SU727210A1 - Method of regenerating pulverulent aluminium-chromium catalyst - Google Patents

Description

one

The invention relates to the field of regeneration of chromium aluminum catalysts for the dehydrogenation of paraffinic hydrocarbons.

A known method for the regeneration of alumino-chromium catalysts for the dehydrogenation of paraffinic hydrocarbons. by burning the coke with the air oxygen ll.

The closest to the described method is the method of regenerating the aluminum chromium catalyst for dehydrogenating paraffinic hydrocarbons by burning coke from the catalyst surface with oxygen at 60--67О ° C with subsequent reduction of hexavalent chromium to trivalent by treating the oxidized catalyst with hydrogen or lower hydrocarbons at 6OO-65O With C2. According to this method, regeneration is carried out for 30 minutes at an oxygen content of 21%, with a yield of butylenes on a regenerated catalyst of 38% by weight. Hexavalent content

chromium in the regenerated catalyst O, 55 wt.%.

A disadvantage of the well-known method is the small depth of regeneration of the spent catalyst.

The aim of the invention is to increase the degree of regeneration of the aluminum chromium catalyst.

This goal is achieved in that the spent catalyst is subjected to the extraction of coke from the catalyst surface by air treatment at 6OO-670 ° C, followed by the reduction of hexavalent chromium to trivalent, while the air treatment is subjected to 5O-9O wt.% Of the total amount of the worked catalyst and recovery of hexavalent chromium to trivalent

is carried out by mixing the remaining part of the spent catalyst with the catalyst after coke under fluidized bed conditions at a temperature of 59065 ° C contact time of 1-10 minutes.

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As a result of carrying out the process in the regenerated catalyst, the content of hexavalent chromium is reduced to 0.05% by weight. The yield of butyl on the regenerated catalyst is 40.5 wt.%.

Example 1. In two heated laboratory reactors in a fluidized bed of fresh and hummochromic catalyst, the dehydrogenation of u-utan was carried out at a temperature of 560 Nm, the volumetric feed rate was 4OO h, the duration | Cyc of contact was 15 min. At the end of the contact cycle, the catalyst

O4

with one of the reactors is subjected to oxidative treatment with air at a temperature of 600 C in order to burn coke. Then, the spent catcher is added to the oxidized catalyst from the second reactor in a 3: 1 ratio and is mixed in a fluidized bed for 1 minute in a stream of dehydrated nitrogen. After the displacement, the initial and catalysts are analyzed for the content of schivalent chromium, coke and catalytic activity in a 15-1 minute dehydrogenation cycle, the data are given in Table. 1, T a b l and c a 1

Output in the calculation:

on missed

on decomposed

. wt.%

Example 2, B of two heated reactors in a laboratory reactor in a fluidized bed of an alumina chromium catalyst reduced by natural gas, the dehydrogenation cycle of n-utan is carried out under the conditions specified in example 1.

The composition of the natural gas supplied to the fresh catalyst reduction is as follows,%:

Methane 81,5

Ethane, propane .4,9

Hydrogen14,5

At the end of the contacting cycle, the catalyst in one of the reactors is

39.5 80.0

oxidizing air treatment at 650 ° C; then the spent catalyst is added to the oxidized catalyst from the second reactor, the torus is in a 10: 1 ratio, and the fluid bed is displaced for 5 minutes

 in a stream of dehydrated nitrogen.

The catalysts, after reduction with natural gas and after displacement, are analyzed for bivalent chromium, coke and catalytic activity in the 15.min dehydrogenation cycle, as shown in Table 2. 2,

Example 3. In two heated reactors, in one of which there is a fresh catalyst, in the other a fresh catalyst reduced by natural gas, n-butane is dehydrated under the conditions of example D. At the end of the contacting cycle, the catalyst in one of the reactors is subjected to air oxidation treatment at a temperature of 670 ° C, then spent 1: 1 from the second reactor is added to the oxidized catalyst and the mixture is mixed in a fluidized bed for 10 minutes in a stream of dry nitrogen.

Catalysts: fresh, reduced natural gas and the catalyst after mixing are analyzed for the content of hexavalent chromium, coke and catalytic activity in a 15-minute dehydrogenation cycle, the data are given in Table. 3

Claims (1)

Gaffers 3 7 7272 Formula invented Method for regeneration of pulverized alumina catalyst for alloying paraffin hydrocarbons by pu-5 by burning coke from the catalyst surface by air treatment at a temperature of 600-670 ° C, followed by reduction of hexavalent chromium to trivalent, characterized by the fact that, in order to increase the degree of catalyst regeneration, the air treatment is subjected to 10O-9O wt.% of the abrasive catalyst and the reduction of 08 hexavalent chromium to trivalent is carried out by mixing After the treatment with air in a fluidized bed at a temperature of 580–850 ° C and a contact time of 1–10 min. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 177855, cl. B 01 J 23/90, 1961, 2, USSR Copyright Certificate Ns 177413, cl. In O1 J 23 / 9O, 1961 (prototype).