Research On Pd Catalyst Supported On MgAl₂O₄ Spinel In Methane Catalytic Combustion

Methane is not only an energy source but also a harmful greenhouse gas.The emission of methane in automobile or industrial exhaust will cause serious environmental problems.Compared with traditional flame combustion treatment method,methane catalytic combustion technology is more efficient.Pd/Al2O3 catalyst is the most widely studied in methane catalytic combustion,but its poor low-temperature catalytic activity,thermal stability and water resistance limit its further application.In this work,the catalytic performance and mechanism of the palladium-based catalyst supported by magnesium-aluminum hydrotalcite-derived spinel in the catalytic methane combustion were investigated.In this work,magnesium-aluminum hydrotalcite was used as the support to prepare Palladium-based catalysts.And the influence of catalyst calcination temperature was investigated.It is found that the catalytic activity was affected by the metal dispersion and the catalyst surface oxygen property.In addition,the higher the calcination temperature,the higher the stability of the catalyst.This is because the increase in the calcination temperature enhances the crystallinity of the support Mg Al₂O₄ spinel phase,thereby enhances the metal-support interaction and stabilizing the active species Pd O.Based on the above research results,co-precipitation method was used to prepare magnesium-aluminum hydrotalcite-derived spinel support,and incipient wetness method was used to prepare the supported Palladium-based catalysts.The influence of Mg/Al molar ratio,Mg promoter doping methods,and the support calcination temperature on the performance of the catalyst in catalytic methane combustion were investigated.Catalysts with Mg/Al ratio of 1/3 presented the highest methane combustion activity.It was found that the well-crystallized Mg Al₂O₄ spinel promoted the dispersion and crystallization of Pd O due to the strong interaction between Pd O and support,and the electrophilicity and basicity originated from Mg doping suppressed the sintering of Pd O particles,leading to the excellent performance of Pd/Mg Al3.Moreover,these factors also inhibited the formation of surface OH-species,therefore,improved the water resistance.