聚乙烯亞胺/聚乙二醇二縮水甘油醚複合孔洞材料親疏水性對於甲烷與二氧化碳水合物的動力學與熱力學之影響

Abstract

本次研究主要是探討固體孔洞材料對於甲烷或二氧化碳水合物在熱力學及動力學上的影響，第一部分是利用聚乙烯亞胺(Polyethylenimine , PEI)、聚乙二醇二縮水甘油醚(Poly(ethylene glycol) diglycidyl ether, PEGDE)及聚乙烯醇(Poly(vinyl alcohol), PVA)三種高分子聚合物製作兩種不同成分比例的球形孔洞材料。第二部分則是對此球形孔洞材料進行疏水性改質，我們利用化學氣相沉積法，將我們的球形孔洞材料與甲基三氯矽烷(Methytrichlorosilane, MTCS)進行反應，使其具有疏水性，後續再進行靜態接觸角的量測測試其疏水性質。 接著是熱力學實驗方面，我們針對四種系統進行實驗，分別是親水性PEI/PEGDE孔洞材料以及疏水性PEI/PEGDE孔洞材料的甲烷與二氧化碳水合物熱力學實驗，在這部分實驗我們個選擇了三個不同的壓力作為實驗點(甲烷：9 MPa, 10 MPa, 11 MPa；二氧化碳：3 MPa, 3.4 MPa, 3.8 MPa)並利用等容法(Isochoric method)進行熱力學性質測定，最後結果顯示不論親水或疏水的PEI/PEGDE孔洞材料對於甲烷與二氧化碳水合物都有熱力學促進效果。 再來是動力學實驗方面，動力學則有六種系統，分別是(1)親水性PEI/PEGDE孔洞材料、(2)疏水性PEI/PEGDE孔洞材料以及(3)親水性PEI/PEGDE/PVA孔洞材料對於甲烷水合物的動力學實驗，以及(4)親水性PEI/PEGDE孔洞材料、(5)疏水性PEI/PEGDE孔洞材料以及(6)更為疏水的PEI/PEGDE孔洞材料的二氧化碳動力學實驗，這部份我們將每個系統的溫度都定為274.15 K(甲烷水合物系統的過冷溫度約為12.3 K；二氧化碳水合物系統的過冷溫度約為7.6 K)，起始壓力分別訂為10 MPa(甲烷)與3.4 MPa(二氧化碳)，最後結果顯示二氧化碳水合物在此種材料上有較快的生成速率，並且疏水性材料比親水性材料來得較佳。

This study investigates the thermodynamic and kinetic effects of solid porous materials on methane and carbon dioxide hydrates. In the first part, two types of spherical porous materials with different compositions were synthesized using three polymers: polyethyleneimine (PEI), poly(ethylene glycol) diglycidyl ether (PEGDE), and polyvinyl alcohol (PVA). In the second part, the surface of these porous materials was modified to enhance hydrophobicity. Chemical vapor deposition (CVD) was employed to react the porous materials with methyltrichlorosilane (MTCS), imparting hydrophobic characteristics. The contact angle measurements were then conducted to evaluate the hydrophobicity. For the thermodynamic experiments, four systems were studied: hydrophilic and hydrophobic PEI/PEGDE porous materials with methane and carbon dioxide hydrates. Three pressure conditions were selected for each gas system (methane: 9 MPa, 10 MPa, 11 MPa; carbon dioxide: 3 MPa, 3.4 MPa, 3.8 MPa). The isochoric method was used to determine the thermodynamic properties. Results demonstrated that both hydrophilic and hydrophobic PEI/PEGDE porous materials enhanced hydrate formation thermodynamically. For the kinetic experiment, six systems were studied. These included: (1) hydrophilic PEI/PEGDE porous material, (2) hydrophobic PEI/PEGDE porous material, and (3) hydrophilic PEI/PEGDE/PVA porous material for methane hydrate formation; as well as (4) hydrophilic PEI/PEGDE, (5) hydrophobic PEI/PEGDE, and (6) more strongly hydrophobic PEI/PEGDE porous materials for carbon dioxide hydrate formation. In all experiments, the temperature was fixed at 274.15 K (the subcooling temperature in the methane hydrate system was approximately 12.3 K, whereas that in the carbon dioxide hydrate system was approximately 7.6 K). The initial pressure was set at 10 MPa for the methane systems and 3.4 MPa for the carbon dioxide systems. The results demonstrated that carbon dioxide hydrate formation proceeded at a faster rate under these experimental conditions, particularly when using hydrophobic porous materials. Furthermore, hydrophobic materials consistently outperformed hydrophilic ones in terms of promoting hydrate formation kinetics.