Preparation Of Magnetic Co-based Catalysts And Their Catalytic Performance Of Isobutyraldehyde

Isobutyric acid is a widely used chemical raw material.The development of isobutyraldehyde oxidation to produce high value-added isobutyric acid has good economic benefits and is of great significance.In this paper,magnetic cobalt-based Fe₃O₄@Co（x）-ZIF and Fe₃O₄@Co（y）/Zn-ZIF catalysts were prepared by the solvothermal method.The catalysts were characterized by XRD,BET,FTIR,XPS,SEM,and TEM.Taking the oxidation of isobutyraldehyde to isobutyric acid as a model reaction,the effects of different cobalt content and different Co/Zn molar ratio on the oxidation performance of isobutyraldehyde were studied,the oxidation mechanism was proposed,and the recovery and regeneration performance of the catalyst was explored.The main results of Fe₃O₄@Co（x）-ZIF catalysts are as follows:（1）the morphology of Fe₃O₄@Co（x）-ZIF catalysts with different Co content is rhombohedral dodecahedral crystal,which is typical of Co-ZIF-67 materials.（2）among the catalysts with different Co/Zn mole ratios,Fe₃O₄@Co（2）-ZIF catalyst has the best catalytic effect,and the order of catalyst activity is Fe₃O₄@Co（2）-ZIF>Fe₃O₄@Co（3）-ZIF>Fe₃O₄@Co（1）-ZIF.（3）the optimum reaction conditions are as follows:75 m L isobutyraldehyde,actual total oxygen/theoretical total oxygen（n）is 1.2:1,0.015 g of Fe₃O₄@Co（2）-ZIF catalyst,and reaction temperature40℃.The yield of isobutyric acid is 93.6%for 150 min.（4）the Fe₃O₄@Co（x）-ZIF catalyst,the Fe₃O₄ core can enhance the ability of Co²⁺to form metal-oxygen complexes with O₂ and promote the circulation of Co²⁺to Co³⁺,while the huge specific surface area of the shell Co-ZIF-67 and ordered Co²⁺ions provide abundant active centers for the oxidation reaction.With the two synergies,the yield of isobutyric acid was increased.The main results of Fe₃O₄@Co（y）/Zn-ZIF catalysts are as follows:（1）the morphology of Fe₃O₄@Co（y）/Zn-ZIF catalysts with different Co/Zn molar ratio is octahedral crystal,which is typical of Zn-ZIF-8 material.（2）among the catalysts with different Co/Zn molar ratios,Fe₃O₄@Co（2）/Zn-ZIF catalyst has the best catalytic effect,and the order of catalyst activity is Fe₃O₄@Co（2）/Zn-ZIF>Fe₃O₄@Co（3）/Zn-ZIF>Fe₃O₄@Co（1）/Zn-ZIF.（3）the optimum reaction conditions are as follows:75 m L isobutyraldehyde,actual total oxygen/theoretical total oxygen（n）is 1.2:1,0.015 g of Fe₃O₄@Co（2）/Zn-ZIF catalyst,and reaction temperature40℃.The yield of isobutyric acid is 93.8%for 120 min.（4）the Fe₃O₄@Co（y）/Zn-ZIF catalyst,Fe₃O₄ core can enhance the ability of Co²⁺to form a metal-oxygen complex with O₂ and promote the circulation of Co²⁺to Co³⁺.The huge specific surface area of shell S-@Co/Zn-ZIF and ordered Co²⁺ions provide abundant active centers for oxidation.With the two synergies,the yield of isobutyric acid was increased.