Yi-Fan Qiao,Wen-Cui Li,Lei He,Jia Wang,Danhui Sun,Zihao Wang,An-Hui Lu
To efficiently convert ethanol into C 4+ olefins without an external hydrogen supply, this study designed an anatase-supported zinc oxide catalyst (ZnO/TiO 2 -A). Combining characterizations with kinetics measurements, we infer that the highly dispersed Zn-O-Ti sites efficiently promote ethanol dehydrogenation to acetaldehyde, which is identified as the rate-limiting step. Concurrently, Ti-O sites with strong C-C coupling ability convert acetaldehyde into high-carbon enal intermediates, which subsequently undergo hydrogenation and dehydration to yield C 4+ olefins with a high formation rate of 43.96 mmol C-atom ·g cat. −1 ·h −1 , outperforming most reported catalysts in the literature. Crucially, nuclear magnetic resonance spectroscopy analysis confirms that ethanol acts as an intrinsic hydrogen donor, supplying active hydrogen for the hydrogenation of C C and C O bonds in enal intermediates, thereby obviating the need for external hydrogen. This work presents a new strategy employing a non-precious metal oxide catalytic system for upgrading ethanol to high-value products.
Zhangkai Qian,Jia-qi Bai,Mei Ma,Huangfei Liu,Mengdie Cai,Jingshuai Chen,Song Sun
N -methylation of amines, nitro compounds and nitriles with CO 2 and H 2 offers a promising strategy for CO 2 utilization. However, developing highly efficient and stable Cu-based catalysts for selective mono- N -methylation of aniline remains challenging. Herein, we report the successful synthesis of a Cu-ZnO/TiO 2 catalyst, with the optimized 5 %Cu-7.5 %ZnO/TiO 2 catalyst achieving a 96.7 % yield of N -methylaniline (MA) and an initial turnover frequency (TOF) of 7.4 h −1 after 6 h under 453 K, 2 MPa CO 2 and 4 MPa H 2 . This performance surpasses all reported Cu-based catalysts and rivals noble metal-based systems. The catalyst demonstrated reusability at least four cycles and versatility in the N -methylation of various amines, nitro compounds, and nitriles. Kinetic studies revealed reaction orders of 0 with respect to aniline concentration and CO 2 pressure, and 1 with respect to H 2 pressure. Based on kinetics and extensive characterization, we propose a reaction mechanism over 5 %Cu-7.5 %ZnO/TiO 2 , identifying Cu nanoparticles as the active sites. The process proceeds via N -phenylcarbamic acid and N -phenylformamide intermediates, with the hydrogenation of N -phenylcarbamic acid as the rate-determining step.
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