Research on the modification of vanadium catalyst carrier diatomite performance index modified by plasma technology

• Categories:Technical Support
• Author:Plasma cleaning machine-CRF plasma plasma equipment-plasma surface treatment machine manufacturer-chengfeng intelligent manufacturing
• Origin:
• Time of issue:2022-03-09
• Views:

(Summary description)Research on the modification of vanadium catalyst carrier diatomite performance index modified by plasma technology: The vanadium catalyst used in the production of sulfuric acid is a catalyst with vanadium oxide as active component, alkali metal oxide as co-catalyst and diatomaceous earth as carrier. The diatom shell in diatomite has a special microporous structure and a shell wall composed of amorphous silica. These small pores distributed on the shell wall can provide good conditions for uniform adsorption or coating of catalyst active components In addition, diatomite itself has good permeability, so that the fluid can pass through at a larger flow rate, so diatomite becomes an important carrier for vanadium catalysts. The reserves of diatomite in my country are very rich, but there are not many high-quality diatomite that can be used as vanadium catalyst carrier. In recent years, due to the protective mining measures adopted by the government, fewer and fewer high-quality diatomite mines are allowed to be mined. Many catalyst factories have begun to use imported diatomite to improve the quality of vanadium catalysts, but imported diatomite has gradually formed a monopoly in China. , the price is expensive, and the domestic catalyst factory is unbearable. How to improve the quality of domestic diatomite and make it meet or exceed the quality of imported diatomite has always been the direction of domestic catalyst factories. The pore size distribution of the carrier has an important relationship with the performance of the vanadium catalyst. In general, the important characteristics of good quality vanadium catalysts are large pore volume and reasonable pore size distribution. It is required that the number of pores with a pore size between 100 and 1000 nm accounts for more than 50% to ensure that there are enough internal diffusion channels for gas molecules in the catalytic reaction. Under the reaction conditions, the pores below 100 nm basically do not exist, and mainly become the storage unit of active substances, while the macropores with a pore size above 100 nm are not only unobstructed, but also provide an active surface. Domestic diatomite has a relatively large proportion of micropores with a pore diameter of less than 1 nm, and a relatively small proportion of mesopores with a pore diameter of 1 to 1000 nm and large pores above 1000 nm, resulting in a small pore volume and high bulk density of the vanadium catalyst, which is not conducive to the reaction. Diffusion of gases. Changing the pore size distribution of diatomite, increasing the pore volume and reducing the bulk density are important ways to improve diatomite in China. The diatomite is modified by plasma technology, the diatomite is treated by the active substance of the plasma, and the surface and internal impurities of the pore channel are cleaned by physical and chemical effects, so as to increase the pore size of the diatomite. Plasma bombardment of diatomite can make diatomite generate local high temperature, and the organic impurities in the pores are removed by high temperature pyrolysis, thus leaving more effective space, which is manifested as the increase of BJH adsorption pore volume. This also shows that plasma technology can be used as an effective method for diatomite modification. The increased pore volume of diatomite can make the reaction gas pass more smoothly and the catalytic efficiency is higher. Modified by plasma technology, a considerable number of micropores in diatomite may be converted into mesopores. The treatment has both physical effect (non-elastic collision effect) and chemical effect (active substance reacts with functional groups on the surface of diatomite), so as to achieve the effect of cleaning the surface of the pores and the internal organic impurities and some inorganic impurities.