N含量对氮化铁催化剂CO2加氢制低碳烯烃催化性能的影响OA

One of the effective ways to achieve CO2 conversion is to hydrogenate CO2 to produce low-carbon olefins through reverse water gas reaction.Iron based catalysts are considered as preferred catalyst candidates due to their suitable hydrogenation activity,carbon chain growth ability and lower cost.As iron-based catalysts,iron nitride catalysts are promising catalysts for the preparation of high-value products from CO2 hydrogenation.However,the distribution pattern of carbon containing products in CO2 hydrogenation catalyzed by iron nitride catalysts with different N contents is still unclear.By precisely adjusting the calcination conditions,three iron-based catalysts with different N contents(Na/Fe2O3,Na/Fe2N and Na/Fe4N)were successfully prepared,and their catalytic performances for CO2 hydrogenation to low-carbon olefins were studied.The results show that under the conditions of 320℃,1.5 MPa,CO2/H2/Ar(volume ratio of 1:3:3)and space velocity of 10000 mL/(g·h),the low-carbon olefins selectivity of Na/Fe4N(49.4%)is higher than that of Na/Fe2N(32.6%)and Na/Fe2O3(33.7%),and the CO selectivity,heavy hydrocarbons with five or more carbon atoms(C5+)selectivity and ratio of olefins with two to four carbon atoms to alkanes selectivity(O/P value)of Na/Fe4N are higher than those of Na/Fe2N,but the CO2 conversion rate is lower than that of Na/Fe2N after 14 h reaction.The XPS characterization results show that the electron cloud density of Fe species and Fe5C2 decreases in Na/Fe2N after reaction,which is not conducive to the generation of low-carbon olefins.