CO_(2)在气体水合物结构特性的固体核磁共振波谱与拉曼光谱实验研究  

Experimental Study on the Structure Characteristics of CO_(2)in Gas Hydrate by Solid-State Nuclear Magnetic Resonance and Raman Spectroscopy

作　　者：付娟[1] 莫家媚 余益松 张青宗 陈晓丽[1] 陈佩丽[1] 张少鸿[1] 苏秋成[1] FU Juan;MO Jia-mei;YU Yi-song;ZHANG Qing-zong;CHEN Xiao-li;CHEN Pei-li;ZHANG Shao-hong;SU Qiu-cheng(Key Laboratory of Gas Hydrate,Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640,China)

机构地区：[1]中国科学院天然气水合物重点实验室,中国科学院广州能源研究所,广东广州510640

出　　处：《光谱学与光谱分析》2022年第2期464-469,共6页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(22008237);中国科学院前沿科学从0到1原始创新项(ZDBS-LY-SLH041);广东省自然科学基金项目(2019A1515012086)资助。

摘　　要：天然气水合物是蕴含着巨大能源潜力的非常规能源,2017年和2020年两次我国南海探索性试采的成功,加快了天然气水合物项目的进展。二氧化碳置换开采法,既能开发CH_(4),又能封存CO_(2)。同时水合物法分离烟气中CO_(2)具有很好的应用前景,而CO_(2)在气体水合物的微观结构和特性尚不明确,实际应用存在一定的未知影响。为了考察其特性,利用^(13)C固体核磁技术(NMR)和拉曼光谱(Raman)进行CO_(2)置换CH_(4)水合物、合成^(13)CO_(2)-H_(2)-CP混合水合物实验表征,讨论CO_(2)在水合物中的定量问题,研究CO_(2)分子在笼型结构中的分布,探讨CO_(2)分子在气体水合物中的结构类型和特性。结果表明:(1)利用Raman费米低频共振1277.5 cm^(-1)峰积分得到CO_(2)在I型大笼(5^(12)6^(2)笼)的占有率为0.9782,CH_(4)在Ⅰ型小笼(5^(12)笼)和大笼(5^(12)6^(2)笼)的占有率为0.0593和0.0095,水合数7.61,Raman费米高频共振1381.3 m^(-1)峰积分得到CO_(2)在5^(12)6^(2)笼的占有率为0.9843,CH_(4)在5^(12)笼和5^(12)6^(2)笼的占有率为0.0237和0.0033,水合数7.70,CO_(2)几乎占满了大笼,CO_(2)气体的加入会导致水合物中,CH_(4)的大、小笼占有率均大幅度降低,置换后水合数略低于纯甲烷水合物,未标记的CO_(2)水合物在核磁中较难测出信号,CO_(2)气体置换后CH_(4)在小笼的占有率仅0.0975,大笼占有率为0.3172,两种方法差异主要原因为核磁的CO_(2)未出峰。(2)利用拉曼费米低频共振1273.4 cm^(-1)峰积分得到H_(2)、CO_(2)在5^(12)笼、CP在5^(12)6^(2)的占有率分别为0.1248,0.3042和0.9978,水合数9.16;Raman费米高频共振1380.6 cm^(-1)峰积分得到H_(2)、CO_(2)在5^(12)笼、CP在5^(12)6^(2)的占有率分别为0.1236,0.5771和0.9851,水合数7.12。13 C标记CO_(2)分子在水合物中达到较好的固体核磁分辨率,首次确认CO_(2)在Ⅱ型小笼中的化学位移为124.8 ppm,计算得到CO_(2)的小笼占有率为0.7831,CP的大笼占有率为0.9718Natural gas hydrate is unconventional energy with huge energy and source potential.In 2017 and 2020,two exploratory trials of marine hydrate in the South China Sea were successful.The incident accelerated the development of China’s natural gas hydrate project.Carbon dioxide replacement and recovery technology can develop natural gas energy sources in a dense solid phase stored in natural gas hydrates and store CO_(2)greenhouse gases in the ocean.The separation of CO_(2)from flue gas by forming hydrates is becoming a promising new separation technology.The microstructure and properties of CO_(2)molecules in gas hydrates are still unclear,and the practical application of CO_(2)technology has certain unknown effects.In this paper,^(13)C solid-state nuclear magnetic technology(NMR)and Raman spectroscopy(Raman)technology were used to characterize CO_(2)molecules from CH_(4)hydrates replaced by CO_(2)gas and the synthesized ^(13)CO_(2)-H_(2)-CP hydrates.The content of CO_(2)molecules stored in hydrate crystals was tested,the distribution of CO_(2)molecules stored in the hydrate cage was analyzed,and the structureal characteristics of CO_(2)molecules in gas hydrates were obtained.The results show that:(1)The 1277.5 cm^(-1)peak integration of the Raman Fermi low-frequency resonance is used in CH_(4)hydrates replaced by CO_(2)gas to obtain CO_(2)molecules occupied in the 5^(12)6^(2) cages and CH_(4) molecules occupied in the 5^(12) and 5^(12)6^(2) cages.They are 0.9782,0.0593,and 0.0095,respectively.The hydration number of the hydrate formed is 7.61.The 1381.3 cm^(-1)peak integration of the Raman Fermi high-frequency resonance is also used to obtain CO_(2)molecules occupied in the 5^(12)6^(2) cages and CH_(4) molecules occupied in the 5^(12) and 5^(12)6^(2) cages.They are 0.9843,0.0237,and 0.0033,respectively.The hydration number of the hydrate formed is 7.70.The large cages(5^(12)6^(2) cages)of the CO_(2)hydrate formed are almost filled with CO_(2)molecules.After the replacement,the addition of CO_(2)molecules in hydra

关 键 词：固体核磁 拉曼光谱 二氧化碳 气体水合物 结构特征 定量分析 

分 类 号：O657.37[理学—分析化学]