Knetics and product distributions of cellulose decomposition in near-critical water were studied with a continuous flow-type apparatus for supercritical and near-critical water reactions.The experimental temperature r...Knetics and product distributions of cellulose decomposition in near-critical water were studied with a continuous flow-type apparatus for supercritical and near-critical water reactions.The experimental temperature range was from 513?K to 583?K and residence time from 0.5?min to 1.6?min.The effects of temperature and residence time on cellulose residue were demonstrated.The apparent actiation energy evaluated was 147?kJ·mol -1 .In addition,the effects of temperature and residence time on the yield distributions of wter soluble oligomers,glucose and levulose,pyruvic aldehyde,5-hydroxymethyl furfural,furfural were described in detail.The experimental results showed that selective decomposition of cellulose in near critical water was possible.展开更多
模拟氮(N)沉降对凋落物分解特征的影响对研究森林生态系统物质循环响应大气N沉降的内在机理和应对N沉降全球化具有重要意义。从2018年2月至2019年1月,对滇中亚高山常绿阔叶林(Evergreen broad-leaf forest)和高山栎林(Quercus semecarpi...模拟氮(N)沉降对凋落物分解特征的影响对研究森林生态系统物质循环响应大气N沉降的内在机理和应对N沉降全球化具有重要意义。从2018年2月至2019年1月,对滇中亚高山常绿阔叶林(Evergreen broad-leaf forest)和高山栎林(Quercus semecarpifolia forest)两种地带性植被进行模拟N沉降试验,利用尼龙网袋法对两种林型凋落叶和凋落枝进行原位分解试验,N沉降处理水平分别为对照CK(Control check, 0 g N m^(-2) a^(-1))、低氮LN(Low nitrogen, 5 g N m^(-2) a^(-1))、中氮MN(Medium nitrogen, 15 g N m^(-2) a^(-1))和高氮HN(High nitrogen, 30 g N m^(-2) a^(-1))。结果表明:常绿阔叶林凋落叶和凋落枝分解率分别为44.84%和21.96%,均高于高山栎林的35.97%(凋落叶)和17.51%(凋落枝);N沉降处理使得常绿阔叶林和高山栎林的凋落叶和凋落枝质量损失95%的时间在对照(CK)的基础上均有一定程度的增加,其中以HN处理下最为显著;经过1年的分解,两种林型凋落叶、枝纤维素和木质素降解均受到N沉降的抑制作用;两种林型中凋落物质量残留率、纤维素和木质素残留率三者间呈极显著正相关。针对滇中亚高山区域范围内的两种地带性植被,凋落物分解对N沉降的响应方向主要取决于凋落物基质质量,其中尤以纤维素和木质素为重要影响因素。展开更多
A pilot-scale apparatus for continuous supercritical and near-critical water reaction was set up. A high-pressure slurry supplying system was developed to feed the solid material-water slurries. The apparatus features...A pilot-scale apparatus for continuous supercritical and near-critical water reaction was set up. A high-pressure slurry supplying system was developed to feed the solid material-water slurries. The apparatus features temperature up to 600℃, pressure up to 40MPa, residence time from 24s to 15min, maximum amount of slurry supply of 2.4 L·h-1, maximum solid content of slurry up to 10%(by mass) for cellulose from Merck, and resistance to corrosion. Long-time runs of decomposition of cellulose were carried out and steady runs were confirmed. Kinetics of cellulose decomposition was studied. The apparent activation energy evaluated was 147kJ·mol-1. In addition, a new three-step pathway for cellulose hydrolysis was proposed. The derived kinetic equation is in good agreement with the experimental data.展开更多
文摘Knetics and product distributions of cellulose decomposition in near-critical water were studied with a continuous flow-type apparatus for supercritical and near-critical water reactions.The experimental temperature range was from 513?K to 583?K and residence time from 0.5?min to 1.6?min.The effects of temperature and residence time on cellulose residue were demonstrated.The apparent actiation energy evaluated was 147?kJ·mol -1 .In addition,the effects of temperature and residence time on the yield distributions of wter soluble oligomers,glucose and levulose,pyruvic aldehyde,5-hydroxymethyl furfural,furfural were described in detail.The experimental results showed that selective decomposition of cellulose in near critical water was possible.
文摘模拟氮(N)沉降对凋落物分解特征的影响对研究森林生态系统物质循环响应大气N沉降的内在机理和应对N沉降全球化具有重要意义。从2018年2月至2019年1月,对滇中亚高山常绿阔叶林(Evergreen broad-leaf forest)和高山栎林(Quercus semecarpifolia forest)两种地带性植被进行模拟N沉降试验,利用尼龙网袋法对两种林型凋落叶和凋落枝进行原位分解试验,N沉降处理水平分别为对照CK(Control check, 0 g N m^(-2) a^(-1))、低氮LN(Low nitrogen, 5 g N m^(-2) a^(-1))、中氮MN(Medium nitrogen, 15 g N m^(-2) a^(-1))和高氮HN(High nitrogen, 30 g N m^(-2) a^(-1))。结果表明:常绿阔叶林凋落叶和凋落枝分解率分别为44.84%和21.96%,均高于高山栎林的35.97%(凋落叶)和17.51%(凋落枝);N沉降处理使得常绿阔叶林和高山栎林的凋落叶和凋落枝质量损失95%的时间在对照(CK)的基础上均有一定程度的增加,其中以HN处理下最为显著;经过1年的分解,两种林型凋落叶、枝纤维素和木质素降解均受到N沉降的抑制作用;两种林型中凋落物质量残留率、纤维素和木质素残留率三者间呈极显著正相关。针对滇中亚高山区域范围内的两种地带性植被,凋落物分解对N沉降的响应方向主要取决于凋落物基质质量,其中尤以纤维素和木质素为重要影响因素。
基金supported by the National Natural Science Foundation of China (20876055, 21076085)Fundamental Research Funds for the Central Universities, SCUT, China~~
基金Partly supported by Research for Future Program"Integrated field 5,causes and effects of environmental loading and its reduction",the Japan Society for the Promotion of Science(JSPS).
文摘A pilot-scale apparatus for continuous supercritical and near-critical water reaction was set up. A high-pressure slurry supplying system was developed to feed the solid material-water slurries. The apparatus features temperature up to 600℃, pressure up to 40MPa, residence time from 24s to 15min, maximum amount of slurry supply of 2.4 L·h-1, maximum solid content of slurry up to 10%(by mass) for cellulose from Merck, and resistance to corrosion. Long-time runs of decomposition of cellulose were carried out and steady runs were confirmed. Kinetics of cellulose decomposition was studied. The apparent activation energy evaluated was 147kJ·mol-1. In addition, a new three-step pathway for cellulose hydrolysis was proposed. The derived kinetic equation is in good agreement with the experimental data.
