Process development for generating high purity hydrogen by using supported palladium membrane reactor as steam reformer

High purity hydrogen has been mainly used as a fuel for low temperature fuel cells such as polymer or alkaline electrolyte fuel cells. Hydrogen is industrially produced by steam reformation of hydrocarbons such as methane, naphtha oil, methanol, etc. Additional purification is invariably required for crude hydrogen and often is a costly step in the whole process. This paper presents an advanced process, in which no additional purification facility is needed, to generate high purity hydrogen (similar to 99.9%) directly from the supported palladium membrane tube incorporated in a steam reforming reactor. The hydrogen produced and purified from the palladium membrane reactor is free of CO and CO2 so that it is suitable for polymer or alkaline electrolyte fuel cells. A unique design of a double-jacketed reactor was set up as a pure hydrogen generator with features of clean emission and energy self-balance. Experiments were conducted to illustrate the process for the direct and continuous generation of high purity hydrogen from methanol. The production flux of pure hydrogen obtained was higher than 5 m(3)/h-m(2) and the recovery yield of hydrogen from methanol was found to be over 70%. This process has opened up a new possibility of on-board hydrogen generation for electric vehicle fuel cells in use of liquid fuel such as gasoline or methanol, which can be refueled fast and are compatible with the infrastructure of the current fuel system. (C) 1999 International Association for Hydgrogen Energy. Published by Elsevier Science Ltd. All rights reserved.