Catalytic Effect Of Co And Ni Oxide Supported Materials On Selective Oxidation Of Styrene

In this paper,Co₃O₄/ZSM-5 was prepared by a simple impregnation method.The composite material with Co₃O₄ nanoparticles supported on ZSM-5 was characterized by XRD,SEM,TEM and N₂ adsorption-desorption technique and its catalytic performance for the selective oxidation of styrene to benzaldehyde without organic solvents was investigated using O₂ instead of H₂O₂ as oxidant.The correlation between the surface composition,structure and the catalytic activity,as well as preparation process conditions of the material were discussed.Meanwhile,the effect of the oxidation reaction conditions on the catalytic performance was studied.The optimal preparation conditions of the catalyst were determined with the dosage 2.4 g Co?NO₃?₂·6H₂O and1.0 g ZSM-5,the calcination at 500?for 4 h;the optimal reaction conditions were:the reaction temperature was 80?,time 8 h,the initial pressure of O₂ 2.0 MPa,10 mL styrene and 0.15 g catalyst.Under these conditions,the conversion of styrene approaches to 42.8%with TON 566.6 mol/mol_Co,and the selectivity to benzaldehyde was 96%.Moreover,under this condition,the only by-product was 4.0%benzoic acid.The catalyst after the first use was recovered by filtration,washed with absolute ethanol,dried at 80°C for 4 h and dried,and then subjected to a reuse test under the same reaction conditions.The test results of the catalyst reusability showed that the catalytic activity is effectively maintained even at the fourth run,indicating that the catalyst has excellent recycling performance.In addition,the catalytic properties of bimetal oxides?Fe-Co,Ni-Co,Cu-Co,Zn-Co?supported on various supports,such as SBA-15,ZrO₂,TiO₂ and ZSM-5,were explored.The results showed that the Co-Ni/ZSM-5 indicated higher catalytic activity than Co/ZSM-5 with 66.7%conversion and 94%selectivity.