A study of K-promoted MoP-SiO2 catalysts for synthesis gas conversion

The conversion of synthesis gas to oxygenated hydrocarbons over a series of K-promoted MoP-SiO2 catalysts, is reported. Catalysts with 5, 10, and 15 wt% MoP on SiO2 and promoted with 1 and 5 wt% K. were prepared, characterized and tested at 548 K, 8.27 MPa and a H-2:CO = 1. An increase in CO conversion was observed with increased MOP and K loading and the highest oxygenate space time yield of 147.2 mg g cat(-1) h(-1) was obtained over the 5 wt% K-15 wt% MoP-SiO2 catalyst. CH4 was produced with high selectivity (29-40 C atom%) over the un-promoted MOP catalysts, but with the addition of K. the CH4 selectivity was suppressed and the C2+ oxygenated product selectivity increased as the surface K/Mo atom ratio increased, up to a maximum at a K/Mo ratio of 3.2. The highest selectivity towards C2+ oxygenates (76.6 C atom%) and lowest selectivity towards CH4 (9.7 C atom%) occurred on the 5 wt% K-10 wt% MoP-SiO2 catalyst. The major oxygenates in the product were acetaldehyde, acetone and ethanol. In all cases, catalyst selectivity to methanol was low (<5.0 atom%). The product distribution obtained over the K-MoP-SiO2 catalysts was distinct from that reported on other Mo-based catalysts. (C) 2010 Elsevier B.V. All rights reserved.