Characterization of the deposit on zeolite β catalyzed benzene propylation

Modified zeolite β shows remarkable performance for benzene propylation under low temperature and liquid phase. Deactivation occurred after 8000 h reaction at pilot-plant scale, due to carbonaceous deposition (coke) within the crystal of the zeolite. 13C NMR, GC–MS, TG, TPO and nitrogen physical adsorption, combined with the solvent extraction method, were applied to determine the nature of the deposit, which mainly consists of multi-propyl-benzenes and tetra-hydro-naphthalene, as the consequence of the alkylation/cyclization of the objective product. The deposit formed initially in intracrystalline pores. The “faster” linear rate of TPO, rather than the opposite one, is suitable for coke removal in a flow of 3% (m/m) O2/N2 mixture.