A Study on Inhibition Performance of Mercaptoalcohols As Corrosion Inhibitors by First Principle and Molecular Dynamics
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TRUCTURE OF MATTER AND QUANTUM CHEMISTRY
A Study on Inhibition Performance of Mercaptoalcohols As Corrosion Inhibitors by First Principle and Molecular Dynamics Simulation Yuanqiang Zhua,b, Qingqing Suna, Yuan Wanga, Junlei Tanga,b,c,*, and Yingying Wanga a School
of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, 610500 China Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Chengdu, 610500 China c State Key Laboratory of Oil and Gas Reservior Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500 China * e-mail: [email protected] b
Received August 19, 2019; revised February 19, 2020; accepted March 17, 2020
Abstract—The structure–activity relationship of ten mercaptoalcohol molecules as corrosion inhibitors for carbon steel was investigated through quantum chemistry calculation and molecular dynamics simulation (MD). Quantum chemical parameters including the energy of the highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO), energy gap (ΔE), electronegativity (χ) have been calculated to investigate the relationship between the corrosion inhibition performance and the molecular structure. Quantum chemical parameters show the corrosion inhibition performance is strengthened with the lengthening of the carbon chain. The theoretical inhibition efficiency increases with the increasing of the length of carbon chain. As a result, the C_11 molecule presents the best corrosion inhibition performance among the studied molecules. At the same time, molecular dynamics simulation results indicate that both the –SH and –OH can be adsorbed onto the Fe (1 1 0) surface and the molecular plane is parallel to the Fe (1 1 0) surface. The absolute values of the adsorption energy increases with the lengthening of the carbon chain. According to the adsorption energy, the longer of the carbon chain is, the easier it is for molecule to be adsorbed onto the Fe (1 1 0) surface. As a result, the corrosion inhibition performance of the mercaptoalcohol molecules becomes better with the lengthening of the carbon chain, and the C_11 molecule is the best one. Keywords: corrosion inhibition performance, mercaptoalcohol, first principle, molecular dynamics simulation, structure–activity relationship DOI: 10.1134/S0036024420090356
INTRODUCTION Carbon steel is widely used in oil and gas industry for its relatively low cost, good machining performance. However, the harsh environment in the oil and gas field is likely to cause steel corrosion. Therefore, the study and development of corrosion inhibitor is of great significance [1–3]. Generally speaking, organic compounds containing heteroatoms (such as N, O, S, etc.) and π electrons have good corrosion inhibition performance [4–7] by forming a protective film on the metal surface [9, 10]. Thiol as a kind of corrosion inhibitor has been studied for several decades [11, 12]. Cakir [13] proposed in his study that the inhibition performance of thiol is due to the fact that it can be adsorbed
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