The title uronates were prepared by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) catalysed sodium hypochlorite oxidation of α- and β-D-glucopyranosylphosphate (α-/β-Glc-1-P) and α-D-glucopyranosyl fluoride (α-Glc-1-F). Quantitative recovery of the TEMPO catalyst was achieved by azeotropic distillation of a small part of the reaction mixture. Also, a heterogeneous catalyst system was prepared by immobilisation of 4-oxo-tetramethyl-1-piperidinyloxy (OTEMPO) on amino-functionalized silica. The protected uronates were hydrolysed to yield D-glucuronate. Since α- and β-Glc-1-P and α-Glc-1-F can be obtained from starch in one step, D-glucuronic acid is now available from starch in a convenient three-step sequence.
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The scope of this thesis of Gerrit Bouwhuis, lecturer at Saxion Research Centre for Design and Technology in Enschede is the development of a new industrial applicable pre-treatment process for cotton based on catalysis. The pre-treatment generally consists of desizing, scouring and bleaching. These processes can be continuous or batch wise. Advances in the science of biocatalytic pre-treatment of cotton and catalytic bleaching formed the scientific basis for this work. The work of Agrawal on enzymes for bio-scouring and of Topalovic on catalytic bleaching led to the conclusion that reduced reaction temperatures for the pre-treatment processes of cotton are possible. A second reason for the present work is a persistent and strong pressure on the industry to implement ‘more sustainable’ and environmental friendlier processes. It was clear that for the industrial implementation of the newly developed process it would be necessary to ‘translate’ the academic knowledge based on the catalysts, into a process at conditions that are applicable in textile industry. Previous experiences learned that the transition from academic knowledge into industrial applicable processes often failed. This is caused by lack of experience of university researchers with industrial product and process development as well as a lack of awareness of industrial developers of academic research. This is especially evident for the so-called Small and Medium Enterprises (SME’s). To overcome this gap a first step was to organize collaboration between academic institutes and industries. The basis for the collaboration was the prospect of this work for benefits for all parties involved. A rational approach has been adopted by first gathering knowledge about the properties and morphology of cotton and the know how on the conventional pre-treatment process. To be able to understand the conventional processes it was necessary not only to explore the chemical and physical aspects but also to evaluate the process conditions and equipment that are used. This information has been the basis for the present lab research on combined bio-catalytic desizing and scouring as well as catalytic bleaching. For the measurement of the performance of the treatments and the process steps, the performance indicators have been evaluated and selected. Here the choice has been made to use industrially known and accepted performance indicators. For the new bio-catalytic pre-treatment an enzyme cocktail, consisting of amylase, cutinase and pectinase has been developed. The process conditions in the enzyme cocktail tests have been explored reflecting different pre-treatment equipment as they are used in practice and for their different operation conditions. The exploration showed that combined bio-catalytic desizing and scouring seemed attractive for industrial application, with major reduction of the reaction and the rinsing temperatures, leading to several advantages. The performance of this treatment, when compared with the existing industrial treatment showed that the quality of the treated fabric was comparable or better than the present industrial standard, while concentrations enzymes in the cocktail have not yet been fully optimized. To explore the application of a manganese catalyst in the bleaching step of the pre-treatment process the fabrics were treated with the enzyme cocktail prior to the bleaching. It has been decided not to use conventional pre-treatment processes because in that case the combined desizing and scouring step would not be integrated in the newly developed process. To explore catalytic bleaching it has been tried to mimic the existing industrial processes where possible. The use of the catalyst at 100°C, as occurs in a conventional steamer, leads to decomposition of the catalyst and thus no bleach activation occurs. This led to the conclusion that catalytic bleaching is not possible in present steamers nor at low temperatur
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Problems of energy security, diversification of energy sources, and improvement of technologies (including alternatives) for obtaining motor fuels have become a priority of science and practice today. Many scientists devote their scientific research to the problems of obtaining effective brands of alternative (reformulated) motor fuels. Our scientific school also deals with the problems of the rational use of traditional and alternative motor fuels.This article focused on advances in motor fuel synthesis using natural, associated, or biogas. Different raw materials are used for GTL technology: biomass, natural and associated petroleum gases. Modern approaches to feed gas purification, development of Gas-to-Liquid-technology based on Fischer–Tropsch synthesis, and liquid hydrocarbon mixture reforming are considered.Biological gas is produced in the process of decomposition of waste (manure, straw, grain, sawdust waste), sludge, and organic household waste by cellulosic anaerobic organisms with the participation of methane fermentation bacteria. When 1 tonne of organic matter decomposes, 250 to 500–600 cubic meters of biogas is produced. Experts of the Bioenergy Association of Ukraine estimate the volume of its production at 7.8 billion cubic meters per year. This is 25% of the total consumption of natural gas in Ukraine. This is a significant raw material potential for obtaining liquid hydrocarbons for components of motor fuels.We believe that the potential for gas-to-liquid synthetic motor fuels is associated with shale and coalfield gases (e.g. mine methane), methane hydrate, and biogas from biomass and household waste gases.
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