Optimization And Control Of Cu-Mn-O Mixed Oxide Catalyst Preparation Process

In this thesis, four series of Cu-Mn-O mixed oxides were prepared by co-precipitation altering anion of metal salts and KOH was the precipitating agent. The effects of anions on structure and catalytic performance for water gas shift reaction （WGSR） of Cu-Mn-O mixed oxides were investigated by XRD, TPR, Low temperature N2 adsorption/desorption and Micro-Reactor Chromatography. The results denote that anions of reaction system had a significant effect on the crystallinity, surface area and pore structure of the samples. After calcination and WGSR, surface area and pore structure variation orders of the catalysts were both Ac- > SO₄^2- > Cl- > NO3-. Reduction temperature of TPR orders were Ac-<SO₄^2-< NO3-< Cl-. Acetate sample had the highest catalytic activity. Nitrate sample had higher catalytic activity than the sulfate and chloride samples which had little activity at the test temperatures.Cu-Mn-O mixed oxides were synthesized by the co-precipitation with CuAc₂·H₂O, MnAc₂·4H₂O and KOH which was the precipitating agent. The experiment scale was enlarged 4 times in this thesis on the earlier optimization experiment in order to study enlargement effect. XRD, TPR, Low temperature N2 adsorption/desorption were introduced into structure characterization. The relationship between the catalytic activity and the structure of the catalyst was explored by means of Micro-Reactor Chromatography. The results denote that enlargement process had a significant effect on the crystallinity, surface area and pore structure of the samples. CO conversion at 250℃was 84.2%, and was only 11.7% lower than the sample enlarged before, whose CO conversion was 93.1%. The enlargement effect was better.Salinization ratio had greatly influence on the surface area and pore structure of the Cu-Mn-O mixed oxides. The results of XRD and Low temperature N2 adsorption/desorption denote that the samples had fine crystallinity, laiger grain size, surface area and pore volume, smaller pore size when the ratio was 1:1. TPR results show that the content of highly dispersed copper was higher when the ratio was 1:1 and the active sites increased, so the catalytic activity and thermal stability of the catalyst were better than the other samples.