Solution Combustion Synthesis of Cr2O3 Nanoparticles and the Catalytic Performance for Dehydrofluorination of 1,1,1,3,3-Pentafluoropropane to 1,3,3,3-Tetrafluoropropene

Kang

et al. 2019

Ind. Eng. Chem. Res.

Self Cite

Vinylidene fluoride (VDF) is one of the major fluorinated monomers. Currently, it is produced via the pyrolysis of 1-chloro-1,1-difluoroethane at above 650 °C without any catalyst. Herein, we propose that metal fluorides are promising catalysts that selectively promote the pyrolysis at 300–450 °C. With various metal fluorides as the catalysts, the conversion rate increases with the amount of acidic sites, which is also reinforced by the Bader charges q. The affinity to Cl of the metal fluorides is responsible for the selectivity. However, the high affinity to Cl also leads to the chlorination of metal fluorides forming metal chlorides followed by the deactivation of the catalyst. Different from other metal fluorides, F defects play a major role in the performance of AlF3. With an increase in F defects, the selectivity changes from vinylidene chlorofluoride (dehydrofluorination) to VDF (dehydrochlorination), which further confirms the role of affinity to Cl in the selectivity.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental and DFT Mechanistic Study of Dehydrohalogenation of 1-Chloro-1,1-difluoroethane over Metal Fluorides

Han

Kang

et al. 2019

Ind. Eng. Chem. Res.

Self Cite

“…The O 1s core-level spectrum can be decomposed into CO (531.48 eV), −OH (533.03 eV), and −COOH (535.38 eV) bonds (Figure G). The Cr 2p core-level spectrum (Figure H) of Cr 2 O 3 NPs showed that there were three different states of chromium in Cr 2 O 3 NPs, including the Cr metallic bond (574.28 eV), , CrO 3 (589.28 eV), , and Cr 2 O 3 (576.38, 577.08, 579.83, 584.38, and 586.73 eV). − According to the Cr 2p signal, the ratios of Cr 2 O 3 , CrO 3 , and metallic Cr in our prepared nanoparticles were calculated to be 90.19, 5.41, and 4.40%, respectively. All of the above results indicate that the resulting nanoparticles prepared by microwave heating Cr 3+ and sodium citrate were citrate-coated Cr 2 O 3 NPs.…”

Section: Resultsmentioning

confidence: 99%

Microwave-Assisted Synthesis of Chromium Oxide Nanoparticles for Fluorescence Biosensing of Mercury Ions and Molecular Logic Computing

Yao

et al. 2021

ACS Appl. Nano Mater.

Cumbersome and inefficient synthesis of chromium-based nanomaterials with unique physicochemical properties and bioactivity limits their wide and practical applications. Simple, fast, and green synthesis of chromium-based nanomaterials will help promote the discovery of their properties and expansion of their application fields. Herein, we proposed rapid, inexpensive, and large-scale methods for the synthesis of chromium oxide nanoparticles (Cr2O3 NPs) by simply microwave-heating Cr3+ ions and citrate for several minutes. The citrate-coated Cr2O3 NPs with a universal fluorescence quenching ability as the sensing platform can combine with biomolecules (DNA) for application in fluorescence biosensing of mercury ions and complex molecular logic computing. The Hg2+ assay had wide linear ranges (0.21–2 and 4.2–50.5 μM), a low detection limit (5.78 nM), and good recovery rates in actual water samples. In addition, the interaction of matter and energy (fluorescence) in the Cr2O3 NPs-based sensing system can be used to perform molecular logic gate operations from simple (YES, NOT, AND, and OR gates) to complex circuits. This research can provide an idea for rapid and large-scale preparation of chromium-based nanomaterials and offer an opportunity for the extensive and in-depth exploration of properties (such as unique optical or enzyme-mimetic) and multipurpose applications (sensing, catalysis, logic computing, and encryption) of chromium-based nanomaterials.

“…Dehydrofluorination of HFC‐134a known as an endothermic reaction shows considerable conversion under a high temperature, fortunately the high performance catalyst will be employed to reduce the reaction temperature and increase yield. In most of literatures, the reported dehydrofluorination catalyst were metal fluorides,, metal oxides,, pyrophosphate and carbon ,. Among these catalysts, metal fluorides are the promising catalysts in a corrosive atmosphere (HF) and elevating temperature conditions.…”

Section: Introductionmentioning

confidence: 99%

A Novel Ni/NiF₂‐AlF₃ Catalyst with Mild‐Strength Lewis Acid Sites for Dehydrofluorination of 1, 1, 1, 2‐Tetrafluoroethane to Synthesize Trifluoroethylene

et al. 2019

ChemistrySelect

A novel Ni/NiF2‐AlF3 catalyst was prepared by impregnation and following vapor hydrofluorination, and it was used to dehydrofluorination of tetrafluoroethane to trifluoroethylene. BET, SEM, XRD, XPS, NH3‐TPD and Py‐IR techniques were employed to characterize the Ni/NiF2‐AlF3 catalysts. Based on the NH3‐TPD results, it was interestingly found that the strong acidic sites of Ni/NiF2‐AlF3 catalyst transformed into the mid‐strength acidic sites with the increase of Ni loading, attributing to the roles of Ni on the catalyst surface. Compared with the NiF2‐AlF3 catalyst, the added Ni particles can improve the catalyst activity and stability for dehydrofluorination of 1, 1, 1, 2‐tetrafluoroethane. The best performance was obtained at Al/Ni=2 over the Ni/NiF2‐AlF3 catalyst, with high trifluoroethylene selectivity(99%) and CF3CFH2 conversion of 21.3%, after the reaction for 20 h on‐time stream at 500 °C, which showed the better application possibility as a heterogeneous dehydrofluorination catalyst. It was suggested that catalytic performance was related with the mid‐strength Lewis acidity on the catalyst surface. And the Ni/NiF2‐AlF3 catalyst (Al/Ni=2) possessed the good catalytic stability due to the mild‐strength Lewis acid sites.