笼型水合物是由水和气体分子形成具有笼型结构的化合物，由于可以包含CH4、CO2等气体，笼型水合物在能源和环境领域极具应用前景。目前人们发现除了稳定于高压低温环境外，笼型水合物还生长于纳米孔隙中，这让笼型水合物的研究面临新的挑战。另外，笼型水合物主要由轻元素组成等特性使人们很难利用传统手段对其进行定量化的研究。中子衍射具有对轻元素敏感、高穿透、高衍射角度强度不衰减等特性，对于笼型水合物的研究极具优势。本项目将在多孔二氧化硅、纳米管、亲水碳纳米管等体系中人工合成CH4、CO2笼型水合物；利用原位高压、低温中子衍射等手段，研究不同体系、不同纳米孔径尺寸对笼型水合物形成/分解反应相图、反应动力学、精细结构、客体分子运动状态等性质的影响；进而逐步揭示纳米孔径限制条件作用于笼型水合物的物理机制。提高人们对笼型水合物-负压水相的进一步认识，为天然气笼型水合物的勘探与开发提供必要的实验依据与理论支持。

Clathrate hydrates are a group of ice-like, crystalline inclusion compounds formed by water and “guest” gas molecules of suitable size, typically under low temperature and high pressure conditions. Because of the storage capacity of CH4 or CO2, clathrate hydrates have important potential applications in energy storage and environmental sciences...Although clathrate hydrates have been known for almost two centuries, it was recognized recently that nature gas clathrate hydrate are in ocean-floor sediments which are in form of nano porous or nano layer structure. This nano structure will exert an influence on the accumulation of clathrate hydrate, however, the fundamental understanding of the nano confinement to clathrate hydrate is still limited. This is because many of the traditional experimental techniques are inapplicable to the clathrate hydrate owing to its requirement for special stable condition (i.e., elevated pressures and low temperature). On the other hand, neutron diffraction, which is light-element sensitive, penetrated to metal, and has strong signal at high diffraction angle, is a great tool for studying the clathrate hydrate...In this project, we propose to synthesis the CH4 and CO2clathrate hydrate in the nano porous silica, silica nano wire and carbon nano wire respectively. Using the in-situ high pressure low temperature neutron diffraction technique on the “typical” clathrate hydrate samples, we will refine the diffraction pattern and obtain the properties of clathrate hydrate synthesized in different nano confinement environment., including space group, atom position and vacancy, atom thermal vibration factors, and the motion of the guest gas molecular. We will then investigate the effect of nano confinement on the clahrate hydrate formation/dissociation reaction, structure, and guest gas condition...In addition, we will examine the physical mechanism of the nano confinement impact on the clahrate hydrate, by performing the NPDF (Neutron Pair Distribution Function) experiments and analysis to get the short range order information, especially between the clathrate hydrate and the silica host, as well as conducting the inelastic neutron diffraction and theoretical simulations. Our proposed research will provide us with a theoretical model of clathrate hydrate formed in nano confined space, which could guide the exploitation of nature gas clathrate hydrate on the sea floor.