Synthesis Of Highly Selective Pd-based Catalysts And Application In Hydrodechlorination Of Chlorophenols

Chlorophenols(CPs)represent an important environmental concern due to their acute toxicity,resistance to biodegradability and strong bioaccumulation potential,their safe disposal has become an important area of research with the ever increasing concern about the environment protection.Catalytic hydrodechlorination(HDC)may be considered as a potential solution since it is a clean,relatively cheap and efficient technique that can be used to treat streams within a wide range of concentrations at ambient or near-ambient temperature.Therefore,it is important to study the behavior of Pd-based catalysts with excellent catalytic performance in HDC of chlorophenols.In this study,carbon nanotubes(CNTs),Iron(III)acetylacetonate(Fe(acac)3)and tetraethyl orthosilicate(TEOS)were used to prepare the magnetic mesoporous silica nanotubes(MSNTs);the amino-functionalization of the MSNTs material with NH2 groups were prepared by 3-aminopropyltriethoxysilane(3-APTES);the Pd@NH2-MSNTs were fabricated using K2PdCl4 as the Pd source through an aqueous impregnation method.The as-synthesized Pd@NH2-MSNTs catalysts were investigated by transmission electron micrograph(TEM),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),vibrating sample magnetometer(VSM),Fourier-transfer infrared spectroscopy(FT-IR)and N2 adsorption-desorption.For the HDC and further hydrogenation of CPs to a useful industrial product C-one,the activity of the catalyst is influenced by dosage of the catalyst?reduction temperature?alkali and different catalyst supports.It is astonishing that the catalysts show better catalytic performance,and it can synthesize cyclohexanone in one pot,in comparison with other heterogeneous catalysts for which phenol is the only reaction product.The catalysts show 100% conversion with 99% selectivity for cyclohexanone in aqueous solution at mild condition of temperature(60 ?)under ambient pressure.In particular,Pd@NH2-MSNTs exhibit an excellent reusable by an external magnet from the reaction and recycled seven times without any significant loss in activity.