Thermodynamic analysis of the production of hydrogen on platinum group metal catalyst surfaces|催化剂技术数据集|氢气生产数据集

The open cell foam catalyst bed structure provides improved heat transfer, improved gas flow characteristics, and maximized catalyst surface area. The weight and size reductions achieved by using the catalyst bed construction are necessary for use in smaller applications such as in mobile vehicles, due to their smaller size and weight. Small size and weight also allow for rapid catalyst bed heat-up to operating temperatures which is a critical requirement for quick start capability necessary in most vehicle applications. The reduced size and weight will also benefit the packaging of stationary power plants. The catalyst bed can be formed from a single monolith core, or can be formed from a plurality of the monolith cores in the form of discs which are stacked one atop another. Existing generators produce significant quantities of carbon monoxide which is often an undesirable by-product. Preferably, the refractory support comprises silica or a silicate especially when in the form of granules so that the mixture of copper and platinum group metal catalysts used in the downstream zone can be easily made by physically mixing together granules supporting copper catalyst with granules supporting platinum group metal catalyst. The catalyst system offers two further advantages. Firstly, soon after the oxidation of methanol has been initiated, the methanol oxidation reactions move away from the platinum group metal catalysts allowing the downstream zone to cool so minimizing the losses of platinum group metal catalysts and the formation of carbon monoxide which would otherwise occur at high temperatures. Secondly, if any unreacted oxygen should arrive in the downstream zone, then it will be converted to water by the platinum group metal catalyst in the downstream zone so avoiding the possibility of dangerous amounts of oxygen being present in the hydrogen produced. The partial oxidation reaction quickly establishes itself in a hot spot adjacent the place of entry of the mixture into the catalyst system. The precise size and location of this hot spot can be adjusted by varying the flow rate at which the mixture is fed into the system and it is preferred to adjust the flow rate so that the hot spot surrounds the place of entry of the mixture.