Effect Of Addition Of Rare Earths To Monolithic Catalyst On Catalytic Activity For Methane Combustion

With the decreasing of the fossil energy, more attention has been paid to achieving efficient utilization of energy. China riches in coal resources, and a huge amount of coal mine gas produced with the coal mining, but in order to ensure the safety of coal mine exploiting, a great amount of coal mine gas was discharged into the atmosphere in the form of ventilation air methane (VAM), resulting in energy waste and environmental pollution. For the purpose of reducing the VAM discharged into the air, and complying with the role of energy conservation and emission reduction, catalytic combustion technology is one of the best methods to utilize the VAM efficiently and ease the energy and environment issues friendly.In this paper, the Pd based catalyst Pd/γ-Al2O3/Cord was prepared with honeycomb ceramic cordierite (Cord), alumina sol and active component Pd. The alumina sol was prepared by pseudo-boehmite, the supporter γ-Al2O3/Cord was prepared by alumina sol dipping operation and kilned in Muffle furnace with550℃for4hours. The Pd was loaded on the surface of the supporter by impregnation method. The catalyst was modified with rare earth elements (La, Ce; noted as RE) by impregnation and gel-sol method, the later was achieved by adding RE into the alumina sol. The catalyst modified by RE was marked as Pd/RE/γ-Al2O3/Cord, RE/Pd/γ-Al2O3/Cord, Pd(RE)/γ-Al2O3/Cord and Pd/γ-Al2O3(RE)/Cord. The catalytic performance was evaluated with catalytic combustion of the gas with0.4%CH4-99.6%air, the influence of the RE additives to the catalyst structure was researched by SEM, XRD and XPS characterization technics. The catalytic activity and stability of the purchased BHG catalyst was also evaluated in the condition of1.0%CH4-99.0%air and GHSV=3315h-1. The results are as follows.The catalytic performance differs in the modified methods, and the alumina sol RE addition method surpasses the impregnation method, the catalyst modified by La slightly surpasses the catalyst modified by Ce overall. The catalyst Pd(RE)/γ-Al2O3/Cord and Pd/γ-Al2O3(RE)/Cord shows the well catalytic activity, and the catalytic activity of Lam-2.0, Cem-1.0and Las-1.0demonstrate best, the CH4catalytic temperature of90%conversion stay in the range of470-500centigrade. The catalytic activity decreases as the catalytic temperature holds at a constant value, The activation treatment at the high temperature (600℃) and oxygen-rich condition can accelerate the transform process of Pd-PdO, achieving the reproduction of the active component PdO and improving the catalytic performance.