Methylal Steam Reforming with Pt/Al2O3, Ni/Al2O3, and Mixed Cu/ZnO/Al2O3 Catalysts

The main purpose of this work was to demonstrate that steam reforming of methylal (dimethoxy-methane, MA), even at low steam-to-MA ratios, can be used for thermal recuperation of the energy of internal combustion engine exhaust gas. This work confirms that high conversion to H-2 and CO can be achieved at temperatures above 450 degrees C on alumina-supported Pt (0.1%) or Cu catalysts, with S/MA = 1. These temperatures can be achieved by heating with exhaust gases and simulations showed that reaction can be completed in a reformer-heat exchanger of a reasonable size. This work differs from previous MA SR studies that employed either S/MA = 5 aimed at maximizing H-2 production for fuel cells or S/MA = 0, which was shown to be insufficient for reasonable recuperation. Several conclusions can be reached from the performance dependence on S/MA ratio. Pt catalyst gives nearly complete MA conversion above 300 degrees C with S/MA = 1 or 4. The major products were H-2, CO, and methanol. Methanol is produced in large amounts with decreased production of dimethyl ether (DME) compared to results with methylal decomposition (S/MA = 0), which showed large DME production. This is consistent with the methanol-DME equilibrium in the presence of water. On a mechanically mixed catalyst of Cu-Al2O3 with alumina, the results with S/MA = 1 show that the catalyst is somewhat less active than the Pt one (requiring more catalyst), but high production of H-2 and CO can be achieved above 450 degrees C. The experimental results in the temperature range of 200-350 degrees C were used to construct a mathematical model of four reactions (MA decomposition, DME hydrolysis, methanol decomposition, and water-gas shift reaction). The model was used for extrapolation to higher temperatures and led to the conclusion above.