Hydrogen Production via Sorption Enhanced Steam Methane Reforming Process Using Ni/CaO Multifunctional Catalyst

Sorption enhanced steam methane reforming (SESMR) is a promising concept for hydrogen production. The in situ removal of CO2 shifts the reaction equilibrium toward increased H-2 production as well as H-2 concentration. Generally, most of the previous studies operated the SESMR system using separate materials of a CO2 adsorbent and a reforming catalyst. In this study, a combined catalyst-adsorbent material (considered as multifunctional catalyst), whose functions are not only to catalyze the reaction but also to adsorb CO2 simultaneously, was developed and utilized for the SESMR process. CaO and hydrotalcite (MIC30-K), well-known adsorbents for CO2 capture, were selected as supports to replace a conventional Al2O3 support for Ni catalyst. The material was prepared in the form of powder by incipient wetness technique, and the tests were carried out in the fixed bed reactor system. Experimental results indicated that the activity of Ni/CaO was less than Ni/Al2O3 but high hydrogen concentration in the product stream can be achieved. The effect of Ni loading was investigated, and it was found that at atmospheric pressure, steam to methane ratio of 3 and T = 873 K, 12.5 wt % Ni/CaO was the appropriate ratio, offering high hydrogen concentration (80%). The study also suggested that the use of the multifunctional catalyst eliminates the use of Al2O3 and thus requires a reactor with a smaller size.