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236 results on '"Fu, Zaihui"'

11. Hydrated Calcium Silicate Supported CaMoO4 as an Efficient and Recyclable Catalyst for Selective Oxidation of Para-Alkylphenols with Hydrogen Peroxide.

Author

Zhong, Sheng, Liu, Zhangzhen, Zhang, Chao, Liu, Yachun, and Fu, Zaihui

Subjects
CATALYSTS recycling, HYDROGEN oxidation, CALCIUM silicates, SELECTIVE catalytic oxidation, HYDROGEN peroxide, CALCIUM silicate hydrate
Abstract

MoO42−-H2O2 is an efficient oxidation system for the conversion of para-alkyl-phenols to high value-added para-peroxyquinols and para-quinols, but its large-scale application is still limited to difficulty in catalyst recovery. This paper discloses that a hydrated calcium silicate (CS)-supported calcium molybdate (CM) catalyst (CMS) is easily fabricated in high-yield and large-scale by simple coprecipitation. Compared to the unsupported CM and Na2MoO4, CMS has an enhanced catalytic activity for the selective oxidation of para-alkyl-phenols, but also it shows a drastically improved selectivity for the target products, which can achieve 84% conversion and 100% selectivity for the goal products in catalyzing the oxidation of 2,4-xylenol with H2O2 in water. Also, it is very efficient for the selective oxidation of other p-alkyl substituted phenols in water or methanol, especially including the highly selective oxidation of p-cresol which is easy to be overoxidized. More importantly, the CMS catalytic system can be conveniently recovered and repeatedly run without significant activity loss, showing a good reusability. In situ UV-DRS and FT-IR spectra, as well as H2O2 decomposition experiments support that the alkaline CS carrier can induce the reaction of CMS with H2O2 to preferentially generate the mono-/di-peroxomolybdates as the key species for the selective oxidation of para-alkyl-phenols. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Ionothermally synthesized S-scheme isotype heterojunction of carbon nitride with significantly enhanced photocatalytic performance for hydrogen evolution and carbon dioxide reduction

Author

Tang, Senpei, primary, Yang, Shitao, additional, Chen, Yuanyuan, additional, Yang, Yi, additional, Li, Zhenhui, additional, Zi, Lin, additional, Liu, Ying, additional, Wang, Yingchun, additional, Li, Zhiping, additional, Fu, Zaihui, additional, and Li, Youji, additional

Published
2023
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33. Fabrication of a solid superacid with temperature-regulated silica-isolated biochar nanosheets

Author

Li Qingfeng, Changzhi Li, Yuxue Xiao, Yao Yuanxiong, Wenhao Luo, Xiaoli Pan, Chao Zhang, Fu Zaihui, Huang Ting, Chen Zengtian, and Shutao Xu

Subjects
chemistry.chemical_classification, Ammonium bromide, Stacking, Nanoparticle, chemistry.chemical_element, 02 engineering and technology, General Medicine, Sulfonic acid, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Catalysis, chemistry.chemical_compound, chemistry, Chemical engineering, Superacid, 0210 nano-technology, Mesoporous material, Carbon
Abstract

This paper reports a new strategy for the structural reconstruction of biomass carbon sulfonic acid (BCSA) to its solid superacid counterpart. In this approach, a cheap layered biomass carbon (BC) source is chemically exfoliated by cetyltrimethyl ammonium bromide and then converted to silica-isolated carbon nanosheets (CNSs) by a series of conversion steps. The state of the silica-isolated CNSs and the stacking density of their nanoparticles are regulated by the dehydration temperature. Only the highly isolated and non-crosslinked CNSs with loose particle stacking structures obtained upon dehydration at 250 °C can be turned into superacid sites (with stronger acidity than that of 100% H2SO4) after sulfonation. This is accompanied by the creation of abundant hierarchical slit pores with high external surface area, mainly driven by the strong hydrogen bonding interactions between the introduced sulfonic acid groups. In typical acid-catalyzed esterification, etherification, and hydrolysis reactions, the newly formed superacid exhibits superior catalytic activity and stability compared to those of common BCSA and commercial Amberlyst-15 catalysts, owing to its good structural stability, highly exposed stable superacidic sites, and abundance of mesoporous/macroporous channels with excellent mass transfer rate. This groundbreaking work not only provides a novel strategy for fabricating bio-based solid superacids, but also overcomes the drawbacks of BCSA, i.e., unsatisfactory structural stability, acidity, and porosity.

Published
2020

34. Selective production of bio-based para-xylene over an FeOx-modified Pd/Al2O3 catalyst

Author

Meng Qingwei, Yuxue Xiao, Chao Zhang, Xiaoli Pan, Fu Zaihui, and Changzhi Li

Subjects
Xylene, Decarbonylation, Substrate (chemistry), engineering.material, Pollution, Combinatorial chemistry, Toluene, Catalysis, chemistry.chemical_compound, chemistry, engineering, Environmental Chemistry, Noble metal, Selectivity, Hydrodeoxygenation
Abstract

para-Xylene (PX) is a basic building block of polyethylene terephthalate, which is currently produced from petroleum resources. Developing a renewable route to PX is highly desirable to address both economic and environmental concerns. Several attempts used noble metal catalysts, e.g. Pd/Al2O3, to synthesize PX from biomass-derived 4-methyl-3-cyclohexene-1-carboxaldehyde (4-MCHCA), but suffered from a severe decarbonylation reaction, resulting in toluene as the main product. In this paper, we report an FeOx modification strategy to suppress the decarbonylation reaction on a Pd/Al2O3 catalyst, leading to a drastic shift in selectivity towards PX with a yield up to 81% via a cascade dehydroaromatization–hydrodeoxygenation (DHA–HDO) pathway. Characterization and control experiments revealed that the electron density of Pd sites decreased in an FeOx-modified Pd/Al2O3 catalyst compared to Pd/Al2O3, thus tuning the preferential adsorption mode of the substrate from η2-(C,O), the key transition state of the decarbonylation reaction, to the η1-(O) mode that favors the hydrodeoxygenation process. Notably, this designed catalyst is highly stable and is readily applicable in the selective synthesis of a broad range of desired aromatic chemicals via the same DHA–HDO pathway from cyclohex-3-enecarbaldehyde derivatives. Overall, this work develops a controllable catalyst modification strategy that tailors an efficient catalyst for petroleum-independent bio-PX synthesis.

Published
2020

48. Mild and efficient photocatalytic coupled alcohol oxidative dehydrogenation and CO2 reduction driven by visible light.

Author

Zhu, Jiekun, Yi, Zheng, Luo, Mingyu, Deng, Youer, She, Jialuo, Liu, Yachun, Zhang, Chao, Yang, Bo, Tang, Senpei, and Fu, Zaihui

Subjects
OXIDATIVE dehydrogenation, ALIPHATIC alcohols, VISIBLE spectra, ALCOHOL, OXYGEN in water, CHARGE exchange
Abstract

The advanced coupled conversion technique based on the oxidative dehydrogenation (ODH) of alcohols and the reduction of CO2 is a potential strategy to solve the current energy and environmental crisis, and is of great significance for the upgrading conversion of CO2 to fuels. This work discloses that the Al3+ species-doped decatungstates (Al-DTs) can efficiently catalyze the coupled conversion of various aliphatic and aromatic primary/secondary alcohols with CO2 in MeCN under visible light illumination and very mild conditions, and the reductive efficiency of CO2 depends on the doping levels of Al3+ species in Al-DTs and the ODH reactivity of alcohols. After continuously illuminating for 12 h, the best, 4% Al-DT can provide 437 μmol acetophenone as the ODH product and 218 μmol CO2 reduction products (formic acid and methanol) with 1.82 h−1 turnover frequency in the photocatalytic coupled conversion of α-phenylethanol with CO2. Also, a trace amount of CO is detected from the photocatalytic coupled reactions. UV-vis spectra and isotope tracing tests using heavy oxygen water (H218O) support that the doubly-reduced blue H2DT species generated from the photocatalytic ODH of alcohols turns into its oxygen-deficient form ([DT2−]v) via an intra-molecular dehydration or lattice oxygen transfer and the latter, with the help of doped Al3+ species, may efficiently reduce CO2 to fuels via the multi-step proton-coupled electron transfer (PET) pathway. [ABSTRACT FROM AUTHOR]

Published
2022
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49. A green catalyst-free concomitant air oxidation of DMSO and cumene to form methylsulfonylmethane (dimethylsulfone).

Author

Li, Xiaolong, Deng, Youer, Zhao, Zhiying, Liu, Yachun, Zhang, Chao, and Fu, Zaihui

Subjects
CATALYSTS, FREE radicals, DIMETHYL sulfone, PEROXY radicals, CUMENE, REACTIVE oxygen species, HYDROXYL group, DIMETHYL sulfoxide
Abstract

Methylsulfonylmethane (MSM) is a newly discovered human nutrient that has significant health care and therapeutic function. In this work, we developed a new type of catalyst-free air oxidation of dimethyl sulfoxide (DMSO) to MSM under relatively mild conditions based on the mechanism of isopropylphenyl free radicals (R·) activating molecular oxygen (O2) generating reactive oxygen species (ROS). Experimental results showed that cumene as a solvent, due to its active tertiary sp3 C–H bond, promotes the efficient catalyst-free air oxidation of DMSO to MSM under relatively mild optimized conditions. Based on the quenching test of free radicals and theoretical calculation of the activation energies of two oxidation pathways of isopropylphenyl peroxy radicals (ROO·) and cumene hydroperoxide (CHP), it has been demonstrated that ROS in this reaction is mainly ROO· and hydroxyl radicals (HO·). Furthermore, we proposed a possible catalyst-free air oxidation mechanism. This work provided a simple and cost-efficient approach for the green synthesis of MSM. [ABSTRACT FROM AUTHOR]

Published
2022
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