- [Show abstract] [Hide abstract] ABSTRACT: An efficient copper-catalyzed radical decarboxylative imidation reaction is presented. This strategy is carried out through the copper(i)-catalyzed decarboxylative C(sp(3))-N and C(sp(2))-N coupling of carboxylic acids with N-fluoroarylsulfonimides. The reaction shows good functional group tolerance and it provides a new approach for decarboxylative imidation. Preliminary mechanistic studies of this transformation suggest an involvement of N-centered radical species.
- [Show abstract] [Hide abstract] ABSTRACT: Mesoporous zeolite ZSM-5 (ZSM-5-M) was synthesized and used as support for the preparation of highly efficient nickel phosphide catalyst (Ni2P/ZSM-5-M) in the deep hydrogenation of phenanthrene and in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DM-DBT). Compared with Ni2P catalysts supported silica and high surface area hexagonal mesoporous silica (HMS) (Ni2P/SiO2 and Ni2P/HMS), Ni2P/ZSM-5-M exhibits higher hydrogenation and HDS activity. The phenanthrene conversion and deep hydrogenation products selectivity over Ni2P/ZSM-5-M (95% and 83%) are much higher than those over Ni2P/SiO2 (61% and 73%) and Ni2P/HMS (69% and 45%) under mild conditions. The 4,6-DM-DBT conversion over Ni2P/ZSM-5-M (93%) was higher than that over Ni2P/SiO2 (62%). This feature is attributed to the difference in surface properties of support. A large amount of acidic hydroxyl groups on the zeolites can interact strongly with catalyst precursor, resulting in the formation of highly dispersed Ni2P particles with small sizes, which provide abundant hydrogenation active sites.
- [Show abstract] [Hide abstract] ABSTRACT: Developing highly active hydrodesulfurization (HDS) catalysts is very important for ultraclean fuel production. Here, we report the successful preparation of crystalline mordenite nanosheet assemblies (NS-HMOR) with large external surface area and micro–mesoporous structure. After introduction of nickel and phosphorus species into NS-HMOR and its activation, the obtained Ni2P/NS-HMOR catalyst exhibits higher HDS activity (TOF = 1.9 × 10−3 s−1) and better stability in 4,6-dimethyldibenzothiophene HDS than a silica-supported Ni2P catalyst (TOF = 1.3 × 10−3 s−1). The large number of acidic hydroxyl groups on the NS-HMOR surface facilitates the formation of very small Ni2P clusters on the outer surface, and the open micropores at the NS-HMOR surface help to prevent their aggregation.
- [Show abstract] [Hide abstract] ABSTRACT: The decarboxylative coupling of cinnamic acids with alcohols and the oxidative coupling of alkenes with aldehydes are typical organic reactions. Considering the characteristics and mechanisms of the reactions, the Cu-doped zeolite-X catalyst (Cu-X) with Lewis basic sites was synthesized and used for the two reactions. Compared with Cu, Cu2O, and CuBr2 catalysts (4–21%), the Cu-X catalyst (99%) shows extraordinary high activity in the decarboxylative coupling of cinnamic acids with alcohols. In addition, the Cu-X catalyst presents excellent performance in the oxidative coupling of alkenes with aldehydes. The strong interaction between Cu+ and the zeolite framework benefits the transformation of Cu2+ and Cu+ in the redox process, enhancing the reaction activity. More importantly, the Lewis basic sites on the Cu-X catalyst could favor the adsorption of the cinnamic acid, resulting in electron-rich density in the CC bond, and therefore greatly improving the reaction activity.
- [Show abstract] [Hide abstract] ABSTRACT: Zeolite Y nanosheets with micro-meso-macroporous structure was synthesized, and applied to assemble Pd catalyst (Pd/NS-Y) for direct vinylation of thiophenes in high activity and selectivity, as compared to Pd(OAc)2, Pd(NO3)2, and Pd(PPh3)4 catalysts. This feature should be assigned to the highly dispersed Pdδ+ (δ<2) species in Pd/NS-Y that are more active than Pd2+.
- [Show abstract] [Hide abstract] ABSTRACT: A strong acidic zeolite Y nanoparticle assembly (HNANO-Y) with a micro-meso-macroporous structure was synthesized and used as a highly efficient heterogeneous catalyst for the hydration of alkynes to prepare ketone compounds, as compared to acidic mesoporous zeolite ZSM-5 and Beta catalysts. This feature should be assigned to the fact that the micro-meso-macroporous structure in the HNANO-Y benefits mass transfer and the strongly acidic sites on HNANO-Y facilitate alkyne hydration activity. The catalyst can be reused six times without loss of activity.
- [Show abstract] [Hide abstract] ABSTRACT: Developing highly active heterogeneous catalyst with strong basicity and porous structure is a highly attractive strategy for the base-catalyzed organic chemistry. Herein, we directly synthesized the mesoporous zeolite ETS-10 (METS-10) from using a water glass contained cationic copolymer with quaternary ammonium groups as a template. Furthermore, when the nickel nitrate solution was added into the starting synthesis gel, the nickel species facilitated the mesopore formation, and the Ni-containing mesoporous zeolite ETS-10 (Ni-METS-10) was obtained. Catalytic test results showed that the conversions of the benzaldehyde and citral over Ni-METS-10 (88.8 and 63.2 %) and METS-10 (85.5 and 60.1 %) catalysts are higher than those over both mesopore-free ETS-10 (77.3 and 47.7 %) and mesoporous NaX (MNaX, 55.0 and 35.2 %) catalysts in the condensation reactions with ethyl cyanoacetate. The higher activity of METS-10 and Ni-METS-10 than ETS-10 and MNaX is assigned to the fact that the strong basic sites on the catalysts can activate the reaction substrate and the mesoporous in the catalyst benefit the mass transfer and enhance the catalytic activity.
- [Show abstract] [Hide abstract] ABSTRACT: Developing highly active hydrogenation catalysts for deep aromatics saturation is of great importance in the production of ultraclean diesel fuel at a low cost. Toward this goal, we synthesized a mesoporous zeolite ZSM-5 (MZSM-5) that was cost-effective and available on a large scale, and used it as a support for the preparation of highly efficient metal sulfide catalysts (NiMoS/MZSM-5 and CoMoS/MZSM-5) for the deep hydrogenation of phenanthrene. The intrinsic activity of the NiMoS/MZSM-5 catalyst (7.4 × 10-4 mol kg-1 s-1) was much higher than that of the alumina-supported NiMo catalyst (NiMoS/γ-Al2O3, 4.8 × 10-4 mol kg-1 s-1), and the selectivity of the deep hydrogenation products over NiMoS/MZSM-5 (20.9%) was higher than for NiMoS/γ-Al2O3 (15.2%). Compared with γ-Al2O3, the relatively weak metal-support interaction could facilitate the formation of polymolybdates on MZSM-5. After sulfidation, the more multistacked MoS2 active phases were formed on the MZSM-5, enhancing the hydrogenation activity of the NiMoS/MZSM-5 catalyst.
- [Show abstract] [Hide abstract] ABSTRACT: Development of the highly active and stable heterogeneous transition metal catalysts is of great importance in synthetic chemistry. Herein, zeolite Beta nanoparticles assembled Cu catalyst (Cu-Beta-Nano) with high external surface area was directly synthesized, and it exhibits excellent catalytic activity and good recyclability in cross-coupling of aldehydes and disulfides for synthesis of thioesters. The high activity and good recyclability of the Cu-Beta-Nano catalyst should be attributed to the high external surface area of the catalyst and highly dispersed active copper species in the zeolite.
- [Show abstract] [Hide abstract] ABSTRACT: A magnesium oxide nanosheet assemblies (NS-MgO) with high surface area (255 m2/g) and nanopore volume (0.30 cm3/g) was prepared by a pressure-assisted carbonation method at large scale. After loading of cobalt and molybdenum (CoMo) species and followed by sulfidation, the NS-MgO supported CoMo catalyst (Co-MoS2/NS-MgO) exhibits high activity (94.2%) and good nitrogen tolerance in the hydrodesulfurization (HDS) of dibenzothiophene (DBT), compared with a conventional γ-alumina-supported CoMo catalyst (64.1%). These results are attributed to the difference in the basicity of the NS-MgO and γ-Al2O3 supports. The large amount of the middle strong basic sites on NS-MgO can avoid the polymerization of Mo species, and form small Mo oxide clusters. After sulfidation, the small MoS2 clusters with shorter lengths and less stackings formed on the NS-MgO contribute to an increase in the sites available for Co-promotion, resulting in the Co-MoS2/NS-MgO catalyst with high HDS activity.
- [Show abstract] [Hide abstract] ABSTRACT: A Cu-doped zeolite ZSM-5 (Cu-ZSM-5-M) with a micro-meso-macroporous structure was directly synthesized, and it exhibits excellent catalytic activity and good recyclability in the cross-coupling of aryl halides with diphenyl disulfides. This feature should be attributed to the structural characteristics of meso-macropores and homogeneous dispersion of active Cu(δ+) (δ < 2) species in Cu-ZSM-5-M.
- [Show abstract] [Hide abstract] ABSTRACT: Developing highly active heterogeneous catalysts for the efficient construction of valuable building blocks is of great importance to synthetic chemistry. For this purpose, a mesoporous zeolite ETS-10 (METS-10) is synthesized by using a mesoscale silane surfactant as a template and applied to achieve highly efficient syntheses of α,β-epoxy ketones by employing simple alkenes and aldehydes as starting materials. The high activity of the METS-10 catalyst is attributed to its unique porous structure and basicity. Electron paramagnetic resonance characterization results and theoretical calculation experimental data reveal that the strong basic sites on METS-10 catalyst can activate the reaction substrate and intermediate. In addition, the mesopores in METS-10 catalyst benefit the mass transfer and further improve the catalytic activity.
- [Show abstract] [Hide abstract] ABSTRACT: Developing a low-cost route to synthesize mesoporous TS-1 (MTS-1) is of great importance because of its practical application in industry. Herein, we first synthesized a copolymer containing quaternary ammonium groups by a mesoporous template comprising inexpensive starting materials. Subsequently, waterglass (sodium metasilicate), TiCl3, and copolymer were dispersed in the preformed seeds emulsion, resulting in a gel for synthesizing MTS-1. The counterpart material (CTS-1) was also synthesized by the same procedure except for the absence of the copolymer. Compared with CTS-1, the MTS-1 exhibits good crystallinity and well-defined tetrahedral coordinated Ti species (Ti-IV) in the framework as well as excellent catalytic activity in the oxidation of bulky molecules, such as dibenzothiophene and benzyl phenyl sulfide. This feature may be attributed to the fact that the quaternary ammonium groups on copolymer facilitates the formation of the MFI structure and energetically incorporates the Ti species into the framework.
- [Show abstract] [Hide abstract] ABSTRACT: Zeolite nanofiber assemblies (HNB-MOR) as efficient heterogeneous catalysts for the formation of a range of acetals in good yields. The mesoporosity of HNB-MOR benefits mass transfer, and the strong acidic sites on HNB-MOR facilitate acetalization activity. The catalyst can be reused 10 times without loss of activity.
- [Show abstract] [Hide abstract] ABSTRACT: Rich man, pore man: A facile and universal route to mesoporous zeolite TS‐1 (MTS‐1) is reported. Compared with mesoporous‐free TS‐1, the MTS‐1 zeolite shows extraordinarily catalytic activity and highly controllable chemoselectivity for the oxidation of sulfides into sulfoxides or sulfones. Based on the catalytic data, the Tihydroperoxo (η2) group is proposed to be the active site for the oxidation of sulfides into sulfoxides and sulfones.
- [Show abstract] [Hide abstract] ABSTRACT: Developing highly active hydrodesulfurization (HDS) catalysts is of great importance for producing ultraclean fuel. Herein we report on crystalline mordenite nanofibers (NB-MOR) with a bundle structure containing parallel mesopore channels. After the introduction of cobalt and molybdenum (CoMo) species into the mesopores and micropores of NB-MOR, the NB-MOR-supported CoMo catalyst (CoMo/NB-MOR) exhibited an unprecedented high activity (99.1%) as well as very good catalyst life in the HDS of 4,6-dimethyldibenzothiophene compared with a conventional γ-alumina-supported CoMo catalyst (61.5%). The spillover hydrogen formed in the micropores migrates onto nearby active CoMo sites in the mesopores, which could be responsible for the great enhancement of the HDS activity.
- [Show abstract] [Hide abstract] ABSTRACT: Noble metal Pd and Pt catalysts with a wide range of surface wettability were fabricated through an electrochemical approach and were characterized with scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and atomic force microscopy. The importance of surface wettability of solid catalysts in multiphase reactions, especially their correlation to the nature of the studied chemical system, was investigated through reducing oxygen in an alkaline solution and oxidizing hydrogen peroxide and sodium formate in alkaline or buffered solutions at the as-prepared catalysts. These experiments illustrate that the nature of a multiphase reaction plays a critical role in determining the influence of surface wettability on the catalyst performance, providing a unique approach to decipher the reaction process. The investigation allows us to gain new insights into the electrochemical oxidation of sodium formate.
- [Show abstract] [Hide abstract] ABSTRACT: We fabricated the first superhydrophobic (SH) surface with microcavities, using a simple process. The process included an improved template method (ITM) for constructing the SH surface with cavities, using taro leaves as a pattern mask, and a dip-coating method for modifying the SH surface. The results obtained using the ITM are significantly better than those achieved using traditional template methods. In addition, the water-repellence of the microcavities surface was significantly enhanced by decorating with a layer of polymerized n-octadecylsiloxane nanosheets.
- [Show abstract] [Hide abstract] ABSTRACT: Design and preparation of highly active hydrodesulfurization (HDS) catalysts is very important for the removal of air pollution. Herein, we report an extraordinarily active HDS catalyst, which is synthesized by loading of Pd on mesoporous zeolite Y (Pd/HY-M). The mesoporous zeolite Y is successfully synthesized using a water glass containing N,N-dimethyl-N-octadecyl-N-(3-triethoxysilylpropyl) ammonium [(C(2)H(5)O)(3)SiC(3)H(6)N(CH(3))(2)C(18)H(37)](+) cation as a mesoscale template. Compared with mesoporous Beta and ZSM-5 supported Pd catalysts (80.0% and 73.4% for Pd/HBeta-M and Pd/HZSM-5-M, respectively) as well as commercial catalyst of γ-Al(2)O(3) supported Pd catalyst (31.4%), Pd/HY-M catalyst exhibited very high activity in HDS of 4,6-dimethyldibenzothiophene (4,6-DM-DBT, 97.3%). The higher activity of Pd/HY-M than that of Pd/HBeta-M and Pd/HZSM-5-M is assigned to the larger micropore size of zeolite Y compared to that of Beta and ZSM-5. Theoretical simulation and adsorption experimental data show that 4,6-DM-DBT has difficulty entering the micropores of ZSM-5 and Beta zeolites, but the micropores of Y zeolite are accessible.
- [Show abstract] [Hide abstract] ABSTRACT: Surfaces with superhydrophobicity are important in a number of biological and industrial processes. Hierarchical film based on polydimethylsiloxane (PDMS) and SiO2 with a water contact angle of 155° and sliding angle of 6° was prepared by a facile drop-coating method. Surface modification of SiO2 spheres was found to improve particle dispersion and increase their compatibility with PDMS, which eventually affected the stability of the hierarchical structure. Different curing temperatures were studied for enhancing the hydrophobicity of the hierarchical structure. We examined the mechanical robustness of the superhydrophobic surface by using a shear test, and found that the hierarchical PDMS-based SiO2 films retained superhydrophobicity after 48KPa mechanical shears.
Wenzhou UniversityYung-chia, Zhejiang Sheng, China
Jilin, Jilin Sheng, China
- State Key Laboratory of Inorganic Synthesis and Preparative