The NH3-TPD measurements verify that the surface acidity of the synthesized PtSnIn/xCa–Al catalysts decreases with the addition of Ca.
The TEM images reveal that PtSnIn/1.5Ca–Al catalyst has the smallest Pt particle size of 5 nm and satisfied particle distribution.
The XPS and H2-TPR verify that the state of metal species and its interaction with support are influenced by Ca species.
After adding 0.6–1.5 wt.% Ca species, the catalytic stability of the PtSnIn/xCa–Al catalysts is evidently improved.
However, over high Ca loading leads to a decrease of propane conversion and catalytic stability.
For PtSnIn/1.5Ca–Al catalyst, the propane conversion has little decline and keep at higher level above 58.0% until 25 h reaction time, and the final propane conversion of 34.0% is obtained
even after 100 h reaction.