The key to catalytic stability on sol-gel derived SnOx/SiO2 catalyst and the comparative study of side reaction with K-PtSn/Al2O3 toward propane dehydrogenation

Side reactions competing with propane dehydrogenation were studied on K-PtSn/Al2O3 and SnOx/SiO2 catalysts. The results showed that hydrogenolysis, hydrogenation, deep dehydrogenation, and coke formation occurred more pronouncedly on K-PtSn/Al2O3, contrasting with the catalytic cracking result. Because of the higher total acidity on SnOx/SiO2, measured by NH3-TPD, more catalytic cracking occurred on this catalyst. However, SnOx/ SiO2 showed a lower coke deposition, although the acid site can promote the coke formation. This contrast was not due to the spillover effect, which can suppress coke formation on the acid site. Essentially, the propylene hydrogenation, H2-TPD, and FTIR results demonstrate that SnOx/SiO2 had a lower hydrogen spillover than that of K-PtSn/Al2O3. On the other hand, TPO results from propylene dehydrogenation and coke formation of propadiene illustrate that the key of distinguished SnOx/SiO2 catalyst stability was owing to a low ability of coke precursor generation.

Automated summary

The study revealed that side reactions such as hydrogenolysis, hydrogenation, deep dehydrogenation, and coke formation were more pronounced on K-PtSn/Al2O3 catalyst, while catalytic cracking occurred more on SnOx/SiO2 due to its higher total acidity. Despite the acid site's capability to promote coke formation, SnOx/SiO2 showed lower coke deposition. Additionally, the lower hydrogen spillover on SnOx/SiO2 compared to K-PtSn/Al2O3 contributed to its distinguished stability in propylene dehydrogenation and coke formation of propadiene.