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/Al 2 O 3 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 CuCo 2 O 4 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, Co 2 C started to generate and Cu@Co@Co 2 C was formed as reacted for 500 h. All of Cu–Co alloy, Cu@Co, and Cu@Co@Co 2 C 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.