High Metal–Acid Balance and Selective Hydrogenation Activity Catalysts for Hydrocracking of 1‑Methylnaphthalene to Benzene, Toluene, and Xylene

Hydrocracking of 1-methylnaphthalene to benzene (B), toluene (T), and xylene (X) was performed over a series of bi-functional catalysts (W/Beta) at 420 °C and 6 MPa. The reaction results and kinetic study indicated that metal–acid balance (metal–acid interaction and metal–acid ratio) and metal dispersion had a great impact on the cracking, hydrogenation, and selective hydrogenation activity, which directly determine the BTX yield. An inappropriate metal–acid ratio would lead to producing plenty of intermediates or by-products, and poor metal dispersion would result in low hydrogenation activity. However, good metal dispersion usually accompanies the strong metal–acid interaction, which reduces the sulfidation of metal. In this work, a new tungsten precursor, W-complex, was used to prepare the catalysts with good dispersion of metal oxides and high hydrogenation activity. The external surface acidity of zeolite was modified to regulate the metal–acid interaction by forming a layer of SiO₂ on acid sites through chemical liquid deposition.