Methanol Synthesis in a Slurry Phase Reactor over Cu/ZnO/Al<sub>2</sub>O<sub>3</sub> Catalyst

Abstract

Methanol synthesis from synthesis gas (syngas, a mixture of hydrogen (H2) and carbon monoxide (CO)) in the presence of copper/zinc oxide/alumina catalyst (Cu/ZnO/Al2O3) was investigated using semi-batch reactor. The process was operated at 280 °C under pressure 40 bar in a slurry reactor (Parr reactor model 4848). The catalyst weight, syngas molar ratio and residence time were optimized for methanol synthesis. Cu/ZnO/Al2O3catalyst was prepared by a two-step surfactant assisted precipitation method using polyethylene glycol (PEG 6000). The catalysts surface area, crystallinity, reducibility and morphology were characterized by BET, XRD, H2-TPR and SEM-EDS, respectively. The BET analysis indicated that the catalyst calcined at 300 °C gave the highest surface area (99.67 m2/g). The crystallite size of Cu in Cu/ZnO/Al2O3catalyst was estimated to be 14.14 nm., after adding the surfactants. The maximum methanol yield (607.53) was achieved after 24 hours of residence time using 5 g of the catalyst under a stream of 2 to 1 molar ratio of H2and CO reactive mixed gas. Under these conditions, 38.26% of CO conversion and 93.11% of selectivity to methanol were achieved. When the residence time was decreased to 12 hours with molar ratio of 0.5 H2to 1 CO, the yield of methanol was 388.11, with a CO conversion of 38.53% and selectivity to methanol of 90.77%.