of deacyloxylation is essentially based on the cleavage of the acyloxy group (Rg-CO-O-) from the hydrocarbon chain of the aliphatic acyloxy derivative of the hydrocarbons together with the hydrogen atom from the adjacent carbon atom or hydroxyl group attached to the carbon atom. Vicinal hydroxyesters under the deacyloxylation reaction conditions either cyclize to form the corresponding oxirane derivative, or form oxirane isomer derivatives, while vicinal non-ester forms the corresponding alkenyl esters (U.S. Pat. 2,441,540, U.S. Pat. 2 251 983. No. 2,485,694, NSR Pat. 2,120,715]. The reaction is characterized in both cases by the formation of the corresponding carboxylic acid as a co-product. From thermodynamic smoothing pyrolysis of hydroxy ester to strong endothermic oxide.

Hydroxyesters can be treated by reaction in liquid / NSR pat. 2 707 638), but more often in the gaseous phase either alone or diluted with a carrier gas, which may also be a liquid condensing at a temperature of about 25 ° C (e.g. benzene. The reaction temperature must be high enough to maintain the vapor phase hydroxyester under reaction conditions: 250-600 ° C. The reaction is carried out in a wide range of pressures: 0.7 to 2,758 kPa, while the partial pressure of hydroxy ester is of key importance. It has been found that under reduced pressure there is a higher conversion of substrate without loss of selectivity. The preferred partial pressure of the hydroxy ester is between 6.9 and 103.4 kPa. The contact time of the substrate (S) may be 0.001 to 20 s, the catalyst load (K) from 0.5 to 1000 molg / mol.

The process for treating a mixture of 1,2-diacetoxypropane and vicinal acetoxypropanols as obtained by the acetoxylation of propene even in the presence of 1,2-propanediol has been prepared for reactions as in liquid / NSR Pat. And in the gas phase (U.S. Pat. No. 4,012,424, NSR Pat. 2,635,566, Ger. 2,624,628, Ger. 2,709,440). The presence of 1,2-diacetoxypropanunia is a defect, but only the processing of the mixture containing the smaller amount of hydroxy ester is so low per pass conversion that the process is virtually unusable for the formation of oxirates. Therefore, a mixture in which the diester is predominantly processed by selective hydrolysis / alcohol lysis / the diester to the hydroxy ester and partly to the diol, while the mixture in which the predominant diolsa is esterified so that the mixture contains 20 to 80% of the resulting esters in the equilibrium mixture, corresponding to the concentration of hydroxy ester min. 32 mol% In the liquid phase reaction, partial hydrolysis is carried out, respectively. esterification directly under the deacyloxylation reaction conditions. All of the above gas phase deacyloxylation processes on heterogeneous catalysts 3 263194 utilize either pure hydroxyester or mixtures thereof with diester / eventually as raw material. also with diol (in which the active ingredient is hydroxyester). This requires increased demands on both the oxy-esterification reaction (expensive palladium catalysts) and the reaction / partial hydrolysis reaction. The composition of the substrate used, particularly the content of diester and / or bodiol, is also influenced by the number of undesired by-products of the deacyloxylation reaction that result from parallel, consecutive and competitive dehydration, esterification, isomerization and pyrolysis reactions. As a result, the selectivity of the reaction to propylene oxide decreases and the catalyst life is also reduced.

It is known to prepare propylene oxide and / or isomers thereof based on the knowledge that only the vicinal diol / vicinal diester mixture is exposed to pyrolytic elimination, either in the equimolar ratio in the liquid phase / NSR pat. Or in a gas phase on heterogeneous catalysts having a diol to diethyl molar ratio of 1: 1 to 4: 1, preferably (CSSR AO 250 584). Under these reaction conditions, the hydroxy ester for the propylene oxide is not required at all, the major propylene oxide precursor is 1,2-propanediol, which undergoes gas phase dehydration under heterogeneous catalytic reaction conditions under the action of its diacetate. The excess diol has a beneficial effect on the propylene oxide formation selectivity and causes the reaction product not to contain acetic acid, which is otherwise produced by deacyloxylation as the dispersion reaction of the resulting hydroxy ester and diester. Acetic acid acts adversely during the reaction / decreases the propylene oxide yield by poor reaction / as well as in the reaction product / decreases propylene oxide selectivity by promoting its isomerization. In addition, it also causes a strong corrosion of the equipment, which technically disadvantages the industrial realization of the process.

Although a mixture of two different chemically different substances (diester and diol) emerges as the substrate, which themselves undergo a series of pyrolytic reactions under the reaction conditions, characteristic decomposition products (allyl acetate and other alkenyl esters, 1- and 2) do not form in their joint gas-phase reaction to heterogeneous catalysts. -propanol, 2-acetoxypropane, methyl ethyl ketone and others (as opposed to their co-reaction in the liquid phase). In addition to propylene oxide and its isomers, only a very small amount of acetaldehyde / selectivity of max. 3% is produced.

The possibly present vicinal Hydroxyester in the substrate is not a problem, but in this case a further increase in the diol content of the substrate is preferred, so that the molar ratio of diol to mixtureidiester and hydroxyester is min. 1.5: 1, preferably 2.5: 1, as opposed to the liquid phase reaction. A certain amount of the hydroxy ester is produced by the alcoholysis at a greater or lesser extent, depending on the reaction conditions, the carrier used and the catalyst, and during the reaction of the diester / diol mixture itself. In a mixture of unreacted diol, diester and the resulting hydroxy ester after separation of the easy-boiling products, the esters are hydrolyzed and the diol obtained is recirculated as a substrate and partially recovered as a by-product. Acetic acid from the hydrolysis of the esters is regenerated, and in the process of acetoxylation of propylene. Said method of preparation is also applicable to higher alkylene oxides, respectively. mixtures of alkylene oxides and / or isomers thereof.

Alkylalcohol and propionaldehyde / NSR are formed by deacyloxylation of vicinal acetoxypropanols on the catalysts with acidic reaction centers or without catalyst, or on inert fillers. 2 504 981), the propylene oxide is formed in the basic centers. In deacyloxylation to allyl alcohol carried out without catalyst, a number of allyl acetate and its isomers are produced by competitive dehydration (U.S. Pat. 2,415,378]. Preeacyloxylation to propionaldehyde is preferred to use as a substrate the vicinal formyloxypropanolypre beneficial effect of the emerging carbon monoxide / brit. pat. 655,968 /. Catalytic deacyloxylation accompanies the formation of a small amount of acetone.

As a catalyst for the formation of propylene oxide, a wide variety of substances have been used, the most common oxides and organic bases of metals I, II. and III.A of the Periodic Table. With decreasing 263194 4, borates, phosphates, oxides and carbonates may be used. As other substances, alkali metal or alkaline earth salts and boronic acids (e.g. tetra-sodium borate, potassium event. calcium, potassium metaborate event. calcium / alumina and sodium silicate eventually. potassium. Other substances that can be used are carbonate or magnesium carbonate. calcium, barium oxide, zinc; Nickel and Sodium Phosphate. Organic bases that could generally be adsorbed on a support are usually aromatic nitrogen compounds such as pyridine, quinoline or acridine and higher molecular weight alkylamines having a boiling point greater than 220 ° C. The more volatile substances can be advantageously used chemisorbed on non-volatile substances. These substances can be used alone or in combination with other substances.

However, alkali salts of carboxylic acids have been found to be most effective, preferably with the same anion as the leaving carboxyl group, e.g., potassium acetate, and neutral or basic carriers such as α-alumina, silicon carbide, zirconium silicate and aluminum silicate. Acidic carriers such as χ-alumina are not suitable because they promote the formation of aldehydes. Thus, in the case of deacyloxylation of vicinal acetoxypropanols alone with a catalyst consisting of 10% AcOK / A12C> 3 at 396 ° C, a hydroxyestet partial pressure of 24 kPa / benzene as the carrier gas and a contact time of 1 s, the selectivity reaches min. 76% at a conversion of 34%. Allyl alcohol under the stated conditions arises. A small portion (about 3%) of the hydroxy ester disproportionate to diester and diol. The acetic acid co-production is regenerated by the efficiency of ca 92% (US Pat. 4,012,423, Ger. 2,412,136]. By using tungsten catalyst (10% Na2 WO4) and -A12O3, 400 [deg.] C., contact time 1 s, carrier gas - benzene, AcOH in the substrate / it is possible to increase the selectivity to propylene oxide up to 100% when the conversion to 3.6% / Jap. pat. 79,144,304].

In deacyloxylation of a mixture of hydroxy ester, diester and / or diol, the same catalysts and carriers were used as in the preparation of propylene oxide by deacyloxylation of vicinal acetoxypropanols alone, ie basic catalysts in an inert solvent / sulfolane / resp. a charged or neutral carrier (e-alumina, silicon carbide, aluminum silicate). They are used either directly in the form of alkali metal carboxylates (e.g. potassium acetate (or are formed in situ), the precursor being alkali salts of weak mineral acids, such as carbonate / potassium / liquid phase / potassium silicate / gas phase reactions. Conversion and selectivity vary according to substrate composition, however, they are usually greater than that of the hydroxy ester itself.

Thus, in the liquid phase / K 2 CO 3 catalyst in sulfolane (270 ° C), the selectivity to propylene oxide is 80% with a total conversion of up to 68% with hydroxyester, as well as the substrate consisting of only an equimolar mixture of diol and diacetate in the range of 250 ° C to 260 ° C. the selectivity to propylene oxide remains substantially maintained (ca 79%), the diol conversion is min. 83%, diacetate min. 72% / NSR Pat. 2,707,638]. In the gas phase (8.65% K 2 SiO 2 / Al 2 O 3, 400 ° C, the partial pressure of the hydroxy ester, respectively. of substrate 7.7 kPa resp. 21.3 kPa, contact time 0.84 s, addition of water vapor / then selectivity reaches 93% at min. 37% conversion of the hydroxyester / US Pat. No. 4,012,424, NSR Pat. 2,635,566). The literature / Ger. No. 2,709,440, reported high values of propylene oxide molar yields (above 62% on a 10% AcOK / H2SiC3 catalyst at 400 DEG C. and a hydroxyester and diol substrate partial pressure of 24 kPa) are based only on the mixture of vicinal acetoxypropanols in simultaneous conversion 1,2-propanediol and / or 1,2-diacetoxypropane. The propylene oxide selectivity does not exceed 77 i.

High selectivity 88% with sufficiently high conversion of hydroxy ester of about 34% boiled on a 14% Na 2 SiO 3 / Al 2 O 3 catalyst at 400 ° C with a substrate formed by a mixture of hydroxyester and diester with a diol content of less than 4% by weight. at substrate partial pressure of 21.3 kPa / NSR Pat. 2,624,628].

In the case of a substrate consisting of an equimolar mixture of diol and diacetate (CSSR 5 263194 AO 250 584), the selectivity to propylene oxide of 80% at a conversion of diol of 13% and diacetate of 9% is achieved on a catalyst of 10% by weight of AcOK / α-Al 2 O 3. was 300 ° C, the initial pressure of the core component of the substrate ie 1,2-propanediol 13,3 kPa and the catalyst loading 16,7 kgg / kg 1/1. Higher yields of propylene oxide without substantial loss of selectivity at the same initial partial pressure of 1,2 -propanediol on the same catalyst can be achieved by optimizing the reaction temperature, catalyst loading and substrate composition, ie diol to diester, and a special transportfluidic catalytic reactor (Eur. Pat. No. 2,561, OSA Pat. No. 399,295) has been proposed to carry out the deacyloxylation reaction. it has some advantages over conventional catalytic reactors, despite the fact that it has achieved selectivity to propylene oxide / m and x. 86% (or yield / ca 34 t) does not exceed the previous methods. It works with the catalyst K2SiOj / A12O3 eventually. SiC or SiO2 at a temperature of 375 ° C, a contact time of 0.8 s with a substrate consisting of a mixture of hydroxyester and diester (diol content less than 0.7% w / w with the addition of aqueous vapor at a hydroxyester partial pressure of 6.9 to 55); 2 kPa. Comparison in a conventional fluidized bed reactor results in substantial mixing and long contact time; poor mixing causes reversible reactions and decreases selectivity, water vapor introduced directly into the reactor during separation condenses and causes product hydrolysis. It is again difficult to maintain a constant temperature in the catalytic converter reactor and selectivity problems arise.

These and other drawbacks of the prior art catalysts are eliminated by the present invention. A catalyst particularly suitable for the preparation of alkylene oxides / epoxy resins, oxiranes (e.g. propylene oxide (and / or isomers thereof) by pyrolytic elimination of aliphatic acyloxy derivatives of hydrocarbons, such as vicinal hydroxy esters or their vicinal diester and / or diol, respectively; only a mixture of vicinal diester and vicinalhodiol, the principle of which is that the catalyst consists of a synergistic mixture of ionic active zeolite based on an alkali metal aluminosilicate and / or alkaline earth metal aluminate which is in the form of a molecular sieve and a base from the group of alkali metal salts of carboxylic or mineral acids the pH in 0.1 molar aqueous solution 8 to 13, the concentration of which, based on the zeolite, is between 0.1 and 50% by weight, preferably between 5 and 15% by weight.

The catalytic activity of zeolites is related to the presence of protons or multivalent cations, which are very potent Brlnnsted centers, in addition, the dehydrated forms of zeolite catalysts contain various large regular porous channels and cavities / cavities which allow them to fill the molecular sieve function, with loss of water at the same time Brønsted's acidity and the formation of Lewis centers, which also has an effect on catalytic activity.

The activity of the catalyst is also influenced by the time and mode of activation.

Under the action of specific adsorption-catalytic and ion-exchange properties, they use inherently active centers, which form proton (H +) and hydroxyl / OH- / acidity, and thus, by hydrolysis, the hydrolytic / Al3 + / acidity / formation of Si-OH / still being obtained, These centers differ in both form and origin. Introduction of one resp. the multivalent ions into the zeolite structure by ion exchange modifies the non-physical-chemical properties / size of the cavity inlets as well as the catalytic activity of the zeolite catalysts. It has been shown that at some degree the catalytic activity of the azazolites reaches optimum for many reactions. In addition to selective adsorption, resulting from the geometric configuration / primary pore structure / and non-selective Langmuir adsorption / secondary pore structure /, the zeolites can also have selectivity, resulting in specific interaction with some active centers / electrostatic interaction with polar or polarizable molecules induced by metal cations present in the zeolite structure and hydrogen forming ability bridges with SiO2 hydroxyl groups. General suitable zeolites are aluminosilicates of the ideal formula 263194 6

Mp, Dq ^ A1p + 2qSir ° 2p + 4q + 2rJ · 8Η2 ° where: Μ - monovalent metal D - divalent metal p, q, r, s - stoichiometric coefficients

The most suitable types are those with a spatially developed structure that are more thermally stable than natural zeolites (e.g. groups of analci, natrolite, heulandite / clinoptiolite /, phillipsite, mordenite, chabazite, faujasite, laumontite /, and synthetic (e.g. type A, X, Y, ZSM /. The advantage of the proposed catalyst system over the known catalysts is the high selectivity of propylene oxide formation at a sufficiently high conversion! of the substrate component of the substrate, or partial conversion of the decomposition product of the substrate substrate, the key component of the substrate is a mixture of vicinal acetoxypropanols in the pyrolysis of the hydroxy ester or 1,2-propanediol in the pyrolysis of the 1,2-propanediol and 1,2-diacetoxypropane mixture. The yield is given as the degree of conversion to the k-th reactant component X X. sk - 100 Wk * ftokk "ftkk

Aokk = NKK / kk PAokk

Kk / P

where: S - selectivity / integral / X - conversion / degree of conversion / or - molar amount of substance tjmol.h-1] indices: k - decomposition component of reaction mixture kk - buckle component reaction mixture P - decomposition products

The loading of the catalyst was characterized by the fact that the reactions are accompanied by a change in the density of the reaction mixture due to a non-zero change in the number of moles during pyrolysis - and the ratio of the total flow rate of the reaction mixture ie substrate / Gg / kgg 8 of inert carrier gas / Gj / kg / h-1) to the total the amount of catalyst W £ kgK]: z - [• '«si ·'*; 1 ·""1]

The ratio of the individual isomers of propylene oxide in the reaction product can be influenced by the known method of impregnating the catalyst support with various active basic substances.

The proposed catalyst system is also applicable to the preparation of higher alkylene oxides and / or alkylene oxide mixtures and / or isanases thereof by the present invention and is exemplified by the following examples, which in no way limit the invention and exclude the possibility of versatility. using the principles of the invention. Examples

The catalyst supports used were the following:

Kremlin: 3 2 -1 -

Chemical composition: SiO, specific surface: 1.2.10 m .kg, equivalent radius of radius * € -3 3 '1 with maximum specific volume: 1.50.10 m, total Specific pore volume: 1.72.10 m .kg. 7 263194-alumina:

Chemical composition: A12O3, prescription! y-Al2O3 and -Al2O3, specific surface area: 18.4.10 m .kg, equivalent pore radius with maximum specific volume: 0.15.10-6 m, total specific pore volume: 0.47.10-3 m3.kg-1.

Nalsit 4A:

Chemical composition: Na2 £ Al2Si2O β] 'form: molecular sieve with cavity diameter 0.42.10-3 m, production standard: PND-9-025-66, surface area: 3.8.10 3 m2.kg 3, intracrystalline surface: / 650 to 800 / .103 m2.kg 3, equivalent pore radius with maximum specific volume: 0.18.10-6 m, total Specific pore volume: 0.26.10-3 m3.kg-1.

Calsit 5A:

Chemical composition: Na2Ca [Al4Si4O16], form: molecular sieve with cavity diameter 0.49.10-9 m, production standard: PND-9-025-66, specific surface area: 5.6.103 m2kg 3, intracrystalline surface: / 650 to 3 2 ” 1 · »- Λ 800 / .10 m .kg, equivalent pore radius with maximum specific volume: 0.11.10- ° m, - 3 3-1 total specific porous volume: 0.38.10 m .kg.

Carriers of a given grain size were impregnated with an active catalytic component which was dissolved in an experimentally determined maximum amount of distilled water capable of total adsorption. The catalysts were then dried in an oven for 4 hours at a temperature that gradually increased from 60 to 180 ° C and activated at 200 to 500 ° C in a stream of nitrogen containing a small amount of water vapor.

For the reaction, a steel tubular reactor with a fixed catalyst bed having an internal diameter of 6.10 3 m and a length of 0.26 m was used. The reaction temperature was measured inside the shell reactor at the center of the catalyst layer by a concentric platinum resistance thermometer with a diameter of 2.5 µm and controlled with accuracy + 1 ° C of a proportional regulator. To reduce the axial temperature gradient, the electric heating of the reactor was adjusted so that the long-term temperature graph was not higher than 1 ° C. The radial gradient of temperature and transfer across the catalytic bed was reduced by the appropriate grain size of the catalyst. The catalyst bed height was chosen taking into account the optimally axially agitated so as to meet the piston flow approximation. The experiments were carried out up to the steady state reaction system / feed mixture feed, reaction temperature and activity catalyst (s). The influence of external diffusion was ruled out by determining the constant value of the conversion of the loop component of the substrate for the same time coordinate values (ie, reciprocal weight of the catalyst load) for different catalyst weights. The internal diffusion efficiency factor for the selected catalyst granules was close to 1.

The area of experimental placement and the ranges of independent variables were determined using the Response Surface Methodology based on preliminary experiments. To achieve maximum selectivity to propylene oxide (80.9%) and a maximum total conversion of 1,2-propanediol and a mixture of vicinal acetoxypropanols (100%) on the catalyst. 20% AcOK / SiO, the optimum loading value of the catalyst Z ranges from 5.9 to 10 -1 20 kgg / kg / hr, reaction temperature from 296 to 448 ° C, initial partial pressure ratio of 1,2-propanediol to 1,2-diacetoxypropane in the range of 2.0 to 2.1; initial partial pressure of vicinal acetoxypropanols from 21 to 48 kPa, provided that the total initial substrate pressure is 66.7 kPa. The experiments were performed over a total working pressure of 100 to 138 kPa. For a different substrate composition, the initial partial pressure of the key component of the substrate was between 0.1 and 53.3 kPa.

The method of measurement is apparent from the following description. The carrier gas / nitrogen flowed from the pressure vessel through a set of reducing valves and adsorption towers filled with successive solid sodium hydroxide, activated carbon, and molecular sieves, through a canostat and a flow meter to a capillary 263194 8 preheater equipped with electric smoking where it was heated to the reaction temperature. From there it flowed into the evaporator where it was mixed with the vapor of the substrate, which was fed to the evaporator by a syringe using a linear dispenser.

The feed gas mixture, the pressure measured with a mercury gauge, flowed into the reactor downward, passed through successive layers of glass beads, catalyst and glass wool. The reacted gas mixture flowed through the concentric ceramic tube and its pressure was measured at the reactor outlet with a mercury gauge. After cooling with water in a spiral cooler, liquid products were collected in a collection flask cooled to -20 + 5 ° C. The last pair of bottled ingredients was condensed in the freezer, cooled to -60 + 10 ° C as well as the collecting flask with acetone-carbon dioxide. The remaining gas was passed through a differential capillary flow meter, a thermometer, and a bubble flow meter to the atmosphere. Liquid reaction products were collected from the collecting flask and freezer by capillaries and analyzed by gas-liquid chromatography. All components were evaluated by direct calibration using direct calibration. Example 1

Deacyloxylation was accomplished with a substrate that is a mixture of 58.2% by weight. 1-acetoxy-2-propanol and 32.4 wt. 2-acetoxy-1-propanol and contains 2.0 wt. 1,2-propanediol, 7.3 wt. 1,2-diacetoxypropane and 0.08 wt. water. The active ingredient of the acetate with potassium acetate was the impregnated carrier (10% w / w), which was a synthetic Calsit5A zeolite. The reaction was carried out at 400 ° C, the initial partial pressure of the mixture of vicinal acetoxypropanols was 13.2 kPa, the total pressure was 112.5 kPa, the catalyst load was • I-1 - 1 - 1 Z = 52.4 kgSI.kgK. . 20.31 kgs.kgR.h, ie, based on the acetoxypropanol 155 mol kg / 1.h-1 mixture. Conversion of the core component of the substrate, ie the mixture of vicinal acetoxypropanols to 42.2%, partial conversion of vicinal acetoxypropanols to decomposition products 23.5%, selectivity to propylene oxide reached 87.1 0, to propionaldehyde 12.0%, to acetone 0.6% ana allyl alcohol 0.3%. Acetic acid from pyrolysis is regenerated with an efficiency of 35.9%.

The mixture of unreacted diol, hydroxy ester and diester, after the first stage distillation of the cracking pyrolysis products in the first stage and the acetic acid in the second stage, is partially processed by the total hydrolysis to 1,2-propanediol, partly to the pyrolysis process. only a mixture of vicinal acetoxypropanol 1,2-diacetoxypropane supplied from the acetoxylation of propylene. Acetic acid from pyrolysis and hydrolysis of the esters is recovered with a total efficiency of 97% and recirculated to the acetoxylate propylene process. 1,300 kg of propylene and 52 kg of acetic acid are consumed per 1,000 kg of propylene oxide, and 922 kg of 1,2-propanediol is obtained as a by-product. Example 2

The procedure of Example 1 was followed except that the loading of the catalyst Z = 16.6 kgg / kg / h. Conversion of the mixture of vicinal acetoxypropanols reached 70.7% and the partial conversion of vicinal acetoxypropanols to decomposition products was 36.9%. The yield of propylene oxide was 46.5%, proion aldehyde 12.4% allyl alcohol 1.8%, acetone 0.7% and acetaldehyde 0.3%. Pyrolysis acetic acid is regenerated with an efficiency of 53.9%. In Examples 1 and 2, the main product is propylene oxide (with the exception of the acetic acid co-product, which also accompanies the formation of propylene oxide isomers, at a lower initial partial pressure of the vicinal acetoxypropanols mixture) over a wide range of catalysts and the initial partial pressure of the isomeric acetoxypropanols mixture. as well as propionaldehyde are the preferred lower value of the initial partial pressure of acetoxypropanols. Propylene oxide behaves as a reaction intermediate. 9 263194 Example 3

Pyrolysis was performed with a substrate that was an equimolar mixture of 1,2-propanediol (32.9% w / w) and 1,2-diacetoxypropane (67.0% w / w) and contained 0.08% w / w. water. The active ingredient of the catalyst with potassium acetate (pa) was the impregnated carrier (10% w / w), which was a Nalsit 4A synthetic zeolite. The reaction was carried out at 350 ° C, the initial partial pressure of 1,2-propanediol was 13.6 kPa, the total pressure was 110.5 kPa, the catalyst load -1 -1 -1 -1Z = 49.8 kggI.kgK .h, ie relative to 1,2-propanediol 123 mol.kgR .h. Conversion of the dough component of the substrate, ie 1,2-propanediol was 17.5 8, partial conversion and 1,2-propanedioluna decomposition products 13.2 8, conversion of 1,2-diacetoxypropane 4.5 8. The selectivity to propylene oxide reached 86.3 8, to propionaldehyde 7.6 8, to acetone 4.5% and to acetaldehyde 1.6 8. The molar ratio of diol reacted to the reacted diester was 4.0. Example 4

The procedure is as in Example 3 except that the catalyst load Z = 10.0 kg / kg / kg Conversion of 1,2-propanediol reached 39.58, the partial conversion of 1,2-propanediol into decomposition products 30, 0 8, conversion of 1,2-diacetoxypropane 10.1 8. The selectivity to individual decomposition products was as follows: propylene oxide 79.4%, propionaldehyde 11.9 8, acetone 5.7% and acetaldehyde 3.0 i. the reacted diester was 4.0.

Example5

The procedure is as in Example 3 except that the initial partial pressure of 1,2-propanediolubol 33.9 kPa, total pressure of 113.0 kPa, catalyst load Z = 24.9 kgg / kg / hr. The conversion of 1,2-propanediol was 27.9 8, the partial conversion of 1,2-propanediol to the decomposition products 21,6 8, the conversion of 1,2-diacetoxypropane 6,6 8. The selectivity to the individual decomposition products followed: propylene oxide 79,6 8, propionaldehyde 14.5 8, acetone 4.2 8, acetaldehyde 1.7 8.

The molar ratio of the reacted diol to the reacted diester was 4.3. In the above examples 3, 4, 5, the main product is propylene oxide, the formation of which is slightly preferred by the greater initial partial pressure of 1,2-propanediol. The propylene oxide selectivity increases with a lower initial 1,2-propanediol partial pressure. The formation of 1,2-propanediol mono-acetate is perforated by a higher partial pressure of 1,2-propanediol in the lower catalyst loading and vice versa, as well as the conversion of 1,2-diacetoxypropane and partial conversion of 1,2-propanediol to hydroxyesters. Conversion of 1,2-propanediol in said area of initial partial pressures of this component is growing. None of the reaction products behaves as a reaction intermediate or a subsequent reaction product. Speeds of each reaction! the systems on these products fall in the order: propylene oxide> vicinal acetoxypropanols>propionaldehyde>acetone> acetaldehyde.

The reaction products are not adsorbed on the catalyst surface. The vicinal hydroxyesters formed by the alcohol diacetate diol are not the major propylene oxide precursor under the reaction conditions, the 1,2-propanediol which undergoes a dehydration reaction under the activation of 1,2-diacetoxypropane. Acetic acid is not formed by the deacyloxylation reaction of vicinal acetoxy-propanols, nor is allyl alcohol a reaction product.

Example6

For comparison, pyrolysis was carried out on a catalyst consisting of an active ingredient, which is potassium acetate (a) and a carrier which was impregnated with this active ingredient (10% by weight) and which was coated with aluminum oxide. The substrate used was a mixture of 1,2-propanediol (49.1% w / w) and 1,2-diacetoxypropane (50.6% w / w) with a molar ratio of 2: 1 containing 0.3% by weight. water.

Claims

Catalyst for the preparation of alkylene oxides and / or their isomers by pyrolytic elimination of aliphatic acyloxy derivatives of hydrocarbons, such as vicinal hydroxyesters, respectively. mixtures thereof with a vicinal diester and / or a diol; only mixtures of vicinal diester and vicinal diol, characterized in that the catalyst consists of a synergistic mixture of an ionic active zeolite based on an alkali metal and / or alkaline earth, which is in the form of molecular sieves, and a basic substance from the group of alkali salts of carboxylic or mineral acids % having a pH in a 0.1 molar aqueous solution of 8 to 13, wherein their concentration relative to the zeolite is in the range of 0.1 to 50% by weight, preferably 5 to 15% by weight.