Synthesis of higher alcohols in a slurry reactor with cesium-promoted zinc chromite catalyst in decahydronaphthalene

Abstract

The synthesis of higher alcohols from H 2/CO mixtures was studied in a continuous slurry reactor using unpromoted “zinc chromite” catalyst and the same catalyst promoted with 6 wt.% cesium (Cs). Decahydronaphthalene (DHN) was used as the slurry liquid. Two temperatures 375 and 400 °C, and three H 2/CO feed ratios 0.5, 1.0, and 2.0 (mol/mol), were explored. The pressure, 13.6 MPa (2000 psig), and the gas hourly space velocity (GHSV), 5000 standard l/(kg (cat) h), were constant. Compared with unpromoted zinc chromite, the Cs-promoted catalyst shifted the product distribution away from methanol towards higher alcohols, although methanol was still the major product. The higher alcohols were primarily ethanol, 1-propanol and isobutanol. Higher temperature favored higher alcohol synthesis (HAS), and a higher H 2/CO ratio led to lower oxygenate selectivity and higher hydrocarbon selectivity. These trends were more pronounced with the Cs-promoted catalyst than with the unpromoted catalyst. The performance of both catalysts was comparable to that of similar catalysts in fixed-bed reactors operating at approximately the same conditions.