RU2177826C1 - Method of preparing platinum-rhenium catalyst for reforming of gasoline fractions - Google Patents

Abstract

FIELD: petroleum processing catalysts. SUBSTANCE: rhenium is deposited onto freshly precipitated aluminum hydroxide from rhenium acid or its ammonium salt aqueous solution. Support is formed into granules, which are dried at 110-130 C, calcined at temperature up to 550 C, impregnated with aqueous solution of platinum-hydrochloride solution, dried, and calcined. Catalyst can be used with no preliminary sulfurization. EFFECT: increased stability of catalyst in early operation period. 2 cl, 1 tbl

Description

 The present invention relates to the field of production of catalysts, in particular platinum-rhenium catalyst for reforming gasoline fractions, and can be used in enterprises of the chemical and oil refining industries.

Known methods for the preparation of platinum-rhenium reforming catalysts include applying platinum and rhenium compounds to active alumina obtained by calcining a hydroxide at a temperature of about 500 ^° C and hydrogen reduction at 400-500 ^° C (M. A. Ryazhentseva, Kh. M. Minachev. Rhenium and its precipitation in heterogeneous catalysis. - M.: Nauka, 1983, p. 157.196).

 Typically, alumina is impregnated with aqueous solutions of platinum chloride and rhenium acid. Rhenium compounds such as ammonium perrhenate and rhenium carbonyl can be used in organic solvents (US Pat. No. 4,157,989, 1979). Chlorinated alumina can also serve as a carrier (ed. St. USSR 1061330, class B 01 J 23/64, 1983).

 The preparation of platinum-orentium catalysts by applying the active components to alumina after reduction leads to an abnormally high activity of the catalyst in hydrocarbon decomposition reactions and an increased tendency to coking in the initial period of their operation (G.N. Maslyansky, R.N. Shapiro. Catalytic reforming of gasolines. - L .: Chemistry. 1983, p. 84, 204). To increase their stability during this period of operation, platinum-rhenium reforming catalysts are dosed sulfurized by introducing small amounts of sulfur compound (0.05-0.15% by weight of the catalyst in terms of sulfur) into the reactors during or after the catalyst recovery. However, in industrial conditions, the source of sulfur is also products of hydrogen sulfide corrosion, which are deposited in heat exchangers and chimneys. Due to the difficulty in determining the optimal dosage of sulfur compound, the metered sulfurization of the platinum-rhenium reforming catalyst is not always effective. In addition, operations associated with metered sulfurization reduce the time of productive work of catalytic reforming units.

 The closest in technical essence to the claimed method is a method of preparing a platinum-rhenium catalyst, in accordance with which the catalyst is prepared by impregnating γ-alumina with an aqueous solution containing all active components, including rhenium, followed by drying and calcination of the obtained catalyst (USSR patent 294297 B 01 J 11/16, 1971 prototype).

 The catalyst prepared according to the prototype has insufficient stability in the initial period of operation: after 100 hours of operation, the octane number of the catalysis decreases.

 The aim of the present invention is to increase the stability of platinum-rhenium catalyst in the initial period of its operation.

в результате чего рений становится компонентом носителя. Полученный носитель формуют в гранулы, сушат при температуре 110-130^oС в течение 6 ч, прокаливают при температуре 500-550^oС в токе воздуха в течение 2 ч, после чего пропитывают водным раствором, содержащим платинохлористоводородную кислоту, соляную и уксусную кислоты. Полученный катализатор сушат при температуре 110-130^oС и прокаливают при температуре 500-550^oС.This goal according to the invention is achieved by the proposed method for the preparation of platinum-rhenium catalyst, which consists in applying rhenium to freshly precipitated aluminum hydroxide by mixing aluminum hydroxide with an aqueous solution of rhenium acid or its ammonium salt with ammonium perrenate. This treatment leads to the formation of aluminum salts of rhenium acid:

whereby rhenium becomes a component of the carrier. The obtained carrier is formed into granules, dried at a temperature of 110-130 ^o C for 6 h, calcined at a temperature of 500-550 ^o C in a stream of air for 2 h, after which it is impregnated with an aqueous solution containing platinum chloride, hydrochloric and acetic acids. The resulting catalyst is dried at a temperature of 110-130 ^o C and calcined at a temperature of 500-550 ^o C.

The difference between the proposed method of preparation of the catalyst from the known one specified as a prototype is the set of stages for preparing the carrier, namely the use of freshly precipitated aluminum hydroxide, mixing it with an aqueous solution of rhenium acid or its ammonium salt, followed by molding, drying at 50-130 ^o С, calcining at 500-550 ^o C, after which the calcined carrier is impregnated with an aqueous solution of platinum chloride, hydrochloric and acetic acids.

 The proposed method for the preparation of platinum-rhenium catalysts allows you to abandon the stage of sulphurization of the catalyst, which is carried out at industrial reforming plants, and thereby increase the production time of the installation. In addition, significantly increases the stability of the catalyst in the initial period of its operation.

 Industrial applicability of the proposed method is illustrated by the following examples.

 Example 1

Aluminum hydroxide is prepared by precipitation from a solution of sodium aluminate with nitric acid, washed with water and squeezed in a filter press. The hydroxide pellet contains 27.0 wt. % dry matter (determined by calcination at 600 ^o C).

260 g of aluminum hydroxide (dry matter content of 27 wt.%) Is mixed with 100 ml of distilled water until a homogeneous liquid consistency is achieved. 7.2 ml of rhenium acid solution (concentration of Re 30.5 g / l) is added and again thoroughly mixed. The mass is dried to a residual water content of 65 wt. %, after which it is formed by extrusion. The extrudate is dried at 50 ^{° C. for} 3 hours, at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours, after which it is calcined for 2 hours at 500 ^{° C.} in a stream of air at a space velocity of 500 h ⁻¹ . Receive carrier granules having a diameter of 1.5 mm and a length of 3-5 mm The rhenium content in the carrier of 0.36 wt. %

The catalyst is prepared by impregnating the obtained carrier with an aqueous solution containing active components, with the exception of rhenium. To do this, prepare a mixture consisting of 23 ml of a solution of platinum chloride (concentration of Pt 9.38 g / l), 10.7 ml of hydrochloric acid (concentration of HC1 53.29 g / l) and 13.8 ml of acetic acid (concentration of CH ₃ COOH 130.8 g / l). Distilled water is added to the resulting solution so that its volume is 90 ml.

60 g of the carrier are poured into the diluted solution, which is kept in the solution for 2 hours. The mother liquor is evaporated at 70 ^° C, mixing the carrier granules. The resulting catalyst was dried at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours. Then, the catalyst was calcined at 500 ^{° C.} for 2 hours.

The composition of the catalyst, wt. %: Pt - 0.36, Re - 0.36, Cl - 1.3, the rest is Al ₂ O ₃ .

The finished catalyst is loaded into the installation and its reduction is carried out with dry electrolytic hydrogen under the following conditions: raising the temperature to 400 ^° C-8 hours, heating at 400 ^° C for 2 hours, a pressure of 2 MPa, the hydrogen circulation rate of 1000 nl / l of catalyst per hour. Then they proceed to the test of the catalyst, which is carried out at 475 ^{° C.} , a pressure of 2 MPa, a mass feed rate of 1.8 h ⁻¹ , a hydrogen-containing gas circulation ratio of 1000 nl / l feed. The catalyst is not discredited. The sulfur content in raw materials of 0.0001 wt. %

 Example 2

The catalyst prepared according to example 1, is tested under stringent conditions (temperature 505 ^o C).

 The octane number (research method) of catalysis after 10 hours of operation is 103.5, and after 100 hours it decreases to 100.6, i.e. by 2.9 points.

 Example 3

260 g of aluminum hydroxide (dry matter content of 27 wt.%) Is mixed with 100 ml of distilled water until a homogeneous liquid consistency is achieved. A solution of ammonium salt of rhenium acid (Re concentration of 30.5 g / l) is added and mixed thoroughly. The mass is dried to a residual water content of 65 wt. %, after which it is formed by extrusion. The extrudates are dried at 50 ^{° C. for} 3 hours, at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours, after which they are calcined for 2 hours at 530 ^° C. The resulting carrier granules have a diameter of 1.5 mm and a length of 3-5 mm . The rhenium content in the carrier of 0.21 wt. %

Then, 23 ml of an aqueous solution of platinum hydrochloric acid (Pt concentration of 9.38 g / L), 13.8 ml of acetic acid (CH ₃ COOH concentration of 130.8 g / L) and 10.7 ml of hydrochloric acid (HCl concentration 53.29 g / l). Distilled water is added to the resulting solution so that its volume is 90 ml.

60 g of the carrier are poured into the solution, which is kept in the solution for 2 hours. The mother liquor is evaporated at 70 ^° C, mixing the carrier granules. The resulting catalyst was dried at 100 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours. Then, the catalyst was calcined at 530 ^{° C.} for 2 hours in a stream of dry air passed at a space velocity of 500 h ⁻¹ .

The composition of the catalyst, wt. %: Pt - 0.36, Re - 0.2, Cl - 1.3, the rest is Al ₂ O ₃ .

Throughout the test of the catalyst, carried out at 475 ^o C, the octane number of the catalysis remains constant and equal to 91 (see table).

 Example 4

260 g of aluminum hydroxide (dry matter content 27 wt.%) Is mixed with 100 ml of distilled water until a homogeneous consistency is achieved. Add 14.4 ml of rhenium acid (Re concentration of 30.5 g / l) and mix thoroughly. The mass is dried to a residual water content of 65 wt. %, after which it is formed by extrusion. The extrudates are dried at 50 ^{° C. for} 3 hours, at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours, and then calcined for 2 hours at 550 ^° C. The obtained granules of the carrier have a diameter of 1.5 mm and a length of 3-5 mm . The rhenium content in the carrier of 0.72 wt. %

Then mix 23 ml of an aqueous solution of platinum hydrochloric acid (Pt concentration 9.38 g / l), 10.7 ml hydrochloric acid (HCl concentration 53.29 g / l) and 13.8 ml acetic acid (CH ₃ COOH concentration 130.8 g / l). Distilled water is added to the resulting solution so that its volume is 90 ml.

60 g of the carrier are poured into the solution, which is kept in the solution for 2 hours. The mother liquor is evaporated at 70 ^° C, mixing the carrier granules. The resulting catalyst was dried at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours. Then, the catalyst was calcined at 550 ^{° C.} for 3 hours in a stream of dry air passed at a space velocity of 500 m ^-1 .

The composition of the catalyst, wt. %: Pt - 0.36, Re - 0.70, Cl - 1.3, the rest - Al ₂ O ₃ . When testing the catalyst at 475 ^o With the octane number of catalysis is practically unchanged (see table).

Example 5 (for comparison)
The catalyst is prepared as in example 1, except that the rhenium-containing support is calcined at 400 ^° C for 2 hours. A decrease in the calcination temperature of the support from 500 ^° C to 400 ^° C degrades the activity of the catalyst and somewhat reduces its stability (see examples 1 and 5).

Example 6 (for comparison)
The catalyst was prepared as in Example 3, except that the rhenium-containing support was calcined at 530 ^° C. An increase in the calcination temperature of the carrier to 580 ^{° C. had} practically no effect on the activity and stability of the catalyst (see Examples 1 and 6).

Example 7 (prototype)
Aluminum hydroxide is obtained by precipitation of sodium aluminate with nitric acid. Washed with water and squeezed on a filter press the cake of aluminum hydroxide contains 27.0 wt. % dry matter (determined by calcination at 600 ^o C). 250 g of cake are dried to a residual water content of 65 wt. %, after which it is formed by extrusion. The extrudates are dried at 50 ^{° C. for} 3 hours, at 100 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours, then calcined for 2 hours at 500 ^{° C.} in a stream of air at a space velocity of 500 h ⁻¹ . The obtained granules γ-Al ₂ About ₃ have a diameter of 1.5 mm and a length of 3-5 mm

The catalyst is prepared by impregnating alumina with an aqueous solution containing all active components, including rhenium. To do this, prepare a mixture consisting of 23 ml of a solution of platinum chloride (concentration of Pt - 9.38 g / l), 7.2 ml of a solution of rhenium acid (concentration Re - 30.50 g / l) 10.7 ml of hydrochloric acid (concentration Hcl - 53.29 g / l) and 13.8 acetic acid (concentration of CH ₃ COOH 13 0.8 g / l).

 Distilled water is added to the resulting solution so that its volume is 90 ml.

60 g of alumina are poured into the diluted solution, kept in the solution for 2 hours. The mother liquor is evaporated at 70 ^o C, mixing the granules of alumina. The resulting catalyst was dried at 110 ^{° C. for} 3 hours and at 130 ^{° C. for} 3 hours. Then, the catalyst was calcined at 500 ^{° C.} for 2 hours in a stream of dry air passed at a space velocity of 500 h ⁻¹ .

The composition of the catalyst, wt. %: Pt - 0.36, Re - 0.36, Cl - 1.3, the rest is Al ₂ O ₃ .

The finished catalyst is loaded into the installation intended for its testing, and carry out its restoration with dry electrolytic hydrogen. The conditions of catalyst recovery: temperature rise to 400 ^o С 8 h, heating at 400 ^o С 2 h, pressure 2 MPa, hydrogen circulation rate of 1000 nl / l of catalyst per hour.

Next, they start testing the catalyst, using a gasoline fraction of 85-180 ^o C, subjected to hydrotreating and containing 0.0001 wt. % sulfur. Octane number of raw materials 35 (research method).

The test of the catalyst is carried out at 475 ^o C (mild conditions) and 505 ^o C (harsh conditions), a pressure of 2 MPa, a mass feed rate of 1.8 h ^-1 , the gas circulation rate of 1000 nl / l of raw material.

 The table shows data on the composition of the catalyst and its stability in the initial period of operation. After 100 hours of operation, the octane number of the catalyst decreases from 92.5 to 86.5, which indicates the insufficient stability of the fresh platinum-rhenium catalyst prepared in a known manner.

Example 8
The catalyst is prepared and reduced as indicated in Example 1.

After recovery of the catalyst, it is subjected to metered sulfurization. For this, a feed containing 0.005 wt. % sulfur, at 300 ^o With a pressure of 2 MPa with a mass feed rate of 1.8 h ^-1 and a hydrogen-containing gas circulation of 1000 nl / l of feedstock. The amount of sulfur supplied to the catalyst is 0.1% of its mass.

After that, the raw materials are replaced and transferred to the gasoline fraction with a sulfur content of less than 0.0001 wt. % and begin to test the catalyst at a temperature of 475 ^o . Other test conditions are given in example 1.

 As can be seen from the table, the stability of platinum-rhenium catalyst obtained in a known manner, after dosed sulfurization is significantly increased. Throughout the test, the octane number of catalysis remains virtually unchanged.

Example 9
The catalyst prepared according to the known method and subjected to metered sulfurization (see example 8), is tested under severe conditions (temperature 505 ^o C).

 The octane number (research method) of catalysis after 10 hours of testing, equal to 103, after 100 hours decreases to 100, i.e. by 3 points.

 As can be seen from the table, in comparison with the platinum-rhenium catalyst prepared by the known method (example 7), the same catalyst prepared by the present method (example 1) is characterized by significantly higher stability. In its stability, it is at least not inferior to the known platinum-rhenium catalyst subjected to metered sulfurization (Example 8).

 In addition, the catalyst prepared according to the present method and not subjected to sulphurization, in its stability under severe process conditions, is equivalent to the sulphurized catalyst obtained in a known manner (examples 2 and 9).

 The table also shows that in the initial period of operation (100 h), the catalyst with a high rhenium content (0.70 wt.%) Is almost as stable as the catalyst with a low rhenium content (0.20 wt.%). These data confirm that the proposed method for the preparation of platinum-rhenium reforming catalyst makes it possible to commission such catalysts without subjecting them to sulphurization, which is an advantage of the catalyst prepared by this method, since operations related to sulphurization of the catalyst, usually carried out in industrial reforming plants, reduce the time catalyst performance.

 In addition, under industrial conditions, one of the sources of sulfur, which is difficult to take into account, is also products of hydrogen sulfide corrosion, which are deposited in heat exchangers and chimneys. Due to the difficulty in determining the optimal dosage of sulfur compound, the method of sulfurization of the alumina-platinum-rhenium reforming catalyst is not always effective.

 The proposed method allows to overcome these difficulties.

Claims (2)

 1. A method of preparing a platinum-rhenium catalyst for reforming gasoline fractions, comprising applying the active components of platinum, rhenium and chlorine to an aluminum-containing support, followed by drying and calcining, characterized in that freshly precipitated aluminum hydroxide is used as an aluminum-containing support and the active components are applied by mixing the freshly precipitated hydroxide aluminum with an aqueous solution of rhenium acid or its ammonium salt, followed by molding, drying, calcining and impregnation the calcined support with aqueous solutions of platinum chloride, hydrochloric and acetic acids. 2. The method according to p. 1, characterized in that the drying of freshly precipitated aluminum hydroxide with active components is carried out at 50 - 130 ^o C, and subsequent calcination at 500 - 550 ^o C.

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