Cetyltrimethylammonium Bromide‐Promoted, ZnO‐Supported, and Mn‐Promoted Cu–Fe Catalyst for the Hydrogenation of CO to Low‐Carbon Alcohols

A Mn-promoted CuFe/ZnO catalyst was synthesized by a coprecipitation method using sodium carbonate as the precipitant and characterized by using BET surface area measurements, SEM, energy-dispersive X-ray spectroscopy, IR spectroscopy, XRD, temperature-programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the reducibility of Cu species was enhanced and that Cu-Fe3C dual active sites were generated over the ZnO support. Therefore, the MnCuFe/ZnO catalyst showed a higher activity and selectivity towards low-carbon (C-2-C-4) alcohols than Cu-Fe-based catalysts with or without a Zn promoter. Meanwhile, the contribution of cetyltrimethylammonium bromide (CTAB) used in the catalyst preparation process was also investigated. As a result, CTAB had a prominent influence on the promotion of the SC2-4OH/S-alc (S=selectivity, alc=total alcohols) ratio, which increased from 52 to 63%, and the yield of low-carbon alcohols reached 0.151gmL(cat.)(-1)h(-1). The TPR and XPS results indicated that more Cu2+ was reduced to metallic Cu-0 on CTAB-MnCuFe/ZnO, which suggests that the catalyst was better reduced. The XRD results insinuated that more Cu-Fe3C dual active sites were generated, which facilitated the formation of low-carbon alcohols. Furthermore, a CTAB/Cu molar ratio of 1.0 was the optimum ratio for the formation of low-carbon alcohols.