Preparation And Properties Of Cu-based Catalyst For Low Concentration Of Methane Catalytic Combustion

Reserves of coal resources in our country are very rich and the amount of annual mined is also huge. In the coal mining process, in order to reduce the occurrence of mining disaster caused by coal-mine gas, a lot of air is put into mine roadway to dilute the gas and than blown into atmosphere. A huge amount of methane is injected to atmosphere in this way, not only caused great waste of resources, but also pollutes the environment. Therefore study how to use of low concentration of methane reasonably and effectively is of great significance. Currently, the main method of using low concentration of methane is catalytic combustion in orderto take advantage of its heat energy. The key of catalytic combustion is to seek economic and efficient catalyst, so that methane can be completely converted at low temperature.First of all, y-A12O3was used as carrier, a series of CuO/Al2O3catalysts were prepared by impregnation and examined their activity of low concentration methane catalytic combustion. The catalysts were characterized by BET specific surface area, X-ray diffraction and H2temperature programmed reduction. Secondly, rare earth metals, transition metals and alkali metals were used as additives to modified catalyst CuO/Al2O3, and examined their activity of low concentration methane catalytic combustion. The catalysts were also characterized by BET specific surface area, X-ray diffraction and H2temperature programmed reduction. Finally, the factors about initial concentration of methane, reaction space velocity and calcination temperature were also examined.The results show that, CuO/Al2O3catalyst for the catalytic combustion of methane has good activity, under the low temperature catalytic activity decreased after rising first with the increase of the Cu loading, under the high temperature catalytic activity decreased with the increase of the Cu loading. Catalyst10%CuO/Al2O3with10%Cu loading (mass fraction) has the highest activity at low temperature. Single metal additives Ce, Fe, Mn are all able to promote CuO in dispersed on the surface of the carrier, improve the activity of catalyst10%CuO/Al2O3at high temperature, but only the transition metal additives Mn can significantly improve the activity of10%CuO/Al2O3catalyst activity at low temperature. Additives La can restrain the crystal transition of carrier at high temperature, improve the high temperature stability of the catalyst. The addition of alkali metal decreases the catalyst activity because it can promot the interaction of CuO with carrier, and is not conducive to the generation of CuO of highly dispersed state. There is a synergistic effect between La and Mn, when rare earth metal additives La and transition metal additives Mn are added to the catalyst10%CuO/Al2O3at the same time, the catalyst activity will be improved significantly. Catalyst10%Cu-4%Mn-2%La/Al2O3calcinated at600℃has the hightest activity, the temperature of10%methane conversion is reduced to about430℃, the temperature of methane conversion completely below640℃. The activity of catalyst10%Cu-4%Mn-2%La/Al2O3decreased with the increase of initial concentration of methane and space velocity. Under high temperature conditions, the methane conversion rate is less affected by the concentration and space velocity.