Surfactant-assisted preparation of Cu/ZnO/Al2O3 catalyst for methanol synthesis from syngas

Cu/ZnO/Al2O3 (CZA) catalysts were prepared by two-step precipitation method with the assistance of the surfactant, tetraethylammonium hydroxide (TEAH) or polyethylene glycol (PEG), and evaluated in methanol synthesis from syngas. Effects of input amount of the surfactant and accelerated thermally induced deactivation (ATD) on the activity of the catalyst were investigated under the reaction conditions of 230 °C, 5 MPa, gas hourly space velocity (GHSV) of 10,000 h−1 and the syngas composition of CO/CO2/H2/N2 (volume ratio) = 15:5:70:10. Among the catalysts investigated, 2T-CZA catalyst, prepared with addition of 2 wt.% TEAH in the course of the coprecipitation of Cu2+ and Zn2+, exhibited better catalytic performance due to its smaller crystallite size of Cu and higher Cu surface area, over which methanol space-time yield (STY) was 1.26 times as heavy as that over blank CZA catalyst, prepared without any surfactant's assistance, and 1.25 times as that over commercially famous CX catalyst for methanol synthesis from syngas in China. Meanwhile, 2T-CZA catalyst showed satisfactory thermal stability, in which methanol STY decreased by only 5.2% because of growing up of crystallite size of Cu and decrease in the number of surface Cu atoms after the ATD test to be conducted in situ at 350 °C for 20 h in syngas.

Catalytic performance over different CZA catalysts before and after the accelerated thermally induced deactivation (ATD) test under the reaction conditions of 230 °C, 5 MPa, GHSV of 10,000 h −1, 1 mL catalyst and syngas composition of CO:CO2:H2:N2 (volume ratio) = 15:5:70:10.Figure optionsDownload high-quality image (116 K)Download as PowerPoint slideHighlights
► Cu/ZnO/Al2O3 (CZA) catalyst was prepared by two-step precipitation method.
► The 2T-CZA catalyst showed better catalytic performance.
► Cu0 is main active site in methanol synthesis from syngas over CZA catalyst.
► Smaller crystallite size of Cu and higher Cu specific surface area are favorable.
► The slight drop of catalytic activity is due to the decrease in surface Cu atoms.