Cobalt-based catalyst having core-shell structure, and preparation method thereof

Abstract

The present invention discloses a preparation method of a cobalt-based catalyst having a core-shell structure. The preparation method comprises: 1) selecting an industrially molded composite oxide as a carrier; 2) dissolving a soluble cobalt salt and a metal auxiliary agent salt in an alcohol and water mixing solvent to prepare an impregnating solution; 3) at the high speed flipping state of the composite oxide carrier, rapidly and uniformly mixing the impregnating solution and the composite oxide carrier to prepare a solid catalyst precursor; and 4) drying, and calcining to obtain the cobalt-based catalyst having the core-shell structure. The present invention further discloses the cobalt-based catalyst having the core-shell structure and prepared through the method. According to the present invention, the industrially molded composite oxide is selected as the carrier, and the cobalt salt and the metal auxiliary agent salt adopted as the active components are uniformly impregnated on the outer surface of the carrier by using the rapid rolling of the carrier, such that the defect that the traditional impregnating method cannot accurately control the active species distribution appearance is broken through, the efficient utilization of the cobalt metal is achieved, the catalyst preparation cost is reduced, and the activity and the operation stability of the catalyst are improved.

Description

technical field [0001] The invention relates to a supported heterogeneous catalyst, in particular to a cobalt-based catalyst for Fischer-Tropsch synthesis and a preparation method thereof. Background technique [0002] Facing the looming energy crisis and the characteristics of my country's energy consumption structure, using Fischer-Tropsch synthesis to convert coal, natural gas or biomass into liquid fuels through syngas has become a feasible way to solve the energy crisis in our country. Fischer-Tropsch synthesis is synthesis gas (CO and H 2 Mixed gas) reacts on transition metal catalysts (such as iron-based, cobalt-based) to generate hydrocarbons and a small amount of oxygen-containing compounds. High-quality liquid fuels (such as gasoline, diesel, aviation kerosene, etc.) can be obtained through deep processing. These fuels do not contain sulfides and nitrogen compounds, and are very clean motor fuels. At present, iron-based and cobalt-based catalysts are commonly use...

AI Technical Summary

Problems solved by technology

However, due to the large size of the prepared catalyst particles, the synthesis gas is prone to diffusion limitation during the reaction process, which makes it difficult for the cobalt active center at the core of the catalyst particles to fully contact with the synthesis gas, and the H 2 The difference in the diffusion rate of CO leads to the surface H of the Co active site at the core position 2 / CO ratio increases, leading to CH 4 increased selectivity

In addition, the larger catalyst particle size also makes it difficult for the formed hydrocarbon products to diffuse out in time, and adsorbed on the active sites of metal cobalt to reduce the number of active sites actually participating in the catalytic reaction, thereby reducing the catalytic activity.

In addition, if the heat of reaction generated by Fischer-Tropsch synthesis cannot be effectively removed, it will easily lead to the generation of local hot spots, which will cause the sintering of the catalyst and cause the deactivation of the catalyst.

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