Influence of support on the catalytic properties of Pt-Sn-K/θ-Al2O3 for propane dehydrogenation

A study on the performance of Pt(0.3 wt%)Sn(0.2 wt%)K(0.5 wt%) catalysts supported on four different θ-Al₂O₃for propane dehydrogenation is reported in this study. Theθ-Al₂O₃ used as supports were prepared by four different methods as (a) calcinations of the commercial γ- Al₂O₃ at 1223 K for 12 h, (b) synthesis by hydrochloric acid reflux method, (c) precipitation of Al(NO₃)₃•9H₂O with ammonia solution and (d) extrusion use pseudo-boehmite powder, respectively. They were characterized by using XRD, BET, SEM, H₂-TPR, NH₃-TPD, CO-chemisorption, XPS and TG-DTA methods to study which characteristic of the carrier will affect the performance of the catalyst. The results show that high acidity and strong interactions of the Sn support can improve the propane dehydrogenation activity of the catalyst, large pore volume and large pore diameter can enhance the stability of the catalyst. Al₂O₃ synthesized by method (b) has the largest pore volume, pore diameter, relatively high surface acidity and strong interaction with Sn, which makes thecatalyst with the support prepared by method (b) showed the highest propane conversion and superior selectivity. The average conversionis 38.6% andthe average selectivity is 95.2% during the reaction time of 25 h.