超细CuO/ZnO/TiO2-SiO2的表征和CO2加氢合成甲醇性能研究
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摘要: 用溶胶-凝胶法制备了铜、锌质量分数不同的超细Cu/ZnO/TiO2-SiO2催化剂。通过BET、TPR、XRD及FT-IR等方法对催化剂前驱体CuO/ZnO/TiO2-SiO2的物化性能进行表征。用固定床连续流动微反装置，考察催化剂CO2加氢合成甲醇的催化性能。研究结果表明，溶胶-凝胶法制备的CuO/ZnO/TiO2-SiO2催化剂比表面较大（240 m2/g～590 m2/g），孔径分布单一，晶相组成为CuO。随着铜、锌质量分数的增大，催化剂的比表面积减小，最可几孔径增大; CuO微晶结晶度增大,同时微晶尺寸逐渐增大至20 nm。催化剂具有较高的反应活性和选择性，当氧化铜、氧化锌质量分数各为25%时，在260 ℃，2 500 h－1，CO2∶H2=1∶3（mol比），2.0 MPa的反应条件下，甲醇时空收率为0.126g/(h·g)。
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关键词:
- 溶胶-凝胶法 /
- Cu-ZnO/TiO2-SiO2催化剂 /
- CO2加氢合成甲醇
Abstract: Ultrafine Cu/ZnO/TiO2-SiO2 catalysts with different content of Cu and Zn ranging from 5% to 25% were prepared by sol-gel method. The physical-chemical properties and catalytic performance of the catalysts were studied by using FT-IR(Fourier Transform InfraRed), BET,TPR(Temperature Programmed Reaction),XRD(X-ray Diffraction) and micro-reactor system. It was found that the catalysts exhibited large BET surface area(590 m2g－1～240 m2g－1) and uniform pore distribution. XRD showed that only crystal phase detected was CuO. With increasing content of Cu and Zn in the sample, the BET surface area of the catalysts gradually decreased, the average pore diameter and the junction temperature of CuO micro-crystal increased, the dimensions of the micro-crystal increased from 10 nm to 20 nm. The presence of ZnO can promote the interaction of CuO and TiO2-SiO2 support. The catalysts showed high activity and selectivity to methanol. When the content of CuO and ZnO both were 25%, a methanol yield of 0.126/g·h－1·g cat－1 was obtained under the conditions of 260 ℃, 2.0 MPa, 2 500 h－1 with a CO2/H2 ratio of 1/3.-
Key words:
- sol-gel method /
- Cu/ZnO/TiO2-SiO2 catalyst /
- CO2 hydrogenation
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