Partial Oxidation of Methanol to Hydrogen

Partial Oxidation of Methanol to Hydrogen

CH3OH + 1/2O2 —→ CO2 + 2H2

△H0298=-192.3kJ/mol

2CH3OH + H2O + 1/2O2 —→ 2CO2 + 5H2

△H0298=-384.6kJ/mol

Methanol and/or desalted water, as well as a certain proportion of oxygen, are preheated and vaporized, superheated to the reaction temperature, and then catalytically reformed into a mixture of hydrogen and carbon dioxide through the catalyst bed.After heat transfer, cooling, condensation, and water washing, the mixture is sent to the separation device (such as PSA system) for separation, and finally the purity of the product hydrogen. Partial oxidation of methanol and partial oxidation reforming for hydrogen production are both exothermic reactions. The advantage of the reaction is that it can provide the heat required by the reaction itself through partial oxidation of methanol.Therefore, there is no need to provide an additional heating device, and the oxygen raw material therein can be directly taken from the oxygen in the air.These advantages are greatly beneficial to the miniaturization of methanol catalytic hydrogen production equipment, and lay the foundation for the future practical use of methanol partial oxidation to hydrogen production.

Since the research on the partial oxidation of methanol is still in its infancy, the catalyst system is not rich enough.There are only two types of catalysts: Cu-based catalysts and Pd-based catalysts.Cu-based catalysts are widely used in various reactions of hydrogen production from methanol due to their excellent catalytic performance for methanol synthesis reactions.For Pd-supported catalysts, the partial oxidation of methanol can be completely fed according to the stoichiometric ratio, which is of great significance for the full utilization of CH3OH and the high hydrogen production rate per unit time.However, when the O2/CH3OH of the above-mentioned Cu/Zn/Al catalyst is greater than 0.3, the selectivity of the reaction will obviously decrease, and a large amount of by-products such as CO2 and H2O will be produced.Therefore, Pd-based catalysts are more practical than Cu-based catalysts, which should be a key research direction in the future.