Hydrogenation of CO for Alcohol Over Cu-ZnO-Al2O3 Catalysts Prepared by Completely Liquid-Phase Technology and Sol-Gel Methods: A Comparative Study

Abstract

Cu-ZnO-Al₂O₃ catalysts for alcohol by hydrogenation of CO were prepared using completely liquid-phase (CZA-L) and sol-gel methods (CZA-T). Characterization showed that there are difference in structure and catalytic performance between CZA-L and CZA-T. Amorphous ZnO, Cu⁺ and Cu⁰ coexist in CZA-L, whereas crystal ZnO and Cu⁰ exist in CZA-T. Compare with CZA-T, the C₂⁺OH selectivity in CZA-L was increased 4 times and provided a CO conversion rate of 33 %, C₂⁺OH selectivity of up to 20.9 % with a total alcohol selectivity of 67 %, meanwhile C₂⁺OH selectivity of 4 % and total alcohol selectivity of 86.5 % with CZA-T under the reaction conditions of 5.0 MPa, 250 ºC, H₂/CO = 1 and a gas hourly space velocity of 360 mL/ (g_cat h). Experimental results showed that the synergy of various valence copper was responsible for improving the selectivity to C₂⁺OH from syngas over Cu-ZnO-Al₂O₃ catalysts.