摘要
用溶胶 凝胶法以磷钨酸(TPA)的铜盐溶液水解钛酸四丁酯制备了CuPW TiO2催化剂。使用ICP、XRD、TG DTA、IR、TPD MS和微反技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能。实验结果表明杂多钨酸盐与TiO2表面通过O2-桥发生键合作用。在623K下,杂多阴离子仍保持原有的Keggin结构。CO2在Lewis酸位Cu(Ⅱ)和Lewis碱位Cu—O—W的桥氧协同作用下形成卧式吸附态。丙烯以分子吸附态在催化剂上选择吸附。在563K,1MPa和空速1500h-1的反应条件下,丙烯的摩尔转化率为4 3%,产物MAA(甲基丙烯酸)的选择性为96%。
The CuPWTiO_2 catalysts were prepared with tetrabutyl titanate hydrolysis by aqueous solutions of Cu salts of the 12-tungstophosphoric acid via sol-gel method. Chemical composition, thermal stability, chemisorption character and reaction behaviours have been studied by different techniques including X-ray diffraction, thermogravimetric analysis, infrared spectrum analysis, inductively coupled plasma atomic emission spectroscopy, temperature-programmed desorption, and microreactor. The experimental results showed that inorganic precursor polyoxotungstate was introduced on the surface of titanium dioxide and formed to the CuPW/TiO_2 hybrid materials. Under temperature of 623?K, the catalyst still remains the original Keggin structure of TPA. The experimental results showed also that CO_2 chemisorbs at bridging oxygen of Cu—O—W(Lewis base site) and Cu^(2+)(Lewis acid site) to form bridged adsorption states, that propylene chemisorbs on the surface of catalyst to form molecular absorption states, and that the main reaction products of CO_2 with propylene on the catalysts are MAA, with propylene conversion of 4.3% under the reaction temperature of 563?K and 1?MPa, MAA selectivity of 96%.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2004年第2期219-224,共6页
Journal of Fuel Chemistry and Technology
基金
国家重大基础研究前期研究专项(2001CCAO3600) ~~
