Synthesis of Mixed Alcohols from Syngas over Cs-modified Cu/Ce<sub>1−<i>x</i></sub>Zr<sub><i>x</i></sub>O<sub>2</sub> Catalysts

Abstract

Cu/Ce1−xZrxO2 (x = 0-1) was prepared by a coprecipitation-decomposition method using NH3 · H2O as precipitant (to avoid residues of alkali metals), followed by a boiling process to eliminate NH3 and decompose [Cu(NH3)4]2 + complex. Then Cs was introduced to Cu/Ce1−xZrxO2 by the impregnation method. The prepared CsCu/Ce1−xZrxO2 catalysts (Cs: 1.0 wt%; Cu: 20 wt%) were used to catalyze the synthesis of mixed alcohols in a high-pressure fixed-bed flow reactor under reaction conditions of T = 573 K, P = 3 MPa, H2/CO = 2/1, and GHSV = 2400 h−1. CsCu/CeO2 showed higher CO conversion than the industrial catalyst CsCu/ZnO due to the reducibility of the CeO2 support. Moreover, the STY of higher alcohols over CsCu/CeO2 was much higher than that over CsCu/ZnO due to the oxygen storage capacity of the CeO2-based compounds. Introduction of Zr4 + ions into CeO2 lattices increased the reducibility and the oxygen storage capacity of the CeO2-based compounds, so the STY of higher alcohols over CsCu/Ce0.8Zr0.2O2 was larger than that over CsCu/CeO2. CO conversion increased but selectivity for methanol decreased with higher reaction temperature over CsCu/Ce0.8Zr0.2O2. The selectivity for higher alcohols was maximum at 573 K over CsCu/Ce0.8Zr0.2O2. Both CO conversion and selectivity for higher alcohols increased with higher reaction pressure over CsCu/Ce0.8Zr0.2O2 for the synthesis of mixed alcohols from syngas.