Zhao Dan, Liu Xiaoqing
College of Safety Science and Engineering, Liaoning Technical University, Fuxin 123000, China.
Key Laboratory of Mine Power Disaster and Prevention of Ministry of Education, Huludao, 125105 Liaoning, China.
ACS Omega. 2022 May 9;7(20):17330-17338. doi: 10.1021/acsomega.2c01278. eCollection 2022 May 24.
To investigate the adsorption mechanism of HO, CO, and CH molecules on oxygen-containing functional groups (OFGs) in coal molecules, quantum chemical density functional theory (DFT) simulations were performed to study the partial density of states and Mulliken bond layout of HO molecules bonded to different OFGs. The adsorption energy and Mulliken charge distribution of the HO, CO, and CH molecules for each OFG were determined. The results showed that HO molecules form 2, 1, 1, and 1 hydrogen bonds with -COOH, -OH, -C=O, and -O-R groups, respectively. Double hydrogen bonds connected the HO molecules to -COOH with the smallest adsorption distances and highest Mulliken bond layout values, resulting in the strongest bonding between the HO molecules and -COOH. The most stable configuration for the adsorption of these molecules by the -OH group was when the O-H bond in the OFG served as a hydrogen bond donor and the O atom in the HO molecule served as a hydrogen bond acceptor. The order of the bonding strength between the OFGs and HO molecules was Ph-COOH > Ph-OH > Ph-C=O > Ph-O-R. The adsorption energy calculation results showed that HO molecules have a higher adsorption stability than CO and CH molecules. Compared with the -OH, -C=O, and -O-R groups, the -COOH group had a higher adsorption capacity for HO, CO, and CH molecules. The adsorption stability of the CO molecules for each OFG was higher than that of the CH molecules. From the Mulliken charge layout, it was clear that after the adsorption of the HO molecules onto the OFGs, the O atoms in the OFGs tend to gain electrons, while the H atoms involved in bonding with the HO molecules tend to lose electrons. The formation of hydrogen bonds weakens the strength of the bonds in the HO molecule and OFGs, and thus, the bond lengths were elongated.
为了研究HO、CO和CH分子在煤分子中含氧官能团（OFGs）上的吸附机理，进行了量子化学密度泛函理论（DFT）模拟，以研究与不同OFGs结合的HO分子的态密度和穆利肯键布局。确定了每个OFG的HO、CO和CH分子的吸附能和穆利肯电荷分布。结果表明，HO分子分别与-COOH、-OH、-C=O和-O-R基团形成2个、1个、1个和1个氢键。双氢键将HO分子与-COOH相连，吸附距离最小，穆利肯键布局值最高，导致HO分子与-COOH之间的键合最强。-OH基团吸附这些分子的最稳定构型是OFG中的O-H键作为氢键供体，HO分子中的O原子作为氢键受体。OFGs与HO分子之间的键合强度顺序为Ph-COOH > Ph-OH > Ph-C=O > Ph-O-R。吸附能计算结果表明，HO分子比CO和CH分子具有更高的吸附稳定性。与-OH、-C=O和-O-R基团相比，-COOH基团对HO、CO和CH分子具有更高的吸附能力。每个OFG对CO分子的吸附稳定性高于CH分子。从穆利肯电荷布局可以看出，HO分子吸附到OFGs上后，OFGs中的O原子倾向于获得电子，而与HO分子键合的H原子倾向于失去电子。氢键的形成削弱了HO分子和OFGs中的键强度，因此键长被拉长。
