Nan Lu,Yifeng Shi,Yutao Ren,Yue Wang,Xinyi Sun,Zejing Wei,Xutao Chen,Jie Fan
The oxidative coupling of methyl chloride (CH3Cl) to vinyl chloride (C2H3Cl) (MCTV) represents a promising yet challenging direct conversion route for C2H3Cl production. In this study, a novel catalyst, cristobalite silica, supported Na2WO4nanoclusters, was fabricated by calcining an intermediate composite composed by β-zeolite and sodium tungstate (Na2WO4). The pore structure of this β-zeolite possesses a regular shape and suitable size distribution, providing an accurate geometric matching effect for Na2WO4to homogeneously distribute in the entire β-zeolite matrix with high loading. Accordingly, the excellent dispersity of Na2WO4nanocluster active sites is well maintained even after calcining at 750 °C, and the microporous β-zeolite matrix is completely converted to dense cristobalite phase silica after the calcination. The high-loading and well-dispersed Na2WO4nanocluster leads to a superior performance in MCTV with a CH3Cl conversion of 81.5%, a C2H3Cl selectivity of 42.4%, and a C2H3Cl yield of 34.6%. Notably, the catalyst exhibits remarkable stability during the catalytic process.
A phosphorus and nitrogen co-doped graphene (PNG) was developed via a two-step pyrolysis approach through the intermedium of g-C 3 N 4 template and glyphosate as the phosphorus source, and was used for the catalytic dehydrochlorination of 1,2-dichloroethane (EDC) to vinyl chloride monomer (VCM) production. The characterization results indicate that a volcano relationship of surface area and surface properties with the usage of phosphorus precursor was observed, and the sample of PNG-900-6 possesses not only the thin film structure with enhanced surface area but also the smaller grain size of PNG attachments. Accordingly, such PNGs show a great improvement of catalytic performance in the dehydrochlorination of EDC, and the PNG-900-6 catalyst behaves the best with a 4-times higher activity than that on the nitrogen doped graphene (NG). It was also proved that the synergetic effect of the unique P-C coordination on the graphene to generate more quaternary nitrogen species was crucial in determining the catalytic performance of EDC conversion. Our results demonstrate that the phosphorus and nitrogen co-doped graphene offers many advantages in physical structure and chemical property, and are also great potential on the catalytic application in the dehydrochlorination of 1,2-dichloroethane.
Wangting Lu,Zhi-Gang Shao,Geng Zhang,Yun Zhao,Baolian Yi
A new material based on crosslinked poly(vinylbenzyl chloride) (PVBC) with a macromolecular crosslinker is synthesized and employed as the membrane for anion exchange membrane fuel cells (AEMFCs). PVBC is used as the hydroxide conducting polymers , while poly(vinyl acetal) (PVAc) containing dimethylamino groups plays the role as macromolecular crosslinker and the supporting matrix simultaneously. Fourier transform infrared (FT-IR) absorption spectra and X-ray photoelectron (XPS) spectra prove successful crosslinking between PVBC and PVAc. The crosslinked membrane shows hydroxide conductivity larger than 0.01 S cm −1 at room temperature , and the swelling by water at elevated temperature is suppressed. The H 2 /O 2 AEMFC using the crosslinked membrane shows a peak power density ( P max ) of 124.7 mW cm −2 at 40 °C, and the decrease of the open circuit voltage (OCV) of the fuel cell is negligible under continuous OCV conditions for 120 h. All the results indicate that the crosslinking with a macromolecular crosslinker may be a promising strategy to fabricate anion exchange membrane for the application in the AEMFCs.
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