Platinum Metals Rev., 1968, 12, (1), 19
Ruthenium as a Methanation Catalyst
The value of natural gas for domestic heating and for industrial power has long been recognised, but in areas of the world not endowed with a convenient supply some alternative economic source of methane is required. The steam-reforming of higher hydrocarbons (for example, “light petroleum distillate” obtained from mineral oil), or the reaction of steam with carbon, yields a mixture of carbon monoxide and hydrogen from which methane may be produced by catalytic hydrogenation. What is then required is a catalyst that will perform this hydrogenation economically, and this must be a catalyst which is not particularly susceptible to poisoning by carbon monoxide.
A recent report from the United States Bureau of Mines (J. F. Shultz, F. S. Karn and R. B. Anderson, U.S. Dept of the Interior, Bureau of Mines, R.I. 6974, July 1967) has re-emphasised the outstanding catalytic properties of ruthenium for carbon monoxide hydrogenation. The authors compare catalysts containing ruthenium, rhodium, platinum, palladium and osmium, but of all the catalysts examined only the ruthenium on alumina catalyst was adequately active. It achieved complete reaction at 220 to 240°C, whereas palladium and platinum failed to do this even at 500°C. The kinetics of the reaction using the ruthenium catalysts were examined in some detail: the rate increases with increasing hydrogen pressure and is slightly decreased by increasing carbon monoxide pressure. High molecular weight products appeared only when the H2/CO ratio in the feed gas fell below two; catalyst poisoning only became important when this ratio fell below unity. The authors concluded that the use of ruthenium for carbon monoxide methanation was economically feasible.