• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetic study on disproportionations of C1 aldehydes in supercritical water: Methanol from formaldehyde and formic acid
【24h】

Kinetic study on disproportionations of C1 aldehydes in supercritical water: Methanol from formaldehyde and formic acid

机译：超临界水中C1醛歧化的动力学研究：甲醛和甲酸制甲醇

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

The reaction pathways and kinetics of C1 aldehydes, formaldehyde (HCHO) and formic acid (HCOOHHOCHO), are studied at 400 degrees C in neat condition and in supercritical water over a wide range of water density, 0.1-0.6 g/cm(3). Formaldehyde exhibits four reactions: (i) the self-disproportionation of formaldehyde generating methanol and formic acid, (ii) the cross-disproportionation between formaldehyde and formic acid generating methanol and carbon dioxide, (iii) the water-independent self-disproportionation of formaldehyde generating methanol and carbon monoxide, and (iv) the decarbonylation of formaldehyde generating hydrogen and carbon monoxide. The self- and cross-disproportionations overwhelm the water-independent self-disproportionation and the formaldehyde decarbonylation. The rate constants of the self- and cross-disproportionations are determined in the water density range of 0.1-0.6 g/cm(3). The rate constant of the cross-disproportionation is 2-3 orders of magnitude larger than that of the self-disproportionation, which indicates that formic acid is a stronger reductant than formaldehyde. Combining the kinetic results with our former computational study on the equilibrium constants of the self- and cross-disproportionations, the reaction mechanisms of these disproportionations are discussed within the framework of transition-state theory. The reaction path for methanol production can be controlled by tuning the water density and reactant concentrations. The methanol yield of similar to 80% is achieved by mixing formaldehyde with formic acid in the ratio of 1:2 at the water density of 0.4 g/cm(3).
机译：C1醛，甲醛（HCHO）和甲酸（HCOOHHOCHO）的反应途径和动力学在400°C的纯条件下和超临界水中在0.1-0.6 g / cm的宽水密度范围内进行了研究（3） 。甲醛表现出四个反应：（i）甲醛产生的甲醇和甲酸的自歧化，（ii）甲醛与甲酸产生的甲醇和二氧化碳的交叉歧化，（iii）甲醛的水不依赖于自身的歧化生成甲醇和一氧化碳，以及（iv）甲醛的脱羰生成氢和一氧化碳。自歧化和交叉歧化压倒了与水无关的自歧化和甲醛脱羰作用。自歧化和交叉歧化的速率常数在0.1-0.6 g / cm（3）的水密度范围内确定。交叉歧化的速率常数比自歧化的速率常数大2-3个数量级，这表明甲酸是比甲醛强的还原剂。将动力学结果与我们先前对自歧化和交叉歧化的平衡常数的计算研究相结合，在过渡态理论的框架内讨论了这些歧化的反应机理。可以通过调节水密度和反应物浓度来控制甲醇生产的反应路径。通过将甲醛和甲酸以1：2的比例在0.4 g / cm（3）的水密度下混合，可以达到接近80％的甲醇产率。

著录项

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