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|Title:||Influence of selected mineral acids and alkalis on cellulose pyrolysis pathways and anhydrosaccharide formation|
|Source:||Shaik, S.M., Sharratt, P.N., Tan, R.B.H. (2013-11). Influence of selected mineral acids and alkalis on cellulose pyrolysis pathways and anhydrosaccharide formation. Journal of Analytical and Applied Pyrolysis 104 : 234-242. ScholarBank@NUS Repository. https://doi.org/10.1016/j.jaap.2013.07.010|
|Abstract:||The primary/initial thermal degradation pathway is via intermolecular transglycosylation reactions within the glucose monomers of cellulose. Formation of liquid tar from cellulose can also occur via β-elimination. Under this mechanism, volatile acids (e.g. carboxylic acids) formed from the initial cellulose decomposition are able to attack the remaining cellulose as Bronsted acids thus catalysing heterolytic (ring-opening) reactions. Here, we have studied the effects of acids (H2SO4, H3PO 4, H3BO3) and alkalis (Ca(OH)2, NH4OH) on the yields of levoglucosan and its derivatives (levoglucosenone, 1,4:3,6-dianhydro-α-d-glucopyranose, 1,6-anhydro-β-d-glucofuranose). It was found that the acids generally decreased the total amount of anhydrosaccharides whilst cellulose infused with the alkalis had increased anhydrosaccharide yields. The results indicate that the β-elimination pathway was catalysed by the presence of acidic species (e.g. H+ ions). The extent of cellulose conversion via the β-elimination pathway was dependant on the amount and strength of acid infused within the cellulose matrix. However, the β-elimination route could also be suppressed or controlled by the introduction of a neutralising species (e.g. OH- ions). © 2013 Elsevier B.V. All rights reserved.|
|Source Title:||Journal of Analytical and Applied Pyrolysis|
|Appears in Collections:||Staff Publications|
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