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691.
Nickel catalysts are effective for the steam reforming of tar derived from biomass pyrolysis,but the improvement is needed in terms of activity,stability,suppression of coke deposition and aggregation,and regeneration.Our recent development of Ni-based catalysts for the steam reforming of tar is reviewed including the modification with CeO2(or MnO),trace Pt,and MgO.The role of additives such as CeO2,MnO,Pt,and MgO is also discussed. 相似文献
692.
Carina A. Esteves Costa Carlos A. Vega-Aguilar Alírio E. Rodrigues 《Molecules (Basel, Switzerland)》2021,26(15)
Lignin is the second most abundant component, next to cellulose, in lignocellulosic biomass. Large amounts of this polymer are produced annually in the pulp and paper industries as a coproduct from the cooking process—most of it burned as fuel for energy. Strategies regarding lignin valorization have attracted significant attention over the recent decades due to lignin’s aromatic structure. Oxidative depolymerization allows converting lignin into added-value compounds, as phenolic monomers and/or dicarboxylic acids, which could be an excellent alternative to aromatic petrochemicals. However, the major challenge is to enhance the reactivity and selectivity of the lignin structure towards depolymerization and prevent condensation reactions. This review includes a comprehensive overview of the main contributions of lignin valorization through oxidative depolymerization to produce added-value compounds (vanillin and syringaldehyde) that have been developed over the recent decades in the LSRE group. An evaluation of the valuable products obtained from oxidation in an alkaline medium with oxygen of lignins and liquors from different sources and delignification processes is also provided. A review of C4 dicarboxylic acids obtained from lignin oxidation is also included, emphasizing catalytic conversion by O2 or H2O2 oxidation. 相似文献
693.
生物质高压密相输送特性试验研究 总被引:3,自引:0,他引:3
生物质气流床气化技术是一项新技术,生物质加压密相输送是需要解决的关键问题之一。本文在大型中试高压密相试验装置上进行两种特殊生物质粉料的输送试验,研究物料特性和操作参数对其流动特性的影响。试验结果表明,本试验系统输送生物质稳定可靠,质量流量随着输送差压和发料罐压力的升高增大。随表观气速增大两种生物质弯管当量长度系数K近似为定值,生物质1的K值大于生物质2,且生物质1的K值随输送差压的增加而增大;两种生物质的固相摩擦系数随着体积分数和接收罐压力的增大逐渐增大。 相似文献
694.
氢气和合成气下生物质高压液化过程的实验研究 总被引:1,自引:2,他引:1
在小型高压反应釜中以四氢萘为溶剂,氢气和合成气为液化反应气,通过对不同液化条件下所得液化产物的收率及性质分析,考察了不同液化条件(反应温度、反应时间、反应气压力)对锯屑高压液化行为的影响;同时在相同液化条件下,通过液化产物收率和性质的分析,考察了气氛对锯屑高压液化行为的影响,探讨了用合成气代替氢气进行液化的可行性。结果表明,在氢气和合成气气氛下,随着反应温度的升高、反应时间的延长或反应压力的提高,液化油的收率都是增加的,但各种条件对液化油收率的影响程度不同。温度影响最大,时间影响次之,而液化气压力的影响最小。其他液化条件完全相同的情况下,氢气和合成气下所得产物的收率及性质相近,用合成气代替氢气液化具有可行性。在此条件下优化的液化反应条件为,以四氢萘为溶剂,反应温度为300℃,气体压力为2MPa,反应时间为30min,转化率为75.1%,液化油收率高达48.4%。 相似文献
695.
696.
High temperature pyrolysis of novolac resin biomass composites 总被引:1,自引:0,他引:1
Johannis Simitzis 《Journal of Analytical and Applied Pyrolysis》1994,30(2):161-171
Composites of novolac resin (N.R.) and biomass derived from olive stones (OL.B.), in various proportions, were cured with hexamethylenetetramine (HTA) and pyrolyzed up to 900°C. The pyrolysis mechanism was monitored using TGA and gas chromatography. The pyrolysis regions, as well as important pyrolysis parameters of the materials used, were determined. Cured and pyrolyzed composites of N.R./OL.B. varied from 20/80 to 75/25, exhibiting at temperatures up to approx. 600°C lower weight losses than expected by the rule of mixtures, owing to additional cross linkages of lignin with HTA. This stabilization effect vanished during pyrolysis at higher temperatures because of the breaking of other chemical bonds, e.g. cross linkages. The release of CH4 during the pyrolysis of OL.B. is derived from the lignin contained in OL.B. The other gases, CO, CO2 and H2, could be formed from celluose, hemicellulose and lignin which are the main components of OL.B. The use of N.R. in the initial mixture with OL.B. reduces the weight losses during pyrolysis compared with OL.B. alone. A heating rate of 10°C/min was necessary for the carbonization processes of OL.B. and its mixtures with N.R. in order to promote minimum weight loss of material and minimum pyrolysis time. 相似文献
697.
Erika Mészáros Emma Jakab G. Várhegyi P. Tóvári 《Journal of Thermal Analysis and Calorimetry》2007,88(2):477-482
The aim of this work was to study the thermal
decomposition of different plant species obtained from energy plantations.
Thermogravimetry/ mass spectrometry (TG/MS) experiments have been performed
with two herbaceous crops (Miscanthus sinensis,
pelletized energy grass) and two wood samples (willow, water locust) in inert
and oxidative atmospheres. Owing to the large number of data obtained in the
experiments, a chemometric tool, principal component analysis (PCA) has been
used to help the interpretation of the results. It has been found that the
thermal decomposition of the studied wood species is similar, whereas that
of the studied herbaceous samples exhibits significant differences. PCA has
been found to be useful for finding correlations between the various experimental
data. 相似文献
698.
699.
The most accurate and up-to-date approach to modeling biomass pyrolysis is to adopt the distributed activation energy model
(DAEM). In this study, a pattern search method to be used for the determination of DAEM kinetic parameters from the nonisothermal
thermogravimetric analysis (TGA) data of biomass has been introduced. The method has been applied to the nonisothermal TGA
data of peanut shell sample, and DAEM kinetic parameters of biomass samples have been determined. Calculated model results
from determined kinetic parameters have been compared with nonisothermal TGA data of biomass. 相似文献
700.