Low-Temperature Conversion of ortho-Hydrogen into Liquid para-Hydrogen: Process and Catalysts. Review

The present review is devoted to some problems of the production of liquid para-hydrogen by catalytic ortho-para conversion (OPC) of molecular hydrogen at cryogenic temperatures, the catalysts of this process, and catalyst operation in hydrogen liquefiers. The methods of evaluating the catalyst activity in OPC and calculations of the performance of hydrogen liquefiers are given. The most important papers that deal with the use of catalysts of OPC under the conditions of hydrogen liquefiers were considered. A procedure for processing the experimental data on catalyst activity was presented for calculations of the laboratory and industrial hydrogen liquefiers working at different temperature levels based on these data.