• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Spatiotemporal temperature patterns of acetylene hydrogenation in a fixed bed catalytic reactor.
【24h】

Spatiotemporal temperature patterns of acetylene hydrogenation in a fixed bed catalytic reactor.

机译：固定床催化反应器中乙炔加氢的时空温度模式

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 axial temperature profile in a catalytic packed bed reactor undergoing an exothermic reaction can attain a local maximum, which is referred to as a hot zone. Transversal hot zones (normal to the direction of bulk flow) may exist in adiabatic packed bed reactors. The localized high temperature regions may cause operational problems ranging from selectivity losses to a runaway reaction that may cause a serious safety or environmental incident.;Experiments were conducted to enhance our understanding of the formation and dynamics of transversal hot regions in a shallow, adiabatic catalytic packed bed reactor in which the hydrogenation of mixtures of acetylene and ethylene was carried out over a non-promoted palladium/alumina catalyst. Infrared imaging was utilized to determine the transversal temperature patterns on top of the shallow catalyst bed. Two qualitatively different types of non-uniform temperature patterns were observed: (a) anti-phase oscillatory patterns and (b) non-uniform stationary hot zones. The oscillatory patterns consisted of a long period (5 to 50 minutes, depending on residence time) during which the catalyst temperature was essentially at a pseudo stationary state. Then during a rather short period (∼1 to 5 minutes, depending on residence time) an anti-phase oscillation occurred, i.e. the hot region moved from one side of the catalyst bed to another and then returned to the original location. This was followed by a long period during which a pseudo stationary state existed. The temperature oscillations ranged from 3°C to 30°C. They were observed for catalyst temperatures between 78°C and 161°C and ethylene feed concentrations greater than or equal to 22.25 mol%. The oscillations were observed over the entire range of carbon monoxide tested, 0--0.05 mol%. When anti-phase oscillatory behavior did not occur, a non-uniform stationary state was observed in which one or two hot zones existed on the surface of the catalyst bed. A mathematical model is proposed that predicts spatiotemporal oscillations qualitatively similar to those observed in the experiments. The model employs a reversible, blocking mechanism to account for intermediates formed during this reaction. The model predicts that oscillations can form over a rather narrow range of parameter values.;All the experiments were performed under conditions in which the acetylene conversion to ethylene was near 100% and a substantial amount of the ethylene was hydrogenated to ethane. It is unlikely that the dynamic behavior encountered during this research will occur under the conditions employed during industrial acetylene hydrogenation as the non-uniform behavior occurred at high conversions of ethylene to ethane.
机译：经历放热反应的催化填充床反应器中的轴向温度分布可以达到局部最大值，这称为热区。绝热填充床反应器中可能存在横向热区（垂直于整体流动方向）。局部高温区域可能会导致操作问题，从选择性损失到失控反应，可能会导致严重的安全或环境事故。;进行了一些实验，以加深我们对浅热绝热催化剂中横向高温区域的形成和动力学的了解填充床反应器，其中乙炔和乙烯混合物的氢化是在非促进型钯/氧化铝催化剂上进行的。利用红外成像确定浅催化剂床顶部的横向温度模式。观察到两种在质量上不同类型的非均匀温度模式：（a）反相振荡模式和（b）非均匀静止热区。振荡模式由较长的时间段（5至50分钟，取决于停留时间）组成，在此期间催化剂温度基本处于伪稳态。然后在相当短的时间段内（约1-5分钟，取决于停留时间）发生了反相振荡，即热区从催化剂床的一侧移到另一侧，然后返回到原始位置。随后是很长一段时间，在此期间存在伪平稳状态。温度波动范围为3°C至30°C。观察到它们的催化剂温度在78℃至161℃之间，并且乙烯进料浓度大于或等于22.25mol％。在测试的一氧化碳的整个范围（0--0.05 mol％）中观察到振荡。当未发生反相振荡行为时，观察到不均匀的稳态，其中在催化剂床的表面上存在一个或两个热区。提出了一个数学模型，该模型在质量上预测时空振荡，与实验中观察到的类似。该模型采用可逆的阻断机制来解释该反应过程中形成的中间体。该模型预测，可以在相当窄的参数值范围内形成振荡。所有实验均在以下条件下进行：乙炔向乙烯的转化率接近100％，大量乙烯被氢化为乙烷。在研究中遇到的动态行为不太可能在工业乙炔加氢过程中采用的条件下发生，因为在乙烯向乙烷的高转化率下会发生不均匀行为。

著录项

  • 作者

    Pinkerton, Brian.;

  • 作者单位

    University of Houston.;

  • 授予单位 University of Houston.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 209 p.
  • 总页数 209
  • 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