本論文主要分為兩大部分，在第一部分研究中，奈米鈀金屬還原在有機中孔洞矽材料(PMOs)BS15Cx當中，利用化學還原劑使金屬還原速率上升，並藉由和BS15C20表面修飾的羧酸官能基，使離子鈀金屬能快速平均分散在BS15C20孔洞之中並還原奈米鈀金屬顆粒。由於BS15C20高比表面積837m2g-1和孔洞體積1.34cm3g-1，使用BS15C20載體可以提高奈米鈀金屬分散率和附載率，並藉由羧酸官能基表面的修飾來降低金屬的顆粒大小，進而提升催化活性。此外為了凸顯化學還原法的優勢，本實驗同時以熱還原的方式將鈀還原成鈀奈米金屬顆粒，來比較兩種還原方式的差異性。用於硼烷氨水解產氫的Pd(10)@BS15C20的轉換頻率(TOF)高達30.08 H2 /mol Pd/min，而活化能（Ea）僅有25.24 kJ mol-1。在此研究當中，Pd(10)@BS15C20展示了其用於從氨硼烷產生氫的高活性觸媒。 在第二部分研究中，利用化學還原法製成的Pd(y)@BS15Cx，應用在苯甲醇氧化催化反應當中。藉由BS15Cx表面上的苯環結構，增強材料與起始物苯甲醇之間的作用力，提升材料對催化反應起始物的吸附能力。在反應24小時之後，作為催化觸媒的Pd(10)@BS15C20使催化轉換率達到44.9%，且選擇性高達99.9%，在重複五次使用後仍維持在第一次使用的轉換水準，回收使用效率極高。 ;There are two part of my study. In the first part, Palladium nanoparticles (Pd NPs) with a particle size of about 4 nm are successfully confined within the mesopores of phenylene-bridged hexagonal periodic mesoporous organosilica, BS15Cx, functionalized with carboxylic acid (-COOH) groups. The deprotonation of -COOH groups under alkaline condition of pH 9 provides more actives sites to interact with the Pd2+ ions, and thus allow a high loading amount of Pd NPs. Two reduction methods are employed to fabricate Pd NPs: one is chemically reduction by using a mixed reagent containing NaBH4 and NH3BH3 and the other is thermal reduction method. For a comparative study, the materials generated from two different reduction techniques are then characterized by powder X-ray diffraction (XRD), nitrogen adsorption-desorption measurements, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to X-ray diffraction pattern and TEM image, it can be confirmed that the particle size of Pd NPs is about 3 nm and highly dispersed without aggregation. The turnover frequency (TOF) and activation energy (Ea) of Pd(10)@BS15C20 for the hydrolysis of ammonia borane reach almost 30.08 molH2 molPd-1 min-1 and 25.24 kJ mol-1. This remarkable catalytic activity for the hydrogen generation can be attributed to the ultra-small Pd NPs confined in the hexagonal-type structure of BS15Cx. In the second part of the study, Pd(y)@BS15Cx made by chemically reduction was used in the catalytic oxidation of benzyl alcohol. The benzene ring structure on the surface of BS15Cx enhances the interaction between the material and the benzyl alcohol, and improves the adsorption ability of the material to the reactants. After 24 hours, Pd(10)@BS15C20 as a catalyst achieves the conversion rate of 44.9%, and the selectivity of 99.9%. After being recycled for five uses, it still maintains the conversion level as the first use.
