CS263400B1 - Catalyst for selective hydrogenation of acetylates and dione - Google Patents

Abstract

Catalyst for selective hydrogenation of acetylenes and dienes in hydrocarbon fractions C2 and C4 working with high selectivity of hydrogenation to alkenes. The catalyst is advantageous for the hydrogenation of methylacetylene and propadiene in pyrolysis C3 fractions or for the hydrogenation of residual butadiene in n-butenes, where it enables 95% conversion of dienes and acetylenes with a selectivity of 85 to 90% for the formation of alkenes. Unlike previously known catalysts for selective hydrogenation, the catalysts use specifically modified zeolites that do not contain acid centers, while they have a high specific surface area with min. precious metal content.

Description

(54) Catalyst for the selective hydrogenation of acetylanes and dione

Catalyst for the selective hydrogenation of acetylenes and dienes in C2 and C4 hydrocarbon fractions operating with high selectivity of hydrogenation to alkenes. The catalyst is advantageous for the hydrogenation of methylacettylene and propadiene in pyrolysis C3 fractions or for the hydrogenation of residual butadiene in n-butenes where it allows 95% conversion of dienes and acetylenes at a selectivity of 85 to 90% for the formation of alkenes. The catalysts, in contrast to the prior art selective hydrogenation catalysts, utilize specifically treated acid-free zeolites, having a high specific surface area of min. containing precious metal.

The invention relates to the production of a catalyst for the selective hydrogenation of acetylene, methylacetylene, propadiene, butadiene and vinylacetylene, divinylacetylene in mixtures thereof with alkenes and alkanes of C8, and C8 hydrocarbons. The catalyst systems comprise elements of VIII. groups, rare earth elements, crystalline zeolites and are used either alone or in admixture with an inert material.

The selective hydrogenation of acetylene and dienic hydrocarbons in admixture with alkenes and alkanes takes place using catalysts that substantially hydrogenate acetylenes and dlenes more rapidly than alkenes. Polyunsaturated hydrocarbons, acetylenes and dienes need to be fully removed while hydrogenating them to produce predominantly alkenes.

In English Patent 968,337, Bayer patented the hydrogenation of methylacetylene and propadiene in the Cg fraction. The hydrogenation is carried out in the liquid phase in a tubular reactor using a catalyst consisting of alumina impregnated with palladium. The catalysts used have a low specific surface area of max. 10 m / g.

French Patent 363,374 claims a method of Shell hydrogenation of C ₄ and C _{g of} the hydrocarbon fraction comprising acetylenic hydrocarbons using catalysts pozostávajúoich of the applied Pd on a macroporous support having a low surface area.

French Patent 1 370 445 from Chemische Werke Htlls protects a method of hydrogenating acetylene and diene hydrocarbons using chromate media.

IPP Patent No. 2,107,568 to IPP protects the selective hydrogenation of a mixture of hydrocarbons containing 3 to 10 carbons per molecule and containing polyunsaturated compounds by two-stage hydrogenation. The mixture entering the first reactor contains 0.5 to 3% unsaturated dienic and acetylenic hydrocarbons. In the second stage the dienes are adjusted to a content of several tens of ppm.

In German Patent No. 2 319 812, the Research Institute for Synthetic Alcohols and Organic Products protects a method of purifying gases containing acetylene or homologues and dienes by hydrogenation, while a stream of acetylene and diene-containing hydrocarbons is bubbled through a layer of aliphatic alcohols or carbonyl compounds or fatty acid derivatives. to keep the catalyst particles in suspension.

The catalyst consists of carbon dioxide, zirconia and platinum group metals.

U.S. Pat. No. 3,804,916 protects a process for the hydrogenation of acetylenes, dienes in an alkene stream and is characterized in that the catalyst consists of graphite on which Ni-metals are anchored,

Pd or Pt.

Czechoslovakian patent 225 435 describes a process for the hydrogenation of a pyrolysis Cg fraction in a mixture with pyrolysis hydrogen using a catalyst containing metals VIII as active ingredients. groups, in particular PD deposited on an active alumina support, at temperatures of 50 to 250 ° C and a pressure of 2 to 6 MPa, the liquid products from selective hydrogenation being partially recirculated.

German patent 1,919,336 from Engelhart protects the hydrogenation of acetylenic compounds from an alkene stream at a temperature of 0-300 ° C, a pressure of 0.035-5.2 MPa, operating at a volumetric velocity of 50,000-4,000,000 using an alumina-based catalyst containing Pd up to 10% wt.

German patent 3 010 289 by VSB Otto Grotewol Bohlen protects a method of catalytic hydrogenation of a liquid Cg fraction in a tubular reactor, the catalyst consisting of two layers, one of which contains 0.5 to 5% Pd and up to 5% Ag, Cu, Ei , Fe, Cr, W, Zn as promoters on a macroporous aluminum oxide support with a specific surface area of 50 m / g, the second layer of the catalytic converter 2 contains 0.1 to 1% Pd on a support with a specific surface area of 25 m / g, more than 50% by volume the pores are greater than 50 nm.

The present invention provides catalysts not only of high activity and productivity, but also of selectivity over a wide catalyst loading range. An essential feature of the preparation of the catalysts of the present invention is the development of a catalytic system in which dienic and acetylenic substances adsorb substantially faster and more firmly while simultaneously hydrogenating substantially faster than olefinic and paraffinic hydrocarbons, and avoiding diene and acetylene side reactions, particularly polymerization reactions. .

SUMMARY OF THE INVENTION The present invention provides a catalyst for the selective hydrogenation of acetylene, methylacetylene and propadiene, butadiene and acetylenes contained in the pyrolysis fractions of C ₂ , C ₃ , and C 4 hydrocarbons, wherein the catalyst comprises crystalline zeolites, preferably Na-type Na-passivated. groups, especially Pd and Ni with a rare earth promoter, preferably Ce. The properties of this catalyst are the high hydrogenation rate of acetylene and dienic hydrocarbons as compared to alkenes, low polymer formation activity, low carbon build-up and long life. The catalysts are heat-resistant and have high mechanical strength. It has been found that for the selective hydrogenation of acetylenes and dienes from pyrolysis C ₂ -C ₄ fractions or fractions obtained from catalytic cracker or fractions obtained by dehydrogenation of ethane, propane and butane, it is preferable to use catalysts prepared from the above components. Elements VIII. Rare earth groups and elements are introduced into the neutral reaction by impregnation or by ion exchange to zeolites, preferably Na alkali-type passivated NaY zeolites. In contrast to the prior art selective hydrogenation catalysts, the zeolites used, as well as the catalysts prepared on the basis thereof, have a high specific surface area of the order of 300 to 600 m / g. Zeolites are prepared for impregnation or ion exchange, either binder-free - forming gel-shaped zeolites in the form of rollers, spheres and, after crystallization and annealing, neutralizing again best with alkali metal solutions, or powdered crystallized zeolites are bonded with binders such as halloyzite, bentonite, clays and, after annealing, are neutralized again with alkali metals.

The invention relates to a process in which salts of Pd, Ni, Cr and Pt as well as rare earth salts are introduced onto the shaped zeolite without a binder or with an alkali metal neutralized binder.

By introducing Ni with Cr to prepare the catalyst, either in the zeolite structure or by deposition on the surface, it is brought into the active form by heating to a temperature of up to 450-500 ° C in an oxidizing atmosphere and subsequent reaction in a hydrogen atmosphere. Similarly, catalysts in combination with Pd with Ni or Ni with Cr are activated. When introducing Pt or Pd, these are treated in a hydrogen atmosphere or by reduction with hydrazine hydrate. rare earth salts are introduced as activators into the catalyst prior to deposition of element VIII. groups or together with elements of VIII. gr.

The crystalline zeolite used is characterized by the general formula ^(Cat 2 ^Z n ^{0 /} x ^Al 2 ° 3 ^{/ SiO} ) wherein the cat is an alkali metal ion - sodium, potassium, rubidium, or cesium and / or a divalent cation of magnesium, calcium, zinc, nickel , palladium and / or a trivalent cation of cerium, lanthanum, chromium, n is an integer of 1-3, x is 0.6-1.8, y is 1-50.

Preferably, a NaY-type zeolite is used in which the cat is a sodium ion, x is 0.9-1.1 and. y is 4-6, or ZSM-type zeolites in which cat is also a sodium ion, x is 0.9 to 1.1 and y is 20-30.

Synthetic zeolites can be prepared by reacting water-soluble silicates, a SiO ₂ sol, with an aqueous solution of alkali metal aluminates. Precipitated alkali aluminosilicates in an aqueous suspension can be filtered, dried and formed, then crystallized in the formed form, either in the filtered mother liquor or in aqueous solution with an alkali metal hydroxide at a concentration of 2-10% by weight. at 50-200 ° C, or an aqueous suspension of aluminosilicates prepared by precipitation is crystallized directly by heating to 50-200 ° C and, after filtration and drying, a crystalline aluminosilicate powder is obtained. In both cases, the crystalline aluminosilicates are washed most preferably with water to pH = 9.

The aluminosilicate powder must be formed by adding a binder such as halloysite, bentonite and the like. The washed zeolites are dried and calcined at 50-70 ° C, preferably at 100-650 ° C, wherein the bound water content of the zeolite ranges from 2-30% after drying and calcining.

Zeolites prior to deposition of the active metals are preferably neutralized and blocked all acid centers by treatment with aqueous solutions of alkali metal salts and hydroxides at a temperature of 20-150 ° C. If a zeolite is used which is formed using a binder such as bentonite, halloysite, kaolin and other clays, then the passivation is always carried out after annealing to neutralize the acidic centers resulting from the crystallization of the binders.

The invention relates to the preparation of a catalyst for selective hydrogenation using metal salts VIII. groups and rare earths which are introduced into the formed zeolites or powdered zeolites associated with halloysite, bentonite or kaolin and which are preferably neutralized after alkali annealing and finally formed. It also relates to a process in which the salts of Ni, Cr, Pd and Pt are applied to the formed zeolite without or with an alkali metal neutralized binder. Preferably, the process utilizes a process in which, after application of the salt solutions of the elements VIII. of the rare earth groups and salts, the catalyst is heated to a temperature of 100 to 150 ° C to remove the solvent and optionally convert the salts to oxides. The amount of Pt or Pd in the catalyst system may be in the range of 0.001-2% by weight. The amount of Ni and Cr may vary from 1 to 50 wt%, the amount of rare earths varies from 0.001 to 5 wt%.

The crystalline zeolites, preferably of the Y type, contain 9 moles of water, with no higher water content. The molar ratio of A? O? may be in the range of 1:50, preferably zeolites having an A? O? SiC? molar content of 1: 4-6 are used. The amount of binder in the zeolite for molding, i. halloysite, bentonite, kaolin or clay is calculated on the weight of zeolite and is in the range of 10-30% by weight.

Binder-free zeolites in the form of beads having a size of 1-3 mm or extrudates having a diameter of 1-3 mm and a length of 2-3 mm are particularly suitable for preparing the catalysts. The catalytically active metals are deposited on the shaped and neutralized zeolite in the form of soluble salts which are sprayed or immersed in the zeolite. Injection or immersion of the carrier is controlled so that the desired amount of active metal is delivered to the carrier.

Although the catalyst system is referred to as a mixture of metals of elements VIII. groups and oxides of Ni, Cr and rare earths in combination with zeolites preferably of the NaY type, it should be noted that the chemical bond may be different. Ni and Pd or rare earths Ce, Na may be bound in the zeolite lattice, or may only be deposited on the zeolite. They may precipitate from the zeolite lattice in the form of oxides or oxides may be formed by the disintegration of salts.

The amount of active metals on the zeolite is selected within certain ranges, changing the activity and selectivity of the catalysts. In general, the amount of active metal Pd or Pt varies in the range of 0.001-2% depending on the reaction conditions, the composition and the amount of acetylenes or dienes to be hydrogenated in the C2, C1-4 or C2 fraction. The use of zeolites makes it possible to actively obtain catalysts with a palladium or platinum content of 10 ppm.

The composition of the zeolite carrier is very important. Its quality determines not only activity and selectivity, but also the time between regenerations, as well as the possibility of healing the catalytic properties after regeneration of the carbonaceous substances. These are read off from the catalyst bed at a temperature of up to 650 ° C by oxidative regeneration after which the catalyst must be reduced again.

The catalyst composition of the present invention is effective over a very wide concentration range for the selective hydrogenation of acetylene to ethylene, methylacetylene and propene to propylene, butadiene and C1-acetylenes to .beta.-butenes and may also be advantageously used with an acetylene and diene content of 35-40% by weight. . in the fraction but also below 10 ppm. The selective hydrogenation temperature over these catalysts can vary from -20 to 300 ° C, the pressure from 0.1 to 4 MPa, and the concentration of acetylenes and dienes in the feedstock from 0.001 to 60% by weight.

The selective hydrogenation process using the catalysts of the present invention is carried out in liquid, gaseous or mixed phase, either in tubular reactors, from which the heat of reaction during selective hydrogenation is removed by various media such as water, steam, hydrocarbons or other substances, or adiabatically operating reactors from which the heat of reaction is removed by the reaction mixture itself.

It has been found that the catalysts of the present invention can be advantageously mixed with an inert material such as e.g. corundum and use this novel method of selective hydrogenation in high heat generation reactions.

The following examples show the preparation of catalysts for the selective hydrogenation of acetylenes and dienes to alkenes. These examples illustrate the preparation of catalysts, but do not limit the invention.

Example 1

An aqueous sodium aluminate solution, prepared by dissolving 582 kg of aluminum hydroxide in 2142 g of an aqueous sodium hydroxide solution at a concentration of 40.1% at 95 ° C, was after dosing continuously dosed by a pump into a reducing vessel equipped with a stirrer into which dosed a 25.4% SiO ₂ sol solution of 8,732.0 g. The reaction mixture was transferred to a reservoir from where the obtained gel-like precipitate was pumped onto the filter. The filter cake was dried to a content of about 40% water and formed by extrusion to rollers of 1,51.5 mm and a length of 2-3 mm. The formed gel was treated with 5% sodium hydroxide, which circulated through the formed rollers at 90 ° C for 24 h. After the liquor was drained and washed with distilled water, the obtained crystalline aluminosilicate was dried at 100-120 ° C and calcined at 600 ° C. The obtained aluminosilicate had the following composition:

Na ₂ O.Al ₂ O ₃ .4,9 SiO ₂ .9H ₂ O and its crystalline structure corresponded to NaY-type zeolite. 2300 g of aluminosilicate were obtained, which was further fed with an aqueous solution of palladium chloride. A portion - 1150 g (1a) was treated with an aqueous solution containing 33.3 g of PdCl ₂ . Another portion of the 1150 g catalyst (1b) was charged with an aqueous solution of PdCl ₂ containing 0.191 g of PdCl _{2 <}

After connecting a _PdCl2 catalyst (Ia) activated in a reactor provided with electric heating, in which a gradual temperature rise of 70-100 ° C for hours, heated in a stream of hydrogen at 400 ° C. After cooling, the catalyst was placed in a tubular reactor tempered with 2 water. (The catalyst had a specific surface of 450 m (g)).

A raw material containing 35.9% C ₃ H ₃ , 38.2% C ₁₁ H 8, 14.4% propadiene, 12.8% methylacetylene and 0.7% C ₄ hydrocarbons was used to test hydrogenation activity and selectivity.

Tests were performed at atmospheric pressure, feedstock feed 6,000-24,000 vol. raw material (calculated as gas at 20 ° C and 0.1 MPa) per catalyst volume per hour, H ₂ : C ₃ H ₄ molar ratio = 1.1-1.2 and 60 ° C. Under these conditions, the conversion of methylacetylene was 83-90 wt. to propadiene 83-89 wt%, the selectivity for propylene formation was 80-85 mol%.

Catalyst activation (1b) was done in a similar manner. After cooling, the catalyst had 2

Specific surface 500 m / g. Activity tests were performed at 6,000 vol. at 60 ° C mol. ratio H ₂ : C ₃ H ₄ = 1.1 and a pressure of 0.6 MPa.

The raw material used had the same composition as described for catalyst (1a). Under the above conditions, conversions of propadiene of 95.8% and methylacetylene of 96% were obtained, with a selectivity of propylene formation of 87%.

and

Example 2

The preparation of zeolite was similar to that described in Example 1b, including the deposition of PdCl ₂ in an amount of 0.191 g per 1150 g of zeolite. After application and drying of _PdCl2 were applied 700 ml of an aqueous solution of ceric ammonium nitrate containing 3.5 g (NH) ₂ Ca (NO ^) _4th Activation was performed in the same manner as in Example 1. The catalyst after activation had a specific.

surface 520 m / g. It was tested for hydrogenation activity using the same raw material as described in Example 1.

6,000 vol. Raw Materials / vol. catalyst per h, temperature 60 ° C, mol. the ratio H ₂ : C ₃ H ₄ = 1.1, the pressure of 0.7 MPa was the conversion of propadiene 97% and methylacetylene 90%, with a selectivity for propylene formation of 91%.

Example 3

An aqueous solution of sodium aluminate was prepared in a manner similar to that described in Example 1.

724 g of this solution were mixed with 8 732 g of a 25.4% SiO 2 silica sol solution. The gelled precipitate was crystallized for 24 h at 98 ° C. The crystalline precipitate was filtered off, washed with water to pH 0 and, after drying, formed with the addition of 20% halloysite. The shaking was done in such a way that the halloysite together with the crystalline zeolite kneaded and the paste formed with the addition of water was extruded onto the rollers by 0 1.5 mm. The rollers were dried, calcined at 650 ° C and treated with a 5% sodium hydroxide solution at 90 ° C after cooling. The obtained passivated aluminosilicate had the composition Na ₂ O.Al ₂ O 5 SiO ₂ -9 H ₂ O.

An aqueous solution of nickel ootane containing 320 g (CH ₃ COO) ₂ Ni was added to 1,370 g of the passivated zeolite in the form of rollers. After bonding, the rollers were dried at 120 ° C again fed with an aqueous solution containing 26 g CrO 3. After coupling, the catalyst was dried at 120 ° C, heated to 400 ° C in an oxidizing atmosphere and activated with hydrogen at 400 ° C. The catalyst had a specific surface area of 400 m / g. It was tested for hydrogenation activity and selectivity using a C ₄ fraction containing 2.5 wt. butadiene, 76% n-butanes and 21.5% n + i-butane.

At a temperature of 20 ° C, a molar ratio of < ₂ : 2 2 ₄ Ηθ = 1.05 and a dosage of 25 volumes of liquid fraction / catalyst volume per hour reduced the butadiene content to 0.01% while the n-butenes content increased to 78.43 %, i.e. the selectivity of hydrogenation was 97.5% for the formation of n-butenes at the conversion of butadiene 96%.

Claims (3)

EXAMPLE 2 The preparation of zeolite was similar to that described in Example 1b, including the deposition of PdCl2 in an amount of 0.191 g per 1,150 g of zeolite. After loading with PdCl 2 and drying, 700 ml of an aqueous solution of ceric ammonium nitrate containing 3.5 g of (NH 4) 2 Ca (NO 4) 4 were applied. Activation was performed in the same manner as described in Example 1. The catalyst had a specificity after activation. 2 surface 520 m / g. It was tested for hydrogenation activity using the same raw material as described in Example 1. With a retraction of 6,000 vol. catalyst at h, temperature 60 ° C, mol. ratio H 2: C 3 H 4 = 1.1, pressure 0.7 MPa, conversion of propadiene 97% and methylacetylene 90%, with selectivity for propylene formation 91%. EXAMPLE 3 An aqueous solution of sodium aluminate was prepared in a manner similar to that described in Example 1. 2724 g of this solution was mixed with 8,732 g of a SiO2 sol solution having a SiO2 of 25.4%, and the gelled precipitate formed was left for 24 hours. at 98 ° C. The crystalline precipitate was filtered off, washed with water to pH 0 and, after drying, formed with the addition of 20% halloysite. The formation was accomplished in such a way that halloysite was co-crystallized with crystalline zeolite and the paste formed by the addition of water was extruded into a 1.5 mm roller. The rollers were dried, annealed to 650 ° C and, after cooling, treated with a 5% sodium hydroxide solution at 90 ° C. The obtained passivated aluminosilicate had a Na2O.Al2O5.5 SiO2-9 H2O composition. To 1370 g of passivated zeolite in roll form, an aqueous solution of nickel acetate containing 320 g (CH 3 COO) 2 N was added. After coupling, the rollers were dried at 120 ° C again with a feed solution containing 26 g CrO 2. After coupling, the catalyst was dried at 120 ° C, heated to 400 ° C in an oxidizing atmosphere and activated with hydrogen at 400 ° C. The catalyst had a specific surface area of 400 m / g. It was tested for hydrogenation activity and selectivity using a C 4 fraction containing 2.5 wt. butadiene, 76% n-butanes and 21.5% n-butane. At 20 ° C, molar ratio Η2: <24Ηθ = 1.05 and dosing 25 volumes of liquid / catalyst volume per hour, the butadiene content was reduced to 0.01% while the n-butene content increased to 78.43%, ie hydrogenation selectivity was 97.5% for the formation of n-butenes in the 96% butadiene conversion. SUBJECT OF THE INVENTION A catalyst for the selective hydrogenation of acetylenes and dienes in the presence of alkene alkanes in hydrocarbon fractions containing from 2 to 4 carbon atoms, or in a mixture thereof in the presence of hydrogen, characterized in that the catalyst consists of a synthetic crystalline zeolite of the formula <Kat2 / n Wherein X is an alkali metal ion of sodium, potassium, rubidium, cesium and / or divalent cation of magnesium, calcium, zinc, nickel, palladium and / or trivalent cation of cerium, lanthanum, chromium, n is an integer of 1-3, x is 0.6-1.8, y is 1-50, preferably zeolite in which the cation is sodium, x is 0.9-1.1 and y is 4-6 with palladium content and / or platinum in an amount of 0.000 1-2% by weight and / or nickel in an amount of 1-20% by weight and / or a rare earth element preferably cerium in an amount of 7 263400 0.001-5% by weight, wherein the crystalline zeolite used is molded into particles directly from the gel prior to crystallization or powdered the crystalline zeolite is formed in the presence of halloysium, bentonite, the amount of which is calculated per zeolite is 10-45% by weight. 2. Catalyst according to claim 1, characterized in that solipalladium, platinum, nickel, chromium and rare earth catalysts are introduced into the structure of the crystalline alumina silicates by ion exchange or surface deposition. 3. Catalyst according to claim 1, characterized in that the acidic centers in the molded particles of crystalline zeolite or halloysite-bonded zeolite particles are blocked with bentonite by the addition of alkali metal hydroxides at 20 to 120 ° C.