水合物动力学抑制剂合成及其作用机理的分子动力学模拟

Synthesis of Hydrate Kinetic Inhibitor and Molecular Dynamics Simulation of the Mechanism

马 超 高胜天 王 诚 刘 鑫 黄晓依

MA Chao GAO Shengtian WANG Cheng LIU Xin HUANG Xiaoyi

针对现有动力学抑制剂耐受过冷度较低、对水合物生成的诱导时间短的问题，采用 N-乙烯基吡咯烷酮 （NVP）、N-乙烯基己内酰胺（NVCL）、甲基丙烯酸二甲氨乙酯（DMAEMA）3种单体，制备了水合物动力学抑制剂 P（NVP-g-NVCL-g-DMAEMA）；以模拟天然气水合物抑制过程中的过冷度和诱导时间为指标，优化了合成条件； 用红外光谱仪表征了产物结构，利用分子动力学模拟软件模拟抑制过程，揭示水合物动力学抑制剂的作用机 理。结果表明，NVP、NVCL、DMAEMA单体质量比为8∶20∶1，引发剂（过硫酸铵、亚硫酸氢钠质量比为1∶1）为单 体总质量的0.5%，反应温度65 ℃，反应时间6 h为最佳反应条件且产物为目标产物。当该条件下合成的抑制剂 加量为1.0%时，常压条件下可将水合物形成的过冷度从2.6 ℃提高到9.6 ℃，诱导时间从20 min延长至945 min。 该抑制剂的作用机理主要是通过分子链上五元环及七元环上的双键氧和酯基上的双键氧与水分子形成氢键吸 附从而抑制水合物的生成，其次分子链上的氮原子也可以形成氢键而吸附；另外，抑制剂的空间位阻也会阻碍水 合物分子的聚集进而抑制水合物的结晶。该抑制剂不仅带有可形成氢键的活性基团，增强抑制剂对水合物笼的 吸附性，还存在能影响甲烷分子运动及分布状态的烷基链，进一步提高过冷度并延长诱导时间。

Aiming at the limitations of conventional kinetic inhibitors，such as low tolerance to subcooling and short induction time in hydrate formations，a novel kinetic inhibitor P（NVP-g-NVCL-g-DMAEMA）was synthesized from N-vinylpyrrolidone（NVP）， N-vinylcaprolactam（NVCL）and dimethylaminoethyl methacrylate（DMAEMA）. The supercooling degree and induction time in the simulated gas hydrate inhibition processes were used as indexes to optimize the synthetic parameters. The product structure was characterized using infrared spectroscopy，while molecular dynamics simulation software extensively simulated the inhibition process and revealed the mechanism of hydrate kinetic inhibitors. The results showed that the optimum reaction condition was obtained as follows：8∶20∶1 mass ratio of NVP，NVCL and DMAEMA，0.5% initiator（1∶1 mass ratio of ammonium persulfate and sodium bisulfite）in total mass of monomer，65 ℃ reaction temperature and 6 h reaction time. When the mass fraction of inhibitor was 1.0%，the supercooling degree of hydrate formation increased from 2.6 ℃ to 9.6 ℃ under atmospheric pressure， meanwhile the induction time extended from 20 min to 945 min. The inhibition mechanism was mainly driven by inhibiting the formation of hydrate via hydrogen bond adsorption between the carbonyl groups on the five-membered ring or the seven-membered ring of molecular chain，as well as that on the ester group，and the water molecule. Nitrogen atoms on the molecular chain also formed hydrogen bonds and contributed to the adsorption. Furthermore，the steric hindrance of inhibitor also prevented the aggregation of hydrate molecules and thus inhibited the crystallization of hydrate. The kinetic inhibitor not only had active groups that could form hydrogen bonds to enhance the adsorption of inhibitor on hydrate cage，but also had alkyl chains that could affect the movement and distribution of methane molecules，further improving the supercooling degree and prolonging the induction time.

10.19346/j.cnki.1000-4092.2024.02.011