چكيده به لاتين
Methane catalytic oxidation is a hopeful technology for the rational and harmless use of this fossil energy source. Catalysts enable the complete oxidation of methane at very low temperatures and prevent the pollutants emission in a great extent.
Among the catalysts used in this process, the ones containing nickel, cobalt, and manganese have shown higher activity and longevity due to better regeneration and high oxygen mobility, and are also more economical. In addition, magnesium aluminate is considered a useful catalyst support in catalytic processes due to the high specific surface area and high porosity, heat resistance, chemical and physical stability, etc.
In this study, first MgAl2O4 spinel was prepared by mechanico chemical method to be used as a catalyst support. Then, 5, 10, 15 and 20 weight percentages of nickel was loaded on the support by impregnation method. The Ni/MgAl2O4 catalyst with 20% weight load showed the highest activity and selectivity compared to carbon dioxide. Then, the effect of loading 1, 3, 5 and 7 weight percentages of cobalt and manganese metals as promoters along 20% nickel was examined. Eventually the catalysts 3%Co-20%Ni/MgAl2O4 and 5%Mn-20%Ni/MgAl2O4 were selected as optimal choices. The use of cobalt and manganese promoters improved the catalyst performance and caused the complete oxidation of methane.
In addition, optimal catalysts were studied under the operational conditions such as gas hourly space velocity, feed ratio and feed dilution with argon carrier gas. Also the stability of optimal catalysts and the effect of calcination temperature on them have been examined. The chemical and physical characteristics of the provided catalysts were evaluated using FTIR, TG/DTA, XRD, BET and FESEM analyzes.
