Juanjuan Shi

A sandwich N-doped graphene/Co3O4 hybrid: an efficient catalyst for selective oxidation of olefins and alcohols

A sandwich-like N-doped graphene/Co3O4 hybrid was prepared via a simple one-pot hydrothermal reaction in a solution of NH3. Characterizations disclosed that highly dispersed Co3O4 nanoparticles with dominant exposed {112} and {110} planes were fabricated on both sides of well-exfoliated N-doped graphene; N-dopants in the graphene matrix can prevent re-graphitization of graphene, strengthen the interaction between Co3O4 and the graphene matrix, and improve the dispersion of Co3O4. This hybrid (Co3O4/RGO-N) exhibited superior activity and stability for the epoxidation of styrene compared to bulk Co3O4 and N-free graphene supported Co3O4. At the same time, the resulting catalyst also showed high compatibility with various olefins and alcohols with good conversion and high selectivity. This synergistic strategy can provide simple, efficient and versatile blue-prints for low-cost fabrication of graphene-based nanocomposites for extending applications where graphene has rarely been exploited and beyond.

MnO2/graphene oxide: a highly active catalyst for amide synthesis from alcohols and ammonia in aqueous media

Rod-like MnO2 uniformly attached on both side of GO sheets (MnO2/GO) is an efficient heterogeneous catalyst for the synthesis of primary amides from primary alcohols and ammonia as well as from aldehydes or nitriles. Water is the best solvent for these reactions, analytically pure crystals of product could be isolated by simply cooling in ice and this catalyst has excellent recyclability.

SnO2-isolated Pt3Sn alloy on reduced graphene oxide: an efficient catalyst for selective hydrogenation of CO in unsaturated aldehydes

In this communication, a pyramid shaped alloy-metal oxide–graphene hybrid was synthesized by a facile procedure, in which SnO2 nanoparticles (NPs) (4.8–5.8 nm) were first coated onto the surface of reduced graphene oxide (rGO), and then very fine Pt3Sn NPs (0.6–1.2 nm) were fabricated on the SnO2 NPs on rGO sheets under microwave irradiation in a few minutes. Characterizations disclosed that the SnO2 NPs on rGO were more favorable for the dispersion of Pt, and Pt3Sn formed mainly on the surface of SnO2 NPs. This pyramid shaped Pt3Sn/SnO2/rGO hybrid was highly active, selective and stable for the hydrogenation of the CO bond in unsaturated aldehydes to unsaturated alcohols under mild conditions.

Catalytic Decarboxylation of Fatty Acids to Aviation Fuels over Nickel Supported on Activated Carbon

Decarboxylation of fatty acids over non-noble metal catalysts without added hydrogen was studied. Ni/C catalysts were prepared and exhibited excellent activity and maintenance for decarboxylation. Thereafter, the effects of nickel loading, catalyst loading, temperature, and carbon number on the decarboxylation of fatty acids were investigated. The results indicate that the products of cracking increased with high nickel loading or catalyst loading. Temperature significantly impacted the conversion of stearic acid but did not influence the selectivity. The fatty acids with large carbon numbers tend to be cracked in this reaction system. Stearic acid can be completely converted at 370 °C for 5 h, and the selectivity to heptadecane was around 80%.

Upgrading of aromatic compounds in bio-oil over ultrathin graphene encapsulated Ru nanoparticles

Fast pyrolysis of biomass for bio-oil production is a direct route to renewable liquid fuels, but raw bio-oil must be upgraded in order to remove easily polymerized compounds (such as phenols and furfurals). Herein, a synthesis strategy for graphene encapsulated Ru nanoparticles (NPs) on carbon sheets (denoted as Ru@G-CS) and their excellent performance for the upgrading of raw bio-oil were reported. Ru@G-CS composites were prepared via the direct pyrolysis of mixed glucose, melamine and RuCl3 at varied temperatures (500–800 °C). Characterization indicated that very fine Ru NPs (2.5 ± 1.0 nm) that were encapsulated within 1–2 layered N-doped graphene were fabricated on N-doped carbon sheets (CS) in Ru@G-CS-700 (pyrolysis at 700 °C). And the Ru@G-CS-700 composite was highly active and stable for hydrogenation of unstable components in bio-oil (31 samples including phenols, furfurals and aromatics) even in aqueous media under mild conditions. This work provides a new protocol to the utilization of biomass, especially for the upgrading of bio-oil.

Microwave-assisted fast fabrication of a nanosized Pt3Co alloy on reduced graphene oxides

Abstract Ultrafine and homogenously dispersed Pt 3 Co alloy nanoparticles were fabricated on reduced graphene oxide (RGO) in a few minutes under microwave irradiation. Characterization results confirmed that microwave irradiation was important for higher metal utilization, the easy control of alloy composition, improved dispersion of the Pt 3 Co particles and minimizing the re-graphitization of the parent RGO by comparison with conventional solvent-thermal and impregnation methods. This Pt 3 Co/RGO-MW catalyst was extremely active and selective during the hydrogenation of cinnamaldehyde to cinnamyl alcohol. The calculated specific activity of each Pt atom in the Pt 3 Co/RGO-MW at 70 °C was 23.8 min −1 .

Selective glycerol oxidation using platinum nanoparticles supported on multi-walled carbon nanotubes and nitrogen-doped graphene hybrid

Abstract Selective oxidation of glycerol is a hot topic. Increased biodiesel production has led to glycerol oxidation over Au- and Pt-based catalysts being widely studied. However, Pt catalysts suffer from deactivation because of weak metal-support interactions. In this study, multi-walled carbon nanotube (MWCNTs)-pillared nitrogen-doped graphene (NG) was prepared by direct pyrolysis of melamine on MWCNTs, and the synthesized NG-MWCNT composite was used as the support for Pt. Characterization results showed that the surface area (173 m 2 /g) and pore volume of the NG-MWCNT composite were greater than those of bare MWCNTs and the separated melamine pyrolysis product (CN x ). Pt (1.4 ± 0.4 nm) dispersion on the NG-MWCNTs was favorable and the Pt/NG-MWCNT catalyst was highly active and selective in the oxidation of glycerol to glyceric acid (GLYA) in base-free aqueous solution. For example, the conversion of glycerol reached 64.4% with a GLYA selectivity of 81.0%, whereas the conversions of glycerol over Pt/MWCNTs and Pt/CN x were 29.0% and 31.6%, respectively. The unique catalytic activity of the Pt/NG-MWCNTs is attributed to well-dispersed Pt clusters on the NG-MWCNTs and the electron-donating effect of the nitrogen dopant in the NG-MWCNTs.

Carbon film encapsulated Fe 2 O 3 : An efficient catalyst for hydrogenation of nitroarenes

Abstract Iron catalysis has attracted a wealth of interdependent research for its abundance, low price, and nontoxicity. Herein, a convenient and stable iron oxide (Fe2O3)-based catalyst, in which active Fe2O3 nanoparticles (NPs) were embedded into carbon films, was prepared via the pyrolysis of iron-polyaniline complexes on carbon particles. The obtained catalyst shows a large surface area, uniform pore channel distribution, with the Fe2O3 NPs homogeneously dispersed across the hybrid material. Scanning electron microscopy, Raman spectroscopy and X-ray diffraction analyses of the catalyst prepared at 900 °C (Fe2O3@G-C-900) and an acid-pretreated commercial activated carbon confirmed that additional carbon materials formed on the pristine carbon particles. Observation of high-resolution transmission electron microscopy images also revealed that the Fe2O3 NPs in the hybrid were encapsulated by a thin carbon film. The Fe2O3@G-C-900 composite was highly active and stable for the direct selective hydrogenation of nitroarenes to anilines under mild conditions, where previously noble metals were required. The synthetic strategy and the structure of the iron oxide-based composite may lead to the advancement of cost-effective and sustainable industrial processes.