High-selective-hydrogenation activity of W/Beta catalyst in hydrocracking of 1-methylnaphalene to benzene, toluene and xylene

Abstract

Hydrocracking of 1-methylnaphthalene to light aromatic hydrocarbons, such as benzene (B), toluene (T) and xylene (X), at 420 °C and 6 MPa was studied over a series of sulfided Metals/Beta catalysts (Metals = NiMo, NiW, CoMo, CoW, Mo, W). Based on reaction results, a six-lump reaction kinetic model was proposed and a mathematic kinetic model was established which agreed well with the experimental data. All the kinetic constants of every step reaction in the reaction model were obtained. Hydrogenation activity of catalysts not only be affected by metal species and their contents, but also be influenced by metal-zeolite interaction. Strong acidity resulting strong interaction between acid centers and metal centers decreased the hydrogenation activity of catalysts. When the amount of loaded metal oxides increases, the Brönsted acid concentration of zeolite decreases. Selective-hydrogenation activity is a key factor to BTX yield and W-based catalysts showed higher selective hydrogenation activity than other catalysts. Both experiments and the kinetic model showed that 25W/Beta catalyst had the highest BTX yield (53 wt%), attributed to its relatively high selective-hydrogenation activity of W and suitable metal-zeolite interaction.