Ruthenium/carbon catalyst with activated carbon subjected to supercritical CO2 treatment as carrier and method for preparing catalyst

Abstract

The invention relates to a ruthenium / carbon catalyst with activated carbon subjected to supercritical CO2 treatment as a carrier and a method for preparing the catalyst. The method comprises the following steps of: (1) putting a certain amount of activated carbon into a reaction kettle, and introducing CO2 by using a high-pressure injection pump to reach the pressure of 8.0 to 14.0MPa; (2) raising the temperature of the reaction kettle to be between 60 and 100 DEG C; (3) keeping the supercritical condition for 2 to 6 hours, reducing the temperature, and relieving the pressure to obtain modified activated carbon; and (4) impregnating a certain amount of modified activated carbon into a RuCl3 aqueous solution for 4 hours, drying at the temperature of 120 DEG C, putting the dried sample intoa quartz tube of a tube-type heating furnace, reducing by using hydrogen at the temperature of 200 DEG C for 2 hours and at the temperature of 300 DEG C for 1 hour, closing a temperature controller, cooling to room temperature, and thus obtaining the ruthenium / carbon catalyst. The activity of the ruthenium / carbon catalyst prepared by the method is obviously improved due to the action of supercritical treatment, and the defect of a supercritical organic medium is overcome.

Description

technical field [0001] The present invention relates to the ruthenium carbon catalyst that is used for the synthesis of ammonia, the hydrogenation of glucose to sorbitol, the hydrogenation of compounds containing benzene ring etc., especially a kind of ruthenium carbon catalyst with supercritical CO 2 The treated activated carbon is a carrier ruthenium carbon catalyst and a preparation method thereof. Background technique [0002] Supported ruthenium on carbon catalyst is an important catalyst, which is widely used in the synthesis of ammonia, the hydrogenation of glucose to sorbitol, and the hydrogenation of compounds containing benzene rings. Catalytic hydrogenation of glucose to prepare sorbitol is currently the main way to prepare sorbitol. Sorbitol is a polyol widely used in food, medicine, cosmetics and industrial production. Under high pressure conditions, batch reactor or circulating fluidized bed is used as reactor, 50% glucose solution is used as raw material, a...

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Problems solved by technology

[0006] The acid-base treatment, liquid-phase oxidation treatment, and gas-phase oxidation treatment of activated carbon are used to increase the oxygen-containing functional groups on the surface of activated carbon. The increase in oxygen-containing functional groups can lead to more adsorption of catalytically active components, which may improve catalyst performance.

However, some researchers gave different results, thinking that the increase of surface functional groups is not conducive to the activity of catalysts.

[0007] Relevant experimental results prove that although the oxygen-containing functional groups on the surface of activated carbon are conducive to the adsorption of the active component ruthenium, due to the different stability of different functional groups, when the catalyst precursor is reduced by hydrogen at a certain temperature, unstable functional groups, such as carboxyl , The carbonyl group is easy to decompose and escape, so that the ruthenium ions originally adsorbed on it will gather, and the particle size of ruthenium will increase, thereby reducing the performance of the catalyst

However, the surface oxidation treatment of activated carbon mainly increases unstable functional groups, which may be the reason why these surface treatment methods are not conducive to catalytic activity.

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