Pt/MCM-41 and Pt/Al2O3 catalysts were prepared by incipient-wetness impregnation method. These catalysts were characterized by X-ray diffraction, nitrogen sorption, CO chemisorption, and temperature-programmed desorption of ammonia. Naphthalene dissolved in n-hexadecane was used as a model compound to simulate the aromatics in diesel fuels for the hydrogenation activity test. The reaction was carried out in a cocurrent down-flow trickle bed reactor at 4.2 MPa, 453 K, an LHSV of 2.8 h(-1), and H-2/liquid feed of 800 mL/mL (in excess). MCM-41 has a medium-strength acidity and large surface area compared to alumina. The metal dispersion on MCM-41 is higher than that on Al2O3. Pt/MCM-41 demonstrating a higher activity than Pt/Al2O3. This is essentially due to its higher acidity of the support and the higher metal dispersion. Both are beneficial to the overall hydrogenation activity. The high acidity can enhance the spillover of aromatics from metal surface to the metal-support interfacial region. Consequently, more acid supports will give an additional contribution to the overall activity. The cis-decalin selectivity of Pt/MCM-41 is lower than that of Pt/Al2O3, owing to the higher acidity of MCM-41 than Al2O3.
JOURNAL OF THE CHINESE INSTITUTE OF CHEMICAL ENGINEERS