The catalytic characteristics of 2-methylnaphthalene acylation with AlCl3 immobilized on Hβ as Lewis acid catalyst

Abstract

The heterogeneous supported Lewis acid catalyst prepared by immobilization technology has high reaction activity. It is an environment-friendly catalyst. Using Lewis acid immobilized as the catalyst, 2-methyl-6-propionyl naphthalene is synthesized by Friedel–Crafts reaction with 2-methylnaphthalene and propionic anhydride, which has a good development prospect. A variety of AlCl3 catalysts supported by H-zeolite molecular sieves are prepared using the solvent reflux method in the paper. It is found that AlCl3/Hβ has better catalytic performance. The results showed that AlCl3/Hβ catalyst is mainly composed of L acid. The acid content of B acid and the specific surface area increase, and the pore volume and pore size decreases. With the increase in AlCl3 concentration, the acid content of strong acid, medium strong acid, and weak acid increases, but the solubility of AlCl3 in CHCl3 is limited. When the concentration of AlCl3 is too high, too much AlCl3 is deposited on the surface of the molecular sieve, which is useless to its binding with Si–OH. AlCl3/Hβ’s activity is higher when the concentration of AlCl3 is 3 g·L−1, and the solvent is refluxed for 8 h and calcined at 550°C for 3 h. Under these conditions, the conversion of 2-methylnaphthalene is 85.86%, and the yield of β,β-methyl propyl naphthalene is increased to 81.19%.

Keywords

• 2-methylnaphthalene
• β,β-methyl propyl naphthalene
• acylation
• immobilized alcl3
• zeolite molecular sieve