Yunhua Li

An efficient and stable Ru–Ni/C nano-bimetallic catalyst with a comparatively low Ru loading for benzene hydrogenation under mild reaction conditions

A prepared 0.024%Ru–1.00%Ni/C nano-bimetallic catalyst reported in this work is a highly efficient and stable catalyst for the hydrogenation of benzene to cyclohexane, with an unprecedented TOF up to 7905 h−1 under mild reaction conditions (20 °C, 40 psi H2) without adding any solvent. The method for the preparation of catalyst is very simple and low-cost. Therefore, this cyclohexane synthetic approach is potentially more environmentally friendly and economical than existing technology.

Hydrodeoxygenation of phenol as a bio-oil model compound over intimate contact noble metal–Ni2P/SiO2 catalysts

This study investigates phenol hydrodeoxygenation on supported Ni2P, prepared via the sol–gel and TPR methods, and noble metal (Pd, Pt and Ru)–Ni2P catalysts, prepared from Ni2P by the partial in situ reduction of a noble metal precursor. 10% Ni2P/SiO2 had a relatively uniform distribution of Ni2P nanoparticles and a highly active activity for phenol hydrodeoxygenation. Phenol conversion increased with increasing reaction temperature and the main products on noble metal–Ni2P/SiO2 also changed from cyclohexanol at 453 K to cyclohexane at 493 K. In comparison with supported Ni2P or noble metal catalysts and their physical mixture, Pd–Ni2P/SiO2 presented the highest conversion activity and cyclohexane selectivity. Physicochemical characterization showed that the number of active sites on the catalysts increased and electron transfer occurred from Ni2P to the noble metal due to the intimate contact between Ni2P and the noble metal. A synergistic effect of the deoxygenation and carbonyl hydrogenation from Ni2P and the hydrodeoxygenation from Pd resulted in an improvement of the catalytic activity and differences in the selectivity of the catalysts.

Decoration of Co/Co3O4 nanoparticles with Ru nanoclusters: a new strategy for design of highly active hydrogenation

Ru/Co/Co3O4/C (Ru nanoclusters-on-Co/Co3O4 nanoparticles) has an unexpected enhancement of activity for benzene hydrogenation which is about 2500 times higher than Ru–Co nanoalloy/C. Detailed nanostructure characterization of Ru/Co/Co3O4/C has revealed that the high activity originates from a synergetic multifunction of the catalytic Ru, Co and Co3O4 sites on the nanocluster/nanoparticle surfaces.

Ruthenium–nickel–nickel hydroxide nanoparticles for room temperature catalytic hydrogenation

Improving the utilization of metals in heterogeneous catalysts with excellent catalytic performance, high selectivity and good stability represents a major challenge. Herein a new strategy is disclosed by enabling a nanoscale synergy between a transition metal and a noble metal. A novel Ru/Ni/Ni(OH)2/C catalyst, which is a hybrid of Ru nanoclusters anchored on Ni/Ni(OH)2 nanoparticles (NPs), was designed, prepared and characterized. The Ru/Ni/Ni(OH)2/C catalyst exhibited a remarkable catalytic activity for naphthalene hydrogenation in comparison with existing Ru/C, Ni/Ni(OH)2/C and Ru–Ni alloy/C catalysts. This is mainly attributed to the interfacial Ru, Ni and Ni(OH)2 sites of Ru/Ni/Ni(OH)2/C, where hydrogen is adsorbed and activated on Ru while Ni transfers the activated hydrogen species (as a “bridge”) to the activated naphthalene on Ni(OH)2 sites, producing decalin through a highly effective pathway.

Synthesis of Different Ruthenium Nickel Bimetallic Nanostructures and an Investigation of the Structure–Activity Relationship for Benzene Hydrogenation to Cyclohexane

The catalytic properties of catalysts are generally highly dependent on their nanostructures in most heterogeneous catalytic reactions. Therefore, to acquire targeted catalytic activity, selectivity, and stability, catalysts with a specific nanostructure should be designed and synthesized. Herein, Ru‐Ni bimetallic nanoparticles with different nanostructures, Ru‐Ni alloy, Ru@Ni, and Ru clusters‐on‐Ni on carbon, have been synthesized by annealing Ru‐Ni/C in flowing N2+10 % H2 at different temperatures. The various nanostructures of the Ru‐Ni bimetallic nanoparticles have been characterized and their catalytic behaviors were evaluated using benzene hydrogenation to cyclohexane. The relationship between the Ru‐Ni bimetallic nanostructures and their catalytic performance is presented. It was found that Ru‐Ni alloy/C and Ru clusters‐on‐Ni/C are much more active than Ru@Ni/C. This study also provides a simple method to design and control the nanostructures of the Ru‐Ni bimetallic nanoparticles.

Activity and kinetics of ruthenium supported catalysts for sodium borohydride hydrolysis to hydrogen

Ru–RuO2/C prepared by galvanic replacement has high catalytic activity for sodium borohydride hydrolysis. In the present study, a series of Ru–RuO2/C catalysts, Ru–RuO2/C reduced, RuO2/C and Ru supported on Ni foam (Ru/Ni foam) are prepared and characterized. Results show that RuO2 on Ru–RuO2/C is formed from both the consumption of the parent Ni and NiO nanoparticles and the disproportionation of RuCl3 with epitaxial growth of Ru species. The quantity of RuO2 with oxygen vacancies in Ru–RuO2/C determines the hydrolysis activity for sodium borohydride. In contrast to Ru–RuO2/C, Ru/Ni foam without oxygen vacancies has the lower hydrolysis activity. Results of kinetics calculation further confirm that without mass transfer limitation, Ru–RuO2/C has lower intrinsic activation energy and correspondingly higher catalytic activity due to existence of oxygen vacancies than those from Ru–RuO2/C reduced, RuO2/C, Ru/Ni foam and catalysts from the literature.

Effect of the thermal treatment temperature of RuNi bimetallic nanocatalysts on their catalytic performance for benzene hydrogenation

The thermal treatment temperature of bimetallic nanocatalysts plays an important role in determining their catalytic performance. In this study, the synthesis of RuNi bimetallic nanoparticles (BNPs) supported on carbon black catalysts (denoted as RuNi BNSC) via hydrazine hydrate reduction and galvanic replacement reaction methods was reported. Then the effect of the annealing temperature in N2 (uncalcined, 160, 230, 280, 380, 480, 580 and 680 °C) of RuNi BNSC on its catalytic activity for the benzene hydrogenation reaction was investigated. It was found that RuNi BNSC calcined at 380 °C exhibited outstanding catalytic activity in the liquid phase hydrogenation of benzene to cyclohexane, which was about 3–4 times higher than that of RuNi BNSC calcined at 680 °C, while RuNi BNSC annealed at 480 °C had no activity for this reaction. The characterization results of the catalysts indicated that various thermal treatment temperatures in N2 affected the RuNi BNP size, chemical states of Ru and Ni, and RuNi bimetallic nanostructures and thus the catalytic properties.

Highly selective hydrodeoxygenation of anisole, phenol and guaiacol to benzene over nickel phosphide

Ni2P supported catalysts have extensively been studied for various hydrodeoxygenation (HDO) reactions. However, the main products are cyclohexane or cyclohexanol for lignin-derived compounds HDO over these catalysts. In this study, we investigate the catalytic conversion of anisole, phenol and guaiacol to benzene over Ni2P/SiO2 by probing the reaction conditions. The results show that a lower reaction temperature and higher H2 pressure favour the hydrogenation of these model chemicals to cyclohexane, whereas a higher reaction temperature and lower H2 pressure aid the generation of benzene. The cyclohexane and benzene yields are 89.8% and 96.0% at 1.5 MPa and 573 K and 0.5 MPa and 673 K, respectively. By eliminating the influence of internal and external diffusion, the low intrinsic activation energy of 58.2 kJ mol−1 is obtained, which explains the high catalytic activity. In addition, although guaiacol HDO has a low conversion due to the space steric effect of its substituents, it presents a similar reaction pathway to obtain anisole and phenol, which is dependent on reaction conditions. The long-run evaluation experiment shows that the activity and selectivity of anisole HDO to benzene changes slightly for 36 h.

Tuning Surface Properties and Catalytic Performances of Pt–Ru Bimetallic Nanoparticles by Thermal Treatment

The surface structure and catalytic properties of Pt–Ru bimetallic catalysts with identical bulk composition can be continuously tuned by treatment at different temperatures. The activity of these catalysts in CO oxidation was positively related to the treatment temperature, but the opposite trend was observed for the solvent‐free oxidation of benzyl alcohol. It was found that migration of Pt to the surface occurred when the treatment temperature was increased. During this process, the surface of the Pt–Ru nanoparticles changed from a Ru‐rich surface to a Pt‐rich surface. The electronic interactions between Pt and Ru became stronger with increased treatment temperature, and the amount of oxidized Pt species on the surface was higher for the samples treated at higher temperatures. Therefore, oxidized Pt species are more active in CO oxidation than other metallic species, but are less active in the selective oxidation of benzyl alcohol.

Rational design and preparation of hierarchical monoliths through 3D printing for syngas methanation

Generally, monoliths have better heat and mass transfer properties and thus are potentially favorable to situations such as highly exothermal reactions. The key advantage of 3D-printed catalysts as compared to the that of the conventionally prepared catalysts is the design of tortuous channels that modulate the transport properties in hierarchical monoliths rather than that of simple, straight or uncontrollable channels. In this study, for the first time, cylinder, tetrahedron, and tetrakaidecahedron periodic structures were modulated via 3D printing and successfully used as a hard template to prepare phenol–formaldehyde-based hierarchical monoliths for CO methanation. The reaction results show that a 3D monolith with a 1.00 mm diameter simple straight channel has a high catalytic performance at similar loadings and compositions of active components. The channel structure can precisely be modulated by 3D printing, and the macro-channels and meso-channels are well connected. More importantly, through modulating the tortuosity of macro-channels, the Ni–Al2O3/C monolith with a 1.25 mm diameter tetrahedral channel shows an excellent CH4 yield as well as a prominent decrease in the temperature gradient and pressure at 24 000 h−1 GHSV as compared to other structures of monolithic catalysts. High mass and heat transport along with reaction activity efficiently facilitate the improvement of catalytic performance. The successful synthesis of these fascinating materials paves the way to explore the application of more complicated hierarchical monoliths for separation and reaction processes particularly for industrial catalyst design.