LAUSR

This work reports on the effect of SiO2/Al2O3 ratio (25, 38, 50 and 80) on the physicochemical properties and performance of PtSnK/ZSM-5 catalysts in butanes aromatization process. It was found that the Pt dispersion decreased obviously with SiO2/Al2O3 increasing. The strength and type of acid sites look similar, while the redox properties were influenced significantly. The Pt–SnOx species are produced except for PtSnK/ZSM-5-80 with large separated Pt ensembles from H2-TPD analysis. The PtSnK/ZSM-5-50 catalyst shows the improved cofeeding (mixed butanes: 50 wt% n-butane + 50 wt% i-butane) conversion (88%) with lower Pt dispersion (25%). Furthermore, dehydrogenation of mixed butanes over Pt–SnOx is more favorable on PtSnK/ZSM-5-50 when both ratios of benzene/C8 aromatics and methane/propane are high, due to the outside contact time is short. So the influence of SiO2/Al2O3 ratio on the aromatics distribution is mainly related to the difference in the Pt dispersion and distribution. However, the predominate process to produce light aromatics (BTX) is still hydrogen transfer, which contributes to the long-life span.Graphical Abstract