摘要
Cu-Fe系催化剂和Cu-Cr<sub>2</sub>O<sub>3</sub>相比,在较低压力下显示出高活性,且无毒、无污染、原料易得。本文用日本Rigaku TG-DTA-DSC热分析仪研究了该催化剂在H<sub>2</sub>气氛下的还原行为。 1.实验部分 样品:Cu-Fe系催化剂用共沉淀法制备,其活性见表1。 气源:高纯H<sub>2</sub>经105催化剂、硅胶、5A分子筛净化处理,流量为60 ml/min。
The catalyst studied shows not only higher activity under lower pressures but also no poison or pollution,and its materials can be easily obtained. By using TG-DTA-DSC thermal analyzer, the reduction behavior of the catalyst has been studied. According to the results of reduction, the following conclusions may be obtained:
1. The reduction process of the catalyst consists of two steps.First, CuO in the catalyst is thoroughly reduced, then the reduction of γ-FetO3 takes place.
2. It is known that the optimum operation temperature of the catalyst is 295℃, while the reduction temperature of CuO in the catalyst lies in the range from 175 to 205℃. The latter is below the operating temperature of the catalyst, but the reduction temperature of the γ-Fe2O3 (230-440℃ ) is beyond 290 ℃. So the CuO is reduced to Cuo but the γ-Fe2O3 is not reduced to Feo under the operating condition of the catalyst.
3.The reduction temperatures of CuO in the catalyst (175-205℃) are lower than that of the pure CuO ( 195-215℃).The lower the initial reduction temperature of the CuO in the catalyst, the higher catalyst activity. As the fatty alcohols formation begins at 180℃, so the fatty alcohols will be formed as soon as the CuO is reduced to Cuo.
The Coats - Redfern method is applied to the reduction curves and it is shown that:
1. The reduction order of CuO in the catalyst is different from that of the pure CuO. This suggests that the key steps of reaction are different for the two cases in the process of reduction. This may be caused by the different states and environment of the CuO concerned.
2. The activation energy E of reduction for CuO in the catalyst is larger than that of the pure CuO.At the same time the frequency factor A is increased. A linear relationship between logA and E is obtained: logA = 0.5134E-5.189.
出处
《分子催化》
EI
CAS
CSCD
1990年第4期335-339,共5页
Journal of Molecular Catalysis(China)
