Thermal transformation of bioactive caffeic acid on fumed silica seen by UV–Vis spectroscopy, thermogravimetric analysis, temperature programmed desorption mass spectrometry and quantum chemical methods

Kinetics of Valeric Acid Ketonization and Ketenization in Catalytic Pyrolysis on Nanosized SiO2, γ‐Al2O3, CeO2/SiO2, Al2O3/SiO2 and TiO2/SiO2

“…The interaction begins with the chemisorption reaction between valeric acid and surface silanols as shown in Scheme a. Carboxylic acids are known to react with silanols during heating in vacuum to form carboxylates bound to the surface in monodentate fashion . The quantum chemical calculations reported recently suggest that chemisorption of caffeic and ferulic acids on silica is likely to proceed as an intramolecular nucleophilic substitution . The energy required for the formation of the chemisorbed surface complexes containing a Si 12 O 30 H 12 cluster was reported to be rather low (−32 kJ mol for ferulic acid and 27.4 kJ mol for caffeic).…”

“…ChemPhysChem 2017ChemPhysChem , 18,1943ChemPhysChem -1955 www.chemphyschem.org 2017 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim nucleophilic substitution. [38,39] The energy required for the formation of the chemisorbed surfacec omplexes containing aS i 12 O 30 H 12 clusterw as reported to be ratherl ow (À32 kJ mol for ferulic acid and 27.4 kJ mol for caffeic). The endothermic nature of this reaction is compensated easily by heatingt he sample up to 100 8Ci nt he mass-spectrometer ampoule.…”

“…Ultrafine particles and nanoparticles of metal oxides have been reported to be particularly useful heterogeneous catalysts for the pyrolytic conversion of aliphatic and cinnamic carboxylic acids . A number of useful thermal transformations for biomass conversion have been reported to proceed on the oxide surfaces, for example—decarboxylation, ketenization and ketonization . In this sense, the identification of reaction products and an understanding of the mechanisms of thermal decomposition of VA on the surface of potential catalysts are essential for the development of alternative routes to utilize the derivatives of cellulosic biomass.…”

“…Ultrafine particles and nanoparticles of metalo xides have been reported to be particularly usefulh eterogeneousc atalysts for the pyrolytic conversion of aliphatic and cinnamic carboxylic acids. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] An umber of useful thermalt ransformationsf or biomass conversion have been reported to proceed on the oxide surfaces, fore xam-Valeric acid is an important renewable platform chemical that can be produced efficiently from lignocellulosicb iomass. Upgradingo fv aleric acid by catalytic pyrolysis has the potential to produce value added biofuelsa nd chemicals on an industrial scale.…”

“…ple-decarboxylation, [37][38][39][40] ketenization [21][22][23][24][25][26] and ketonization. [16,[27][28][29][30][31][32][33][34][35][36] In this sense,t he identification of reaction products and an understanding of the mechanismso ft hermald ecom-positionofV Aonthe surface of potential catalysts are essential for the development of alternative routes to utilize the derivatives of cellulosic biomass.…”