Enthalpies of Formation and C—C Bond Dissociation Energies of C1-C14 Alkanes and Alkyl Radicals Calculated via Density Functional Theory Methods
WANG Feng
a,b,
,
REN Jie
a,
,
LI Yong-Wang
a,
,
1.
a State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001;
2.
b Graduate School of Chinese Academy of Sciences, Beijing
Corresponding author:
李永旺,男,博士,研究员;E-mail:wfchem@sxicc.ac.cn;研究方向:计算机工业化学及化学反应工程
Received Date:
15 December 2008
Fund Project:
国家杰出青年科学基金(20625620)资助项目
Abstract:
Enthalpies of formation and bond dissociation energies(BDE) of n-alkanes and the corresponding radicals of up to 14 carbons,involved in pyrolysis of Fischer-Tropsch naphtha were calculated using various density functional theory(DFT) methods.It was found that the MPW1B95/6-311G(d,p) method was the best in term of accuracy among the methods evaluated,including B97-1,BB1K,B1B95,MPWB1K and MPW1B95.On the basis of this good performance,the MPW1B95/6-311G(d,p) method was used for the estimation of large n-alkanes and their resulting radicals.C—C BDEs of n-alkanes were also examined.The enthalpies of formation of n-alkanes and the radicals had deviations of 0.8 and 2.7 kJ/mol respectively compared with experimental data.For C—C BDEs of n-alkanes,this method predicted the results with a mean absolute deviation of 3.1 kJ/mol.It is noted that by means of the MPW1B95/6-311G(d,p) method the enthalpies of formation can be calculated satisfactorily and the C—C BDEs and their change trend can be predicted reasonably.
Key words:
density functional theory
/
bond dissociation energy
/
enthalpy of formation
/
n-alkane
/
alkyl radical