Bimetallic Nano Cu–Co Based Catalyst for Direct Ethanol Synthesis from Syngas and Its Structure Variation with Reaction Time in Slurry Reactor

The catalytic performance of Cu–Co/Al2O3 in the slurry reactor for direct ethanol synthesis from syngas was investigated. The reduced catalyst and catalyst reacted for 100, 300, 500, and 750 h were characterized by using XRD, TEM, EDS, BET, and ICP-MS techniques. Compared with that in the fixed-bed reactor, the catalyst in the slurry reactor exhibited higher selectivity to ethanol, which was above 70 wt % in the total alcohols. The structure variation of the bimetallic Cu–Co with reaction time is that CuCo2O4 was transformed into Cu–Co alloy after reduction, and Cu–Co alloy was decomposed into Cu and Co after reaction for 100 h. After reaction for 300 h, Co2C started to generate and Cu@Co@Co2C was formed as reacted for 500 h. All of Cu–Co alloy, Cu@Co, and Cu@Co@Co2C are highly selective to ethanol, which was maintained for 750 h. Meanwhile, the slurry solvent of PEG-400 is another reason for the high ethanol selectivity.