CIESC Journal ›› 2022, Vol. 73 ›› Issue (12): 5427-5437.DOI: 10.11949/0438-1157.20221301

• Catalysis, kinetics and reactors • Previous Articles     Next Articles

Effect of oxygen concentration on homogeneous/heterogeneous coupled reaction characteristics of methane in microchannel

Xiao YANG(), Rui DING, Mohan LI, Zhengchang SONG   

  1. School of Low-Carbon Energy and Power Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
  • Received:2022-09-27 Revised:2022-11-06 Online:2023-01-17 Published:2022-12-05
  • Contact: Xiao YANG

氧浓度对微通道内甲烷均相/非均相耦合反应特性的影响

杨霄(), 丁锐, 李墨含, 宋正昶   

  1. 中国矿业大学低碳能源与动力工程学院,江苏 徐州 221116
  • 通讯作者: 杨霄
  • 作者简介:杨霄(1993—),男,博士,准聘副教授,yangxiao@cumt.edu.cn
  • 基金资助:
    江苏省自然科学基金项目(BK20210509);国家自然科学基金项目(52206185);中央高校基本科研业务费专项资金资助项目(2022QN1085)

Abstract:

Based on the detailed homogeneous and heterogeneous reaction mechanisms of methane, the catalytic combustion process of methane in a planar microchannel was simulated, and the effect of inlet oxygen concentration on the coupled reaction characteristics and its regulation mechanism were analyzed. The results show that the increase of oxygen concentration causes the exothermic position of the homogeneous and heterogeneous reactions of methane to move to the inlet side, shortening the homogeneous ignition distance and broadening the stable combustion range. At a fixed methane concentration at the inlet, increasing O2 concentration lowers the equivalence ratio of mixture and changes the competition mechanism between homogeneous and heterogeneous reactions for reactant O2; the combined effect of O2 concentration and equivalence ratio changes the adsorption and desorption behavior of gas radicals. The increase of O2 concentration promotes the homogeneous reaction consumption of CH4 and H radicals and also inhibits the heterogeneous reaction rate of CH4 and H on the catalytic surface. With the increase of O2 concentration, the rates of O2, and intermediate gas phase products CO and H2 participating in the heterogeneous reaction first increase and then decrease.

Key words: microscale combustion, methane, catalysis, microchannels, oxygen concentration, reaction kinetics

摘要:

基于详细的甲烷均相与非均相反应机理,对平板微通道内甲烷催化燃烧反应过程模拟,探究入口氧浓度变化对耦合反应特性的影响与调控机制。结果表明,氧浓度升高导致甲烷均相与非均相反应放热位置向入口侧移动,缩短均相着火距离,拓宽稳燃范围。固定入口甲烷浓度,氧浓度升高导致化学当量比降低,同时也改变了均相/非均相反应对反应物O2的竞争机制;氧浓度与化学当量比共同作用改变了气相自由基的吸附与脱附行为。增加O2浓度促进CH4和H自由基的均相反应消耗同时抑制CH4和H的非均相反应速率。随着O2浓度的升高,O2以及中间产物CO和H2参与非均相反应速率先升高后降低。

关键词: 微尺度燃烧, 甲烷, 催化, 微通道, 氧气浓度, 反应动力学

CLC Number: