Jianguo Wang

New Organic Semiconductors with Imide/Amide‐Containing Molecular Systems

Due to their high electron affinities, chemical and thermal stabilities, π-conjugated molecules with imide/amide frameworks have received considerable attentions as promising candidates for high-performance optoelectronic materials, particularly for organic semiconductors with high carrier mobilities. The purpose of this Research News is to give an overview of recent advances in development of high performance imide/amide based organic semiconductors for field-effect transistors. It covers naphthalene diimide-, perylene diimide- and amide-based conjugated molecules and polymers for organic semiconductors.

Insight into CH4 Formation in Iron-Catalyzed Fischer-Tropsch Synthesis

Spin-polarized density functional theory calculations have been performed to investigate the carbon pathways and hydrogenation mechanism for CH(4) formation on Fe(2)C(011), Fe(5)C(2)(010), Fe(3)C(001), and Fe(4)C(100). We find that the surface C atom occupied sites are more active toward CH(4) formation. In Fischer-Tropsch synthesis (FTS), CO direct dissociation is very difficult on perfect Fe(x)C(y) surfaces, while surface C atom hydrogenation could occur easily. With the formation of vacancy sites by C atoms escaping from the Fe(x)C(y) surface, the CO dissociation barrier decreases largely. As a consequence, the active carburized surface is maintained. Based on the calculated reaction energies and effective barriers, CH(4) formation is more favorable on Fe(5)C(2)(010) and Fe(2)C(011), while Fe(4)C(100) and Fe(3)C(001) are inactive toward CH(4) formation. More importantly, it is revealed that the reaction energy and effective barrier of CH(4) formation have a linear relationship with the charge of the surface C atom and the d-band center of the surface, respectively. On the basis of these correlations, one can predict the reactivity of all active surfaces by analyzing their surface properties and further give guides for catalyst design in FTS.

Graphene-supported Au-Pd bimetallic nanoparticles with excellent catalytic performance in selective oxidation of methanol to methyl formate.

Graphene supported Au-Pd bimetallic nanoparticles exhibit high catalytic activity in methanol selective oxidation, with a methanol conversion of 90.2% and selectivity of 100%, to methyl formate at 70 °C, owing to the synergism of Au and Pd particles as well as the strong interaction between graphene and Au-Pd nanoparticles.

Ionothermal Synthesis of Zirconium Phosphates and Their Catalytic Behavior in the Selective Oxidation of Cyclohexane

On their best behavior: Three zirconium compounds with one-, two-, and three-dimensional structures have been successfully synthesized by the ionothermal approach. The 3D zirconium phosphate (see picture; F green, H white, O red, P pink, Zr yellow) exhibits high catalytic performance, with a cyclohexane conversion ratio of 32% and cyclohexanone selectivity of up to 83%.

A Novel Catalyst for CO Oxidation at Low Temperature

Supported catalysts of palladium over ceria–titania mixed oxides (Pd/CeO2–TiO2) were prepared and tested for carbon monoxide oxidation. The catalysts exhibited high catalytic activity at room temperature. The Pd/CeO2–TiO2 catalyst was more active than Pd/CeO2, Pd/SnO2–TiO2, Pd/ZrO2–TiO2, Pd/Al2O2–TiO2 and Pd/TiO2 catalysts under the same conditions examined. The effects of preparation methods of the support, the mole ratio of ceria and titania in mixed supports as well as Pd loading upon the catalytic activity of CO oxidation were investigated. Among the Pd/CeO2–TiO2 catalysts, the best one corresponds to the Pd loading of 1.0 wt% or above, and the mole ratio of ceria and titania ranging from 1 : 7 to 1 : 5. The steady-state catalytic performance of such catalyst was recorded without any deactivation over 8 h time-on-stream in the present study.

A highly efficient and robust Cu/SiO2 catalyst prepared by the ammonia evaporation hydrothermal method for glycerol hydrogenolysis to 1,2-propanediol

A highly efficient and robust Cu/SiO2 catalyst from a pure-phase copper phyllosilicate precursor was successfully fabricated by the ammonia evaporation hydrothermal (AEH) method. The impregnation (IM) Cu/SiO2 catalyst was prepared for comparison. The structure, morphologies, thermal stability and surface chemical state of these catalysts were comprehensively characterized by ICP, BET, XRD (in situ XRD), N2O chemisorption, H2-TPR, IR and Raman spectroscopy, TEM and XPS. Compared to the IM sample, the AEH catalyst was exceedingly highly active and stable (300 h) for glycerol hydrogenolysis to 1,2-propanediol. The unprecedented catalytic performance was attributed to the strong interaction between Cu and SiO2 species derived from copper phyllosilicate, well-dispersed Cu nanoparticles and the cooperative effect of Cu0 and Cu+. Moreover, active Cu0 species were identified as the primary active sites for glycerol hydrogenolysis, as corroborated by the strong correlation between 1,2-propanediol yield and Cu surface area.

Multiply Confined Nickel Nanocatalysts Produced by Atomic Layer Deposition for Hydrogenation Reactions

To design highly efficient catalysts, new concepts for optimizing the metal-support interactions are desirable. Here we introduce a facile and general template approach assisted by atomic layer deposition (ALD), to fabricate a multiply confined Ni-based nanocatalyst. The Ni nanoparticles are not only confined in Al2 O3 nanotubes, but also embedded in the cavities of Al2 O3 interior wall. The cavities create more Ni-Al2 O3 interfacial sites, which facilitate hydrogenation reactions. The nanotubes inhibit the leaching and detachment of Ni nanoparticles. Compared with the Ni-based catalyst supported on the outer surface of Al2 O3 nanotubes, the multiply confined catalyst shows a striking improvement of catalytic activity and stability in hydrogenation reactions. Our ALD-assisted template method is general and can be extended for other multiply confined nanoreactors, which may have potential applications in many heterogeneous reactions.

Synthesis of polyoxymethylene dimethyl ethers from methanol and trioxymethylene with molecular sieves as catalysts

Abstract Polyoxymethylene dimethyl ethers (PODE n or DMM n ) were synthesized by the condensation of methanol and trioxymethylene over the catalysts of several molecular sieves like HY, HZSM-5, Hβ, and HMCM-22; the effect of their acidic properties on product distribution was investigated. The results indicated that the acidic molecular sieves, especially HMCM-22, are catalytically active for the condensation of methanol and trioxymethylene to form DMM n . Over HY, the main product is dimethoxymethane (DMM), with a selectivity of 92.87%. Over HZSM-5 and Hβ, the main products turn out to be DMM 1-3 and the yields of DMM 3-8 , which are ideal additives for diesel fuel, reach 6.40% and 13.78%, respectively. With HMCM-22 as the catalyst, the formation of long chain DMM n products is further enhanced and the yield of DMM 3-8 attains 29.39%. The results of NH 3 -TPD demonstrated that the product distribution is related to the surface acidic properties of the catalyst used; short chain DMM may be primarily formed on weak acidic sites, while the acidic sites of medium strength can enhance the formation of diesel fuel additive components DMM 3-8 .

Graphene Oxide: An Efficient Acid Catalyst for Alcoholysis and Esterification Reactions

Evidence is presented for graphene oxide (GO), prepared by modified Hummers method, as a highly active, selective and reusable solid‐acid catalyst for the production of alkyl levulinates via alcoholysis or esterification. 95.5 % yield of ethyl levulinate was achieved by GO in furfuryl alcohol alcoholysis. Moreover, the surface SO3H groups were identified as the primary active sites, while the surface carboxyl groups worked synergistically to adsorb furfuryl alcohol.

High Si/Al ratio HZSM-5 zeolite: an efficient catalyst for the synthesis of polyoxymethylene dimethyl ethers from dimethoxymethane and trioxymethylene

The catalytic performance of HZSM-5 zeolite in the synthesis of polyoxymethylene dimethyl ethers (PODEn) from dimethoxymethane (DMM) and trioxymethylene (TOM) is closely related to its Si/Al ratio; HZSM-5 with a high Si/Al ratio exhibits high PODE2–8 yield and excellent stability and reusability.