Pt confined in Sn-ECNU-46 zeolite for efficient alkane dehydrogenation

Highly dispersed and stable Pt-based catalysts play a crucial role in constructing efficient catalytic systems for alkane dehydrogenation.In this study,a novel bimetallic Pt-Sn catalyst confined in extra-large-pore ECNU-46 zeolite(denoted as Pt/Sn-ECNU-46)is prepared by post-treatment.The open-site framework Sn species((SiO)_(3)Sn-OH)serve as anchors to interact with Pt species,favoring the high dispersion of Pt.On the other hand,the framework Sn species act as the second metal to regulate the geometrical and electronic environment of Pt species,thus suppressing their accumulation.Pt/Sn-ECNU-46 achieves a good performance in propane dehy-drogenation(PDH)reaction with high initial propane conversion(46%)and propylene selectivity(>99%)as well as regeneration ability.In addition,Pt/Sn-ECNU-46 is also active in the dehydrogenation of n-hexane.This study explores the application of extra-large-pore zeolite as support in constructing metal-confined catalysts for alkane dehydrogenation.

Catalytic alkane dehydrogenations

Olefins find widespread applications in the synthesis of polyolefins and fine chemicals. With an increasing demand for olefins, the technologies for alkane dehydrogenation have drawn much attention. Several types of heterogeneous catalysts have found applications in industry for the dehydrogenation of light alkanes, mainly ethane, propane, and butane. In the past three decades, a number of transition-metal complexes,particularly pincer-ligated iridium complexes, have been developed as the homogeneous catalysts for alkane dehydrogenations. The homogeneous catalyst systems operate under much milder conditions compared with the heterogeneous systems, and some systems exhibit good activity and high regioselectivity in dehydrogenation of alkanes longer than butane.

Potassium-promoted single-atom Co-N-C catalyst for direct dehydrogenation of ethylbenzene

Alkali metals have been widely used as promoters of metal catalysts in various applications,yet the atomic understanding of the promotional mechanism remains elusive.In this work,we for the first time report the significant promotional effect of potassium to the Co-N-C single-atom catalyst for the direct dehydrogenation of ethylbenzene.K cation was introduced by impregnation of Co-N-C with KCl followed by calcination at 600℃,which resulted in the bonding of K to the Co-O moiety of the Co-N-C catalyst as revealed by X-ray absorption spectroscopy in combination with theoretical calculations.The formation of Co-O-K moiety led to the increase of electron density at the O atom due to electron transfer of K to O,and consequently facilitated the heterolytic cleavage of the C-H bond of ethylbenzene across the Co-O moiety.The promotional effect of K was found to be a volcanofunction with the K/Co ratio and became the greatest at the K/Co ratio of 1.36,which resulted in the highest steady-state reaction rate of 9.7 mmolEB·gcat^(−1)·h^(−1)reported thus far.Moreover,the catalyst exhibited excellent stability during 100 h time on stream.