Tungsten-based catalysts for lignin conversion: A review

Lignin is the most abundant renewable resource composed of aromatic moieties in nature. The highlight aromatic characteristics of lignin renders it a sustainable feedstock for aromatic chemicals and naphthene fuels. Tungsten is a typical rare metal for the synthesis of non-noble metal catalysts which show potential in catalyzing lignin depolymerization/valorization. This review highlights the latest advances in the application of tungsten-based catalysts for the transformation of lignin into value-added chemicals and fuels. We focus on the synthesis and application of tungsten carbides, tungsten sulfide, tungsten phosphide, tungsten acids, and tungsten-based bimetallic catalysts on lignin conversion. Among them, tungsten carbides are extensively summarized. Perspectives for the future investigation on the lignin depolymerization are also presented.