| According to the requirements of the State Environmental Protection Act, the containing S exhaust generated by petroleum refining, natural gas purification required the processing of Claus method, in which the sulfur recovery rate doesn't exceed97%.The Claus tail gas needs the further processing through the SCOT reduction method, and its conventional catalyst CoMo/y-Al2O3has a high operating temperature and high price. However, the Ni-based catalyst studied earlier by our research group has a high activity and low cost features.On the basis of pre-study of our research group, the work explored the mechanism about water vapor poisoning for Ni-based catalyst, and improved the performance of Ni-based catalyst prepared by impregnation method through the methods of chelating agents modification, doping modification and supporter modification, and made a molding processing for the catalyst prepared by co-precipitation method that developed by our research group. We compared the two kinds of catalysts made by ourselves with several conventional catalysts at home and abroad to explore the possibility of industrial application of the catalysts made by ourselves. Conclusions as follows:1. The electronegativity of oxygen in H2O molecule is larger than the sulfur in SO2molecule, but the bond angle of H2O is smaller than that of the SO2, and the O-H bond is shorter than the S-O bond, so the steric hindrance of H2O is smaller, and it is more easily absorbed in the NiS2sulfur vacancies. Though XRD TPD FI-IR XPS and BET, the absorbed and in the surface of catalyst react with each other and produce sulphite species, they not only occupy the sulfur vacancies which break its regenerating cycle, but also decline the activity of catalyst because they cover on the surface of the catalyst and make the pore structureis smaller.2. Compared the influence of three kind of chelating agents with different number of teeth (nA=2nB=3, nC=6) on the structure and performance of Ni-based catalysts, we found that the effect of chelating agent B is the best because of its moderate chelating ability to chelate metal Ni ions, while its moderate chelating ability ensures the sulfide effects of Ni, and promotes the formations of NiS2with more sulfur-rich space, thereby increasing the pores and specific surface area of catalyst, so that the catalyst has a better pore structure and higher metal active component dispersion.3. The catalytic activity of the citric acid modification catalyst doped Mo metal has improved significantly. With the increasing of Mo content, the catalytic activity also increased. The catalytic performance of the catalyst containing5%Mo is that SO2has been completely converted at220℃. Continuing to increase the content of Mo doesn't improve the catalytic activeity obviously. TiO2/Al2O3composite carrier was made by wrapped TiO2. When the content of TiO2was10%, and at190℃, the NiMo catalyst modified by chelating agent B with TiO2/Al2O3composite carrier has the ability to convert the SO2completely,4. In the extruding and molding process, the extruded strip catalyst has good molding effect when water/powder is0.15, and the amount of nitric acid is about0.95w%, the amount of compound to help squeeze phthalocyanine powder is2.0w%, and the amount of the polycarboxylic acid B is4.0w%.5. Compared two home-made catalysts with several catalysts at home and abroad by several conventional industrial evaluations of catalysts, and confirmed the feasibility of two home-made catalysts at industry apply application. |
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