Improved oxidation of hydrogen off-gas by hydrophobic surface modification: A multiscale density functional theory study--颗粒学报PARTICUOLOGY

Lian, C., Cai, C., Shen, X., Zhao, S., Yu, X., & Liu, H. (2019). Improved oxidation of hydrogen off-gas by hydrophobic surface modification: A multiscale density functional theory study. Particuology, 44, 28-35. https://doi.org/10.1016/j.partic.2018.04.002

Improved oxidation of hydrogen off-gas by hydrophobic surface modification: A multiscale density functional theory study

Cheng Lian ^{a b 1}, Cheng Cai ^{b 1}, Xiangjian Shen ^c, Shuangliang Zhao ^a *, Xinhai Yu ^d *, Honglai Liu ^b

a State Key Laboratory of Chemical Engineering and School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
b School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 220237, China
c Research Center of Heterogeneous Catalysis and Engineering Science, School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou 450001, China
d Key Laboratory of Safety Science of Pressurized System (MOE), School of Mechanical Engineering, East China University of Science and Technology, Shanghai 200237, China

10.1016/j.partic.2018.04.002

Volume 44, June 2019, Pages 28-35

Received 28 January 2018, Revised 18 April 2018, Accepted 20 April 2018, Available online 14 July 2018, Version of Record 30 April 2019.

E-mail: szhao@ecust.edu.cn; yxhh@ecust.edu.cn

Highlights

• A multiscale approach was developed towards the surface catalytic reaction efficiency.

• Hydrogen off-gas oxidation on different surface-modified catalytic substrates was investigated.

• Optimum surface modifications for efficient reaction is identified and compared with experiment.

Abstract

A catalytic micro-reactor for converting hydrogen off-gas into water was recently developed, through which the conversion efficiency of hydrogen gas was greatly improved by hydrophobic modification of the catalytic substrate. Herein, a hybrid theoretical method is reported that combines density functional theory (DFT) on both the quantum and molecular scales. This method allows the microscopic study of the mechanism by which the surface catalytic reaction can be manipulated. Specifically, quantum DFT calculations are performed to quantify the molecular interaction between the catalytic substrate and reagent or product. Classical DFT investigations are subsequently carried out to determine the local concentrations of reagents near catalytic sites subject to different surface coating conditions. Finally, the reaction efficiency is determined from the local concentrations based on collision theory. This multiscale method provides molecular insight for quantifying the effect of catalytic surface modification on the reaction efficiency. The method reveals that an optimal surface hydrophobic modification can promote the densities of reagents near the substrate, while depleting the produced water. These two factors promote the conversion efficiency. The exclusion of produced water from the catalytic substrate is affected more by the degree of polymer grafting than by the chain length of hydrophobic polymer moieties.

Graphical abstract

Keywords

Surface reaction; Hydrophobic modification; Density functional theory; Multiscale

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