Balancing the Activity and Selectivity of Propane Oxidative Dehydrogenation on NiOOH (001) and (010)
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RESEARCH ARTICLE
Balancing the Activity and Selectivity of Propane Oxidative Dehydrogenation on NiOOH (001) and (010) Lisheng Li1 · Hua Wang1 · Jinyu Han1 · Xinli Zhu1 · Qingfeng Ge2 Received: 7 July 2020 / Revised: 10 July 2020 / Accepted: 11 July 2020 / Published online: 5 August 2020 © The Author(s) 2020
Abstract Propane oxidative dehydrogenation (ODH) is an energy-efficient approach to produce propylene. However, ODH suffers from low propylene selectivity due to a relatively higher activation barrier for propylene formation compared with that for further oxidation. In this work, calculations based on density functional theory were performed to map out the reaction pathways of propane ODH on the surfaces (001) and (010) of nickel oxide hydroxide (NiOOH). Results show that propane is physisorbed on both surfaces and produces propylene through a two-step radical dehydrogenation process. The relatively low activation barriers of propane dehydrogenation on the NiOOH surfaces make the NiOOH-based catalysts promising for propane ODH. By contrast, the weak interaction between the allylic radical and the surface leads to a high activation barrier for further propylene oxidation. These results suggest that the catalysts based on NiOOH can be active and selective for the ODH of propane toward propylene. Keywords Density functional theory · Oxidative dehydrogenation · Propane · Nickel oxide hydroxide · Two-step radical mechanism · Selectivity
Introduction The demand for propylene has remarkably increased over the past decade. Such increase is predicted to continue due to its importance as an industrial chemical in the production of polypropylene, propylene oxide, acrylic acid, ethanol, acrylonitrile, and other products [1–7]. Propylene can be produced from catalytic and steam cracking, as well as propane dehydrogenation (PDH) [8–10]. These processes suffer from high energy consumption because of the high endothermic reactions and fast deactivation of catalysts due to carbon deposits. In addition, catalytic and steam cracking use nonrenewable petroleum-based feedstock, making these processes unsustainable [11]. * Xinli Zhu [email protected] * Qingfeng Ge [email protected] 1
Collaborative Innovation Centre of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, IL 62901, USA
2
Over the past decade, the exploitation of shale gas has provided an abundant supply of light alkanes, including propane, making PDH and oxidative dehydrogenation (ODH) potentially cost-effective processes for propylene production [11–13]. ODH has the following advantages over PDH: (1) The ODH reaction is exothermic with a reaction enthalpy of − 117 kJ/mol and is highly favorable over the PDH reaction (ΔH = 124 kJ/mol); (2) The presence of oxidation reagents in ODH helps oxidize the residual carbon, thereby preventing coke deposition [14–16]. However, the presence of oxidation reagents in
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