Jinming Xu

A Schiff base modified gold catalyst for green and efficient H2 production from formic acid

Formic acid (FA) dehydrogenation is an atom-economic method for H2 production, while diluted FA with extra additives is generally required in heterogeneous dehydrogenation of FA. Here, we report a novel Schiff base functionalized gold catalyst, which showed excellent catalytic performances for H2 production in catalytic dehydrogenation of high-concentration FA without any additives. The record turnover frequency (TOF) was as high as 4368 h−1 in 10 M FA solutions, and was up to 2882 h−1 even in 99% FA at a mild temperature of 50 °C. According to characterization results, a synergetic mechanism for C–H activation between the protonated Schiff base and electronegative gold nanoparticles (NPs) at the interface was suggested to be responsible for its unusual catalytic activity toward H2 production from FA.

Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles.

Porous carbon in catalytic transformation of cellulose

The application of porous carbon in catalytic transformation of cellulose has received considerable interest owing to increasing energy and environmental pressures. In this mini-review, we first outline the featured properties of porous carbon in catalytic cellulose transformation in terms of porosities and surface functionalities. An interconnected hierarchical structure and enrichment of mesopores are highly desired for reactant, intermediate, and product diffusion; while hydrophilic surfaces are favored in aqueous phase transformation and certain acidic oxygen functionalities play a role of acid sites as well as enhancing the adsorption of feedstock via 1,4-glycosidic bonds. We then summarize specific reactions in cellulose transformation in the order of hydrolysis and hydrolytic hydrogenation. In the hydrolysis of cellulose, porous carbon is generally used as a solid acid by taking advantage of its enriched oxygen functionalities, while in the hydrolytic hydrogenation, carbon serves as the support of bifunctional catalysts with active acidic sites. Finally, the synthesis and potential application of specific novel porous carbon materials, such as heteroatom-modified porous carbon and mesoporous carbon composites, are highlighted.

Chemocatalytic Conversion of Cellulosic Biomass to Methyl Glycolate, Ethylene Glycol, and Ethanol

Production of chemicals and fuels from renewable cellulosic biomass is important for the creation of a sustainable society, and it critically relies on the development of new and efficient transformation routes starting from cellulose. Here, a chemocatalytic conversion route from cellulosic biomass to methyl glycolate (MG), ethylene glycol (EG), and ethanol (EtOH) is reported. By using a tungsten-based catalyst, cellulose is converted into MG with a yield as high as 57.7 C % in a one-pot reaction in methanol at 240 °C and 1 MPa O2 , and the obtained MG can be easily separated by distillation. Afterwards, it can be nearly quantitatively converted to EG at 200 °C and to EtOH at 280 °C with a selectivity of 50 % through hydrogenation over a Cu/SiO2 catalyst. By this approach, the fine chemical MG, the bulk chemical EG, and the fuel additive EtOH can all be efficiently produced from renewable cellulosic materials, thus providing a new pathway towards mitigating the dependence on fossil resources.

Decorated resol derived mesoporous carbon: highly ordered microstructure, rich boron incorporation, and excellent electrochemical capacitance

Nanoarchitecturing of carbon with assembled building blocks in diverse scales with superior physical properties and tunable chemical characters is of great importance for energy storage. Therefore, exploring boron-modified ordered mesoporous carbons (OMCs) with tailorable microstructure and controllable incorporation become scientifically necessary. In this contribution, the boron-rich ordered mesoporous carbons were formed via a solvent evaporation-induced self-assembly strategy with controllable boron incorporation, tailorable microstructure, and extraordinary electrochemical capacitance. The incorporated boron content can be verified from 0 to 1.64 wt%, and the obtained B-OMCs exhibited widened potential window and enhanced specific capacitance. A maximum value of B incorporation (1.01-1.35 wt%) was detected in improving the specific capacitance (0.38-0.39 Fm-2). This is attributed to the specific oxygen chemisorption and the strengthened surface polarization accompanied with B modification. These results demonstrate the material chemistry, widen the potential applications, and in consequence allow mechanistic insight into the roles boron played for OMC textures and electrochemical activities.

Effect of magnesium substitution into Fe-based La-hexaaluminates on the activity for CH4 catalytic combustion

With the introduction of Mg2+ into Fe-substituted La-hexaaluminate precursors, a series of monophasic LaMgxFeAl11−xO19 (x = 0, 0.3, 0.7, 1) catalysts were prepared and tested as catalysts for CH4 catalytic combustion. The results show that the introduction of an appropriate amount of Mg2+ (x = 0.7) could significantly enhance the catalytic activity of Fe-substituted La-hexaaluminates and promote the resistance to deactivation after calcination at 1300 °C. The beneficial effect of Mg2+ is attributed to the fact that the presence of Mg2+ not only increased the distribution of Fe3+ in the mirror planes of La-hexaaluminates but also effectively suppressed the generation of catalytically inactive Fe2+. Besides, the LaMg0.7FeAl10.3O19 catalyst exhibits excellent stability for 100 h at 700 °C under the reaction conditions.

A two-step synthesis of Fe-substituted hexaaluminates with enhanced surface area and activity in methane catalytic combustion

Hexaaluminates have been regarded as one of the most promising candidates for methane catalytic combustion due to their superior thermal stability up to 1600 °C. However, the main challenge for their further application lies in the difficulty in enhancing the surface area. Herein, Fe-substituted hexaaluminates (LaFexAl12−xO19, x = 0–2) with high surface areas (44–51 m2 g−1) have been successfully synthesized via a new two-step method for the first time, in which N,N-dimethylformamide (DMF) was used as a difunctional solvent to derive the precipitant dimethylamine and to control the precipitation rates of the three metal cations, leading to superior homogeneity of the precipitate and thus lowering of the phase formation temperature (lower than 1100 °C), and the resin/carbon coating process was employed to separate the crystallization and grain-growth process, avoiding the aggregation of particles. Methane catalytic combustion tests revealed that both the high surface area and the introduction of Fe could result in low apparent activation energy. The LaFeAl11O19 catalyst exhibited even higher activity than the conventional Pd/Al2O3 catalyst and those prepared by other methods such as the reverse microemulsion method. Mossbauer spectroscopy characterization verified that the catalytic activity of Fe cations should be related to the Fe3+ ions in Al(3) sites and Al(5) sites in the mirror planes.

Catalytic cascade conversion of furfural to 1,4-pentanediol in a single reactor

The synthesis of bio-based linear diols is the subject of many research studies. However, one of the main obstacles in industrial development is the difficulty in controlling product selectivity. Here, we report the catalytic conversion of furfural to 1,4-pentanediol (PD) in the presence of Ru supported on an ordered mesoporous carbon (CMK-3) under pressure of H2 and CO2 in water. In contrast to previous catalytic pathways, this work is distinct in that it yields 1,4-PD as an exclusive product, instead of a mixture of 1,2- and 1,5-PD as usual. Under optimized conditions, 1,4-PD was obtained in 90% yield, and in a one-pot reaction, directly from furfural. We disclose that the conversion of furfural to 1,4-PD followed an unusual catalytic route. It implies a bifunctional catalytic pathway based on sequential catalytic hydrogenation reactions and an acid-catalyzed Piancatellis rearrangement.