Catalytic hydrodeoxygenation of lignin enhanced by selectively etching ZSM-5

Abstract

Cyclanes, a major component of aviation fuel, can be obtained from the catalytic hydrodeoxygenation (HDO) of lignin, which not only reduces the dependence on fossil resources, but also makes lignin refining economically viable. The adsorption capacity and dwell times of reactants and H₂ on the catalyst play a key role in the HDO of lignin. It remains a difficult challenge to enhance the adsorption capacity of the catalyst for reactants and H₂ and to prolong their extended dwell times on the catalyst. Based on this, a nickel-based catalyst with moderate corrosion was prepared by the dissolution of ZSM-5 single crystals induced by ammonia, and was used for value-added conversion of lignin. It was confirmed by experiments and complementary characterizations that the corrosion of Ni/ZSM-5 for etching 2 h (Ni/ZSM-5₂) enhanced the adsorption capacity of H₂ and extended the dwell times of the reactant and H₂. Furthermore, the uniformly dispersed Ni nanoparticles stimulated the intrinsic catalytic activity and efficiently generated H^…H and H⁺, which synergistically promote the HDO of lignin with the cyclanes yield up to 58.6 %. As a result, BOB was completely converted to cyclanes over Ni/ZSM-5₂ at 140 °C under 2 MPa of H₂ for 4 h, suggesting Ni/ZSM-5₂ exhibits excellent HDO activity under mild conditions.