助剂Ba对Pd/Al2O3和Pt/Al2O3催化剂的C1-C3烷烃催化燃烧性能的影响

The role of Ba additive on the catalytic performance of Pd/Al2O3 and Pt/Al2O3 for C1-C3 alkanes deep oxidation

通过浸渍法制备了Al2O3负载的Pd和Pt催化剂,考察催化剂的甲烷、乙烷和丙烷催化燃烧活性,以及助剂Ba对催化性能的影响。对于Pd/Al2O3催化剂,加入Ba使活性物种PdO颗粒变大和还原温度升高,形成更稳定的PdO活性物种,是Pd-Ba/Al2O3催化剂活性提升的主要原因。对于Pt/Al2O3催化剂,加入Ba助剂使活性物种Pt0含量降低,PtOx与Al2O3载体相互作用增强,使PtOx物种更难被还原为Pt0,导致Pt-Ba/Al2O3催化剂活性降低。Pd和Pt催化剂催化烷烃氧化反应活性规律一致:丙烷>乙烷>甲烷。Pd/Al2O3催化剂有利于C—H键活化,Pt/Al2O3催化剂有利于C—C键活化。Pt/Al2O3催化剂对C1-C3烷烃氧化活性的差别明显大于Pd/Al2O3催化剂。Pt/Al2O3催化剂对碳比例高的烷烃活性更高。

The Pd and Pt catalysts supported by Al2O3 were prepared by impregnation method.The catalytic combustion activities of catalysts for methane,ethane and propane,and the effect of Ba additive on the catalytic performance were investigated.For Pd/Al2O3 catalyst,both the size of PdO active species and its reduction temperature increased when Ba additive was added,which resulted in the formation of more stable PdO active species.This should be the main reason for the improved activity of the Pd-Ba/Al2O3 catalyst compared with Pd/Al2O3 catalyst.The amount of active species Pt0 reduced and PtOx species became difficult to be reduced to Pt0 due to the enhanced interaction between PtOx and Al2O3 support after introduction of Ba for Pt/Al2O3 catalyst,which was responsibility to the decrease of the catalytic activity of Pt-Ba/Al2O3.The same activity regular pattern of Pd and Pt catalysts was obtained for alkane oxidation:propane>ethane>methane.The Pd/Al2O3 catalyst might be favorable for C—H bond activation,while Pt/Al2O3 catalyst should be beneficial for C—C bond break.The Pt/Al2O3 catalyst gave significant difference of catalytic performance for C1 to C3 alkane deep oxidation compared with of Pd/Al2O3 catalyst.The Pt/Al2O3 catalyst showed a higher activity for alkanes with high carbon content.