Study on the growth kinetics of methane hydrate in pure water system containing ZIF-8

Xiaofang Lv; Boyu Bai; Shangbin Liang; Wenguang Zeng; Yang Liu; Qianli Ma; Haifeng Zhang; Chuanshuo Wang; Shidong Zhou

doi:10.1039/d2ra03768h

Study on the growth kinetics of methane hydrate in pure water system containing ZIF-8

RSC Adv. 2022 Aug 1;12(33):21203-21212. doi: 10.1039/d2ra03768h. eCollection 2022 Jul 21.

Authors

Xiaofang Lv^{1

2}, Boyu Bai¹, Shangbin Liang², Wenguang Zeng², Yang Liu¹, Qianli Ma¹, Haifeng Zhang³, Chuanshuo Wang¹, Shidong Zhou¹

Affiliations

¹ Jiangsu Key Laboratory of Oil and Gas Storage & Transportation Technology, Changzhou University Changzhou 213016 China lvxiaofang5@cczu.edu.cn liu.y@cczu.edu.cn +86 0519-8633-0860.
² China Petroleum & Chemical Corporation Northwest Oilfield Branch, Petroleum Engineering Technology Research Institute Urumqi 830011 China.
³ Research Institute of Tsinghua Pearl River Delta Guangzhou 510700 China.

Abstract

The hydrate formation rate is the key to the implementation of solid gas storage and transportation technology by the hydrate method. As a MOF material with strong hydrothermal stability, ZIF-8 has been proved to play a significant role in promoting the nucleation and growth of hydrate. However, the growth kinetics promotion mechanism and growth law of methane hydrate in the ZIF-8 promoter system have not been clarified at present. Therefore, the growth kinetics experiment of methane hydrate in the ZIF-8 promoter system was carried out in a high-pressure visualization reactor to systematically study the effects of the ZIF-8 concentration, undercooling degree, and pressure on the growth law of methane hydrate. The experimental results showed that: (1) the concentration of ZIF-8 had a significant shortening effect on the induction period of methane hydrate. With the increase in the ZIF-8 concentration, the induction time of methane hydrate was shortened from 5.85 h to 0.85 h. The methane gas consumption showed a gradually increasing trend at first, and then with the reaction going on, a dense hydrate film was formed at the gas-liquid interface, which increased the mass transfer resistance, resulting in the increase in the methane gas consumption gradually becoming stable. There were four stages in the growth process of hydrate, namely rapid formation, slow formation, secondary formation, and end formation and the optimal dosage of ZIF-8 promoter exists, and the optimal critical specific content was 0.02 mg mL^-1. (2) With the increase of undercooling, the induction time of methane hydrate decreased significantly, and the increase in the methane consumption also showed an increasing trend at first and then decreased. (3) With the increase of the system pressure to 7 MPa, the induction time of methane hydrate decreased from 1.02 h at 6 MPa to 0.2 h at 7 MPa, and the decrease rate was 80.8%, which was mainly due to the presence of "OPEN GATE" in the ZIF-8 accelerator. With the increase of the system pressure, the pore opening of the ZIF-8 material increased, the adsorption of methane increased, and the nucleation and growth of methane hydrate were promoted.