MCM-41 overgrown on y composite zeolite as support of Pd-Pt catalyst for hydrogenation of polyaromatic compounds

A composite zoelite Y overgrown with a thin layer of mesoporous MCM-41 was prepared as the support of a sulfur-tolerant catalyst for aromatics reduction in diesel cut. This material is different from the mechanical mixture of the two zeolites in many aspects, that is, the FTIR spectra, appearance of particles, distribution of Si and Al, ²⁹Si MAS NMR spectra, acid strength, and amount of acid sites on the surface. The composite was used as the support of a Pd-Pt catalyst for the hydrogenation of polyaromatic compounds, pyrene and naphthalene. Sulfur tolerance of the catalyst was investigated with naphthalene hydrogenation in the presence of thiophene and 4,6-dimethyldibenzothiophene. It was demonstrated that the introduction of mesopores enhances the activity of pyrene hydrogenation and the sulfur tolerance during naphthalene hydrogenation.