Using β-MCM41 composite molecular sieves as supports of bifunctional catalysts for the hydroisomerization of n-heptane

beta-MCM41 composite molecular sieves were hydrothermally synthesized using NaOH treated beta zeolite as precursors, and Pt/beta-MCM41 bifunctional catalysts were prepared by impregnation. H beta, desilicated H beta by NaOH treatment (D beta), and the physical mixture of H beta and MCM41 (beta+MCM41) were also used as control supports for bifunctional catalysts. All the catalysts were characterized by ICP, XRD, BET, nitrogen adsorption-desorption isotherm and NH3-TPD, and evaluated in the hydroisomerization of n-heptane using an atmospheric fixed bed flow reactor. D beta, beta+MCM41, or beta-MCM41 supported Pt catalysts showed higher selectivity to isoheptanes than the counterpart Pt/H beta did due to the presence of mesopores in addition to the zeolite micropores. Moreover, Pt/beta-MCM41 was demonstrated to be a much more selective catalyst among them because the connection between mesopores and micropores accelerated the diffusion of larger molecules of isoheptanes. Under optimal conditions, Pt/beta-MCM41 provided a very high selectivity to isomerization of 96.5%, coupled with a considerable high conversion of n-heptane of 56.0%.