Chemical Insight into the Structure and Formation of Coke on PtSn Alloy during Propane Dehydrogenation

Propane dehydrogenation (PDH) catalyzed by PtSn/Al(2)O(3)is a vital industrial process for producing propylene, a significant building block in the chemical industry. However, coke produced in the process deactivates the catalyst and the energy-intensive regeneration procedures can produce considerable CO(2)emission. In this work, coke on the spent catalysts is analyzed by thermogravimetric-mass spectra, Raman spectra,H-1 solid NMR spectra, and infrared spectra. Several C(3)species, including propyl, propylidene and propylidyne are found on the surface of the PtSn alloy. Several reaction pathways are investigated by density functional theory (DFT) calculations. It is also found that this coke can be hydrogenated to propylene in the PDH process. These results could provide theoretical guidance for optimizing process parameters in industry.