Fabrication and characterization of porous phosphated TixZr1-xO2 solid acids

• Main Authors: Lin, Ya-Rui, 林亞銳
• Other Authors: Chang, Sue-Min
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/88849795020413512985

碩士 === 國立交通大學 === 環境工程系所 === 103 === In this study, phosphated TixZr1-xO2 solid acids with porous structures were prepared by using an ionic-liquid-assisted hydrothermal method. The microstructures, chemical compositions, and surface acidity of resulting materials were characterized by N2 adsorption/desorption, XRD, TEM, ESCA, ICP-MS, pyridine-FTIR and NH3-TPD. The 0.4P-Ti0.5Zr0.5O2 powders, in which the P/Ti/Zr = 2：1：1, exhibited the highest surface area of 278 m2/g. Phosphate species dominates surface acidity. In addition, the different oxygen coordinations between the Ti4+ and the Zr4+ ions bring extra surface acid sites. Brönsted acids are the primary type of the acids. High elecronagativity of the P5+ ions leads to weak and medium Brönsted acidity on the P-OH and Ti-OH/Zr-OH sites, respectively. The total amount of acidic sites is 1.27 mmol/g. There are little amounts of Lewis acid sites on the surface until 650 C. The Ti4+, Zr4+ and P5+ ions in the matrix inhibit the grain growth during thermal treatment and maintain the high surface areas. The sample exhibited high thermal stability during repeated NH3 adsorption and desorption cycles. The quantity of the desorbed NH3 molecule declined only by 10% due to dehydroxylation after the first cycle and maintained constant in the following cycles, indicating the high reusability of the material in the applications.