Low-Temperature C-H Bond Activation: Ethylbenzene-to-Styrene Conversion on Rutile TiO2(110)

The low-temperature C-H bond activation of alkanes remains a big challenge in alkane dehydrogenation. In this work, ethylbenzene (EB) oxidative dehydrogenation has been investigated on rutile(R)-TiO2(110) under both ultrahighvacuum (UHV) and ambient conditions. Under UHV conditions, styrene is produced with nearly 100% selectivity in a stepwise manner, in which the first C-H bond dissociation of EB occurs at <285 K with the help of surface O22-species, followed by the second C-H bond dissociation at about 400 K. However, styrene, acetophenone,and 2,3-diphenylbutane products are produced from EB oxidative dehydrogenationunder ambient conditions, suggesting that alpha-H dissociation is the initial step of EBoxidative dehydrogenation. This may be also possible for EB oxidative dehydrogenation on R-TiO2(110) under UHV conditions.The different pathways of EB oxidative dehydrogenation under UHV and ambient conditions may originate from differentintermediates and O2concentrations. This work provides new insight into the fundamental understandings of the low-temperatureC-H bond activation of alkyl chains of aromatic hydrocarbons, which may promote the development of new catalysts for efficientstyrene production from EB oxidative dehydrogenation under mild conditions.

Automated summary

The low-temperature C-H bond activation of alkanes is a challenging process in alkane dehydrogenation. This study investigates the oxidative dehydrogenation of ethylbenzene on rutile(R)-TiO2(110) under ultrahighvacuum (UHV) and ambient conditions. The results suggest that the initial step of EB oxidative dehydrogenation differs under UHV and ambient conditions, leading to different product distributions. The findings provide new insights into the fundamental understanding of low-temperature C-H bond activation and can contribute to the development of efficient catalysts for styrene production.