Hierarchically nanostructured bimetallic NiCo/MgxNiyO catalyst with enhanced activity for phenol hydrogenation

Co-Promoted CoNi Bimetallic Nanocatalyst for the Highly Efficient Catalytic Hydrogenation of Olefins

Bimetallic catalysts, especially non-noble metals, hold great potential for substituting for noble metals in catalytic hydrogenation. In present study, a series of Co_xNi_y (x + y = 6) bimetallic catalysts were prepared through the impregnation-reduction method and cyclohexene was chosen as probe-molecule to study the promotion effect of Co on the catalytic olefin hydrogenation reactions. Meanwhile, density functional theory (DFT) was utilized to investigate the formation energies and the charge distribution of CoNi bimetals, as well as the transition state (TS) searches for hydrogen dissociation and migration. The results suggest that bimetals tend to have superior catalytic performance than pure metals, and Co₃Ni₃ shows the highest catalytic activity on the cyclohexene hydrogenation. It was found that the charge transfer from Co to Ni and the alloying give rise to the refinement of CoNi grains and the improvement of its catalytic activity and stability. Thus, it may be possible to obtain better catalytic performance by tuning the metal/metal atomic ratio of bimetals.

Anisole hydrodeoxygenation over Ni–Co bimetallic catalyst: a combination of experimental, kinetic and DFT study†

Catalytic hydrodeoxygenation (HDO) of anisole was performed with a series of Ni and Co containing catalysts with different weight ratios on activated carbon (AC) for cyclohexanol production. The catalytic activities of various catalysts revealed that Ni₅Co₅-AC was the best catalytic system. Structural analysis obtained from XRD, TPR, XPS, and TEM evidently demonstrates that Ni₅Co₅-AC sample consists of a distorted metal alloy spinel structure and optimum particle size, enhancing its catalytic performance. Kinetics were investigated to identify cyclohexanol production rate, activation energy, and reaction pathway. Structural, experimental, kinetics and density functional simulations suggested that high amount of distorted metallic alloy in Ni₅Co₅-AC, presence of water, high adsorption efficiency of anisole, and low adsorption tendency of cyclohexanol on metallic alloy surface were the critical factors for HDO of anisole to cyclohexanol.

High reducible distorted bimetallic sites with medium size in Ni₅Co₅-AC promoted the production of cyclohexanol by hydrogenation of anisole and subsequent cleavage of C₆H₁₁O–CH₃ bond.

Hydrogenation of phenol to cyclohexanol using carbon encapsulated Ni–Co alloy nanoparticles

Highly active NiCo alloy nanoparticles for phenol hydrogenation to cyclohexanol were developed.

Recent progress on selective hydrogenation of phenol toward cyclohexanone or cyclohexanol

Phenol is considered as an important platform molecule for synthesizing value-added chemical intermediates and products. To date, various strategies for phenol transformation have been developed, and among them, selective hydrogenation of phenol toward cyclohexanone (K), cyclohexanol (A) or the mixture KA oil has been attracted great interest because they are both the key raw materials for the synthesis of nylon 6 and 66, as well as many other chemical products, including polyamides. However, until now it is still challengeable to realize the industrilized application of phenol hydrogenation toward KA oils. To better understand the selective hydrogenation of phenol and fabricate the enabled nanocatalysts, it is necessary to summarize the recent progress on selective hydrogenation of phenol with different catalysts. In this review, we first summarize the selective hydrogenation of phenol toward cyclohexanone or cyclohexanol by different nanocatalysts, and simultaneously discuss the relationship among the active components, type of supports and their performances. Then, the possible reaction mechanism of phenol hydrogenation with the typical metal nanocatalysts is summarized. Subsequently, the possible ways for scale-up hydrogenation of phenol are discussed. Finally, the potential challenges and future developments of metal nanocatalysts for the selective hydrogenation of phenol are proposed.