RU2051741C1 - Method of activation of catalyst for aromatization of hydrocarbons - Google Patents

Abstract

FIELD: petroleum refining. SUBSTANCE: catalyst, containing zeolite, binder and platinum compound, is subjected to heat treatment with a nitrogen-oxygen mixture, containing 20 to 50 volume percent of oxygen, in atmosphere containing water vapor at a pressure of 0.4 to 0.5 MPa and temperature of 400 to 500 C. EFFECT: facilitated procedure. 2 tbl

Description

 The invention relates to catalytic processes in the petrochemical industry and can be used in the petrochemical industry for the production of aromatic hydrocarbons, and specifically to methods for increasing the catalytic activity of zeolite-containing catalysts.

The catalyst is zeolite L in potassium form (KL) with a binder on which the active component is applied, most often platinum. Zeolite L is a crystalline aluminosilicate whose composition can be described by the following molar ratios of oxides
M _{2 / n} ^O. Al ₂ O3 ^. xSiO ₂ where M is one or more metals, most often K, but part of it can be replaced by other cations, in particular Na, Mg, Ca, Ba.

n valency M
x coefficient equal to 5.0-7.5 (preferably 6.5-7.5).

The synthesis of zeolite L is carried out by known methods. The process for preparing hydrocarbon aromatization catalysts typically involves the following main steps.
Synthesis of zeolite KL followed by drying.

 Granulation of zeolite KL with a binder and drying of granules.

 Impregnation of a granular zeolite-containing support with a platinum compound followed by drying.

 Hydrogen reduction.

 In order to improve the catalytic characteristics of a zeolite-containing catalyst, the latter is often subjected to additional heat treatment operations in various environments during the preparation process.

Since it is known that heat treatment of the zeolite is carried out at 300-600 ^C in a Freon medium (6) to increase the stability of the catalyst.

According to the method (7), the finished catalyst was treated at 80-600 ^{° C} halogen gases.

 A known method of activating a catalyst is that the finished catalyst, after reduction in a hydrogen medium, is cooled, exposed to air, and then again subjected to heat treatment in a hydrogen medium. This method allows to increase the selectivity of aromatization and increase the stability of the catalyst (8).

The closest known technical solution and taken as a prototype is a method involving additional heat treatment of the catalyst in air containing water vapor (9). In accordance with the prototype, the extrudates of zeolite KL with a binder are dried, calcined, impregnated with a solution of [Pt (NH ₃ ) ₄ ] (NO ₃ ) ₂ based on the platinum content on the catalyst of 0.64 wt. and dried for 16 hours at ²⁵⁰ F (120 ^C). The dried catalyst was calcined at atmospheric pressure at 500 ^o F (260 ^o C) for 2 hours in a stream of air, containing 3 or 50% steam. The catalyst obtained in a known manner is tested during the aromatization of a gasoline fraction of C ₅ -C ₈ containing (wt.) 80.9 paraffins (mainly C ₆ -C ₇ ), naphthenes and 1.7 aromatic hydrocarbons.

 The disadvantages of this method include the relatively low activity and selectivity of the catalyst in the process of aromatization of paraffins.

 The aim of the invention is to increase the activity of the catalyst for aromatization of paraffins and increase the selectivity of its work.

This goal is achieved by conducting thermocouple treatment of the aromatization catalyst under a pressure of 0.4-0.6 MPa and a temperature of 400-500 ^about With a nitrogen-oxygen mixture containing 20-50 about. oxygen.

In accordance with the proposed method is subjected to activation treatment termoparovoy dried at 130 ^{° C} aromatization catalyst composition (wt.) Zeolite L in a potassium form 75, platinum 0.8, remainder binder. The thermocouple treatment was carried out with a nitrogen-oxygen mixture with different oxygen contents at a space velocity of 1000 h ^-1 in wide pressure and temperature ranges for 2 hours. The concentration of water vapor in the gas mixture was 25-35%. The catalysts treated in this way were tested during aromatization straight-run gasoline fraction 62-105 ^about C.

 An analysis of the prior art shows that the technique for increasing the activity of zeolite-containing catalysts for thermocouple treatment of the latter in a stream of air or nitrogen is well known (9-11). However, all known methods do not involve the use of pressure.

It was experimentally established that the thermocouple treatment of a paraffin aromatization catalyst by the proposed method at atmospheric pressure does not lead to an improvement in the catalytic characteristics of the catalyst. Moreover, its activity is sharply reduced in comparison with the sample of the catalyst not subjected to thermocouple processing. An increase in the pressure of the thermocouple treatment from atmospheric to 0.6 MPa leads to an increase in the activity of the catalyst in the aromatization reaction. At the same time, the yield of C ₁ -C ₄ gases decreases, which indicates an increase in the selectivity of aromatization. A further increase in the heat treatment pressure from 0.6 MPa to 1.0 MPa has practically no effect on the catalytic characteristics of the catalyst. An analysis of the results of experimental studies shows that the preferred heat treatment pressure in this case is 0.5-0.6 MPa.

Thermocouple treatment of catalysts at elevated pressure requires higher temperatures than is conventional in known methods for processing at atmospheric pressure. Thus, according to the prior art (9), the catalyst-steam treatment is conducted at ⁵⁰⁰ ° C (260 ° ^C), while on the proposed method of heat treatment temperature at a pressure of 0.5 MPa should be not lower than 750 (400 ° ^C).

 A significant effect on the catalytic characteristics of the catalyst during thermocouple processing by the proposed method also has the ratio of nitrogen: oxygen in the gas mixture. The best experimental results were obtained by thermocouple treatment of catalysts with a gas-vapor mixture containing 20-50 vol. oxygen.

 A comparative analysis of the proposed technical solution with the method according to the prototype (9) shows that the proposed method is characterized by the pressure of the thermocouple treatment, temperature, and also the composition of the nitrogen-oxygen mixture.

 PRI me R 1. (Preparation of catalyst).

Dried zeolite L in an amount of 60 g (58 g in terms of dry matter) is mixed with 71.2 g of aluminum hydroxide paste (19.3 g in terms of oxide) and 1.3 ml of 49% nitric acid. The resulting mass is thoroughly mixed and molded in a screw extrudate through a die with a diameter of 3 mm. The extrudates were dried at 130 ^{° C} for 4 hours and calcined in muffle at ⁵⁰⁰ ° C for 2 hours. The obtained 73.4 g of the extrudates size 2 (3-5) mm.

73.4 g of the extrudates were impregnated with 103 ml of an aqueous solution containing 0.587 g of platinum as [Pt (NH _{3) 4]} Cl ₂ and dried in an oven at 140 ^C for 6 hours.

 Thus prepared catalyst contains (wt.): 75 zeolite KL, 0.8 platinum, the optimal binder.

 PRI me R 2. (Activation of the catalyst).

Prepared, as described in example 1, the mass of catalyst (100 cm ³ ) is divided into 8 equal parts and each part is heat treated with a gas stream containing 30 wt. water vapor and feeding at a speed of 12 l / h, while varying the processing temperature, pressure and nitrogen-oxygen ratio in the gas stream. The following are the activation conditions for aromatization catalysts.

 PRI me R 3. (Tests of catalysts).

Samples 1-8 of Example 2 catalyst (Table. 1) were tested in the aromatization of straight-run gasoline fraction 62-105 ° ^C under pressure of 1.0 MPa, a temperature of 480 ^{° C,} the feed rate of 2 hr ^-1. and about. the ratio of hydrogen raw materials 1500. The test results after 100 hours of catalyst operation are presented in table. 2.

 Analysis of the test results shows that the activation of the catalyst according to the proposed method can significantly increase the activity of the latter in the process of aromatization.

 The proposed method can be successfully implemented in large-scale petrochemical processes, in particular, the production of aromatic hydrocarbons, gasolines, motor fuels.

Claims (1)

METHOD OF ACTIVATION OF A HYDROCARBON AROMATIZATION CATALYST, consisting of zeolite L, a binder and a platinum compound, by heat treatment in an atmosphere containing water vapor, characterized in that the heat treatment is carried out at a pressure of 0.4 - 0.5 MPa and a temperature of 400-500 ^o With nitrogen-oxygen a mixture containing 20-50 vol.% oxygen.

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