| The selective hydrogenation of a, β-unsaturated aldehydes is a green technology, and a, β-unsaturated aldehydes hydrogenation product has good application prospect. At ptesent, the selectivity hydrogenation a, β- unsaturated aldehydes has caught more attention. However, because of the conjugated C=C bonds and C=0 bonds are present in α, β-unsaturated aldehydes moleeules at the same time, the hydrogenation of C=O bonds is more difficult. To prepareing more hydrogenation products of the C=O bonds, the key is to research and the development of the catalysts of high activity and high selectivity and the selective hydrogenation reaction medium. Cinnamaldehyde(CMA) is a typical of α, β-unsaturated aldehydes. The hydrogenation products of CMA are widely applied in the production of perfumes, flavorings, pharmaceuticals, and other fine chemicals. Therefore, the study of the selective hydrogenation of CMA is not only have important theoretical implications, but also has important practical applications. In addition, citral is another a, β- unsaturated aldehydes which has as important as CMA in the field of pharmaceutical intermediates and perfume and so on. The hydrogenation product of citral(unsaturated alcohols): geraniol and nerol are two expensive pharmaceutical intermediates of spice which were widely used in the medicine, flavor and other industries. Therefore, it has important practical significance for research on the selective hydrogenation of citral to geraniol and nerol. The main research work are as follows:1. This paper used the impregnation method: With Zr O2, PPy-Zr O2, Ti O2, PPy-Ti O2, CNTs and γ-Al2O3 as the carrier, study on the reactivity of the bimetallic transition metal catalyst which has supported Ru or Pt. Study on the effect of the different carriers to the selective hydrogenation of CMA. The results show that the activity and selectivity of the bimetallic metal catalyst that modified by PPy improved significantly compared to the unmodified carrier-supported catalyst. At the same time, study on the effect of different kinds of transition metals to the selective hydrogenation of CMA. The strueture and morphology of catalysts are characterized by Transmission electron microscope(TEM), X-ray powder diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier Translation Infrared Spectroscopy(FT-IR). The results show that Co-supported catalysts improve the selective of cinnamyl alcohol, and Ni-supported catalysts are favor of the selective hydrogenation of C = C bonds. The activity and selectivity of Pt-based catalyst are greater than Ru-basedcatalyst.2. This paper studies oil in water(O/W) microemulsion system as the medium of the selective hydrogenation reaction, creatively. And used in the selection hydrogenation of the two representative a, β- unsaturated aldehydes---CMA and citral. Use different kinds of surfactants: cationic surfactant--- hexadecyl trimethyl ammonium bromide(CTAB), sodium surfactant---dodecyltrimethylammonium bromide(DTAB), anionic surfactant---bis(2-ethylhexyl) sulfosuccinate(AOT) and polyoxyethylene ether sulfate formaldehyde condensate(SOPA); a non-ionic surfactant---Tween 80(Tw80) and different kinds of co-surfactants: ethanol, n-propanol, n-butyl alcohol. Configure the appropriate ratio of microemulsion system as a selective hydrogenation reaction medium. Experimental results show that the conversion and the selectivity of CMA and citral has been significantly improved in the microemulsion system compared to pure alcohol. While in pure alcohol system, the conversion of CMA and the selectivity of CMO order: ethanol> n-propanol> n-butanol.3. With Pt-based catalysts(Pt Co/CNTs, Pt Co/Al2O3 and Pt Co/Ti O2), compared the selective hydrogenation of citral in pure ethanol and several microemulsion system, respectively. The results show that the microemulsion can improve the conversion of α, β- unsaturated aldehydes and the selectivity of unsaturated alcohol compared to pure alcohol system. |
PDF Full Text Request