Catalytic Conversion And Application Of CO Small Molecule Gas

Small molecule gas CO widely exists in the coke oven gas,calcium carbide furnace exhaust and smoke exhaust,ammonia gas,etc,in the process of CO gas not only pollute the environment as a pollution also pose a threat to human life safety.At present,the elimination of CO by catalytic conversion of CO has been promoted to a large extent,and the utilization of CO as feedstock gas also has great practical significance.In this thesis,low temperature catalysts for CO methanation and hydrogenation were studied,and CO removal and resource utilization were realized at low temperature.At the same time,CO selective catalytic reduction（SCR）catalyst was explored to achieve simultaneous removal of CO and NO_xat low temperature.The main work is as follows:（1）Low temperature activity of Ni-based catalysts in CO hydrogenation reactionIn this part,a Ce-doped Ni-based catalyst precursor was prepared by double-titration coprecipitation method,and then Ni-Cebimetallic catalyst was prepared by H₂high temperature reduction pretreatment,and the catalyst was applied to CO methanation reaction.The Cespecies mainly exists in the catalyst in the form of CeO₂,and the active sites of elemental Ni species are increased by changing the specific surface area and pore volume of the catalyst,thus increasing the low temperature performance of the catalyst.Moreover,the catalyst obtained after H₂reduction pretreatment contains a large amount of elemental Ni.The presence of CeO₂reduces the agglomeration and sintering of elemental Ni,increases the contact area between catalyst and reaction gas,avoids the phenomenon of carbon deposition on catalyst caused by instantaneous strong heat release,and greatly improves the catalytic performance.100%CO conversion and 85%CH₄selectivity were achieved at 200℃.（2）Low temperature activity of CeNiO_xcatalyst in CO-SCR reactionNi-doped Ce-based catalyst was prepared by double-titration coprecipitation method,and a CeNiO_xbimetallic composite catalyst was obtained for CO-SCR reaction.This paper mainly explores the influence of Ni doping amount on catalytic performance of catalyst.The results show that Ni doping contributes to the improvement of Ce-based catalyst performance,mainly due to the synergistic effect between Ni and Ce.The addition of Ni is conducive to the generation of more Ce³⁺species,and the higher proportion of Ce³⁺in the catalyst is conducive to the increase of the number of oxygen vacancies on the surface,so as to promote the adsorption of active or intermediate species on the catalyst in the SCR reaction at low temperature,which improves the catalytic performance of the catalyst.It can achieve 100%NO conversion rate and 99%CO conversion rate at 300℃,and basically complete the collaborative removal of CO and NO.