Hydrogen production by steam reforming of bioethanol and fusel oil over Ni/ZSM-5 nanosheet and Ni/SiC

Abstract

In this research, hydrogen production is performed by steam reforming of bio-alcohol over Ni-based catalysts. First section of the study, Ni/SiC catalyst was synthesized and used in steam reforming of fusel oil (FSR). The SiC support was prepared by pyrolysis of rice husk at 1500 °C to obtain β-SiC phase, which benefit to reduce the carbon formation due to its good thermal conductivity and durability. The Ni/SiC1500 indicated 90% of fusel oil gas conversion and 29% of hydrogen yield during a 300 min of steam reforming of fusel oil at 700 °C, hence presenting a good performance, and remaining stable in the steam reforming test. However, there were some restrictions in FSR catalytic performances. This is because fusel oil is a mixed alcohol, suggesting the complexity of reactions when applying to a steam reforming reaction. To improve the catalytic performances in terms of catalyst development, two-dimension ZSM-5 nanosheet was considered as a catalyst support for Ni catalysts due to its high surface area, porous structure properties, and thermal stability. Moreover, Ni/ZSM-5 nanosheet was applied to bioethanol steam reforming (ESR) instead of FSR because the reaction mechanism of ESR has been widely considered in the previous literature for many years and it provides insights into the catalyst development. Hence, the second part of the research investigates on ESR over Ni/ZSM-5 nanosheet. Ni/ZSM-5 nanosheet (in-situ) catalyst was successfully synthesized by hydrothermal process, using ethylenediamine as surfactant directing agent for nickel stabilizing precursor. The catalyst presented 65% of H2 yield, 88% of ethanol conversion and only 17wt% of coke deposition under steam reforming of bioethanol at 550 °C, compared to impregnated catalyst. This was because two-dimension ZSM-5 nanosheet benefits to reduce the carbon formation due to the decrease in surface diffusion barriers. Moreover, in-situ method presented well encapsulated small size of nickel particles in the interconnected lamellar layers of ZSM-5 nanosheet to prevent nickel sinter and coke, hence giving an excellent catalytic performance, and maintaining a 48 h of longevity during the steam reforming of bioethanol.