摘要
目前关于含四氢呋喃(THF)水合物形成过程的研究多采用间接法,由于这些方法都不是直接测量反应物或生成物的量,其研究结果受实验环境、仪器精度以及计算误差的影响较大。为此,突破传统的检测技术手段,采用低场核磁共振技术研究了19%THF水溶液从室温开始到水合物形成过程中试样的T2时间(氢核横向弛豫时间)分布和核磁总信号量随温度的变化,以探讨THF水合物形成过程的特征。实验结果表明:T2分布和核磁总信号量均与温度有较好的相关性,说明THF水合物的生成与温度密切相关。根据核磁总信号的变化将THF水合物的整个生成过程划分为4个阶段:初始期、诱导期、加速生长期和稳定期:在诱导期阶段的物质组成具有随机性,有水合物簇出现,但这些水合物簇不稳定,随机的分解和长大,导致此阶段的核磁总信号有一定的波动。当经过诱导期后,水合物簇尺寸达到晶核临界尺寸,水合物开始大量生成。且随着水合物的生成,THF溶液逐渐消耗,生成速度逐渐变慢,直到达到稳定期。
Indirect tests are most often used in the studies of the tetrahydrofuran(THF) but their shortcomings are obvious: not only can the quantities of reactants and final products not be measured directly,but the test results are greatly influenced by experimental environment,instrument accuracy,and calculation error.In view of this,the low-field nuclear magnetic resonance(NMR) was adopted to investigate into the characteristics of THF hydrate formation process.The low-field NMR proton spin-spin relaxation time(T2) distribution measurements were employed to investigate tetrahydrofuran(THF)-water clathrate hydrate formation process in 19% THF aqueous solution starting from room temperature.The experiments show that the T2 distribution and the cumulative signals are well correlated to the temperature,which proves that the formation of the THF clathrate hydrate is closely related to the temperature.According to the change in the cumulative NMR signals,the whole formation process of the THF clathrate hydrate is divided into initial,induction,accelerating,and steady stages.The cumulative NMR signals in the induction stage are fluctuating because the unsteady hydrate cluster decomposes and grows in size randomly;but after this induction stage,when the crystal nucleus of hydrate cluster reaches the critical size,hydrate starts to generate in a great volume.And with more and more hydrate forms,less and less THF solution is left,and the formation of hydrate becomes slow until it comes to the steady stage.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2011年第7期97-100,114,共4页
Natural Gas Industry
基金
中国科学院"百人计划"择优支持项目
中国科学院知识创新工程重要方向项目(编号:KZCX2-YW-JS108)
岩土力学与工程国家重点实验室前沿领域探索性项目(编号:SKLQ014)
