Catalytic Performance for the Conversion of Potent Fluorinated Greenhouse Gases by Aluminium Fluorides with Different Mo
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Catalytic Performance for the Conversion of Potent Fluorinated Greenhouse Gases by Aluminium Fluorides with Different Morphology Hong Yang1 · Sen Wu1 · Zhengfei Chen2 · Lichun Li1 · Haili Wang1 · Bing Liu1 · Haodong Tang1 · Ying Li1 · Aimin Chen1 · Wenfeng Han1 Received: 1 August 2020 / Accepted: 28 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The AlF3 catalysts with controlled morphology (cubic, hexahedron and octahedron) were synthesized via hydrothermal method using different solvents. The dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was used as the model reaction to evaluate the catalytic performance of the AlF3 catalysts with different morphology. Results showed that surface area, crystal structure, surface acidic properties together with the chemical composition of the A lF3 catalyst were substantially influenced by the different morphology. XRD results showed that κ-AlF3 crystalline structure was formed when using ethanol as solvent while β-AlF3 crystalline structure was formed when using water as solvent. Among the three prepared AlF3 samples, the A lF3-C catalyst with cubic shape demonstrated not only largest surface area but also most amount of medium-strength surface acid sites, resulting in enhanced reaction activity towards the dehydrofluorination reaction. The characteristic high Miller index crystal planes of (402) and (321) exposed on the cubic shaped AlF3-C catalyst is believed to be the main reason accounting for the high catalytic performance as there are equal amount of Al and F atoms exposed. Moreover, a reaction mechanism describing dedehydrofluorination of HFC-245fa on AlF3 catalyst with equal amount of Al and F atoms exposed on certain crystal planes was proposed. Graphic Abstract
AlF 3-C 1420 µmol.h-1.g cat-1
AlF 3-H 840 µmol.h-1.g cat-1
AlF 3-O 620 µmol.h-1.g cat-1
CF 3CH2CHF 2
AlF3 350 o C
CF 3CH=CHF+HF
Electronic Supplementary Material The online version of this article (https://doi.org/10.1007/s10562-020-03446-y) contains supplementary material, which is available to authorized users. Extended author information available on the last page of the article
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H. Yang et al.
Keywords AlF3 · Morphology effect · Dehydrofluorination reaction · Crystal plane
1 Introduction Hydrofluoroolefins (HFOs) are well-accepted as the fourth-generation of the fluorine-based refrigerants due to its lower global warming potential (GWP) and shorter lifetime in atmosphere than the third-generation refrigerant hydrofluorocarbons (HFCs) [1]. Compare with other reaction processes, catalytic dehydrofluorination reaction offers a straightforward route to convert HFCs to HFOs. 1,3,3,3-Tetrafluoropropene (HFO-1234ze) is one of the promising substitutes for 1,1,1,2-tetrafluoroethane (HFC134a) as it has many advantages including low GWP, low toxicity, low flammability and zero ozone depletion potential (ODP) [2–4]. Owing to the substantial advantages including simple reaction route, high yield and cheap inves
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