Classical Organic Reactions in Pure Superheated Water

Kuhlmann, Barbara; Arnett, Edward M.; Siskin, Michael

doi:10.1021/jo00090a030

Cited by 201 publications

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“…Furthermore, there has been evidence of proton-deuterium exchanges during organic chemical reactions in supercritical water using deuterated water (D2O) as reaction medium [10]. More recently, Park and Tomiyasu [11] used D2O as the reaction medium during SCWG of biomass and found that the hydrogen atoms in the hydrogen gas and methane obtained from the reactions were deuterium, indicating that D2O supplied the hydrogen atoms in the gasification products.…”

Section: Introductionmentioning

confidence: 99%

“…It has been shown that the mechanism for hydrogen formation during SCWG is mainly through the formation of CO, followed by the water-gas shift reaction (WGSR) of the CO [7][8][9]. In addition, methane formation in SCWG would usually involve demethylation but methanation of CO or CO2 using the in situ produced hydrogen from the WGSR has been reported as equally important.Furthermore, there has been evidence of proton-deuterium exchanges during organic chemical reactions in supercritical water using deuterated water (D2O) as reaction medium [10]. More recently, Park and Tomiyasu [11] used D2O as the reaction medium during SCWG of biomass and found that the hydrogen atoms in the hydrogen gas and methane obtained from the reactions were deuterium, indicating that D2O supplied the hydrogen atoms in the gasification products.…”

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confidence: 99%

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Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst: New insights into RuO2 catalytic reaction mechanisms

Onwudili

2016

Fuel

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Five samples, including a composite refuse derived fuel (RDF) and four combustible components of municipal solid wastes (MSW) have been reacted under supercritical water conditions in a batch reactor. The reactions have been carried out at 450 °C for 60 min reaction time, with or without 20 wt% RuO2/gamma-alumina catalyst. The reactivities of the samples depended on their compositions; with the plastic-rich samples, RDF and mixed waste plastics (MWP), giving similar product yields and compositions, while the biogenic samples including mixed waste wood (MWW) and textile waste (TXT) also gave similar reaction products. The use of the heterogeneous ruthenium-based catalyst gave carbon gasification efficiencies (CGE) of up to 99 wt%, which was up by at least 83% compared to the non-catalytic tests. In the presence of RuO2 catalyst, methane, hydrogen and carbon dioxide became the dominant gas products for all five samples. The higher heating values (HHV) of the gas products increased at least two-fold in the presence of the catalyst compared to non-catalytic tests. Results show that the ruthenium-based catalyst was active in feedstock steam reforming, methanation and possible direct hydrogenolysis of C-C bonds. This work provides new insights into the catalytic mechanisms of RuO2 during SCWG of carbonaceous materials, along with the possibility of producing high yields of methane from MSW fractions.Keywords: MSW, supercritical water gasification, ruthenium catalysis, mechanisms, methane * Corresponding Author. Tel.: +44 121 204 4703 Email address: j.onwudili@aston.ac.uk 2 IntroductionRapid urbanization and technological developments are largely responsible for the increasing generation of millions of tonnes of municipal solid wastes (MSW) in major cities around the world. MSW can be broadly classified into organic and inorganic fractions. Among the organic components of MSW, further classifications can be made into biodegradable and nonbiodegradable fractions. By far, food and garden wastes occupy a huge proportion of MSW but these are biodegradable and are often treated by anaerobic digestion (AD) to produce biogas, leading to complete mineralization. After the separation of recyclables, the mixture of nonreadily biodegradable organic components make up a combustible fraction of MSW, which can be made into solid recovered fuels (SRF) and refuse derived fuels (RDF), depending on the specification. The stringent regulations concerning the production and utilization of SRF and RDF indicate that many components of MSW cannot be directly burned as fuels [1][2]. Massproduced synthetic polymers such as plastics and textile materials fall into the category of combustible MSW fractions [3]. Other organic components of MSW that do not hold huge attractions for AD operators include waste wood and reinforced cardboards.Advanced thermochemical technologies suitable for treating plastics and other combustible organic wastes and materials include incineration, pyrolysis and gasification. These technologies convert organic ...

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst: New insights into RuO2 catalytic reaction mechanisms

Onwudili

2016

Fuel

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“…The lower dielectric constant of subcritical water enables it to dissolve hydrophobic substances, [2][3][4] while the increase in ion product, by up to 3 orders of magnitude, owing to temperature increase renders subcritical water capable of acting as an acid or base catalyst for hydrolysis and degradation. [5][6][7] Thus the use of subcritical water can also be regarded as a potential replacement for environmentally undesirable acid catalysts. On account of these advantages, subcritical water has increasingly received attention for application in chemical and biochemical processes.…”

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Degradation Kinetics of Glucuronic Acid in Subcritical Water

Wang

Neoh

Kobayashi

et al. 2010

Bioscience, Biotechnology, and Biochemistry

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“…Két fontos dolgot meg kell említenem: a rozsdamentes acél reaktorok a vizsgálatok alapján nem befolyásolják a reakciók lejátszódását (Hoering, 1984;Torry et al, 1992), illetve a vízben nem mutatható ki számottevő fémtartalom 10 napos, 300°C-os kezelés után sem (Kuhlmann et al, 1994). Az alább felsorolt hőkezelések mindig oxigénmentes környezetben történtek.…”

Section: Irodalmi áTtekintésunclassified

“…-A dimetilfuránok 250°C-on, 30 perc alatt, D 2 O közegben hexándiont (Kuhlmann et al, 1994), a dihidrobenzofuránok fenolokat (Katritzky et al, 1994b) képeznek, ami azt mutatja, hogy a furán gyűrű felnyílásra hajlamos. Ezzel együtt az egy órán át, 460°C-on kezelt dibenzofurán nem bizonyult reaktívnak (Katritzky et al, 1994a).…”

Section: Irodalmi áTtekintésunclassified

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Classical Organic Reactions in Pure Superheated Water

Cited by 201 publications

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Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst: New insights into RuO2 catalytic reaction mechanisms

Supercritical water gasification of RDF and its components over RuO2/γ-Al2O3 catalyst: New insights into RuO2 catalytic reaction mechanisms

Degradation Kinetics of Glucuronic Acid in Subcritical Water

Aromás vegyületek vizsgálata hévizekben és keletkezésük kísérleti modellezése

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