Au/Fe2O3 water-gas shift catalyst prepared by microemulsion method -: I.: Effect of synthesis parameters on catalyst activity

The Au/Fe2O3 catalyst was prepared by the microemulsion method in two inverse microemulsions, Triton X-100/n-hexanol/cyclohexane/( aqueous metal salt solution) and cetyttrimethylammonium bromide (CTAB)/n-hexano/(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 HAuCl4 and Fe(NO3)(3) were mixed to form a homogeneous microemulsion. Then the Au/Fe2O3 catalyst was prepared by mixing the microemulsion and ammonia solution. The effects of synthesis parameters, such as water to surfactant mass ratio (r(w)), surfactant concentration ( W), surfactant type, calcination temperature and gold loading, on the activity of Au/Fe2O3 for the water-gas shift reaction were investigated. The results show that all the synthesis parameters have remarkable effects on the catalyst activity. The catalyst sample calcined at 250 degreesC has the highest activity and the activity decreases with increasing rw 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 degreesC.