Elucidating the Reaction Pathways of Veratrylglycero-β-Guaiacyl Ether Degradation over Metal-Free Solid Acid Catalyst with Hydrogen

Efficient cleavage of β-O-4 bonds in lignin to high-yield aromatic compounds for the potential production of fuels and chemicals is vital for the economics of the modern biorefinery industry. This work is distinct in that a detailed mechanistic analysis of the reaction pathways of veratrylglycero-β-guaiacyl ether (VGE) catalyzed by transition-metal-free solid acid zeolite in aqueous conditions at high hydrogen pressure has been performed. VGE degradation produced high monomers yields (≈87 %), including guaiacol (48.2 %), 1-(3,4-dimethoxyphenyl)ethanol (10.3 %), 1-(3,4-dimethoxyphenyl)-2-propanol (6.1 %), 3,4-dimethoxyphenylpropanol (4.7 %), 3,4-dimethoxycinnamyl alcohol (4.1 %), and 1,2-dimethoxy-4-propylbenzene (2 %). The products were identified and confirmed by the in situ solid-state magic angle spinning (MAS) ¹³ C NMR spectroscopy in real-time conditions and the two-dimensional gas chromatography (GC×GC). A variety of products reveal the crucial role of hydrogen, water, and acid sites for heterolytic cleavage of the β-O-4 bond in VGE. Decarbonylation, hydrogenolysis, hydrogenation, and dehydration reaction pathways are proposed and further validated using first-principles calculations.

Advanced Carbon-Based Nanocatalysts and their Application in Catalytic Conversion of Renewable Platform Molecules

The transformation of renewable platform molecules to produce value-added fuels and fine-chemicals is a promising strategy to sustainably meet future demands. Owing to their finely modified electronic and geometric properties, carbon-based nanocatalysts have shown great capability to regulate their catalytic activity and stability. Their well-defined and uniform structures also provide both the opportunity to explore intrinsic reaction mechanisms and the site-requirement for valorization of renewable platform molecules to advanced fuels and chemicals. This Review highlights the progress achieved in carbon-based nanocatalysts, mainly by using effective regulation approaches such as heteroatom anchoring, bimetallic synergistic effects, and carbon encapsulation to enhance catalyst performance and stability, and their applications in renewable platform molecule transformations. The foundation for understanding the structure-performance relationship of carbon-based catalysts has been established by investigating the effect of these regulation methods on catalyst performance. Finally, the opportunities, challenges and potential applications of carbon-based nanocatalysts are discussed.

Pd NP-Decorated N-Rich Porous Organic Polymer as an Efficient Catalyst for Upgradation of Biofuels

Hydrodeoxygenation process is a potential route for upgrading biofuel intermediates, like vanillin, which is obtained in huge quantities through the chemical treatment of the abundant lignocellulosic biomass resources of nature, and this is attracting increasing attentions over the years. Herein, we report the grafting of palladium nanoparticles at the surface of porous organic polymer Pd-PDVTTT-1 synthesized through the co-condensation of 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione and divinylbenzene in the presence of radical initiator under solvothermal reaction conditions. The Pd-PDVTTT-1 material has been characterized thoroughly by powder X-ray diffraction, nitrogen sorption, ultra-high-resolution transmission electron Microscopy, Fourier-transform infrared spectroscopy, ¹³C MAS NMR, and X-ray photoelectron spectroscopy analyses. High surface area together with good thermal stability of the Pd-PDVTTT-1 material has motivated us to explore its potential as heterogeneous catalyst in the hydrodeoxygenation of vanillin for the production of upgraded biofuel 2-methoxy-4-methylphenol in almost quantitative yield and high selectivity (94%).

Cobalt Nanoparticles Supported on Nitrogen-Doped Carbon: An Effective Non-Noble Metal Catalyst for the Upgrade of Biofuels

A new method has been developed for the deoxygenation of vanillin to produce 2-methoxy-4-methylphenol (MMP) as a promising liquid fuel over a heterogeneous non-noble metal catalyst. Cobalt nanoparticles supported on nitrogen-doped carbon (Co/N-C-600) exhibit high activity and stability for the deoxygenation of vanillin into MMP under mild conditions (150 °C, 10 bar H₂ ). Nearly quantitative MMP yield is obtained in isopropanol after 8 h at 150 °C and 10 bar H₂ pressure. According to the distribution of products with time, the deoxygenation of vanillin into MMP mainly proceeds through the hydrogenation of vanillin into vanillyl alcohol and the subsequent hydrogenolysis of vanillyl alcohol into MMP, of which the latter is the rate-determining step, owing to a much higher activation energy. Moreover, after being recycled several times, the loss of catalytic activity is negligible, which demonstrates that the Co/N-C-600 catalyst shows good resistance to deactivation.

Cu–Pd bimetallic nanoalloy anchored on a N-rich porous organic polymer for high-performance hydrodeoxygenation of biomass-derived vanillin

A N-rich porous organic polymer-anchored bimetallic Cu–Pd nanoalloy exhibited superior catalytic activity with improved stability for biomass-derived selective hydrodeoxygenation of vanillin.

Transfer hydrogenation of bio-fuel with formic acid over biomass-derived N-doped carbon supported acid-resistant Pd catalyst

The strong Pd–N interaction on biomass-derived N-doped highly mesoporous carbons (NMCs) generates co-existence of electron-deficient Pd (Pd^δ+) and metallic Pd (Pd⁰), leading to Pd/NMC as novel bifunctional catalyst for both FA dehydrogenation and vanillin hydrogenation.