Mo, Cu Bimetallic Loaded Hierarchical Pore ZSM-5 Catalysts for the Hydrothermal Aromatization of Algal Bio-Oil Model Compounds

In this work, the hierarchical pore HZSM-5 zeolite was synthesized by the method of alkali treatment, and the bimetallic loading of Mo and Cu was investigated for the hydrothermal aromatization of stearic acid. After alkali treatment, the pore size of HZSM-5 increased, but the acid sites decreased. The metal loading reintroduced the Lewis acid sites, greatly increasing the ratio to Brönsted acid sites. Therefore, the treated catalyst achieved higher hydrothermal stability while maintaining the high activity of hydrothermal aromatization of stearic acid. Mo0.02Cu0.01/Z-0.2M achieved excellent activity in the stearic acid hydrothermal aromatization with a high overall TEX (toluene, ethylbenzene, and xylenes) yield of 50.19 wt %, including 10.30 wt % toluene, 3.82 wt % ethylbenzene, and 36.07 wt % xylene. In addition, Mo0.02Cu0.01/Z-0.2M still showed excellent catalytic activity while applied in the system of the simulated microalgal bio-oil. As the reactant changed to the mixture of stearic acid and hexadecanamide, an overall TEX yield of 34.11 wt % was obtained at 450 °C. These results demonstrate the excellent hydrothermal aromatization ability of the MoCu-supported hierarchical pore ZSM-5 zeolite, which provides the potential to produce value-added chemicals from algal biomass.