Low temperature water-gas shift: Characterization of Pt-based ZrO2 catalyst promoted with Na discovered by combinatorial methods

In one view, CH bond breaking of the formate has been proposed to be the rate-limiting step of the low temperature water-gas shift mechanism. In combinatorial catalytic testing, enhanced water-gas shift rates were observed by incorporating Na to Pt/ZrO2 catalysts. DRIFTS investigations suggest that electronic modification of formate was achieved, leading to an important weakening of the formate CH bond. Three separate DRIFTS investigations were carried out, including (1) dynamic formate coverage studies during steady state water-gas shift, (2) transient forward formate decomposition tests at low temperature in steam, and (3) formate H–D exchange studies in the absence of steam (i.e., reverse decomposition). In each investigation, the decomposition rate of formate was much more facile for the Na promoted catalyst relative to Pt/ZrO2 alone.

Addition of Na to Pt/ZrO2 low temperature water-gas shift catalysts led to an important weakening of the formate CH bond, as indicated by a shift to lower wavenumbers in infrared spectroscopy. In one view, formate CH bond breaking is proposed to be the rate-limiting step of the cycle. Enhanced WGS rates and formate decomposition rates are demonstrated with Na doping. Figure optionsDownload as PowerPoint slide