Experimental study on the kinetic effect of N-butyl- N-methylpyrrolidinium tetrafluoroborate and poly(N-vinyl-caprolactam) on CH4 hydrate formation

Jun-Jie Ren; Zhi-Lin Lu; Zhen Long; Deqing Liang

doi:10.1039/c9ra10998f

Experimental study on the kinetic effect of N-butyl- N-methylpyrrolidinium tetrafluoroborate and poly(N-vinyl-caprolactam) on CH₄ hydrate formation

RSC Adv. 2020 Apr 17;10(26):15320-15327. doi: 10.1039/c9ra10998f. eCollection 2020 Apr 16.

Authors

Jun-Jie Ren^{1

2

3

4}, Zhi-Lin Lu^{1

2

3

5}, Zhen Long^{1

2

3}, Deqing Liang^{1

2

3}

Affiliations

¹ CAS Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China longzhen@ms.giec.ac.cn.
² Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou Guangdong 510640 China.
³ Guangzhou Center for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences Guangzhou 510640 China.
⁴ University of Chinese Academy of Sciences Beijing 100049 China.
⁵ Nano Science and Technology Institute, University of Science and Technology of China Suzhou Jiangsu 215123 China.

Abstract

In this work, a series of experiments were carried out to study the kinetic inhibition performance of N-butyl-N-methylpyrrolidinium tetrafluoroborate ([BMP][BF₄]), poly(N-vinylcaprolactam) (PVCap) and compound inhibitor systems on methane hydrate from both macroscopic and microscopic perspectives. In the macroscopic experiments, the influence of the concentration, the ratio of inhibitors, the subcooling on the induction time and gas consumption rate of methane hydrate were studied. The results indicated that [BMP][BF₄] could inhibit the growth rate of CH₄ hydrate, but failed to delay the nucleation. An improved inhibitory effect was observed by combining [BMP][BF₄] and PVCap, and the optimal ratio of the two inhibitors was obtained to gain the best inhibition performance. Furthermore, the microstructure and morphology of methane hydrate crystals formed in different inhibitor systems were investigated through powder X-ray diffraction (PXRD), Raman spectroscopy and scanning electron cryomicroscopy (Cryo-SEM) methods. It was found that [BMP][BF₄] and PVCap had different influences on the large cage occupancy by CH₄ and the morphology of methane hydrate.