Synthesis of C1–C6 alcohols over copper/cobalt catalysts: Investigation of the influence of preparative procedures on the activity and selectivity of Cu–Co2O3/ZnO,Al2O3 catalyst

The effects of selected preparative variables on the performance of Cu/Co/Al/Zn catalysts during the conversion of synthesis gas (CO/H2) to higher alcohols, C2–C6, have been investigated. A series of Cu/Co/Al/Zn catalysts with fixed composition have been prepared by the co-precipitation method. The catalysts and their precursors were analyzed by techniques such as X-ray diffraction (XRD), thermogravimetry (TG), IR, chemical analysis and adsorptive decomposition of N2O. Dried precursors mainly were formed of semi crystalline hydrotalcite-type phase, but some amorphous malachite-type phase is also present. The catalytic activity for the synthesis of higher alcohols were determined in a flow reactor under P, 40 atm; H2/CO, 1; GHSV, 3410 h−1; T, 285 °C conditions. In optimum condition, the selectivity for alcohols (SA) and heavier alcohols (SC2OH+)SC2OH+ were more than 65% and 38%, respectively. The order of importance for the effective parameters in preparation of the catalysts is determined by measuring the active surface area of the catalysts by using chemisorption of N2O and catalytic test. This order is: calcination condition > precipitation temperature > maintaining the precipitate at 80 °C for 1 h > precipitation pH > drying temperature > aging of the precipitate at room temperature for one night.