Catalytic Deoxygenation of Bio-Oil Model Compounds over Acid–Base Bifunctional Catalysts

Abstract

An acid−base bifunctional catalyst was synthesized by treating a natural mixed-metal oxide, serpentine, with sulfuric acid. Catalyst characterization revealed that the number of acidic and basic sites increased after the acid treatment largely due to an increase in surface area. However, stronger acid sites were also introduced by the formation of bridged hydroxyl groups between a Si atom and a heteroatom, as inferred by H NMR and NH 3 -TPD analysis. Results from SEM-EDS and 1 H NMR suggested that the acid and base sites were in close proximity. Catalytic conversions of carbohydrate-derived bio-oil model compounds were performed over different acid/base catalysts. Eight single bio-oil model compounds and two binary mixtures were used. The reactivity of the model compounds was found to be strongly correlated to the number of oxygencontaining functional groups in the reactant. The results from the binary mixtures showed that the acid−base bifunctional catalyst had the highest activity in aldol condensation reactions. The best deoxygenation performance was also observed with the bifunctional catalyst for the model compounds. Reaction pathways were proposed on the basis of an isotope labeling study. Deoxygenation reactions were found to be promoted by the cooperative catalysis between closely located acid and base sites.

Nuclear magnetic resonance in chemical structures authentication and pyrolysis oil characterization

“…For example, we may track the efficacy and performance of modified red mud for hydrogenation and compare the upgraded products derived from red mud as catalyst and Ni/Silica-Alumina to determine the best parameters for red mud modification. Furthermore, studying lignocellulosic biomass at the model compound level (e.g., using guaiacol and 5-HMF as reaction representations) might offer important information about the thermochemical behavior of parent cellulose, hemicellulose, or lignin [31][32][33][34]. 4.…”

Transportation fuels from biomass fast pyrolysis, catalytic hydrodeoxygenation, and catalytic fast hydropyrolysis

“…Unsaturated hydrocarbons such as aromatics and alkenes have a high affinity for carbon formation as they have a significantly stronger interaction with the catalyst surface compared to saturated analogues [336]. For oxygenates, the propensity of coking is increased for compounds with more than one oxygen atom in its structure [336,340] while carbonyls (i.e. ketones) may polymerize through aldol condensation [341].…”

Atmospheric hydrodeoxygenation of bio-oil oxygenated model compounds: A review

“…Bio-oil is generally a mixture of primarily phenolic oligomers derived from lignin in an aqueous phase comprising predominantly carbohydrate derived compounds (7)(8)(9)(10). Several deteriorating properties such as high acidity, low higher heating value (HHV), high viscosity, poor storage stability and others have made bio-oil undesirable to instant usage as high grade fuels, mainly due to high amounts of oxygenated compounds as well as complex mixtures of chemical compounds (11)(12)(13).…”