Cats from Oxford

The production of synthesis gas (carbon monoxide + hydrogen) is currently carried out via steam reforming. Steam passes over a carbon source, often methane or coal, and is heated to produce the synthesis gas. Synthesis gas is commercially valuable for the production of methanol, hydrocarbons, higher alcohols for use in detergents and ammonia for use in fertilisers. There is also significant interest in the production of hydrogen for fuel cells.

The problem is that steam reforming has a major disadvantage of being endothermic and hence requires a large amount of wasted energy to drive the reaction. An alternative to steam reforming is the partial oxidation of the hydrocarbons, especially methane; this process is commonly referred to as the Partial Oxidation of Methane, or POM. The major advantage here is that the process is exothermic, so energy is not consumed in order to drive the reaction.

Today, catalysts for these POM processes are heterogeneous, i.e. they are prepared on a solid support. The traditional methods for preparation typically involve coating the catalyst precursor on an inert support such as alumina or silica, then calcining (heating).

One problem, however, is that catalysts produced by this method employ rare and expensive elements such as the platinum metals. Worse, they have limited activity and selectivity and become less active over time due to poisoning by carbon dioxide and water.

Not so with a new method for producing catalysts, termed the Organic Matrix Combustion Method (OMCM) developed by Professor Malcolm Green, Professor of Inorganic Chemistry and head of the Wolfson Catalysis Centre in Oxford.

First, catalysts made with the OMCM can be manufactured from economical metals such as nickel and cobalt. And secondly, the catalytically active component or its precursor can be deposited on the solid support in a controlled manner. Accordingly, the activity and/or selectivity of the catalyst may be controlled, leading to better quality of manufactured products.

According to Professor Green, catalysts prepared by the new method have already demonstrated excellent performance in a range of important industrial processes, including Fischer-Tropsch, partial oxidation of methane and hydrotreating crude oil to give clean fuels.

Stable in the presence of carbon dioxide and water, the new catalysts are immediately active and produce a very high proportion of light products, C5-C7, with a high level of unsaturates as well as a low proportion of methane, important characteristics of the manufacturing process.