Hydrogen recovery from steam methane reforming using the ITQ-12 zeolite

The aim of this work is to investigate the potential use of the ITQ-12 zeolite in a PSA process to obtain purified hydrogen from the SMR product stream using molecular simulation. Since the main components of the product stream are hydrogen and carbon dioxide, we put the focus on the separation of these two gases. The separation of hydrogen from the other components (methane, carbon monoxide and nitrogen) will be briefly touched upon as well. From inspection of the adsorption isotherms of carbon dioxide and hydrogen in ITQ-12 we found that the former gas dominates at industrially relevant conditions (311 K and 16 Pa). Breakthrough curves reveal that the ITQ-12 zeolite is likely to perform well in a PSA process for the separation of hydrogen from carbon dioxide. We found that in general higher column lengths and lower gas feed velocities are favorable for a good separation while higher gas feed velocities are favorable for the cleansing of carbon dioxide from the column. For the full mixture it is necessary to employ longer column lengths in order to separate hydrogen from the other components. This is because nitrogen and carbon monoxide exhibit retention times similar to hydrogen, though the latter still travels through the column the fastest. Alternatively the use of ITQ-12 could be combined with other separation techniques, where ITQ-12 is used to mainly remove CO and CH from the SMR product stream. These findings suggest that SMR could become an economically viable way to produce hydrogen by using ITQ-12 in the separation process.