Low temperature catalytic partial oxidation of methane for gas-to-liquids applications

Abstract

The catalytic partial oxidation (CPO) of methane in the presence of steam (low temperature catalytic partial oxidation, LTCPO) over noble metal catalysts was investigated. The “dry” CPO over ruthenium and rhodium catalysts was studied by thermogravimetric analyses coupled with IR spectroscopy. For CPO conditions, high CO selectivities at comparably low temperatures were observed for a rhodium/γ-alumina catalyst (5% rhodium) and a 1% ruthenium/TiO 2 catalyst giving evidence that a direct reaction mechanism is involved at low temperatures. It was found that under CPO conditions at low temperatures (<450 °C) the catalysts are in an oxidised state, which is probably responsible for the formation of carbon dioxide. At higher temperatures, the catalysts are in a reduced state. The CO selectivity increases with the reduction of the catalyst. Our results indicate that a direct CO formation mechanism is also possible for ruthenium/alumina catalysts. The platinum catalysts studied in the LTCPO of methane were less active than rhodium and ruthenium catalysts and revealed a lower hydrogen yield. It was found that the steam reforming activity of the ruthenium/alumina catalyst was reduced inhibited by ceria. The long term stability (80 h) of a ruthenium catalyst for LTCPO of methane was demonstrated.