Kelland Malcolm A, Dirdal Erik G, Knutsen Cecilie Meidell
Department of Chemistry, Bioscience and Environmental Engineering, Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger, Norway.
ACS Omega. 2024 Mar 7;9(11):12956-12966. doi: 10.1021/acsomega.3c09260. eCollection 2024 Mar 19.
Kinetic hydrate inhibitors (KHIs) are a chemical method of preventing gas hydrate plugging of oil and gas production flow lines. The main ingredient in a KHI formulation is one or more water-soluble amphiphilic polymers. Poly(-vinyl caprolactam) (PVCap) is an unbranched polymer and a well-known industrial KHI, often used as a yardstick to compare the performance of new polymers. The effect of branching PVCap on KHI performance has been investigated by polymerizing the VCap monomer in the presence of varying amounts of trimethylolpropane triacrylate, pentaerythritol tetraacrylate, or bis-pentaerythritol hexaacrylate cross-linkers to give PVCap polymers with 3, 4, and 6 branches, respectively. If the ratio of cross-linker to VCap was too high (6:1 to 8:1), gelling and/or poor water solubility was observed, giving short polymer chains and poor KHI efficacy. For higher ratios (30:1 to 60:1), it was found that the concentration of the polymer needed to give total inhibition of structure II tetrahydrofuran hydrate crystal growth could be lowered by using tribranched rather than linear PVCap. Slow constant cooling (1 °C/h) gas hydrate experiments with a synthetic natural gas in steel rocking cells at 76 bar were also carried out. A small improvement in KHI performance was observed for one of the branched PVCaps compared with a linear PVCap. Branched and linear poly(-isopropylmethacrylamide) (PNIPMAm) polymers were also investigated in the gas hydrate system, but there was no benefit observed when branching this polymer class.
动力学水合物抑制剂（KHIs）是防止油气生产流线中气体水合物堵塞的一种化学方法。KHI配方中的主要成分是一种或多种水溶性两亲聚合物。聚（乙烯基己内酰胺）（PVCap）是一种无支链聚合物，是一种著名的工业KHI，常被用作比较新型聚合物性能的标准。通过在不同量的三羟甲基丙烷三丙烯酸酯、季戊四醇四丙烯酸酯或双季戊四醇六丙烯酸酯交联剂存在下使VCap单体聚合，分别得到具有3、4和6个支链的PVCap聚合物，研究了PVCap支化对KHI性能的影响。如果交联剂与VCap的比例过高（6:1至8:1），则会观察到凝胶化和/或水溶性差，导致聚合物链短且KHI功效不佳。对于更高的比例（30:1至60:1），发现通过使用三分支而非线性PVCap，可以降低完全抑制结构II四氢呋喃水合物晶体生长所需的聚合物浓度。还在76巴的钢摇床中用合成天然气进行了缓慢恒定冷却（1℃/小时）气体水合物实验。与线性PVCap相比，其中一种支化PVCap的KHI性能有小幅提高。还在气体水合物体系中研究了支化和线性聚（异丙基甲基丙烯酰胺）（PNIPMAm）聚合物，但在支化这类聚合物时未观察到益处。
