• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance.
【24h】

Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance.

机译：了解生物质的热化学转化以克服生物质的顽固性。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Thermochemical conversion technologies are promising pathways for producing environmentally benign, sustainable biofuels and value-added chemicals from biomass. However, reaction pathways and chemistry behind these technologies such as pyrolysis and solvolysis of biomass are very complex. Contributing to the complexity are the many factors that could affect the reaction mechanisms. This research focuses on an external effect on thermal decomposition and internal reaction chemistry to provide an insight into the biomass decomposition for better performance.;First, the effect of low concentration of oxygen in sweep gas during biomass pyrolysis in fluidized bed was investigated for practical purpose. It was found that the partial oxidative pyrolysis can increase the yield of pyrolytic sugars. A continuation of the study was performed to produce sugar-rich bio-oil from the biomass passivation of alkali and alkaline earth metals. Partial oxidative pyrolysis of passivated biomass produced approximately 21 wt% hydrolyzable sugars in bio-oil. Additionally, partial oxidative pyrolysis also prevented clogging within the reactor by reducing char agglomerations ensuring continuous operation.;Second, solvolytic conversion of lignin was studied using a micro reactor in the presence of a hydrogen donor solvent. The results showed that hydrogen donor solvents were effective in converting lignin into alkylphenols. It was found that a hydrogen donor solvent could suppress repolymerization reactions by stabilizing the primary products to alkyl-substituted phenols.;Pyrolysis mechanisms of lignin were further studied using methoxy substituted &agr;-O-4 dimeric model compounds. Pyrolysis of aryl-ether linkage primarily involved homolytic cleavage. It was discovered that methoxy group substitution on the aromatic ring increases the reactivity toward C -- O homolysis. Additionally, free radicals in the condensed phase of the pyrolysis products were detected by electron paramagnetic resonance spectroscopy, providing information on the presence of oxygen-centered phenoxy and carbon-centered benzyl radicals. Furthermore, methoxy group substitution was revealed to promote oligomerization reactions to form large molecular weight compounds.;Lastly, a quantitative investigation of free radicals in bio-oil and their potential role in condensed-phase polymerization was conducted. It was confirmed that both lignin and cellulose pyrolysis involve homolytic cleavage generating free radicals. Lignin bio-oil fractions contained a significant amount of radicals, which were found to be stable species due to highly delocalized in a pi system.
机译：热化学转化技术是从生物质生产对环境无害，可持续的生物燃料和增值化学品的有前途的途径。但是，这些技术背后的反应途径和化学反应（例如生物质的热解和溶剂分解）非常复杂。造成复杂性的因素是可能影响反应机理的许多因素。这项研究着重于对热分解和内部反应化学的外部影响，以提供对生物质分解以提高性能的认识。首先，为了实际目的研究生物质在流化床热解过程中吹扫气中低浓度氧气的影响。已发现部分氧化热解可增加热解糖的产率。进行了继续研究，以从碱金属和碱土金属的生物质钝化产生富含糖的生物油。钝化生物质的部分氧化热解在生物油中产生约21 wt％的可水解糖。另外，部分氧化热解还通过减少确保连续操作的炭结块而防止了反应器内的堵塞。第二，使用微型反应器在氢供体溶剂的存在下研究了木质素的溶剂化转化。结果表明，氢供体溶剂可有效地将木质素转化为烷基酚。发现氢供体溶剂可通过稳定初级产物为烷基取代的酚来抑制再聚合反应。木质素的热解机理进一步研究了使用甲氧基取代的-O-4二聚体模型化合物。芳基-醚键的热解主要涉及均相裂解。发现芳环上的甲氧基取代增加了对CO均裂的反应性。另外，通过电子顺磁共振波谱检测了热解产物的缩合相中的自由基，从而提供了有关以氧为中心的苯氧基和以碳为中心的苄基存在的信息。此外，揭示了甲氧基取代可促进低聚反应以形成大分子量化合物。最后，对生物油中的自由基及其在缩合聚合中的潜在作用进行了定量研究。证实木质素和纤维素热解均涉及均裂裂解产生自由基。木质素生物油馏分包含大量自由基，由于在pi系统中高度离域，它们被发现是稳定的物种。

著录项

  • 作者

    Kim, Kwang Ho.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Engineering.;Agricultural engineering.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 162 p.
  • 总页数 162
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号