Stabilization of gas hydrate by addition of anti-freeze protein like peptide-modified polymer particles

天然气水合物是包裹体的一种，由水和气体分子组成。制备天然气水合物的通常方法是用气体和水对系统进行压缩和冷却。稳定和控制甲烷水合物的生成是甲烷水合物利用的关键技术。然而，甲烷水合物的生长抑制作用一直是研究的重点。我们提出了用于稳定甲烷水合物的聚合物添加剂。聚合物添加剂的优点是(1)低挥发性，(2)可回收利用，(3)化学稳定性。提出了在气水体系中加入表面改性聚合物粒子，使天然气水合物生成的平衡温度-压力曲线(T-P曲线)向高温低压侧移动。这意味着通过添加聚合物粒子来稳定天然气水合物。首先，我们将聚(苯乙烯-二乙烯基苯)(PSt)粒子加入到甲烷和水的体系中。添加PST…更多的颗粒使甲烷水合物的T-P曲线向更低的温度和更高的压力移动。我们还制备了表面修饰的PSt粒子。例如，在类似的条件下，对烷氧基苯甲醇单元改性的PST颗粒(c-PSOH)进行了检测。然而，c-PSOH颗粒的加入并不改变甲烷水合物的T-P曲线。众所周知，抗冻蛋白(AFP)与水分子相互作用，抑制冰的生长。AFP具有富含丙氨酸(ALA)的肽序列。我们用富含丙氨酸的序列-(Ala)_&lt；10&gt；-、-(Ala)_5-和-(Ala)-修饰c-PSOH粒子。富Ala序列的颗粒不能稳定甲烷水合物。但形成的水合物中甲烷的储存率高于不加添加剂的水合物。这表明富含丙氨酸序列修饰的PST颗粒抑制了结冰，即无甲烷固体。在有水和二氧化碳的体系中进行了类似的实验。向二氧化碳和水系统中添加PST颗粒也可以稳定二氧化碳水合物。较少

Gas hydrate is one of the inclusion compounds, which consist of water and gas molecules. Usual procedure for preparation of gas hydrate is compressing and cooling of the system with gas and water. Stabilization and controlled formation of methane hydrate is a key technology for its utilization. However, growth inhibitor of methane hydrate has been investigated mainly. We proposed polymeric additives for stabilization of methane hydrate. Merits of polymeric additives are (1) low volatility, (2) recyclability, and (3) chemical stability of them. We proposed that the equilibrium temperature-equilibrium pressure curve (T-P curve) of gas hydrate formation will be shift to higher temperature and lower pressure side by addition of surface modified polymer particles into the gas-water system. This means that stabilization of gas hydrate by addition of the polymer particles.First, we added the poly(styrene-co-divinylbenzene), (PSt) particles to the system with methane and water. Addition of PSt … More particles shifted the T-P curve of methane hydrate to lower temperature and higher pressure. We also prepared surface-modified PSt particles. For example, p-alkoxybenzylalcohol-unit modified PSt particles (c-PSOH) were examined under similar condition. However, addition of c-PSOH particles did not shift the T-P curve of methane hydrate. It is known that anti-freeze protein(AFP) interacts with water molecules and inhibits the growth of ice.AFP has alanine (Ala)-rich peptide sequence. We modified c-PSOH particles with alanine-rich sequence, -(Ala)_<10>-, -(Ala)_5-, and -(Ala)-. The particles with Ala-rich sequence could not stabilize methane hydrate. However, storage ratio of methane in the formed hydrate was higher than that of the additive-free hydrate. This suggests that alanine-rich sequence modified PSt particles inhibit ice formation, i.e., methane-free solid.Similar experiments were performed in the system with water and carbon dioxide. Carbon dioxide hydrate is also stabilized by addition of PSt particles into the carbon dioxide and water system. Less