Metastable state of gas hydrate during decomposition: A novel phenomenon

• Published in: Chinese journal of chemical engineering Vol. 28; no. 4; pp. 949 - 954
• Main Authors: Sun, Ronghui, Fan, Zhen, Yang, Lei, Li, Yuanping, Lü, Xin, Miao, Yang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2020; Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116023, China%School of Chemistry, University of Glasgow, Glasgow G128QQ, United Kingdom%Institute of Science and Technology, Shenzhen Branch, China National Offshore Oil Corporation, Guangzhou 510420, China%CNOOC Research Institute Co. Ltd, Beijing 100028, China%Xingang Shipbuilding Heavy Industry Co., Ltd., Tianjin 300452, China
• Subjects: Dissociation; Hydrates; Metastability; Self-preservation; Supersaturation; Self-preservation; Supersaturation; Dissociation; Hydrates; Metastability
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/j.cjche.2020.02.003

Natural gas hydrates are solid compounds with cage-like structures formed by gas and water. An intriguing phenomenon that gas hydrates can dissociate at a low rate below the ice freezing point has been viewed as the metastability of hydrate. The mechanisms of hydrate metastability have been widely studied, and many mechanisms were proposed involving the self-preservation effect, supercooled water-gas-hydrate metastable equilibrium, and supersaturated liquid–gas-hydrate system etc. The metastable state of hydrate could be of crucial significance in the kinetics of hydrate formation and decomposition, heat and mass transfer during gas production processes, and the application of hydrate-based technique involving desalination, energy storage and transportation, and gas separation and sequestration. Few researches have systematically considered this phenomenon, and its mechanism remains unclear. In this work, various mechanisms and hypothesis explaining the metastable state of gas hydrates were introduced and discussed. Further studies are still required to reveal the intrinsic nature of this metastable state of gas hydrate, and this work could give some implications on the existing theory and current status of relevant efforts.