Properties Of Zirconia Nanotube Arrays Loading Phospotungtic Acid

In this paper, the zirconia nanotube arrays were synthesized in organic solution byelectrochemical anodization. SEM, TEM,XRD,FTIR investigations were carried out to showthe morphology, microstructure and characteristics of the nanotubes. Then we preparedH₃PW/ZrO₂ catalysts. The catalyst were characterized, and used in the esterificationexperiments.1. ZrO₂ nanotube arrays were prepared in organic electrolyte containing F^- by anodization.A series of experiments showed that highly self-organized ZrO₂ nanotube arrays can be formedin organic electrolyte of formamide and glycerol (volume-ratio 1:1) containing 1.0 wt % NH4F.These nanotubes also showed smooth and straight walls, homogeneous pipe diameter and longlength. Then, the formation mechanism of the ZrO₂ nanotube arrays was discussed. Besides,ZrO₂ nanotubes were optimized by different treatment technologies.2. The best catalyst preparation process was proposed as follows: using ZrO₂ nanotubesannealed at 400℃as support, phosphotungstic acid (load of 35%) as active center; ZrO₂ wasimpregnated in ethanol solution containing phosphotungstic acid, and then dried the samples at100℃; at last H₃PW/ZrO₂ was calcined in muffle furance for 4 h at 200℃in air atmosphere.3. The optimum synthesis conditions of ethyl oleate were given: the molar ratio of ethanolto oleic acid was 6:1, the dosage of catalyst was 5 mass%, the reaction time was 4 h. Finalconversion rate can reach 86.27%. The optimum conditions of synthesis of ethyl laurate were:the molar ratio of ethanol to lauric acid was 5:1, catalyst amount was 4 mass%, and the reactiontime was 4 h. The most favorable esterification reaction parameters of ethanol and stearic acidwere: ethanol and stearic acid mole was 6:1; catalyst dosage of 5 mass%, reaction time is 4h aswell.