SU760996A1 - Method of producing catalyst for dehydrogenating 1-tetralon - Google Patents

Description

The invention relates to methods for producing catalysts for the dehydrogenation of 1-tetralone based on active alumina.

A known method for producing catalysts for the mash for the dehydrogenation of 1-tetralone by impregnating the active aluminum oxide with solutions of nickel nitrate with copper and chromium (nickel concentration 15%) [1]. TO

Closest to the proposed technical essence and the achieved effect is a method of producing a catalyst for dehydrogenating 1-tetralone by impregnating alumina with an aqueous solution of nickel nitrate and solutions of copper and chromium salts, calcining followed by treatment with potassium sulfate and reduction with hydrogen | X | . * 2 (

The known method requires a greater consumption of metal salts, since the catalyst contains over 30 wt.% Nickel, 15-40 wt.% Copper, 0.5-4 wt.% Chromium, 0.3-1.0 wt.% Potassium oxide; 2! characterized by uneven distribution of the active component on the carrier (aluminum oxide), requires calcination after each stage of impregnation. In addition, catalyzate, 3 (

2

obtained in this way, is characterized by insufficient activity and selectivity '. Thus, the degree of conversion of 1-tetralone in the presence of a known catalyst containing 15 wt.%, 0.3-1.0 wt.% K, 0 on alumina is 74.0%, and the selectivity for I-naphthol is 90 % in the case of introducing into the catalyst an additional 15-40 wt.% copper, 0.5-4.0 wt.% chromium, the degree of conversion increases to 80% with a selectivity of 90.0%.

The purpose of the invention is to obtain a catalyst with increased activity and selectivity.

The goal is achieved by the fact that a method has been proposed for preparing a catalyst for the dehydrogenation of 1-tetralone by irbiptic alumina with a solution of Nickel salt in 0.55 - 0.80 M ammonia solution, followed by treatment with potassium sulfate and reduction with hydrogen.

The proposed method allows to obtain a catalyst with increased activity and selectivity (the degree of conversion of 1-tetralone increases to 94-96%, selectivity to 95-98.0%). At the same time activity and selectivity

760996

Nickel catalyst is increased without the addition of copper and chromium, the concentration of nickel is reduced several times in comparison with the known (from 15-30 wt.% to 2.0-12.3 wt.%) while maintaining and improving the activity and selectivity ( dehydrating 1-tet- ⁵ 'ralon.

The method consists in the following. Active alumina is placed

in a glass vessel, pour a solution of nickel salt in a 0.55-0.8 M solution of ammonia, incubate under static conditions with periodic stirring for a certain time depending on how much nickel needs to be added to the composition

solid phase.

The mechanism of interaction of active aluminum oxide with ammonia solutions of nickel salts is that, 20 in addition to the substitution of nickel ions for hydrogen ions in the surface OH groups of alumina oxide,

2 partial dissolution of aluminum oxide, the interaction of the dissolved forms with 25 nickel ions in solution and epitaxial deposition of the resulting slightly soluble hydroaluminate nickel compound on the surface of the starting oxide. Due to the formation of the complex of nickel with ammonia in the solution, the total content of nickel ions necessary for the conversion of the initial aluminum oxide is created and the precipitation of nickel hydroxide is prevented at sufficiently high pH values, ³³ required for the reaction to occur.

The decrease in nickel ion concentration in the solution as the di-aluminate is precipitated is replenished due to the dissociation of complex ions.

The composition of the resulting products is regulated by the conditions of the reaction, which vary within the following limits: Nickel concentration 0.01-0.02M;

"the duration of the contact of the solutions with the solid phase from several hours to ten days; T: W = 1: 250; ammonia concentration 0.55-0.8 M. ^{3 3}

Prod implementation of the proposed method for the preparation of catalyst Nickel

'*'6k'azyoae^; Tsya 'chemically "associated with /

The surface and alumina skeleton of aluminum oxide, as a result of which the maximum fixation strength of the active component with the carrier is achieved, the uniform distribution of the active component on the carrier and the number of active centers increase.

The obtained highly porous compounds have a developed specific surface area exceeding the value of the specific surface area of the initial AO _g 0 _Oe . With the proposed method, it is possible to obtain products with different preset ratios Νϊ 0: A? ₂ 0 ".

PRI me R 1. a portion of active aluminum oxide grade A-64 specific surface 180 m ² / g, a particle size of 0.6-0.7 mm in an amount of 10 g is placed in a glass vessel and pour 2.5 liters of {T: L - 1: 250) solution nickel ammoniate with a concentration of 0.0170 M, pH 10.8; ammonia concentration C _MNE = "0.55 M. The process is conducted under static conditions with occasional stirring. During the contact time of 6 hours, a product containing 0.35 mg-ion получают is obtained! per 1 g of the sample or as a percentage - 2.0 wt.% of nickel per 1 g of the sample.

PRI me R 2. Under conditions similar to example 1, with varying concentrations of nickel salts in ammonia solution and contact time of the solid and liquid phases. Samples of catalysts with different nickel content in the solid phase are obtained.

The composition of the synthesized nickel catalysts based on active alumina is given in Table. one.

The resulting catalysts are investigated in the reaction of dehydrogenation of 1-tetralone. The catalyst is preliminarily treated by treatment with potassium sulfate, decomposed in a stream of helium at 500 ° C for 2 h, and reduced with hydrogen for 3 h at 500 ° C. The catalyst contains 0.3-1.0% K ₂ O. The dehydrogenation is carried out at elevated temperatures in a flow type reactor, 70 g of 1-tetralone is passed at 400 ° C through a catalyst containing various amounts of nickel per AG _g O ₃ .

The amount and composition of Catalysis, the degree of conversion and the selectivity of the reaction are given in Table. 2

For comparison, in table. 3 shows the degree of conversion and selectivity of the dehydrogenation reaction of 1-tetralone in the presence of catalysts obtained by a known method and containing nickel with chromium and copper additives.

"Ί: '-' '

Table 1

760996

When- Continued Concentration Concentration Quantity- N1 in N1 0: measures strength tration PH tration in ί in soy- contact • one ammoniac N1, M ΝΗ ₄ 0Η, M sample mg-ion / g one tave solid phases, weight.%

8 h - ... _____ „ , - ....... .......-. · __ one 0.0202 10.9 0.61 0.70 4.1 0.086: 1 2 3 days 0.0202 10.9 0.61 1.40 7,8 0.17: 1 3 10 days 0.0206 11.2 0.80 2.10 12.3 0.26: 1 table 2 When- Contains If- Composition catalyzate, g Power Selective measures ние in the sample, wt.% honor catalyzate g 1-tetralone Naphthalene 1-Naphthol transformations % ness,%

one 2.0 67.0 9 r1 1,3 56,6 87., 7 98.0 2 4.1 66.8 7 , 0 2.7 57.1 90.0 95.5 3 7,8 66 7 3 , 6 2.8 60.3 94.8 95.6 four 12.3 66.8 2 ,eight 4.4 59.6 96.0 93.0 • T a b persons 3 When- Contains Content add Power Selective measures Ν ί, wok on 100 g N1 transform ness,% weight.% Si Cr hunt % X, - .... .....; ·. · '<_ then .., ·, · · one 15 - 74.0 90.0

thirty

15-40 0.5-4

80.0

90.0

Claims (1)

Claim method for producing a catalyst for dehydrogenating 1-tetralone by impregnating alumina with a nickel salt solution followed by treatment with potassium sulfate and reduction with hydrogen, characterized in that, in order to produce a catalyst with increased activity "and selectivity45 impregnation is carried out with a solution of nickel salt. In a 0.55 - 0.80 M solution of ammonia.