Investigation of Pt-Ga/CeO2-ZrO2-Al2O3 bifunctional catalyst for the catalytic conversion of n-butane into olefins
The molecular structure of n-butane is relatively stable with high C—C bond energy,which makes it difficult to be effectively utilized,and most of it is currently burned as a low-value fuel.The study of converting n-butane into high-value-added light olefins through dehydrogenation,cracking,and other reactions is also of great scientific significance.In this study,Pt and Ga were sequentially impregnated onto CeO2-ZrO2-Al2O3(CZA)support by using a stepwise method to prepare the PtGa/CZA catalyst.Pt-Ga2 O3 was introduced as a dehydrogenation catalyst for the conversion of C4 H10 to C=4,while CZA functions as an acid catalyst for the cracking reactions leading to C=4→C=3 and C=2.Simultaneously,PtGa and CZA synergistically enhance the surface oxygen adsorption capacity and reduce the activation temperature required for n-butane.The results demonstrated that simultaneous loading of Pt and Ga onto the CZA support significantly enhanced both conversion rate and selectivity compared to single-loaded Pt or Ga catalysts.At 500℃,the conversion rate of n-butane over the PtGa/CZA catalyst reached 64.3％,which was 55.9％higher than that achieved with the Pt/CZA catalyst and 53.9％higher than that obtained with the Ga/CZA catalyst.All three catalysts exhibited selectivity above 95％.The PtGa/CZA catalyst was made into a coated catalyst to improve n-butane conversion and catalyst stability.The excellent activity of the PtGa/CZA catalysts was attributed to the lower Ce4+reduction temperature and surface adsorbed oxygen desorption temperature,as well as the larger surface adsorbed oxygen site content and strong acid site content.
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