Search

The selectivity of phenol hydrogenation over Pd/C was successfully tuned by various Bronsted acid and base additives. Compared with neutral reaction condition, the basic condition witnessed decreased catalytic activity and cyclohexanone selectivity while the opposite trend was observed under acidic condition. Mechanistic studies indicated the varied interaction of substrate with acid and base is responsible for the activity difference, while the changed keto-enol tautomerization correlates directly to the selectivity variation. [ABSTRACT FROM AUTHOR]

On the way to exploring superior hydrogenation catalysts, Ir-based catalysts with a record catalytic activity (up to 40 h−1) for the hydrogenation of benzoic acid to cyclohexanecarboxylic acid under mild reaction conditions (85 °C, 0.1 MPa H2, in water) have been successfully developed. By excluding various factors, the experimental results showed that the main factor governing the activity discrepancy between the Ir-based catalysts is actually the dispersion stability of the supports (such as N-doped carbon, active carbon, SBA-15 and various metal oxides) in the reaction solution, rather than the interaction between the Ir active component and the supports. Combined with theoretical investigation from first principles, an activity volcano curve considering the competing adsorption between the reactants (H2) and solvent (H2O) for aqueous aromatic ring hydrogenation was presented for the first time. The high activity of Ir can be deduced by the proper discrepancy of dissociation energies or adsorption energies between H2 and H2O on the catalysts. This activity volcano curve provides guidance for further rational design of promising catalysts for benzoic acid or even aromatic ring hydrogenation under true reaction conditions for practical applications. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticles (2.6 nm) uniformly dispersed on a three-dimensional (3D) interconnected hierarchical porous N-doped carbon (Ru/NHPC) have been successfully developed, serving as a highly active and stable catalyst for the selective hydrogenation of aromatics under mild conditions. A novel “leavening” strategy, i.e. using biomass-derived α-cellulose as a carbon precursor and ammonium oxalate as both a nitrogen source and foaming agent, affords the NHPC material a large surface area (870 m2 g−1), an excellent hierarchical nanostructure which acts as a convenient mass transfer channel and a high ability in stabilizing and dispersing Ru nanoparticles. The Ru/NHPC catalyst exhibits a substantially enhanced activity for the hydrogenation of toluene (TOF up to 39 000 h−1) and quinoline (TOF up to 2858 h−1) in comparison with Ru/HPC (3D-hierarchical porous carbon without nitrogen doping) and Ru/AC (commercial activated carbon) under the same reaction conditions. Further investigations indicate that the 3D interconnected porous structure and N-doping contribute to the improved diffusion and mass transfer, homogeneous dispersion of ruthenium nanoparticles and high percentage of Ru0 (active sites), which results in considerable catalytic performance. This work offers great potential for the application of supported catalysts based on NHPC materials in fine chemical production with high activity. [ABSTRACT FROM AUTHOR]

Due to their industrial indispensability, heterogeneous catalytic oxidation and hydrogenation continue to be topics of great interest in both experimental and theoretical studies. Graphitic carbon nitride (g-C3N4), due to its unique structure and thus excellent properties such as semiconductivity and nitrogen richness, is suitable to act as a metal-free catalyst or catalyst support for these two significant transformations. This critical review will summarize the recent significant advances achieved in the field of oxidation and hydrogenation realized by g-C3N4 based catalytic systems. The review covers the practical applications and brief mechanistic discussions in three broad catalytic cases, catalytic oxidation under light irradiation, catalytic oxidation without light illumination, and catalytic hydrogenation with g-C3N4 supporting metal nanoparticles. The state-of-the-art and future challenges of heterogeneous hydrogenation and oxidation by g-C3N4 based systems are also discussed. [ABSTRACT FROM AUTHOR]

• Using the biomolecular electrocatalytic amplification of l -cysteine in combination with the switching characteristics of the hydrogel films, a 4-input/9-output binary logic gate network, a 2-to-4 encoder, and a 4-to-2 decoder were constructed. • By simplifying and designing the constructed logic gate network, a 4-input/2-output keypad lock based on biomolecule electrocatalysis was completed, providing an example of a keypad lock built without the use of optical detection. • The P(DEA-co-VPBA) hydrogel film was polymerized on the electrode surface by a simple one-step method in the form of free radical polymerization and showed switching properties with varying degrees of response to a variety of stimulus factors. In this work, poly(N',N-diethylacrylamide-co-4-vinylphenylboronic acid) (P(DEA-co-VPBA)) hydrogel films were successfully assembled on the pyrolytic graphite (PG) electrode by a simple radical polymerization. Reversible thermal, glucose and pH-triggered electrochemical reactions were obtained in the presence of 1,1′-ferrocene dicarboxylic acid (FDA) with electro-redox properties. The thermal response performances of the thin-film electrode were attributed to the PDEA component, the sensitive behaviors of glucose were ascribed to the VPBA component, and the sensitive behaviors of pH were affected by PDEA and VPBA. The electrocatalytic oxidation of l -cysteine by FDA on the hydrogel film electrodes significantly enhanced the difference between the on and off states of the multi-response cyclic voltammetry (CV) signals. This smart polymer hydrogel film electrode with amplified signals could be further used to realize a 4-input/9-output binary logic circuit, which was constructed with temperature, glucose, pH, and cysteine as inputs and different levels of I pa and I pc responses as outputs. Furthermore, a 2-to-4 decoder, a 4-to-2 encoder, and a 4-input keypad lock were built on the same platform. This polymer electrocatalysis system provides a novel idea for constructing complex biological computing systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Review: 183 refs. [ABSTRACT FROM AUTHOR]

This work highlights a novel hybrid catalyst, intermetallic PdZn on CN@ZnO (PdZn/CN@ZnO), which serves as a highly efficient heterogeneous catalyst for semihydrogenation of 2-methyl-3-butyn-2-ol utilizing water as the solvent. Compared with intermetallic PdZn on ZnO (PdZn/ZnO), PdZn/CN@ZnO displays almost sixfold higher TOF while retaining high selectivity. It is assumed that the introduction of biomass-derived hydrophilic nitrogen-doped carbon into the ZnO helped to promote catalyst dispersion in aqueous media, ensuring better mass transfer. Further experiments and theoretical calculations showed that from Pd particles to intermetallic PdZn, the decrease of corner and edge Pd atoms might be a factor leading to the improvement of selectivity. Recycling experiments demonstrated that the PdZn/CN@ZnO catalyst could be reused at least eight times without significant decrease in activity or selectivity. Furthermore, when applied to industrially relevant alkenols that are building molecules for the production of vitamin E, the present catalyst still offered excellent performance. It is expected that the present catalytic system will demonstrate its high potential for practical production of vitamin E. [ABSTRACT FROM AUTHOR]