Hydrogen production from biomass not only provides a sustainable approach to address the growing energy demand but also reduces the carbon footprint of hydrogen compared to conventional coal gasification and stream methane reforming. Alkaline Thermal Treatment (ATT) reaction has been developed as a unique bioenergy conversion integrated with carbon capture and storage (BECCS) under moderate reaction conditions (T ≤ 500 °C). In our previous study, Ni showed the highest catalytic activity for H2 production from cellulose via reforming gaseous intermediates. Ca(OH)2 has been employed to promote ATT reaction and to capture CO2 in-situ. In this study, we have developed a series of bimetallic Ni-Pt catalysts for alkaline thermal treatment of cellulose and investigated the hydrogen formation behaviors and mechanisms. It is found that trace amount of Pt significantly promoted tar cracking and enhanced H2 production. The Ni:Pt alloy with a mass ratio of 19:1 showed a significantly enhanced hydrogen yield, 5.06 mol H2/mol cellulose compared to 10wt% Ni catalyst, which produced 3.98 mol H2/mol cellulose. The GC/GC-MS analysis of condensed higher molecular weight products is also carried out to reveal the role of Pt in the decomposition of the derivatives. The compositions of the bimetallic catalysts are modified to optimize the H2 production and its purity. Finally, a real biomass, seaweed, is used to test the developed catalysts. Seaweed is one of the bioenergy sources that is available worldwide. When using Ni catalyst, ATT of brown seaweed showed a high purity H2 (69.69 mmol/g seaweed) with substantially suppressed CO2 formation making the overall biomass conversion not only carbon-neutral but also potentially carbon-negative. Brown seaweed is very rich in carbohydrate, including mainly alginates (C6H8O6), laminarin (C6H10O5), mannitol (C6H14O6) and fucoidan (C7H14O7S). In addition, the effect of salt (e.g., Na, K, Ca and Mg) is investigated in order to investigate the long-term stability of ATT catalysts and the fate of carbon throughout the ATT reaction.

Bimetallic alkaline thermal treatment catalysts for enhanced H2 production with suppressed CO2 formation from unconventional biomass

2019 Fall National Meeting

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