Investigation On The Key Factors Of MoP Catalysts For Dry Reforming Of Methane

Due to the special structure of transition metal phosphide,its catalytic performance is similar to that of noble metal.It not only has good performance in catalytic performance,but also has high activity,stability,good resistance to carbon accumulation and resistance to neutral toxicity,etc.The performance of catalytic hydrogenation,desulfurization,denitrification,photocatalysis,etc.are far stronger than transition metal nitrides and transition metal carbides.Transition metal phosphides have become a new research hotspot in the field of catalytic materials.However,at this stage,a large number of methods for preparing transition metal phosphides cannot meet the current production needs due to many factors such as complicated operation,harsh conditions and unfriendliness to the environment,so it is necessary to seek a green,convenient and simple preparation method.Carbothermal reduction(CR)method for the synthesis of MoP catalyst has been received much attention due to the increase of carbon materials as promising supports in various MoP-catalyzed reactions.In this work,we prepare three MoP catalysts(MoP-Glu,MoP-HMT and MoP-PFR)with different specific surface areas,particle sizes and surface carbon contents using CR method,and give new insights into the key factors of the MoP catalysts for dry(CO₂)reforming of methane(DRM).The results of the study are as follows:(1)The specific surface areas of the MoP-Glu,MoP-HMT and MoP-PFR catalysts prepared in the experiment were 84.3 m~2 g^-1,29.4 m~2 g^-1 and456.2 m~2 g^-1,respectively.Their particle sizes were 25.7 nm,17.2 nm and138.3 nm,respectively,and their surface carbon contents were 46.3%,78.5%and 67.4%,respectively.The catalytic activity results of these three different MoP catalysts in the DRM reaction were in the order of MoP-Glu>MoP-PFR>MoP-HMT.(2)The catalytic performance of MoP catalysts in the DRM reaction is related to their oxidation resistance ability(ORA)and methane dissociation ability(MDA).The ORA order of the three different MoP catalysts prepared in the experiment was:MoP-HMT>MoP-Glu>MoP-PFR,and their MDA order was:MoP-Glu>MoP-HMT?MoP-PFR.(3)According to the redox mechanism on MoP,the key factors should be those which can influence the oxidation resistance ability(ORA)and methane dissociation ability(MDA)of MoP.It is found that the surface carbon content and particle size have main effects on the ORA and MDA of MoP,respectively.However,the specific surface area is not associated with any of them.The higher content of surface carbon can promote ORA and the MoP particles with smaller size favor the increase of MDA.It was worthy to note that excess surface carbon(oversized MoP particles)can weaken the MDA(ORA).Therefore,surface carbon content and particle size are proposed as the key factors of MoP prepared by CR method for DRM.The MoP-Glu with appropriate surface carbon content and particle size showed much higher catalytic stability than MoP-HMT and MoP-PFR.