Utilizing DSC to Determine the Influence of Guest Molecules on the Dissociation Heat of Gas Hydrates

• Main Authors: Liang-Kai Chu, 朱亮愷
• Other Authors: Li-Jen Chen
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3vvxcd

碩士 === 國立臺灣大學 === 化學工程學研究所 === 106 === Promotion effects of cyclic ethers, including tetrahydrofuran, 1,3-dioxane, 1,3-dioxolane, 2,5-dihydrofuran, and propylene oxide, were explored by a high pressure micro differential scanning calorimeter (μDSC) with the pressure range from 5.0 MPa to 30.0 MPa. The promotion abilities of these structure II promoters are in the order: tetrahydrofuran > 2,5-dihydrofuran ≒ 1,3-dioxane ≒ 1,3-dioxolane > propylene oxide. Furthermore, the magnitude of dissociation heats are relevant to the highness of dissociation temperatures when it comes to the same structure of methane hydrate. Besides, structure H methane hydrate with 1-methylpiperidine was also examined. The promotion effect is weaken than any sII promoter mentioned above while the dissociation heat based on one mole water is larger than that of 1,3-dioxolane hydrate and that of propylene oxide hydrate. Moreover, the influences of gases, (methane, carbon dioxide, nitrogen, argon, and krypton) on dissociation temperature and on dissociation heat were studied for pure gas hydrates and for THF mixed hydrates. The dissociation temperature are in the order: krypton hydrate ≒ carbon dioxide hydrate > methane hydrate > argon hydrate > nitrogen hydrate. And for THF mixed hydrates, the dissociation temperatures are in the order: krypton-THF hydrate > methane-THF hydrates > argon-THF hydrate ≒ carbon dioxide-THF hydrate > nitrogen-THF hydrate > helium-THF hydrate. Except for carbon dioxide hydrate, the dissociation heats are related to the highness of dissociation temperatures. It is noted that within 10.0 MPa, the dissociation heats of THF mixed hydrates decreased along with the pressure change obviously; however for pressure over 10.0 MPa, the dissociation heats of pure gas hydrates seemed independent from operation pressure.