Preparation Of Pt-based Catalysts By Reverse Microemulsion And Study On Its Hydrogenation Performance

The principle of microemulsion with nano particles prepared have simple device, easy operation, etc., And the controlled growth and shape of nanometer particles can be achieved by changing the composition of microemulsion.By combination of conductivity with the visual was researched the the phase diagrams of the pseudo-ternary-component of the system of water / CTAB/n-butanol and H2PtCl6 / CTAB / n-butanol/cyclohexane, which determined the composition ratio of microemulsion, As the basis for the research,. the Pt/γ-Al₂O₃ catalyst was prepared with CTAB / n - butarol / cyclohe - xane / H2PtCl6 microemulsion using hydrazine as reductant. The support and catalyst were characterized by XRD, XPS, IR, TEM and EDS. The Pt particle size is about 5 nm, and the electronic effectit between Pt particle and carrier is not significantly.Using chloronitrobenzene selective hydrogenation as a probe reaction. Effect of type of cosurfactant and oil phase, the composition of microemulsion, type of carriers, reductant dosage on the activity for selective hydrogenation over Pt-based catalysts were studied. And compare the catalyst preparation method on the catalyst Hydrogenation. The results showed: (1) The different cosurfactants and oil influce the emulsified effect of the emulsion, as n– butanol for the cosurfactants and cyclohexane for the oil phase, forming the stable microemulsion. (2) The Pt/γ-Al₂O₃-ME catalyst made from the microemulsion with a CTAB: n - butarol: cyclohexane mass ratio of 9:21:70 and H2PtCl6 concentration of 3.6 wt% exhibited the highest activity. (3) Usingγ-Al₂O₃ as carrier and the content of hydrazine hydrate 100μL shows the best activity. (4) Comparing with impregnation, Pt/Al₂O₃ catalyst made from microemulsion shows higher activity. The conversion rate of the o, m, p, - chloronitrobenzene were 95.6 %, 99.9 %, 84.2 %, The selectivity of corresponding chloroaniline were 97.4 %, 98.1 %, 97.6 %; The corresponding to TOF values were 20.2×10^-2 s^-1, 21.2×10^-2 s^-1, 17.8×10^-2 s^-1. While Pt/Al₂O₃ is prepared by the impregnation method, the conversion rate, corresponding product selectivity and TOF values were lower.