Catalytic effect of calcium on reaction of phenol using reactive molecular dynamics simulation

HONG Dikun1 CAO Zheng1 YANG Changmin1 LIU Liang1 GUO Xin1

(1.State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, Hubei, China 430074)
【Knowledge Link】kinetics

【Abstract】The process of calcium-catalyzed secondary reaction of coal pyrolysis tar is complicated, and it is difficult to deeply explore its mechanism through experimental research methods. The effect of calcium on the reaction of phenol (tar model compound) is studied using ReaxFF molecular dynamics simulations. The results show that calcium promotes the reaction rate of phenol, and promotes the conversion of phenol to gaseous, heavy tar and coke products. At low temperatures, very little amount of gas-Ca is observed. Ca is mainly involved in a repeated bond-breaking and bond-forming process between tar and coke. Ca species only promotes the polymerization of phenol at the low temperatures. While at high temperatures, a large amount of Ca is released in the form of gas-Ca, promoting the cracking of phenol. Ca promotes the production of H2, but has little effect on the production of CO. The activation energy for the polymerization and cracking of phenol are determined to be 52.96 kcal/mol and 16.08 kcal/mol respectively in the absence of Ca, compared to 37.33 kcal/mol and 13.34 kcal/mol respectively in the presence of Ca. This means that the role of Ca in reducing the activation energy for phenol polymerization is much more significant than that for phenol cracking reactions.

【Keywords】 pyrolysis; phenol; catalytic; ReaxFF; kinetics;

【Funds】 National Natural Science Foundation of China (51876073)

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This Article

ISSN:0438-1157

CN: 11-1946/TQ

Vol 70, No. 05, Pages 1788-1794

May 2019

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Abstract

  • Introduction
  • 1 Simulation methods
  • 2 Results and discussion
  • 3 Conclusion
  • References