چكيده به لاتين
One way to remove CO2 as a greenhouse gas, is to convert catalytic CO2 into fuels and chemicals. Methane is one of the main products of this conversion, which is one of the main components of natural gas and can be separated and burned for energy production. Therefore, the CO2 methanation process has been investigated. This process is also used as a method of removing carbon oxides from gas mixtures in hydrogen or ammonia production units and to purify the hydrogen flow in refineries, ethylene production units and in the use of fuel cells. Many catalysts have been studied for CO2 methanation reaction, including Ni, Fe, Co, Rh, Ru, Pt, etc. Among these common catalysts, nickel catalysts are used due to their high activity, good selectivity and satibility, and most importantly, their low cost. Al2O3 support has high surface area, low price and more basity sites to absorb carbon dioxide and special electronic structure and features. This support is resistant to high pressure and temperature and is the most suitable support for nickel catalysts. In this study, the effect of nickel loading on the catalytic performance of Ni-Al2O3 catalysts prepared by novel and simple mechanochemical methods. This method is known to be a suitable method due to the use of simpler reactors, faster reaction at room temperature with high efficiency and minimizing the use of solvents and waste production compared to other synthesis methods. The results showed that nickel alumina catalyst with 15% nickel loading has the highest activity and selectivity to produce maximum methane and was selected as the optimal catalyst. The Ni-Co-Al2O3 catalyst was synthesized and tested by various Ce, La, Ba, Mn, Fe and Zr promoters, of which iron had the highest and best performance. The effect of different iron loadings was also investigated and the promoted Ni-Co-Fe-Al2O3 catalyst with 5% iron loading, 12.5% cobalt and 15% nickel supported on alumina was selected as the optimal catalyst and showed CO2 conversion 71.90% and 99% CH4 selectivity at 400 °C were due to higher dispersion of nickel particles. The physical chemistry properties of the prepared catalysts were also evaluated using various analyzes including XRD, BET, TGA, Fe-SEM, FTIR and EDX-maping.
