Highly dispersed Pt on core–shell micro-mesoporous composites assembled by mordenite nanocrystals for selective hydrogenation of polycyclic aromatics

A core–shell Pt/MOR-PMOs-x@MSNs (Periodic mesoporous organosilica@mesoporous silica nanoparticles, PMOs@MSNs) catalysts with hierarchical pore structures and suitable acidities were prepared and showed excellent sulfur resistance in hydrogenation of polycyclic aromatic hydrocarbons. The hierarchical pore structure not only facilitates the accessibility of macromolecular aromatic compounds and active sites, but also reduces the mass transfer resistance of reactant and product molecules. The higher metal support interaction (MSI) can reduce the aggregation of active sites, and generate electron-deficient metals, improving the sulfur resistance of the catalyst. Among them, the Pt/MOR-PMOs-100@MSNs catalyst shows the higher activity of naphthalene hydrogenation that the conversion reaches nearly 100 % at 280 °C, the rate constant and turnover frequency (TOF) at 50 % conversion are 6.2 × 10−6 mol·g−1·s−1 and 81.5 h−1, respectively. Moreover, in the 9 h sulfur resistance test at 300 °C, the conversion of naphthalene hydrogenation is still 84.9 %, and the dibenzothiophene (DBT) desulfurization rate is 91.5 %. This is due to the fact that it has a certain specific surface area, synergistic MSI, and active metal Pt nanoparticles with an average size of about 3.5 nm. Moreover, the additions of mordenite (MOR) zeolites bring more acid sites, which in turn form “electron-deficient” adducts with small-sized Pt NPs, thereby raising the sulfur tolerance of the catalysts.