Lattice distorted MnCo oxide materials as efficient catalysts for transfer hydrogenation of levulinic acid using formic acid as H-donor

Confining Co-Based Nanocatalysts by Ultrathin Nanotubes for Efficient Transfer Hydrogenation of Biomass Derivatives

Catalytic transfer hydrogenation (CTH) based on non-noble-metal catalysts has emerged as an environmentally friendly way for the utilization of biomass resources. However, the development of efficient and stable non-noble-metal catalysts is crucially challenging due to their inherent inactivity. Herein, a metal-organic framework (MOF)-transformed CoAl nanotube catalyst (CoAl NT160-H) with unique confinement effect was developed via a "MOF transformation and reduction" strategy, which exhibited excellent catalytic activity for the CTH reaction of levulinic acid (LA) to γ-valerolactone (GVL) with isopropanol (2-PrOH) as the H donor. Comprehensive characterizations and experimental investigations uncovered that the confined effect of the ultrathin amorphous Al2O3 nanotubes could modulate the electronic structure and enhance the Lewis acidity of Co nanoparticles (NPs), thus contributing to the adsorption and activation of LA and 2-PrOH. The synergy between the electropositive Co NPs and Lewis acid-base sites of the CoAl NT160-H catalyst facilitated the transfer of α-H in 2-PrOH to the C atom of carbonyl in LA during the CTH process via a Meerwein-Ponndorf-Verley mechanism. Moreover, the confined Co NPs embedded on am-Al2O3 nanotubes endowed the CoAl NT160-H catalyst with superior stability and the catalytic activity was nearly unchanged for at least ten cycles, far surpassing that of the Co/am-Al2O3 catalyst prepared by the traditional impregnation method.

Recent Advances on Synthesis of CoCO3 with Controlled Morphologies

Cobalt carbonates and derivatives represent most promising cost-effective materials for energy storage, conversion and upgrading. Morphology determines the performances, as size, shape and electronic configuration are key factors for tunable properties in the area of batteries, catalysis, magnetics and plasmonics. However, there is lack of insights in literature on morphological control of cobalt carbonates during hydrothermal and solvothermal conditions. Therefore, this review provides detailed discussion on synthesis, formation mechanism and morphological control of nanosheets, wires, spheres and cubes of cobalt carbonates. Furthermore, the influence of experimental conditions and plausible mechanism which govern the growing processes were further discussed in details. The outcome of this short review will offer insights into rational design of inexpensive metal carbonates for numerous other energy and environment applications.

Catalytic valorisation of biomass levulinic acid into gamma valerolactone using formic acid as a H2 donor: a critical review

This review sheds light on the catalytic valorisation of agroforestry biomass through levulinic acid and formic acid towards γ-valerolactone and other higher-value chemicals. γ-Valerolactone is produced by the hydrogenation of levulinic acid, which can be achieved through an internal hydrogen transfer reaction with formic acid in the presence of catalyst. By reviewing corresponding catalysts, the paper underlines the most efficient steps constituting an integrated sustainable process that eliminates the need for external H2 sources while producing biofuels as an alternative energy source. Furthermore, the review emphasizes the role of catalysts in the hydrogenation of levulinic acid, with special focus on heterogeneous catalysts. The authors highlighted the dual role of different catalysts by comparing their activity, morphology, electronic structure, synergetic relation between support and doped species, as well as their deactivation and recyclability. Acknowledging the need for green and sustainable H2 production, the review extends to cover the role of photo catalysis in dissociating H2-donor solvents for reducing levulinic acid into γ-valerolactone under mild temperatures. To wrap up, the critical discussion presented enables readers to hone their knowledge about different schools and emphasizes research gaps emerging from experimental work. The review concludes with a comprehensive table summarizing the recent catalysts reported between the years 2017-2021.

Mechanochemical redox: a calcination-free process to support CoMnOx catalysts

A calcination-free process (mechanochemical redox loading method) to load CoMnO_x onto various supports for efficient and stable CO oxidation.