MX2007005055A - Alkylation catalyst, its preparation and use - Google Patents

Abstract

Process for the preparation of a catalyst comprising the steps of:(a) combining solid acid particles with a binder to form a catalyst precursor;(b) calcining the catalyst precursor at a temperature in the range of 400-575°C, (c) impregnating the calcined catalyst precursor with a solution of a Group VIII noble metal and NH4+ions;and (d) calcining the impregnated particles at a catalyst temperature in the range of 400-500°C. The use of two calcination steps in the above temperature ranges results in alkylation catalysts with improved performance.

Description

CATALYST OF RENT, ITS PREPARATION AND USE DESCRIPTION OF THE INVENTION The present invention relates to a process for the preparation of a catalyst suitable for alkylating a hydrocarbon feed. The invention also relates to the catalyst thus obtained, and to its use in alkylation processes. Within the scope of the present invention, the term "alkylation" refers to the reaction of an alkylatable compound, such as aromatic or saturated hydrocarbon, with an alkylating agent, such as an olefin. Without limiting the scope of the invention, the invention will be further illustrated by discussing the alkylation of saturated hydrocarbons, in general branched saturated hydrocarbons, with an olefin to give highly branched, saturated hydrocarbons with a higher molecular weight. Hydrocarbons do not contain atoms other than hydrogen and carbon. The reaction is of interest because it makes it possible to obtain, through the alkylation of isobutane with an olefin containing 2-6 carbon atoms, an alkylate having a high octane number and which boils in the range of gasoline. Contrary to gasoline obtained by the catalytic cracking of Ref. S181743 smaller oil fractions such as vacuum gas oil and atmospheric residue, gasoline obtained by alkylation is essentially free of contaminants such as sulfur and nitrogen, thus having clean ignition characteristics. Its high anti-piston properties, represented by the high octane number, decreases the need to add environmentally hazardous anti-piston compounds such as aromatics or lead. Also contrary to gasoline obtained by the reforming of naphtha or by the catalytic disintegration of heavier petroleum fractions, the alkylate contains little or almost no aromatics or olefins, which, environmentally speaking, is an additional advantage. The alkylation reaction is catalyzed by acid. To date, liquid acid catalysts such as sulfuric acid and hydrogen fluoride are used in commercial alkylation equipment. The use of such catalysts is accompanied by a wide range of problems. For example, sulfuric acid and hydrogen fluoride are highly corrosive, so the equipment used has to meet high quality requirements. Since the presence of highly corrosive materials in the resulting fuel is objectionable, the remaining acid has to be removed from the alkylate. Also, because the phase separations that have to be carried out, the process is complicated and in this way expensive. In addition, there is always a risk that toxic substances such as hydrogen fluoride are emitted. A more recent development in this field is the use of solid acid catalysts, such as zeolite-containing catalysts. WO 98/23560, describes the use in the alkylation of hydrocarbons of a catalyst containing a zeolite, such as a Y zeolite, a noble metal of group VIII (e.g., platinum or palladium) as a hydrogenation component, and optionally a matrix material, such as alumina. Such a catalyst can be prepared by mixing the solid acid with matrix material, shaping the mixture to form particles, and calcining the particles. The hydrogenation component can be incorporated into the catalyst composition by impregnation of said particles. European Patent No. 308 207 describes an alkylation process using a catalyst comprising a solid acid, a hydrogenation component consisting essentially of one or more noble metals of group VIII, and at least 0. 05% by weight of sulfur. This catalyst is prepared by contacting a material comprising the solid acid and the hydrogenation component with a sulfur-containing component.

This document describes the different methods for preparing the material comprising solid acid and the hydrogenation component, one of these methods involves the steps of: (i) forming, for example, extrusion, of the solid acid, optionally after mixing it with a matrix material, to form particles, (ii) the calcination of the resulting particles, and (iii) the incorporation of the hydrogenation component into the calcined particles by, for example, impregnation of the particles with a solution of one or more noble metals of group VIII and / or by ion exchange (competitive). The material thus prepared is preferably calcined and reduced before being brought into contact with the sulfur-containing compound. European Patent No. 0 640 575 A1 describes a process for catalytically improving a paraffinic feedstock. Preferred catalysts comprise zeolite beta and a hydrogenation material such as palladium. The metal is loaded onto the zeolite by ion exchange with an aqueous solution of Pd-tetraamine chloride, followed by calcination at 450SC. U.S. Patent No. 3,851,004 describes a process for the alkylation of hydrocarbons using catalysts containing zeolite, in conjunction with nickel or a hydrogenation agent of the platinum or palladium group metal. The preferred technique for the combination of the noble metal of group VIII with the molecular sieve is by ion exchange of an aqueous solution of the noble metal as a complex cation of amine. Subsequently, the molecular sieve combined with the hydrogenation metal is calcined in air at a temperature in the range of 400 to 800 ° C, preferably 450 to 650 ° C. British Patent No. 1,162,969 describes a process for converting hydrocarbons with a catalyst comprising one or more hydrogenation metal components and a decationized zeolite. Preferred hydrogenation materials include palladium and tungsten-nickel. After the deposition of the catalytically active metal component (s), the catalyst is dried and calcined at a temperature of about 450-700 SC. U.S. Patent Application No. 2002/198422 describes a process for the catalytic alkylation of hydrocarbons. The catalytic material comprises a metallic hydrogenation component and a solid acid. The process by which the catalysts are prepared is not described. British Patent No. 1 452 521 describes the preparation of the hydroconversion catalysts of zeolite, of crystalline aluminosilicate. The process involves the provision of a physical mixture of zeolites with channel pore structure and zeolites with three-dimensional pore structure, in particular L-sieve and omega-sieve. The metal component is incorporated into the mixed zeolite support by impregnation or by ion exchange. A specific example uses aqueous nickel acetate and matatungs tato ammonium. The samples were calcined at 200, 300 and 500aC. British Patent 1,189,850 discloses a process for the manufacture of a metal comprising a zeolite catalyst based on a metal o-silicate zeolite. If some ammonium is present in the catalyst, it is removed by calcination at a temperature above 2002C, but below 400 ° C, with a calcination temperature of 350 ° C being used in the examples. U.S. Patent No. 6,342,200 Bl describes a process for preparing a zeolite with EUO type structure. The zeolite material can be used in isomerization reactions. Platinum can be introduced into the catalyst in the form of hexachloroplatinic acid, but ammonia compounds can also be used. The preparation of the catalyst is generally completed by calcination at a temperature in the range of about 250 ° C to 600 ° C.

U.S. Patent No. 5,830,345 discloses a process for producing a benzene-free gasoline blending material, by the use of a double-function catalyst. The catalyst can be prepared by the ion exchange of a pre-formed and precalcined zeolite material, with platinic ammonium nitrate. The catalyst is calcined at 350 ° C for 3 hours. It has now been found that the operation and alkylation reactions of the solid metal catalyst containing noble metal can be further improved if the calcination steps before and after the incorporation of the hydrogenation component - for example, steps b) and d ) mentioned below, are both driven in a specific temperature window of the catalyst. The present invention therefore relates to a process for the preparation of a catalyst comprising the steps of: a) combining the particles of a solid acid selected from the group consisting of beta zeolite, MCM-22, MCM-36, mordenite , X-zeolites, Y-zeolites, and mixtures thereof, with a binder material to form a catalyst precursor, b) calcining the catalyst precursor at a temperature in the range of 400-575aC, c) impregnating the precursor of the catalyst. calcined catalyst, in a solution of a noble metal compound of group VIII, the solution also comprising NH4 + ions; and d) calcining the impregnated catalyst precursor obtained in step c), in air and / or inert gas, at a temperature in the range of 400 to 500 BC. As illustrated by the following examples, it is important that the temperature during the first and second calcination steps be in the claimed temperature window.

Particles containing the solid acid The particles containing the solid acid generally comprise a solid acid and a matrix material. Examples of suitable solid acids are zeolites such as zeolite beta, MCM-22, MCM-36, mordenite, X-zeolites and Y-zeolites, including HY-zeolites and USY-zeolites, non-zeolitic solid acids, such as silica-alumina , sulphated oxides such as sulfated oxides of zirconium, titanium, or tin, mixed oxides of zirconium, molybdenum, tungsten, phosphorus, etc., and chlorinated aluminum oxides or clays. Preferred solid acids are zeolites, including mordenite, beta zeolite, X-zeolites and Y-zeolites, the latter include H-Y-zeolites and USY-zeolites. Mixtures of solid acids can also be used.

The X- and Y-zeolites can also be exchanged with multivalent cations such as (mixtures of) rare earth ions. An even more preferred solid acid is Y-zeolite with a unit cell size of 24.34-24.72 angstroms, and more preferably is a Y-zeolite with a unit cell size of 24.42-24.56 agstroms. Examples of suitable matrix materials are alumina, silica, titania, zirconium, clay, and mixtures thereof. Matrix materials comprising alumina are generally preferred. Preferably, the particles containing solid acid comprise 2-98% by weight of the solid acid and 98-2% by weight of the matrix material, based on the total weight of the solid acid and the matrix material present in the particles. More preferably, the particles containing solid acid comprise 10-90% by weight of the solid acid, and 90-10% by weight of the matrix material. Even more preferably, the particles containing the solid acid comprise 10-80% by weight of the matrix material and the remainder is solid acid, most preferably, these comprise 10-40% by weight of the matrix material and the remainder is acidic. solid, based on the total weight of the solid acid and the matrix material contained in the particles. The particles containing the solid acid can be prepared by standard methods, for example, mixing a solid acid and a matrix material, and shaping the mixture to form shaped bodies. A preferred forming method is extrusion, but also the agglomeration, the spray drying, and the formation of spheres, for example, by the oil droplet method. Suitable forms of such particles include symmetrical or asymmetric spheres, cylinders, rings and polylobes, for example, tri- and four-lobes. Preferably, the catalyst particles have an average particle diameter of at least 0.5 mm, more preferably at least 0.8 mm, and most preferably at least 1.0 mm. The upper limit of the average particle diameter preferably falls by 10 mm, more preferably by 5.0 mm, still more preferably by 3.0 mm.

Step a) The solid acid particles are combined with a binder material to form a catalyst precursor. Binder materials are well known in the art, and may comprise silica, alumina or silica / alumina. For the preparation of the catalyst of the present invention, alumina is the preferred binder material.

Step b) The catalyst precursor is calcined at a temperature in the range of 400-575 SC, preferably 450-5502C, more preferably 460-5002C. The heating rate is preferably in the range of 0.1 to 100 ° C / minute, more preferably 0.5 ° C to 50 ° C / minute, most preferably 1 to 30 ° C / minute. The calcination is preferably conducted for 0.01-10 hours, more preferably 0.1-5 hours, most preferably 0.3-2 hours. This is preferably conducted in a flow of air and / or inert gas (eg, nitrogen). More preferably, this atmosphere is dry. Preferably, the catalyst precursor is dried before being calcined. This drying is preferably conducted at a temperature of about 110-150 ° C. The calcination must be performed on any equipment, such as a fixed bed reactor, a fluidized bed calciner, and a rotating tube calciner.

Step c) A noble metal of group VIII is then incorporated into the particles containing the calcined solid acid. This is preferably done through impregnation with competitive ion exchange of the particles containing the solid acid, using a solution comprising noble metal ions of group VIII and / or their complexes in NH4 + ions. The preferred noble group VIII metals are platinum, palladium and combinations thereof. More preferably, at least one of the noble metals of group VIII is platinum. The noble metal salts of group VIII include nitrates, chlorides and ammonium nitrates of noble metals or their complexes (for example, NH3 complexes).

Step d) The resulting particles containing the noble metal are then calcined at a temperature in the range of 400-5002C, preferably 450-5002C. It is important to calcify at a temperature of at least about 400 ° C to remove substantially all of the nitrogen compounds that were introduced during the impregnation. It has been found that the presence of the nitrogen compounds in the catalyst adversely affects the operation of the catalyst. This temperature is preferably reached by heating the particles by 0.1-1002C / minute, more preferably 0.5-502C / minute, most preferably 1-302C / minute to the desired final value between 400 and 5002C. The calcination is preferably conducted for 0.01-10 hours, more preferably 0.1-5 hours, most preferably 0.3-2 hours. The calcination is more preferably conducted in a flow of air and / or inert gas (for example nitrogen). More preferably, the atmosphere is anhydrous. Optionally, a drying step is applied between steps (c) and (d). Alternatively, the particles containing noble metal are dried during the calcination step. Also optionally, a residence of about 15-120 minutes, preferably 30-60 minutes at a temperature of about 200-250aC is introduced. After the calcination step (d), the resulting catalyst particles are preferably reduced in a preferred temperature range of 200 to 500 ° C, more preferably 250 to 350 ° C, in a reducing gas such as hydrogen. Before or after this reduction treatment, water can be added to the catalyst particles. As described in the unpublished European Patent Application No. 04075387.3, the presence of 1.5-6% by weight of water, more preferably 1.8-4 and most preferably 2-3% by weight - measured as the loss on ignition to 600SC - it has a positive effect on the alkylation activity and the quality of the alkylate.

The alkylation process Preferably, the hydrocarbon to be alkylated in the alkylation process is a branched saturated hydrocarbon such as an isoalkane having 4-10 carbon atoms. Examples are isobutane, isopentane, isohexane or mixtures thereof, with isobutane being the most preferred. The alkylating agent is preferably an olefin having 2-10 carbon atoms, more preferably 2-6 carbon atoms, still more preferably 3-5 carbon atoms, and most preferably 4 carbon atoms. Most preferably, the alkylation process consists of the alkylation of isobutane with butenes. As will be apparent to the person skilled in the art, the alkylation process can take any suitable form, including fluidized bed processes, suspension processes and fixed bed processes. The processes can be carried out in a number of beds and / or reactors, each with separate addition of the alkylating agent, if desirable. In such a case, the process of the invention can be carried out in each separate bed or reactor. The suitable process conditions known to the person skilled in the art. Preferably, a alkylation process as described in WO 98/23560. In this process, the catalyst is intermittently subjected to a gentle regeneration step when contacted with a feed containing a saturated hydrocarbon and hydrogen. This soft regeneration is preferably carried out at 90% or less of the active cycle of the catalyst, whereby the active cycle is defined as the time from the start of feed of the alkylating agent to the moment when, in comparison with the input of the the reactor section containing catalyst, 20% of the alkylating agent leaves the section of the reactor containing the catalyst, without being converted, not counting the isomerization within the molecule. The process conditions applied in the present process are summarized in the following table: The gentle regeneration is preferably conducted at temperatures and pressures that differ from the reaction temperature by no more than 50%, more preferably by no more than 20%, still more preferably by no more than 10%. Optionally, in the above process, the catalyst particles can be subjected to a high temperature regeneration by hydrogen in the gas phase. This regeneration at a temperature is preferably carried out at a temperature of at least 150SC, more preferably at 150-6002C, and most preferably at 2002-400sC. For details of this regeneration process, reference is made to WO 98/23560. The high temperature regeneration can be applied periodically during the alkylation process and is preferably applied after every 50, more preferably after every 100, and most preferably after every 200-400 mild regenerations. If as a result of the high temperature regeneration, the water content of the catalyst particles has decreased below the desired level, the catalyst particles can be rehydrated during the process in the ways described in the aforementioned Patent Application. Preferably, in addition to the treatment of regeneration at high temperature, a softer regeneration is applied during the alkylation process, as described in WO 98/23560, in particular page 9, line 13 to page 13, line 2. This text passage is incorporated in the present by reference. More particularly, during the alkylation process the catalyst particles are preferably intermittently subjected to a regeneration step when contacted with a feed containing a hydrocarbon and hydrogen, with the regeneration being carried out preferably at 90% or less, more preferably to 60% or less, or more preferably at 20% or less, and most preferably at 10% or less of the active cycle of the catalyst. The active cycle of the catalyst is defined as the time from the start of the feed of the alkylating agent to the moment when, in comparison with the alkylating agent added to the section of the reactor containing the catalyst, 20% of the alkylating agent leaves the section of the reactor that contains the catalyst without being converted, not counting the isomerization within the molecule. The quality of the alkylated product obtained in the process according to the invention can be measured by its Research Octane Number (RON). The RON is a measure of an anti- Pistoning of gasoline and / or the constituents of gasoline. The higher the RON, the more favorable is the anti-piston rating of gasoline. Depending on the type of gasoline engine, generally speaking, a higher anti-piston rating is of advantage when it enters the engine work. The product obtained in the process according to the invention preferably has a RON of 90 or higher, more preferably of 92 or higher, most preferably 94 or higher. The RON is obtained by determining, for example, via gas chromatography, the percentages by volume of the various hydrocarbons in the product. The percentages in volume are then multiplied by the contribution of RON and aggregates. Examples of compounds with a RON of 90 or greater are isopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, trimethylbutane, 2,3-dimethylpentane, 2,2,4-trimethylpentane, 2, 2, 3-trimethylpentane, 2, 3, 4-trimethylpentane, 2,3,3-trimethylpentane and 2,2,5-trimethylhexane.

EXAMPLES Examples 1-6 The dry extrudates comprising 70% by weight of USY-zeolite and 30% by weight of an alumina matrix were calcined in air at different final temperatures by about 1 hour after being heated at a rate of approximately 5sC / minute. The calcining temperatures applied are listed in Table 1 as "T calcination 1". The calcined extrudates were subsequently impregnated with an aqueous solution of Pt (NH3) Cl2 and NH4N03 by incipient wetting. The amount of NH4 + ions was equivalent to the number of Na + interchangeable sites in the catalyst. After drying at 120 ° C. for 2 hours, the impregnated extrudates were calcined for 2 hours in air at different final catalyst temperatures ("T calcining 2" in Table 1) to obtain catalyst particles. The heating rate at the final temperature of about 52C / minute (with a residence time of about 2 hours at 230eC). The platinum content resulting from the extrudates was 0.34% by weight. These catalyst particles were subsequently tested according to the following procedure. A fixed-bed recycle reactor as described in O 98/23560 having a diameter of 2 cm was filled with a 1: 1 volume / volume mixture of 38.6 grams of the catalyst extrudates (wetted in ambient air a a Loss of Ignition (6002C) of approximately 4.5% by weight) and carborundum particles (60 mesh). A 6 mm diameter thermocouple was accommodated in the center of the reactor tube. The reactor was flooded with nitrogen for 30 minutes (21 Ni / hour). Next, the system was tested for high pressure leaks, after which the pressure was raised to 21 bar and the nitrogen replaced by hydrogen (21 Ni / hour). The temperature of the reactor was then raised to 2752C at a rate of 12C / minute and the catalyst was reduced to 2752C. After 2 hours, the temperature of the reactor was lowered to the reaction temperature. The hydrogen vapor was stopped with the achievement of the reaction temperature. Isobutane was supplied to the reactor at a rate of about 4,000 grams / hour. Approximately 95-98% of isobutane was fed back into the reactor. Approximately 2-5% were drained for analysis. Such an amount of isobutane was supplied to the reactor to ensure a constant amount of liquid in the system. When the system had stabilized, such an amount of cis-2-butene was added thereto to give a cis-2-buten-WHSV of 0.19 (calculated on the weight of the zeolite in the catalyst sample). The total velocity of the liquid flow in the system was maintained at approximately 4,000 g / hour. The weight ratio of isobutane to cis-2- butene at the reactor inlet was about 750. The pressure in the reactor was raised to 21 bar. Each time after 1 hour of reaction, the catalyst particles were regenerated when washed with isobutane for 5 minutes, followed by 50 minutes of regeneration when put in contact with a solution of 1 mol% of H2 in isobutane, and then when washed in isobutane for another 5 minutes (total washing and total regeneration time of 1 hour). After this washing step, the alkylation was initial again. The temperature during the washing steps, the regeneration step and the reaction step was the same. After processing as described above for 24 hours at the same temperature, a pseudo-stable state was achieved. Then, the temperature was decreased and the process was conducted as described above for another 24 hours. Therefore, the catalytic performance was measured at different temperatures going from the highest to the lowest. The operation was characterized by the reaction temperature and the research octane number (RON) at an olefin conversion of 99.5% per reactor passage. The RON was determined as described on pages 13 and 14 of WO 0923560, the only exception being that the RON contribution of the total C9 + (excluding 2, 2, 5-trimethylhexane) was estimated as 84 instead of 90. The yield of C5 + alkylate is defined with the amount by weight of the alkylated C5 + produced divided by the total weight of the olefin consumed. The effect of the calcination temperatures on the operation of the catalyst particles is indicated in Table 1: Table 1 Example T T T of RON calcination calcination Reaction to 99.5% 1 (2C) 2 (2C) 99.5% conv conv. (SC) 1 450 450 61 96.7 2 475 450 52 97.7 3 500 450 57 97.3 4 540 450 58 97.2 5 500 600 60 97.0 6 600 450 64 96.6 Table 1 clearly shows that the operation of the alkylation catalyst can be optimized by varying the calcination temperature before and after impregnation. The application of calcination temperatures in the reclaimed range results in catalysts from improved rental.

Examples 7-8 A catalyst was prepared as in Examples 1-6 using 475SC for T calcining 1. After impregnation a mixture of this catalyst was calcined at a catalyst temperature of 3502C (example 7). A second example of this catalyst was calcined at a temperature of 4502C (example 8). Both samples were analyzed for residual nitrogen. The nitrogen content of the catalyst of Example 7 was 408 ppm. The nitrogen content of the catalyst of Example 8 was < 30 ppm. The catalyst of Example 7 showed a conversion of 99.5% at 552C and RON from 97.2 at a conversion of 99.5%. The catalyst of Example 8 showed a conversion of 99.5% at 522C and RON from 97.5 at a conversion of 99.5%.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Claims (9)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A process for the preparation of a catalyst that is suitable for alkylating a hydrocarbon feed, the process is characterized in that it comprises the steps of: a) combining the solid acid particles selected from the group consisting of beta zeolite, MCM-22, MCM -36, mordenite, X-zeolites, Y-zeolites and mixtures thereof with a binder material to form a catalyst precursor; b) calcining the catalyst precursor at a catalyst temperature in the range of 400-5752C, c) impregnating the calcined catalyst precursor with a solution of a noble metal compound in group VIII, the solution further comprising NH4 + ions, and ) calcining the precursor of the impregnated catalyst obtained in step c), in air and / or inert gas at a catalyst temperature in the range of 400-500BC.

2. A process according to claim 1, characterized in that the temperature applied in step b) is in the range of 450-5502C.

3. A process according to claim 2, characterized in that the temperature in step b) is in the range of 460-500sC.

4. The process according to any of the preceding claims, characterized in that the temperature in step d) is in the range of 450-5002C.

5. The process according to any of the preceding claims, characterized in that the solid acid is a zeolite selected from the group consisting of mordenite, beta zeolite, X-zeolites and Y-zeolites.

6. The process according to any of the preceding claims, characterized in that the binder is alumina.

7. Catalyst, characterized in that it is obtained by the process according to any of the preceding claims.

8. The use of the catalyst according to claim 7, for the alkylation of hydrocarbons.

9. The use according to claim 8, wherein the hydrocarbons are saturated hydrocarbons.