Correlation between structure, acidity and activity of Mo-promoted Pt/ZrO₂-TiO₂-Al₂O₃ catalysts for n-decane catalytic cracking

Highlights: • The performances of Mo-promoted composite oxide catalysts were investigated. • Surface acidity of the catalysts was modulated by MoO₃ additive. • The correlation between structure, acidity and activity of catalysts were studied. • The catalyst containing 7.0 wt.% MoO₃ exhibited the best catalytic activity. - Abstract: A series of Pt/MoO₃/ZrO₂-TiO₂-Al₂O₃ composite oxides with various MoO₃ contents were prepared by incipient wetness impregnation method, and coated on the inner wall of stainless-steel microchannels. Catalytic cracking of n-decane (as model molecule of hydrocarbon fuel) over such monolithic catalysts were investigated under high temperature and high pressure conditions. The catalysts were characterized by N₂ adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS) and temperature programmed desorption of ammonia (NH₃-TPD) techniques. The correlation between the catalytic performances of MoO₃ modified catalysts and their structure as well as acidic property were observed. It was found that the conversion and heat sink of n-decane were obviously heightened compared with that obtained from thermal cracking. In particular, the catalyst which contains 7.0 wt.% MoO₃ exhibited the best catalytic cracking activity among the prepared catalysts, which is in well agreement with its highest amount of total acid sites and strong acid centers, along with the finely dispersed isolated and octahedral molybdenum species.