چكيده به لاتين
Reduction of energy resources and global warming are vital phenomena that affect human life. The dry reforming of methane reaction, which uses methane and carbon dioxide to produce synthesis gas, is environmentally friendly. Catalysts that have indicators such as relatively high activity and cheap price, so they are directly used in this process. But these catalysts are prone to sintering at high temperature and carbon deposition, which may lead to the deactivation of the catalysts during the reaction. In this study, alumina silicate mesoporous with high surface area (180.87 m2. g-1) and with Al2O3/SiO2 ratio equal to one is used as a catalyst support, which was utilized to produce catalysts by impregnation method. In the first part, the effects of nickel and calcination temperature on the structural properties and performance of the catalyst have been investigated. It can be seen that the catalysts have a large surface area and a nanocrystalline structure, and with the increase of nickel, the surface area of the samples decreased from 180 to 48 m2/gr. With different percentages of nickel, feed conversion increased, which is due to the better reducibility of nickel and the presence of more active sites on the surface of catalyst. The highest conversion rates (XCH4= 80 % and XCO2= 85 %, respectively) were obtained for catalyst with 15 wt.% nickel. All catalysts have high stability at 700oC and for 300min. All catalysts have high stability at 700 °C during 300 min of reaction, but the 15wt.% nickel catalyst has the lowest percentage of methane activity loss. By increasing the calcination temperature, the performance decreases due to the agglomeration of nickel particles. In the second study, alkaline earth metal promoters (MgO, CaO, SrO, BaO) were used in the support, and their structural properties and catalytic performance were investigated in order to reduce the coke formed. The addition of the promoter did not affect the activity of the catalyst. Among these promoters, support with calcium oxide has been formed lower carbon compared to other promoters. In both projects, the effect of feed ratio, GHSV rate, reduction temperature on yield has been studied. By increasing the GHSV, due to the short contact time between the reactant and the catalyst, a decrease in activity is observed. As the CH4/CO2 ratio increases, the methane conversion decreases and the CO2 conversion decreases. Also, by increasing the reduction temperature, no change has been observed on reactive activities.
