Carriers for Methane Hydrate Production: Cellulose-Based Materials as a Case Study

Abstract

Methane hydrate growth and decomposition in the cellulose-based materials containing water were studied. Cellulose microfibrils (CMFs) and their composite with polyacrylamide (CMF@PAM) were employed as carriers for methane hydrate formation and storage. Water distribution over the CMF porous surface creates a developed water–gas interface, which leads to enhanced gas hydrate formation. The tested water content in the materials was 45 and 70 mass %. The efficiency of methane binding in the hydrate state increased in the order of CMF@PAM70 < CMF@PAM45 < CMF70 < CMF45 (numbers mean the water content). The water-to-hydrate conversion in 40 h was 3, 28, 73, and 83% in the same order. The most intensive hydrate growth is observed in the first 100–200 min after nucleation. In the case of CMF45, 70–90% of the water turns into a hydrate during this time depending on the water distribution. The presence of the hydrate in the studied samples was confirmed by powder X-ray diffractometry and differential scanning calorimetry. Partial decomposition of the methane hydrate in the CMF at atmospheric pressure and a constant temperature (−20 °C) led to a sharp decrease in the rate of its further dissociation. In the case of the CMF@PAM material, the initial rate of hydrate decomposition was an order of magnitude lower than that for the CMF one; it decreased gradually. Thus, cellulose-based materials can be suggested as an efficient carrier for gas hydrate production. CMFs provide a developed water–gas interface that facilitates hydrate formation. Applying polyacrylamide to the CMF allows one to reduce the rate of methane hydrate decomposition formed in this material. However, it retards the hydrate formation as well. Cellulose-based materials are easily scalable and can be used in many technologies where a gas hydrate needs to be produced fast.

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