微乳法制备Au/Fe_2O_3水煤气变换反应催化剂Ⅰ.制备参数对催化剂活性的影响

Au/Fe_2O_3 Water-Gas Shift Catalyst Prepared by Microemulsion MethodⅠ.Effect of Synthesis Parameters on Catalyst Activity

分别在TritonX 10 0 /正己醇 /环己烷 /水和十六烷基三甲基溴化铵 (CTAB) /正己醇 /水的W /O型微乳液体系中合成了Au/Fe2 O3 催化剂 ,考察了主要制备参数对催化剂水煤气变换活性的影响 .结果表明 ,催化剂的焙烧温度、水与表面活性剂的质量比 (rw)、表面活性剂浓度 (W)、表面活性剂种类及催化剂活性组分金的负载量均对催化剂活性有显著的影响 .催化剂的最佳焙烧温度为 2 5 0℃ ,催化活性随着rw 和W的增加而降低 ,由TritonX 10 0制得的催化剂的活性高于由CTAB制得的催化剂 .当金负载量为 3% ,水煤气变换反应温度为 2 0 0℃时 ,CO的转化率可达 99 5 % .

The Au/Fe 2O 3 catalyst was prepared by the microemulsion method in two invers e microemulsions, Triton X-100/n-hexanol/cyclohexane/(aque ous metal salt solution) and cetyltrimethylammonium bromide (CTAB)/n-hexano l/(aqueous metal salt solution), respectively. Ternary phase diagrams of the two systems were first determined to get the inverse microemulsion area. According to the phase diagrams, surfactant, oil and aqueous solution of HAuCl 4 and Fe(N O 3) 3 were mixed to form a homogeneous microemulsion. Then the Au/Fe 2O 3 c atalyst was prepared by mixing the microemulsion and ammonia solution. The effec ts of synthesis parameters, such as water to surfactant mass ratio (r w), s urfactant concentration (W), surfactant type, calcination temperature and go ld loading, on the activity of Au/Fe 2O 3 for the water-gas shift reaction we re investigated. The results show that all the synthesis parameters have remarka ble effects on the catalyst activity. The catalyst sample calcined at 250 ℃ has the highest activity and the activity decreases with increasing r w and W. The sample prepared by the microemulsion consisting of nonionic surfactant (Triton X-100) shows a higher activity than that from cationic surfactant (CTAB ). CO conversion reaches 99 5% at gold loading of 3% and 200 ℃.