▎ 摘　　要

NOVELTY - Method for preparing graphene composite hydrogel to promote efficient generation of methane hydrate, involves (i) adding concentrated sulfuric acid to a three-necked flask, placing in an oil bath, cooling, adding graphite and sodium nitrate, adding potassium permanganate, heating, heat-preserving, adding hydrogen peroxide, filtering, washing, and drying to obtain graphene oxide, (ii) placing acrylic acid aqueous solution, adding sodium hydroxide aqueous solution for neutralization, heating and heat-preserving, adding acrylamide and N,N-methylenebisacrylamide, pouring graphene oxide aqueous solution, dripping an aqueous solution of ammonium persulfate, drying, and crushing, and (iii) mixing granular graphene composite hydrogel with water, leaving still, sealing, opening methane cylinder to inflate high-pressure reaction kettle, closing methane cylinder and starting methane hydrate reaction, and monitoring temperature and pressure of high-pressure reaction kettle. USE - The method is used for preparing graphene composite hydrogel to promote efficient generation of methane hydrate. ADVANTAGE - The graphene composite hydrogel has ability to improve heat transfer and mass transfer efficiency of methane hydrate reaction. DETAILED DESCRIPTION - Method for preparing graphene composite hydrogel to promote efficient generation of methane hydrate, involves (i) adding 98 %mass concentrated sulfuric acid to a three-necked flask, placing in an oil bath, cooling to 0-4 degrees C, placing a magnetic stirrer on the top, stirring at a constant speed, adding graphite and sodium nitrate to completely dissolve, adding potassium permanganate to three-necked flask for 6 times to completely dissolve, stirring at 10-15 degrees C for 2.5 hours, heating at 35 degrees C, heat-preserving for 30 minutes, heating at 80-100 degrees C, heat-preserving for 30 minutes, adding 5 %mass hydrogen peroxide, filtering, collecting the filter residue, washing the filter residue with an aqueous solution of hydrochloric acid with a concentration of 5 %mass, and drying to obtain graphene oxide, (ii) placing the acrylic acid aqueous solution in three-necked flask, adding sodium hydroxide aqueous solution for neutralization, placing the three-necked flask in an oil bath, heating to set temperature and heat-preserving, placing a magnetic force on the upper end stirrer, maintaining a constant speed and stirring, adding acrylamide and N,N-methylenebisacrylamide to the three-necked flask, continuously stirring until fully dissolved, pouring the ultrasonically treated graphene oxide aqueous solution in three-necked flask and continuously stirring, dripping an aqueous solution of ammonium persulfate to the three-necked flask as initiator, continuously stirring, when solids appeared in the three-necked flask stopping stirring, taking out the solids, washing with deionized water, drying, and crushing to obtain granular graphene composite hydrogel, and (iii) mixing the granular graphene composite hydrogel with water, leaving still until the graphene composite hydrogel fully absorbs water, so that the water content reaches 97.56% and the water absorption multiple is 40 times, sealing the high-pressure reaction kettle and placing in a 1 degrees C water bath to cool down, when the temperature of the high-pressure reaction kettle drops to the set temperature and no longer changes, opening methane cylinder to inflate the high-pressure reaction kettle, and after the high-pressure reaction kettle is inflated to the set pressure, closing the methane cylinder and starting the methane hydrate reaction, and continuously monitoring the temperature and pressure of the high-pressure reaction kettle.