Liquid-phase alkylation of naphthalene by isopropanol over zeolites Part II: Beta zeolites

The title reaction has been investigated over Beta zeolites of different Si /Al ratio. Surface acidity has been assessed by adsorption microcalorimetry and FTIR, using pyridine as probe molecule. Catalytic tests were carried o ut at 623 K and 40 bar in liquid phase, with decalin as solvent, in flow re actor. Isopropylation is initially accompanied by remarkable oligomerisatio n/cracking of the reactant alcohol and limited cracking of the solvent. The formation of the small-sized products of the side reactions is initially f avoured over the cumbersome alkylation products, due to the slow diffusion rate of the latter. Transalkylation between polyisopropylnaphthalenes and n aphthalene sets in, leading to increasing conversion of naphthalene with ti me-on-stream. For the strongly dealuminated sample naphthalene conversion r eaches a maximum and then decreases; the decreasing trend seems associated to insoluble coke formation and the confinement of transalkylation at the p ore mouth. (C) 1999 Elsevier Science B.V. All rights reserved.