Towards Zero Carbon Emissions: Novel Low Pressure Molecular Natural Gas/CO2/H2 Storage and Separation using Semi-Clathrates

该实验室最近开展的工作表明，在非常低的压力（大气压）和环境温度（30℃）下，大量的低分子量气体，包括甲烷、二氧化碳和氢气，可以被纳入一类鲜为人知的笼形水合物（或“气体水合物”）的结构腔中，即季铵盐（QAS）的半笼形水合物，例如四正丁基溴化铵（TBAB）。除了热力学稳定性的有利条件外，QAS水合物还具有许多其他有利性质，包括：1。相对容易形成/解离（通过适度的压力和/或温和的温度变化）储存大量气体的潜在容量（在我们的初步实验中CH4和H2分别达到62和52 vol/vol）在气体吸收/水合物生长过程中（由QAS类型和水溶液浓度控制）强烈区分不同气体的能力。生产易于运输（如在间歇式反应器、管道中）的水合物浆料的能力。非常低的母体液体蒸气压（类似于普通盐溶液），这意味着水合物释放的气体纯度非常高（不像其他挥发性有机水合物促进剂，如四氢呋喃）6。与其他有机水合物促进剂（如THF）和气体处理中使用的化学品（如胺溶液）相比，QAS半包合物的毒性相对较低。这些特性使QAS半包合物具有作为工业储存/运输和气体分离的新工具的巨大潜力。基于迄今为止的成果强度，该技术已申请专利（GB 0511546.4：一种气体储存、运输、调峰和能量转换方法（2005））。本文提出的工作目的是通过密集的综合实验和理论研究来评估这一水合物形成家族的潜力。该技术将使用三种气体进行研究，这些气体是根据目前在全球能源行业中的重要性而专门选择的，即天然气(NG)/甲烷（CH4）、二氧化碳（CO2）和氢气（H2）。

Recent work carried out in this laboratory has revealed that considerable volumes of low molecular weight gases, including methane, CO2 and hydrogen, can be incorporated into structural cavities of a class of little known clathrate hydrates (or 'gas hydrates'), namely the semi-clathrate hydrates of Quaternary Ammonium Salts (QAS, e.g. tetra-n-butylammonium bromide (TBAB) at very low pressures (to atmospheric) and ambient temperature (30 oC). In addition to favourable conditions of thermodynamic stability, QAS hydrates have numerous further advantageous properties, including:1. The relative ease with which they can be formed/dissociated (by modest pressure and/or gentle temperature change) 2. The potential capacity to store large volumes of gas (62 and 52 vol/vol achieved for CH4 and H2 respectively in our preliminary experiments)3. The capability to strongly discriminate between different gases during gas uptake/hydrate growth (controlled by QAS type and aqueous concentration)4. The ability to produce readily transportable (e.g. in batch reactors, pipelines) hydrate-water slurries5. A very low parent liquid vapour pressure (similar to common salt solutions), meaning gases released from hydrates are of a very high purity (unlike for other volatile organic hydrate promoters such as THF/tetrahydrofuran)6. A relatively low toxicity compared with other organic hydrate promoters (e.g., THF) and chemicals used in gas processing (e.g., amine solutions)These properties give QAS semi-clathrates significant potential as a novel tool for the industrial storage/transportation and separation of gases. Based on the strength of results to date, a patent for this technology has been filed (GB 0511546.4: A method for gas storage, transport, peak-shaving, and energy conversion (2005)). The aim of the work proposed here is to assess the potential of this family of hydrate formers through an intensive integrated experimental and theoretical study. The technology will be investigated using three gases chosen specifically for their current importance in the global energy industry, namely natural gas (NG)/methane (CH4), carbon dioxide (CO2) and hydrogen (H2).