Pyrolysis mechanism of carbon matrix precursor cyclohexane--the formation of condensed-ring aromatics and the growing process of molecules.
Based on the experiments, the UAM1 method was adopted to investigate benzene condensation of an important intermediate and the molecule growing mechanism during the cyclohexane pyrolysis process. The conclusions were drawn as follows: (1) from the viewpoint of thermodynamics, the condensation of benzene and C4H5* is a spontaneous reaction and the rising temperature will increase the spontaneous tendency of the reaction. (2) From the viewpoint of kinetic, the condensation of benzene and C4H5* is a two-step reaction. The rate-determining step is step 2 of hydrogen removal from intermediate C10H10 (I1) with the activation energy of 350.61 kJ/mol below 1473 K while the rate-determining step is step 1 that free radical C4H5* attacks benzene to form intermediate C10H10 (I1) with the activation energy DeltaE(0)(not equal to theta)=31.74 kJ/mol above 1473 K. (3) The space structure, electronic structure and thermodynamics parameters of molecular reaction of dense-ring aromatizing compounds can be used to replace the resonance energy and free valence to judge the activation of thermodynamic reaction of compounds. And (4) the analysis of the space structure, electronic structure and thermodynamic parameters show that the growing process of molecules with benzene used as initial reactants becomes more easier as the multi-ring aromatizing molecular system increases.
Wang
Hui
H
Chemistry Department, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, Northwest University, Xian 710069, PR China. huiwang@nwu.edu.cn
Yang
Haifeng
H
Chuang
Wang
W
Ran
Xinquan
X
Shi
Qizhen
Q
Wen
Zhenyi
Z
D001554:Benzene / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D013816:Thermodynamics
D003510:Cyclohexanes; C506365:Cyclohexane; D002244:Carbon; D001554:Benzene