Modification And Secondary Transformation Of Iron - Silicon Catalyst And Its Catalytic Reaction

In recent years, new structural catalysts have attracted lots of attentions. In order to protect the environment and improve utility efficiency of petrochemical raw materials, it’s necessary to design and produce new structural catalysts. Researchers aim at improving the conversion and selectivity of targeted products through the new structures.New material technologies especially the nanomaterial technology has promoted the research of new catalyst. Layer-by-layer assembly of nanocrystals and nanowire synthesis methods have been proved to be useful to synthesis new kinds of catalysts. Based on the two synthesis methods, new kinds of catalysts have been synthesized:(1) core-shell zeolite reactors (2) nanowire accumulated spherical catalyst. The catalysis performances are tested by Fischer-Tropsch synthesis.Core-shell zeolite reactors are widely concerned for the bi-function and synergistic effect in continuous reactions. Through layer-by-layer assembly technology, zeolite nanocrystals are adsorbed onto the surface of catalysts. As a result, zeolite shell can protect the inner catalyst. Meanwhile, the zeolite channel will sieve both reactants and products, so-called bi-functional catalysts are constructed. For the sieving effect of zeolite shell, products with moderate chains are obtained in catalytic reactions.Nanowire accumulated spherical catalyst has an excellent diffusion capability for its accumulated structure. Additionally, for the one-pot transformation method, the obtained new catalyst remains the spherical morphology of original catalyst. In the transformation process, iron species induce the growth of SiO2 nanowire. Furthermore, the iron species are highly dispersed on the nanowire supporters along with the growth. For the high dispersity of active species and good diffusion capability of the new catalyst, primary products tend to leave the surface of catalyst instead of reabsorbing onto the surface.Fischer-Tropsch synthesis is hired to test the new kinds of catalysts. With the shortness of petroleum resources, Fischer-Tropsch synthesis is thought to be a reasonable solution method. Besides that, Fischer-Tropsch synthesis is a typical secondary reaction. The influences of core-shell and accumulated structures are clearly showed to us through the analysis of secondary products. By the comparison of different catalysts, it can be concluded the selectivity and olefin/paraffin ratio are improved through compressing the secondary reaction.Generally speaking, a series of new catalysts based on industrial catalysts has been synthesized in our work. Better catalysis performances are obtained for the new structures. Additionally, the morphology and mechanical strength of original catalysts are reserved in our experiments. This work not only shows a method to improve the selectivity of short chain olefins olefin/paraffin ration in Fischer-Tropsch synthesis, but also provides a clue to the design of new structural industrial catalyst!...