Ammonia treated Mo/AC catalysts for CO hydrogenation with improved oxygenates selectivity

Abstract

Abstract: A series of ammonia treated Mo/Activated Carbon (AC) catalysts were synthesized by wet impregnation method by nominal incorporation of 5, 10 and 15 wt% of molybdenum. The calcined catalysts (500 ∘C , 4 h, N 2 flow) were subjected to a stepwise ammonia treatment at temperatures from 25 up to 700 ∘C. This work reports for the first time, ammonia treated different loadings of Mo on DARCO mesoporous activated carbon for CO hydrogenation reaction. These catalysts were tested in the reaction temperature range of 250–325∘C , 7 MPa and 12000/h (GHSV for reactor volume 0.5 mL). At 250 ∘C , all the catalysts showed total oxygenate selectivity of ∼ 50%, mainly methanol. At 325 ∘C , total oxygenate selectivity of 16.5% with 18% CO conversion was obtained on 10Mo-N/AC. The result of alcohol distribution revealed high selectivity to propanol (39%) over methanol (34%) at 325 ∘C on 10Mo-N/AC which highlights its unique catalytic behavior in CO hydrogenation. Further, 10MoO 3/ AC catalyst, with no treatment of ammonia, showed only 4% of CO conversion with 96% hydrocarbon selectivity. Only 0.5% of CO conversion was observed on AC itself at 325 ∘C. The improved oxygenates selectivity on 10Mo-N/AC was associated with Mo δ + sites on AC generated via ammonolysis. Graphical Abstract: SYNOPSIS A series of ammonia treated Mo/Activated Carbon (AC) catalysts were synthesized by wet impregnation method by nominal incorporation of 5, 10 and 15 wt% of molybdenum. These catalysts were tested for CO hydrogenation reaction at 250–325∘C , 7 MPa and 12,000/h (GHSV) for the first time. At 325 ∘C , total oxygenate selectivity of 16.5% was observed on 10Mo-N/AC. [Figure not available: see fulltext.].