Regulation of CuFeZn catalysts by K3PO4 and its effect on CO2 hydrogenation to C2+ alcohols

CO 2 hydrogenation to C 2+ OH is an effective way to diminish CO 2 emissions. Although challenges still exist in large-scale applications, CuFeZn catalysts attract extensive attention due to their low-cost. Herein, CuFeZn catalysts are modified by different amounts of K 3 PO 4 , (KP) 0.1 CuFeZn exhibits an excellent catalytic performance (total alcohols selectivity of 15.76 % at CO 2 conversion of 38.10 %, C 2+ OH/ROH fraction of 94.23 %, and C 2+ alcohols space–time-yield (STY) of 53.81 mg·mL −1 ·h −1 ). Combined with a series of characterization results, it is found that the effect of K 3 PO 4 is complex, and the proportion of Fe 2+ , Cu 0 and medium base shows perfect linear relation to STY of C 2+ OH. The significance level of the above three factors is in the following sequence: Cu 0 ＞Fe 2+ ＞medium base. The introduction of K 3 PO 4 decreases the proportion of Fe 2+ (active site for RWGS, the competitive reaction for C–C coupling) and increases the proportion of Cu + /(Cu + +Cu 0 ) (Cu + is the active site for C–C coupling) due to the synergistic effect of Cu 0 and Cu + , thereby improving the synthesis of C 2+ OH. Moreover, conversion of Fe 0 to Fe 3 C or Fe 3 O 4 plays negative roles in the stability of the catalysts.