RU2073566C1 - Method of preparing alumino-cobalt-molybdenum catalyst for hydrofining of mineral oil fractions - Google Patents

Abstract

FIELD: oil refining. SUBSTANCE: dry molybdenum and cobalt salts are introduced into aluminium hydroxide paste followed by addition of 0.015-0.025 mol nitric acid per 1 mol alumina. EFFECT: simplified preparation procedure and improved catalyst characteristics. 2 cl, 3 tbl

Description

 The invention relates to oil refining and petrochemicals, in particular, to the preparation of alumina-cobalt-molybdenum catalyst for hydrotreating oil fractions.

Known methods for the preparation of alumina-cobalt-molybdenum catalyst by introducing aqueous solutions of ammonium molybdenum acid and cobalt nitrate in an aqueous suspension of aluminum hydroxide obtained by reprecipitation, evaporation, molding, drying and calcination [1]
The disadvantage of this method is that the catalysts prepared by it have a low activity, do not meet the modern requirements of hydrotreating oil fractions. Among the disadvantages is the low strength of the catalysts, which limits their service life to 2-3 years.

Known methods for the preparation of alumina-cobalt-molybdenum hydrotreating catalysts by coextrusion (mixing) of boehmite (aluminum hydroxide obtained by reprecipitation of trihydrate) with aqueous solutions of cobalt and molybdenum salts, or with an aqueous solution of a salt of one of the metals, drying, calcining and impregnating an aqueous solution of a second metal salt [2]
The disadvantage of these methods is the low activity of the catalysts: in the hydrodesulfurization of a low-sulfur straight-run fraction containing only 0.45 wt. sulfur, the degree of desulfurization does not exceed 85%
A known method of preparing an alumina-cobalt-molybdenum hydrotreating catalyst by preparing a suspension of a nickel-molybdate complex by pouring aqueous solutions of ammonium molybdenum acid and cobalt nitrate in the presence of hydrogen peroxide, mixing with a suspension of aluminum hydroxide, filtering, molding, drying and calcining [3]
The disadvantage of this method is the low strength of the catalyst and low activity in the hydrotreating of sour raw materials.

Closest to the proposed technical solution according to the technical essence and the effect achieved is a method of preparing an alumina-cobalt-molybdenum catalyst for hydrotreating petroleum distillates, comprising introducing freshly precipitated aluminum hydroxide with a 75% PPP into the paste in the first stage of an aqueous solution of cobalt nitrate, mixing at a temperature of 80-90 ^o C for 90 min, evaporation, extrusion molding, drying at 50-130 ^o C for 10 h, calcination at 550 ^o C for 4 h, impregnation with an aqueous solution of ammonium molybdate with the addition of pouring ammonia as a solution stabilizer for 1 h at room temperature, drying at 50-130 ^o C for 10 h, calcining at 500-550 ^o C for 4 h [4]
The disadvantage of this method is the complex long multi-stage, energetically disadvantageous technology, including double heat treatment, as well as low strength and low activity in the hydrotreating of high sulfur oil fractions.

 The aim of the invention is to simplify the technology by reducing the number of stages, duration and energy intensity, expanding the raw material base of the carrier, increasing the strength and activity in the hydrotreatment of high sulfur oil fractions.

This is achieved by the fact that in the method for preparing an alumina-cobalt-molybdenum catalyst for hydrotreating petroleum fractions, including introducing cobalt and molybdenum compounds into aluminum hydroxide, molding, drying and calcining, an aluminum hydroxide paste with annealing loss of 75–85 wt% is used as aluminum hydroxide. the compounds of molybdenum and cobalt are introduced sequentially in the form of dry salts with intermediate stirring, and when the PPK reaches 60-65 wt. make nitric acid in an amount of 0.015-0.025 mol per mol of Al ₂ O ₃ .

In the proposed method, either aluminum hydroxide paste obtained by reprecipitation of aluminum trihydrate or a mixture of aluminum hydroxide paste obtained by reprecipitation and obtained by etching metallic aluminum with a solution of hydrochloric acid, followed by neutralization of sodium hydroxide solutions, washing and filtering, in a ratio of 3: 1 to 1: 3 in terms of Al ₂ O ₃ .

Comparative analysis with the prototype shows that the claimed technical solution differs from the prototype in that the use of a hydroxide paste with a moisture content of 75-85 wt. obtained by reprecipitation of aluminum oxide trihydrate (I) or its mixture with a hydroxide paste obtained by etching metallic aluminum with a solution of hydrochloric acid, followed by neutralization with sodium solution, washing and filtering (II), in a ratio of 3: 1 to 1: 3, molybdenum oxides and cobalt is introduced in the form of dry salts with intermediate stirring, and upon reaching PPK 60 65 wt. make nitric acid in an amount of 0.015 to 0.025 mol per mol of Al ₂ O ₃ .

Example 1. In the mixer load 325 kg of aluminum hydroxide obtained by reprecipitation of alumina trihydrate, with a PPK of 80 wt. 12 kg of ammonium molybdenum acid are poured, stirred for 20 minutes, 12 kg of cobalt nitrate are poured, mixed with simultaneous evaporation of the mass to a PPD of 65 wt. then pour 1.0 l of nitric acid, mix with simultaneous evaporation to AUC 55 wt. the resulting mass is fed to a screw press machine, the extrudates are molded, sent for drying, dried at a temperature of 130 ^{° C.} for 4 hours, poured into a calcining furnace and calcined at 550 ^{° C.} for 8 hours.

 The resulting catalyst is analyzed for the content of active components, specific surface area, strength index according to OST 38.01130-95 and determine the activity in the process of hydrotreating high sulfur diesel fraction.

 The size (diameter) of the extrudates is 2.4 mm.

MoO content ₃ 9.8%
NiO 3.1 wt.

Specific surface S _beats 220 m ² g
Strength 2.2 kg / mm diameter
Example 2. Determination of activity in the process of hydrotreating high sulfur diesel fractions 180-360 ^o With a sulfur content of 0.9 wt.

Flow type reactor, catalyst loading of 100 ml, hydrogen consumption of 300 nl / l of catalyst, feed space velocity of 4 hours, pressure 30 atm, temperature 340 and 380 ^o C. Raw material sulphurization for 24 hours

 The result of determining the activity is estimated by the sulfur content in the hydrogenate 2 hours after sulphurization and expressed as residual sulfur content, wt. or in the form of a degree of desulfurization, rel.

For the catalyst according to example 1, the degree of desulfurization was at 340 ^o With 84.4% at 380 ^o With 88.7%
In the table. 1 shows the loading conditions of aluminum hydroxide in the preparation of the catalyst, in table. 2 conditions for the preparation of the catalyst, and in table. 3 comparative data on the quality of the catalysts, as well as a comparative example for the prototype and industrial alumina-cobalt-molybdenum catalyst.

As can be seen from the embodiments of the proposed method for the preparation of the catalyst, it allows you to get a catalyst with a strength index exceeding the strength index of the catalyst according to the prototype method by 0.1-0.7 kg mm of diameter, with an activity exceeding the activity of the catalyst of the prototype by 1.1 -5.6% at a temperature of 340 ^{o C.} and 1.0-5.2% at a temperature of 380 ^o C.

 At the same time, the raw material base of the catalyst carrier is expanding due to the use of aluminum hydroxide paste obtained by etching metallic aluminum with a solution of hydrochloric acid, followed by neutralization with a sodium hydroxide solution, and the technology is simplified by reducing the number of stages of introducing active components from dry salts instead of solutions, reducing the number of heat treatments.

Claims (2)

1. A method of preparing an alumina-cobalt-molybdenum catalyst for hydrotreating petroleum fractions, comprising introducing molybdenum and cobalt compounds into aluminum hydroxide, molding, drying and calcining, characterized in that aluminum hydroxide paste with losses during calcination of PPK 75 85 wt. compounds of molybdenum and cobalt are introduced sequentially in the form of dry salts with intermediate stirring, and upon reaching a PPK of 60 to 65 wt. make nitric acid in an amount of 0.015 to 0.025 mol per mol of Al ₂ O ₃ . 2. The method according to claim 1, characterized in that as a paste of aluminum hydroxide using a mixture of pastes of aluminum hydroxide obtained by reprecipitation of the trihydrate and etching of aluminum metal with a solution of hydrochloric acid, followed by neutralization with sodium hydroxide solution, washing and filtering, in a ratio of 3: 1 1 : 3 in terms of Al ₂ O ₃ .

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