FR3061168A3 - - Google Patents

Abstract

The present invention relates to a process for the preparation of a catalyst for the aromatization of alkanes giving a high percentage conversion, a high yield, a high selectivity of aromatic compounds and a high selectivity of p-xylene in xylene, including the following steps: (a) contacting a zeolite with a Group IIIA metal salt solution; (b) contacting the zeolite obtained in step (a) with the metal salt solution selected from Group VIIB metal, Group VB metal or a mixture thereof; and (c) contacting the zeolite obtained in step (b) with alkoxysilane, characterized in that the metal salt solution of step (b) comprises a glycolic solvent as a reducing agent in basic conditions, and step (b) is carried out at a temperature above 120 ° C.

Description

PROCESS FOR THE PREPARATION OF A CATALYST FOR ALCOHANE FLAVORING

Technical area

The present invention relates to the field of chemistry, a chemical composition and a process for preparing a catalyst for the aromatization of alkanes. State of the art

At present, aromatic compounds such as benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene are important intermediates in the petrochemical industry because they are widely used in the preparation process of styrene, polyester fiber, nylon 6,6, phenol and terephthalic acid. It is well known that aromatic compounds can be prepared generally from the reforming reaction of a heavy naphtha compound having 7 to 12 carbon atoms by a dehydrocyclization reaction on a Pt / Cl-Al 2 O 3 catalyst. Said reaction must use the heavy naphtha compound as a raw material, which leads to a limitation of the use of the less expensive light naphtha compounds. Therefore, attempts to develop a catalyst for the production of aromatic compounds from light naphtha compound or alkane having less than 7 carbon atoms have ceased.

It has been reported that zeolite is the catalyst capable of converting the short-chain alkane into aromatic compounds. Therefore, several studies have been carried out in order to develop the catalyst having good properties and proving to be suitable for the industry. Said catalyst, however, still contains undesirable properties such as its shelf life, the low selectivity of aromatic compounds and p-xylene, and the formation of coke during use, etc.

US 4,861,933 and US 4,304,686 disclose the process for preparing aromatic compounds from an aliphatic hydrocarbon using a zeolite catalyst loaded with gallium. Nevertheless, it has been discovered that the selectivity of the mixture of benzene, toluene and xylene (BTX) is low, so other methods are required to separate and purify them for industrial applications.

EP 0841092 discloses the hydrocarbon formation reaction to give less coke formation and a high yield of light olefins. The catalyst used in said process was the zeolite which was subjected to a silylation reaction with a silylating agent and treated with steam or acid. Nevertheless, it has been discovered that said improved catalyst gives a low yield of aromatic compounds.

US 20130237734 discloses the process for preparing the aromatization catalyst comprising the step of contacting the zeolite with an organic acid and then contacting the resulting zeolite with solutions of Group IB metal and metal group IIIA, and then contacted with the silylating agent. It has been found that zeolite treated with the organic acid, particularly oxalic acid, gives higher aromatics yields.

US 20130172648 discloses the catalyst and catalyst preparation process for the production of aromatics from propane. Said catalyst has been prepared by treating the zeolite with about 0.2 to 2% by weight of gallium and about 0.01 to 2% by weight of palladium or platinum metal. Said treatment was carried out by impregnation and ion exchange. However, this document does not disclose the effectiveness of said reaction on the selectivity of p-xylene.

From all the foregoing, it is apparent that the present invention aims at preparing the catalyst for the aromatization of alkanes in order to obtain a high conversion in percentage, a high selectivity of the aromatic compounds and a high selectivity of p-xylene in the xylene. Summary of the invention

The present invention relates to the process for preparing a catalyst for the aromatization of alkanes, wherein said process comprises the following steps: (a) contacting a zeolite with a metal salt solution of the group ΠΙΑ; (b) contacting the zeolite obtained in step (a) with the metal salt solution selected from Group VIIB metal, Group VB metal or a mixture thereof; and (c) contacting the zeolite obtained in step (b) with alkoxysilane, characterized in that the metal salt solution of step (b) comprises a glycolic solvent as a reducing agent in basic conditions, and step (b) is carried out at a temperature above 120 ° C.

Description of the invention

The present invention relates to the process for preparing a catalyst for the aromatization of alkanes, as described in the following embodiments.

Any aspect shown herein refers to the inclusion of its application in other aspects of the present invention, unless otherwise stated.

The technical or scientific terms used herein have the definitions commonly understood by those skilled in the ordinary art unless otherwise stated.

Any tool, equipment, process or chemical referred to herein means tools, equipment, processes or chemicals commonly handled or used by those skilled in the art unless it is explicitly stated that they are tools, equipment, processes or chemicals specific to the present invention only. The use of a singular name or pronoun jointly with "comprising" in the claims or the specification refers to "one" and also "one or more", "at least one", and "one or more than one" .

All the compositions and / or methods disclosed and claimed in the present application are intended to cover embodiments from any action, embodiment, modification or adjustment without any experiment which differ significantly from the present invention and obtained with the claimed utility. and resulting in the same embodiment of the present embodiment from a person skilled in the art, although not specifically mentioned in the claims. Therefore, an object substitutable or similar to the present embodiment including little modification or adjustment that can be clearly perceived by those skilled in the art should be interpreted as remaining in the spirit, intent and concept of the invention. as they appear in the appended claims.

Throughout this application, the term "about" refers to any number that has appeared or is shown here that may vary or deviate from any error value of the equipment, process or personnel using said equipment or process including variation or deviation resulting from changes in physical properties.

In the following, embodiments of the invention are indicated without intending to limit the scope of the invention.

The present invention relates to the process for preparing a catalyst for the aromatization of alkanes, said process comprising the steps of: (a) contacting a zeolite with a metal salt solution of the group ΠΙΑ; (b) contacting the zeolite obtained in step (a) with the metal salt solution selected from Group VIIB metal, Group VB metal or a mixture thereof; and (c) contacting the zeolite obtained in step (b) with alkoxysilane, characterized in that the metal salt solution of step (b) comprises a glycolic solvent as a reducing agent in basic conditions, and step (b) is carried out at a temperature above 120 ° C.

In one embodiment, the glycolic solvent is an alkylene glycol, preferably propylene glycol and ethylene glycol, more preferably ethylene glycol.

Preferably, step (b) is carried out at the temperature in the range of 140 to 190 ° C to reduce the metal of step (b) to a nanoscale metal giving a good distribution in the zeolite.

The zeolite according to the invention comprises an aluminosilicate compound comprising silicon, aluminum and oxygen in its structure. It can be a natural or synthetic zeolite.

In one embodiment, the molar ratio of silica to alumina in the zeolite used in the invention is greater than 20, preferably in a range of about 20 to 80 and more preferably in the range of about 20 to 50.

In one aspect, the zeolite may be selected, but not limited to, MFI zeolites selected from ZSM-5, ZSM-11, or a mixture thereof, most preferably ZSM-5.

In one embodiment, the metal of group ΠΙΑ is gallium. The metal salt of the group ΠΙΑ may be chosen from gallium nitrate, gallium chloride, gallium bromide, gallium hydroxide, and gallium acetate, preferably gallium nitrate.

In one aspect, the ratio of the group ΠΙΑ metal to the zeolite of step (a) is in the range of about 0.5 to 2% by weight, preferably in the range of about 0.5 to 1 % in weight.

In one aspect, step (a) is performed by impregnation or ion exchange, preferably ion exchange.

In one aspect, step (a) is conducted at a temperature of from room temperature to 100 ° C, preferably in the range of 50 to 90 ° C.

In one embodiment, the metal of the group ΥΠΙΒ may be chosen from nickel, palladium and platinum, preferably palladium.

In one aspect, the group VII1B metal salt may be selected from nickel nitrate, nickel chloride, nickel bromide, platinum hydroxide, platinum nitrate, platinum chloride, platinum bromide, and the like. , platinum hydroxide, palladium nitrate, palladium chloride, palladium bromide, palladium hydroxide, or a mixture thereof, preferably nickel nitrate, platinum chloride and chloride palladium, most preferably palladium chloride.

In one embodiment, the group VB metal may be selected from vanadium and niobium, preferably niobium.

In one aspect, the group VB metal salt may be selected from vanadium nitrate, vanadium chloride, vanadium bromide, vanadium hydroxide, vanadium acetate, niobium nitrate, sodium chloride, and the like. niobium, niobium bromide, niobium hydroxide, niobium acetate, ammonium oxalate niobium, or a mixture thereof, preferably vanadium chloride and ammonium oxalate niobium, most preferably ammonium oxalate niobium.

In one embodiment, the ratio of the group VUIB metal and the group VB metal to the zeolite of step (b) is in a range of about 0.1 to 1% by weight, preferably in the range of from about 0.1 to 0.5% by weight.

In one embodiment, step (c) may be carried out by a chemical vapor deposition process or a liquid phase chemical deposition process, preferably the liquid phase chemical deposition method.

For the liquid chemical deposition process, alkoxysilane in solution form is used. The solvent for dissolving the alkoxysilane solution may be selected from, but not limited to, aromatic hydrocarbons, aliphatic hydrocarbons, cyclic hydrocarbons, alicyclic hydrocarbons, cyclic olefins and ethers, preferably cycloalkane.

In one embodiment, the alkoxysilane of step (c) may be selected from primary alkoxysilane, secondary alkoxysilane, tertiary alkoxysilane, quaternary alkoxysilane, or a mixture thereof, preferably the quaternary alkoxysilane chosen from tetramethoxysilane and tetraethoxysilane, most preferably tetraethoxysilane.

In one embodiment, the ratio of the alkoxysilane to the zeolite of step (c) is in the range of about 5 to 20% by weight.

In one aspect, the concentration of an alkoxysilane solution of step (c) is in a range of about 1 to 30% by volume.

In one embodiment, step (c) may be carried out at a temperature in a range of about 20 to 50 ° C for about 5 to 20 hours.

In one embodiment, the method of preparing said catalyst may further include the steps of drying and calcining. The drying step can be carried out by a general drying method using an oven, drying under vacuum and evaporation with stirring. The calcination step may be carried out under atmosphere for about 1 to 10 hours at the temperature in a range of about 400 to 800 ° C, preferably about 4 to 6 hours at the temperature in the range of about 500 at 600 ° C.

In another embodiment, the present invention relates to the use of the catalyst prepared from the process according to the invention for the aromatization reaction of alkanes having 4 to 9 carbon atoms in order to produce aromatic compounds, preferably a mixture of benzene, toluene and xylene (BTX), more preferably p-xylene.

In one embodiment, the aromatization reaction can be carried out by contacting an alkane feedstock with a catalyst prepared by the process according to the invention under conditions suitable for the reaction. This can be achieved by a fixed bed system, a moving bed system, a fluidized bed system or a batch mode system.

The aromatization reaction of alkanes can be carried out at a temperature in the range of about 400 to 800 ° C, preferably in the range of about 500 to 600 ° C, and under the pressure below atmospheric pressure. up to about 3000 kPa, preferably in the range of about 100 to 500 kPa, more preferably at atmospheric pressure.

The hourly space velocity (WHSV) of the alkane feedstock during the aromatization reaction of the alkanes is in a range of about 1 to 30 hours, preferably in the range of about 3 to 10 hours. '1.

In general, anyone skilled in the art can modify the conditions of the aromatization reaction of alkanes as appropriate to the types and compositions of the catalyst charge and reactor systems.

The following examples are indicated as one aspect of the invention, not for the purpose of limiting the scope of the present invention in any way.

Catalyst preparation

The preparation of the catalyst according to the invention can be carried out by the following methods.

Contacting the metal salt solution of the MA group

The zeolite was contacted with the metal salt solution by the ion exchange method using about 150 ml of a gallium nitrate solution with the gallium to zeolite ratio of about 1% by weight. Then, the resulting mixture was stirred at a temperature of about 80 ° C for about 10 hours. The resulting mixture was washed with distilled water and dried at a temperature of about 110 ° C overnight. Then, it was calcined at the air temperature of about 550 ° C for about 5 hours. The calcination temperature was increased from room temperature to about 10 ° C per minute.

Contacting the metal salt solution of group VB or group VIIIB or the group containing the solvent glvcoliaue

The metal chloride salt was added to about 50 ml of ethylene glycol. The metal to zeolite ratio was about 0.5% by weight. The pH of the solution was adjusted to about 10. Next, the zeolite was added at about 2 g and refluxed at about 180 ° C for about 3 hours. Then, the resulting mixture was filtered and washed with acetone and distilled water and dried at a temperature of about 110 ° C overnight. Then, it was calcined at the air temperature of about 550 ° C for about 5 hours. The calcination temperature was increased from room temperature to about 10 ° C per minute.

Contacting with the alkoxysilane

About 1 g of zeolite was contacted with the tetraethoxysilane solution with the ratio of tetraethoxysilane to zeolite of about 25% by weight for about 12 hours. Then, it was dried at a temperature of about 120 ° C for about 2 hours. Then, it was calcined in air at a temperature of about 550 ° C for about 5 hours. The calcination temperature was increased from room temperature to about 10 ° C per minute.

Comparative Sample Cat A (Ga / ZSM5f

The zeolite with the silica to alumina mole ratio of about 25 was contacted with the gallium nitrate solution by the method described above.

Comparative sample Cat B (Pd (impVGa / ZSM5)

The zeolite with the silica to alumina mole ratio of about 25 was contacted with the gallium nitrate solution by the method described above. The zeolite obtained was brought into contact with the palladium chloride with the ratio of palladium to zeolite of about 0.5% by weight. The zeolite obtained was dried at the temperature of about 110 ° C overnight, and calcined at the air temperature of about 550 ° C for about 5 hours, the calcination temperature having been increased from room temperature to the speed of about 10 ° C per minute.

Comparative sample Cat C (Pd (glvcolVGa / ZSM5 ~)

The zeolite with the silica to alumina mole ratio of about 25 was contacted with the gallium nitrate solution. The zeolite obtained was brought into contact with the palladium chloride containing the glycolic solvent by the method described above.

Cat D Comparative Sample (CLD / Pd (impVGa / ZSM5 ~) Comparative sample Cat D was prepared by the method described in the comparative sample Cat B. Then, the zeolite obtained was brought into contact with the tetraethoxysilane according to method described above.

Sample according to the invention Cat 1 (CLD / Pd (glvcolVGa / ZSM5 ') The sample according to the invention Cat 1 was prepared by the method described in the comparative sample Cat C. Then, the zeolite obtained was put into operation. contact with tetraethoxysilane according to the process described above.

Sample according to the invention Cat 2 (CLD / Nb (glvcoD / Ga / ZSM5) The sample according to the invention Cat 2 was prepared by the method described in the sample according to the invention Cat 1 using a chloride solution of niobium instead of the palladium chloride solution.

Sample according to the invention Cat 3 (CLD / V (glvcolVGa / ZSM51 The sample according to the invention Cat 3 was prepared by the method described in the sample according to the invention Cat 1 using a solution of vanadium chloride to instead of a solution of palladium chloride.

Alkane aromatization reaction test The alkane aromatization reaction test may be carried out by the following conditions:

The aromatization reaction of alkanes was carried out in a fixed bed reactor. About 0.2 g of the catalyst was used before the reaction. The catalyst was contacted with hydrogen at a temperature of about 500 ° C for about 1 hour. Then, the hydrogen was converted to nitrogen with a flow rate of about 20 ml / min. Then, the pentane was charged at the rate of about 1.6 ml / hour. The reaction was carried out at a temperature of about 500 ° C at atmospheric pressure and the mass hourly space velocity (WHSV) was about 5 hours.

The following are the test examples of the compositions of the products obtained from the catalyst according to the invention. The methods and equipment used for each test are processes and equipment used in general and not intended to limit the scope of the invention.

The compositions of the products were determined by a gas chromatography technique (Shimadzu 17A-GC, HP-PLOT / A1203 "S" capillary column deactivated). The temperature of the column has been set to separate each composition in the products. The starting temperature was maintained at 40 ° C for about 10 minutes. Then, the temperature was increased at a linear rate to a temperature of about 195 ° C and held steady for about 30 minutes. The xylene isomer compositions were analyzed using the Agilent Model 6890N equipped with a Stabilwax capillary column.

The conversion in%, the yield in%, the selectivity in% of the product in each composition and the selectivity in% of p-xylene in xylene were calculated from the following equations:

Table 1: conversion in%, selectivity in% of aromatic compounds and selectivity in% of p-xylene over time of 4 hours.

Table 1 shows the effectiveness of the comparative samples and samples according to the invention for the aromatization reaction of alkanes. In view of the table, of the comparison between the Cat B comparative sample, the Cat C comparative sample and the Cat D comparative sample and the sample according to the invention 1, it was discovered that the comparative sample Cat C treated with the palladium chloride solution containing the glycolic solvent as the reducing agent gave a% conversion and% selectivity of the higher aromatic compounds.

In addition, it was found that the catalyst prepared from the process according to the invention gave a high% conversion, a high% selectivity of aromatic compounds, and a high% selectivity of p-xylene for the reaction of aromatization of alkanes, as indicated in the objectives of the present invention.

Best mode of realization of the invention

The best embodiment of the invention is that indicated in the description of the invention.

Claims (10)

A process for preparing a catalyst for the aromatization of alkanes, wherein said process comprises the following steps: (a) contacting a zeolite with a Group IIIA metal salt solution; (b) contacting the zeolite obtained in step (a) with the metal salt solution selected from Group VIIB metal, Group VB metal or a mixture thereof; and (c) contacting the zeolite obtained in step (b) with alkoxysilane, characterized in that the metal salt solution of step (b) comprises a glycolic solvent as a reducing agent in basic conditions, and step (b) is carried out at a temperature above 120 ° C. 2. Process for the preparation of a catalyst according to claim 1, wherein the glycolic solvent is an alkylene glycol. 3. Process for the preparation of a catalyst according to claim 1 or 2, wherein the glycolic solvent is ethylene glycol. The process for preparing a catalyst according to claim 1, wherein step (b) is carried out at a temperature in a range of 140 to 190 ° C. The process for preparing a catalyst according to claim 1, wherein the zeolite is selected from ZSM-5, ZSM-11, or a mixture thereof. The process for preparing a catalyst according to claim 1, wherein the metal of the IDA group of step (a) is gallium. A process for preparing a catalyst according to claim 1 or 6, wherein the ratio of the group ΙΠΑ metal to the zeolite of step (a) is in the range of 0.5 to 2% by weight. The process for preparing a catalyst according to claim 1, wherein the group VIIIB metal is palladium and the group VB metal is vanadium or niobium. A process for preparing a catalyst according to claim 1 or 8, wherein the ratio of the metal of the group HIVB and the group VB metal to the zeolite of step (b) is in a range from 0.1 to 0 , 5% by weight. The process for preparing a catalyst according to claim 1, wherein the ratio of the alkoxysilane to the zeolite of step (c) is in the range of 5 to 20% by weight.