TRANSFORMATION OF CYCLOHEXANOL OVER CUO-ZNO AND CUO-ZNO-SNO2 CATALYSTS IN THE VAPOR-PHASE

Transformation of cyclohexanol over oxidized and reduced CuO, ZnO, CuO -ZnO and CuO-ZnO-SnO2 catalysts were carried out in the temperature ra nge of 250-450-degrees-C. It was found that CuO-ZnO is more active in both the states, than CuO-ZnO-SnO2. The higher activity of CuO-ZnO com pared either to CuO or ZnO may be attributed to flow of electrons from the 3d orbitals of Cu to the empty 4s orbital of zinc both of which a re in the same energy level. This decreases the electron density aroun d copper which facilitates the adsorption of cyclohexanol through oxyg en and thus increases its activity. The lower activity of CuO-ZnO-SnO2 compared to CuO-ZnO may be due to the possible flow of electrons from higher energy levels of tin to 3d orbitals of copper which increases the electron density around copper. Consequently the adsorption of cyl ohexanol on copper surface decreases, as a result, dehydrogenation act ivity decreases. Total acidity of CuO-ZnO-SnO2 is higher than that of CuO-ZnO while the acidic strengths of the two samples are almost simil ar.