| Popis: |
The use of environmentally friendly catalysts obtained by the transport of transition metals on solid or polymer carrier materials, in chemical reactions has become quite common recently. Studies in which zinc complexes are used as homogeneous and heterogeneous catalysts are frequently encountered in literature. In addition to many advantages of homogeneous catalysts, there are some disadvantages such as difficulty in separating from reaction medium, recycling and limited chemical-thermal stability. The solution of problems can be achieved by using solid catalyst support materials and transferring the active ingredients to these support materials. Therefore, catalysts prepared by transporting transition metal complexes onto solid supports have become interesting for researchers. Natural or processed clays can be used as catalysts or catalyst carriers as well as having many uses due to their cheapness and abundance in nature. In this study, natural Enez/Edirne bentonite was acid activated (HB) and converted to organo-clay (HB/CTAB) with hexadecyltrimethyl ammonium bromide (CTAB). Then, heterogeneous catalysts were prepared by direct transport of the synthesized [Zn(acac)2H2O] or [Zn(p-H2NC6H4COO)2]1.5H2O complexes onto modified clays separately. The characterization of the catalysts have been performed by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, surface scanning electron microscope and Brunauer-Emmett-Teller specific surface analysis methods. |
