Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions

The paper reports the cellobiose hydrothermal decomposition at 200–250 °C under non-catalytic (with an initial pH close to 7) and weakly acidic conditions (with an initial pH of 4–6). It was found cellobiose decomposition under both non-catalytic and weakly acidic conditions follows similar primary...

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Main Authors: Mohd Shafie, Zainun, Yu, Yun, Wu, Hongwei
Format: Journal Article
Published: Elsevier Ltd 2015
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/19118
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author Mohd Shafie, Zainun
Yu, Yun
Wu, Hongwei
author_facet Mohd Shafie, Zainun
Yu, Yun
Wu, Hongwei
author_sort Mohd Shafie, Zainun
building Curtin Institutional Repository
collection Online Access
description The paper reports the cellobiose hydrothermal decomposition at 200–250 °C under non-catalytic (with an initial pH close to 7) and weakly acidic conditions (with an initial pH of 4–6). It was found cellobiose decomposition under both non-catalytic and weakly acidic conditions follows similar primary decomposition pathways, i.e., isomerization and hydrolysis reactions being the main primary reactions. However, cellobiose decomposition under acidic conditions decreases the selectivities of isomerization reactions but increases the selectivity of hydrolysis reaction. While the rate constants of isomerization reactions under various pH conditions are found to be similar, that of hydrolysis reaction increases significantly with reducing the initial pH of the solution. Therefore, the acceleration of cellobiose decomposition under acidic conditions is mainly due to the increased contribution of hydrolysis reaction. Further analysis suggests that the rate constant of hydrolysis reaction is dependent on the hydrogen ion concentration of the solution at reaction temperature. A kinetic model was then developed, considering the isomerization and hydrolysis reactions. The model can well predict the cellobiose hydrothermal decomposition under various initial pH conditions at low temperatures (i.e., <225 °C). However, the model underestimates the rate constant of cellobiose hydrothermal decomposition at higher temperatures (i.e., 250 °C), suggesting the increased contribution of other reactions (e.g., reversion reactions) under the conditions.
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publishDate 2015
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spelling curtin-20.500.11937-191182017-09-13T15:42:43Z Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions Mohd Shafie, Zainun Yu, Yun Wu, Hongwei Biofuel Acidic conditions Hydrothermal Isomerization Cellobiose The paper reports the cellobiose hydrothermal decomposition at 200–250 °C under non-catalytic (with an initial pH close to 7) and weakly acidic conditions (with an initial pH of 4–6). It was found cellobiose decomposition under both non-catalytic and weakly acidic conditions follows similar primary decomposition pathways, i.e., isomerization and hydrolysis reactions being the main primary reactions. However, cellobiose decomposition under acidic conditions decreases the selectivities of isomerization reactions but increases the selectivity of hydrolysis reaction. While the rate constants of isomerization reactions under various pH conditions are found to be similar, that of hydrolysis reaction increases significantly with reducing the initial pH of the solution. Therefore, the acceleration of cellobiose decomposition under acidic conditions is mainly due to the increased contribution of hydrolysis reaction. Further analysis suggests that the rate constant of hydrolysis reaction is dependent on the hydrogen ion concentration of the solution at reaction temperature. A kinetic model was then developed, considering the isomerization and hydrolysis reactions. The model can well predict the cellobiose hydrothermal decomposition under various initial pH conditions at low temperatures (i.e., <225 °C). However, the model underestimates the rate constant of cellobiose hydrothermal decomposition at higher temperatures (i.e., 250 °C), suggesting the increased contribution of other reactions (e.g., reversion reactions) under the conditions. 2015 Journal Article http://hdl.handle.net/20.500.11937/19118 10.1016/j.fuel.2015.05.023 Elsevier Ltd restricted
spellingShingle Biofuel
Acidic conditions
Hydrothermal
Isomerization
Cellobiose
Mohd Shafie, Zainun
Yu, Yun
Wu, Hongwei
Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title_full Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title_fullStr Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title_full_unstemmed Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title_short Effect of initial pH on hydrothermal decomposition of cellobiose under weakly acidic conditions
title_sort effect of initial ph on hydrothermal decomposition of cellobiose under weakly acidic conditions
topic Biofuel
Acidic conditions
Hydrothermal
Isomerization
Cellobiose
url http://hdl.handle.net/20.500.11937/19118