Accelerated and Natural Aging of Cellulose-Based Paper: Py-GC/MS Method

Samples of papers artificially (2 to 60 days) and naturally (10, 45, and 56 years) aged were studied by the Py-GC/MS method to identify decomposition products. Possible reaction scenarios for cellulose degradation were developed. One of the degradation products is acetic acid, which can (auto)catalyze the cleavage of cellulose β(1→4)-glycosidic bonds of cellulose polymer chains. However, during 20 s of Py-GC/MS analysis, temperatures of up to 300 °C did not significantly increase or modify the formation of decomposition products of paper components. At 300 °C, the amount of several cellulose decomposition products increased regularly depending on the number of days of artificial aging and natural aging, demonstrated mainly by the generation of 2-furancarboxaldehyde, 5-hydroxymethylfurfural, and levoglucosan and its consecutive dehydration products. No correlation between the amount of lignin decomposition products and the time of aging was found when the pyrolysis was performed at 300 °C and 500 °C. Compounds present in the products of decomposition at 500 °C bear the imprint of the chemical composition of the sampled paper. Pyrograms taken at 300 °C using the Py-GC/MS method can give additional information on the changes in the chemical structure of paper during natural or artificial aging, mainly about the cleavage of β(1→4)-glycosidic bonds during aging

Unique efficiency of copper-indium catalyst in octanoic acid reduction

Octanoic acid (OA), as model reactant, was hydroconverted in a flow through reactor at 21 bar total pressure and 240-380 C over various copper catalysts composed with indium or its neighbors in the periodic table (gallium, tin, thallium and cadmium) for comparison. The In-doped sample was proven to be much more advantageous than the other bimetallic analogs tested. © 2013 Elsevier B.V. All rights reserved

Gel-type ion exchange resin stabilized Pd-Bi nanoparticles for the glycerol oxidation in liquid phase

Palladium-bismuth nanoparticles were supported into strongly basic anion-exchange resin of gel-type and tested as catalysts for the selective oxidation of glycerol with molecular oxygen at atmospheric pressure. Detailed study of the precursors preparation and reduction were undertaken. The catalyst 3%Pd-1%Bi where the bismuth was deposited on the palladium particles (3.4 nm) exhibited at 95% glycerol conversion more than 63% yield toward glyceric acid and tartronic acid after 3 h of reaction. The catalyst maintains practically similar catalytic performance as in fresh state for at least five consecutive catalytic cycles without extra catalyst treatment and reactivation. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved

Selective Reduction of Acetic Acid to Ethanol over Novel Cu2In/Al2O3 Catalyst

Volatile fatty acids (VFAs) can be produced efficiently by simple thermochemical or biological biomass degradation. For the processing of these organic acids in hydrogen atmosphere, the consecutive reactions of acetic acid (AA) hydroconversion were studied in details looking for conditions of selective ethanol production over a novel and advantageous bimetallic composite applying indium as co-catalyst. The reactions were investigated in vapor phase at 240–380 °C, 7–21 bar hydrogen and 0.5–3.5 bar acetic acid partial pressures in a fixed bed flow-through reactor using supported copper catalysts. In2O3 admission can significantly increase AA hydroconversion activity of copper catalysts supported on various oxides and the yield of the produced ethanol. Efficient hydrogenating catalysts, containing finely dispersed metal particles were obtained by in situ reduction with H2 at 450 °C. In the catalysts modified with In2O3 additive, formation of an intermetallic compound (Cu2In) was strikingly observed resulting in a different, more advantageous catalytic behavior as of pure copper particles supported on different oxide supports. On comparing a commercial, conventionally used catalysts (Adkins: 72 wt% CuCr2O4 + 28 wt% CuO) with the bimetallic alumina supported composite (Cu2In/Al2O3) the new catalyst proved to be much more active and selective for producing ethanol. A schematic representation of reactions involved in the hydroconversion of acetic acid was explored and verified. The activity dependence on the reactant partial pressures denotes rate-controlling surface reaction according to Langmuir–Hinshelwood mechanism