H2 production by steam reforming of Saccharina japonica-derived liquefied oils on NixCuy hydrotalcite-derived catalysts

H2 is highlighted as a sustainable energy resource, and mainly produced by steam reforming of fossil fuels, which emit greenhouse gases. Marine biomass can be an alternative because of high productivity and carbon neutrality compared to terrestrial biomass. In this work, we studied bio-oil from Saccharina japonica (macroalgae) as a renewable H2 resource by steam reforming on NiCu hydrotalcite-derived catalysts (NixCu1.5-xMg1.5Al1.0). After the hydrothermal liquefaction of S. japonica, minerals were removed by the desalting process. GC-MS showed bio-oil mainly consists of ketone and N-containing compounds. Increasing Cu content improved the reducibility of Ni, evidenced by H2-TPR and XPS, suggesting the synergetic interaction between Ni and Cu. Chemisorption showed the catalyst had the smallest particle sizes (∼19 nm) at 1 to 1 Ni:Cu atomic ratio. As for steam reforming of bio-oil, NixCu1.5-xMg1.5Al1.0 catalysts, except Cu1.5Mg1.5Al1.0, were stable with >89% of carbon conversion and H2 selectivity of 76–78% during 5 h. Especially, at 1:1 Ni:Cu atomic ratio, the catalyst maximized H2 production rates with the highest H2/CO ratio of 28. It suggests that designing small NiCu particles is critical for H2 production. In summary, NixCu1.5-xMg1.5Al1.0 catalysts are promising for H2 production by the steam reforming of the bio-oil from macro algae.