Effect of Mn Promoter on CuFe-based Catalysts for CO2 Hydrogenation to Higher Alcohols

A series of Mn promoted CuFe based catalysts with different Mn contents was synthesized with the co-precipitation method. The promoting effect of Mn on CuFe based catalyst in CO2 hydrogenation to higher alcohol (HA) was studied. The catalytic results show the HA selectivity and space time yield (STY) could be effectively improved by introducing moderate Mn. The optimized catalyst denoted as 2.1MCFZ-K with 2.1% (mass fraction) Mn content exhibits the best catalytic performance with CO2 conversion of 29.4%, HA selectivity (CO-free) of 23.2%, HA space time yield of 41.1 mg.g(cat)(-1).h(-1), and C2+OH/ROH fraction of 96.9% at 320 degrees C and 5 MPa. X-ray diffraction (XRD) , N-2 sorption experiments, X-ray photoelectron spectroscopy (XPS) , transmission electron microscopy (TEM) and H-2 temperature-programmed reduction (H-2-TPR) experiments reveal that Mn as a structural promoter with moderate content can reduce the particle size of Cu and promote the formation of Fe5C2 active phase, thus fabricating rich Cu-Fe5C2 active interface for HA synthesis. Overly high Mn content can block active sites, inhibiting the catalytic activity.