Study On Preparation Of Novel Magnetic Metal-Organic Framework Catalyst And Its Performance Of Heck Reaction

Heck reaction is a kind of coupling reaction of aryl halide and compounds with double bond at the terminal. This process need catalysts. The previous Heck coupling catalysts are mainly Pd based homogeneous catalysts which have the disadvantages of environmental pollution and the difficulties of separation. They have been replaced by heterogeneous metal loaded catalysts. Supports of these catalyst are usually carbon materials, zeolites and other porous materials with large specific surface. In order to further increase the supports' specific surface area and improve the dispersion of Pd nanoparticles, metal organic framework material ZIF-8 was in-situ synthesized on the magnetic microspheres as a support to enhance the recovery ability of the catalysts.We explored the method to prepare several novel magnetic metal organic framework catalysts in which magnetic ZIF-8@SiO2@Fe3O4 microsphere as the carrier, Pd as the active component, Cu and Co as additives. Comprehensive study of the performance of the catalyst for Heck reaction was carried out. Firstly, ZIF-8@SiO2@Fe3O4 was prepares by stepwise synthesis as a magnetic composite carrier with three-layer core-shell structure.Subsequently, Pd, Cu and CO nanoparticles was load on the carrier by impregnation method and liquid phase reduction method. Pd/ZIF-8@SiO2@Fe3O4, PdCu/ZIF-8@SiO2@Fe3O4 and PdCo/ZIF-8@SiO2@Fe3O4 were synthesized as three kinds of typical catalysts. XRD,SEM,TEM,FT-IR were used to characterize the structure of these catalysts.Then the performance of three kinds of catalyst for Heck reaction was studied. The results are as follows:(1) 0.01 g 1 wt%Pd/ZIF-8@SiO2@Fe3O4 was used as catalyst for Heck reaction under the conditions of 5 mmol iodobenzene,7.5 mmol of butyl acrylate,5 mL DMF,10 mmol triethylamine,0.5 ml of dodecane,120?. Iodobenzene conversion reached 98.53% for 2 h. 1wt%Pd/ZIF-8@SiO2@Fe3O4 could be reused for 3 times.(2) The best Cu loading amount of bimetallic PdCu catalyst containing 1 wt%Pd was 3wt%.0.01 g bimetallic 1wt%Pd3wt%Cu/ZIF-8@SiO2@Fe3O4 catalyst was used as catalyst for Heck reaction under the conditions of 5 mmol iodobenzene and 7.5 mmol of butyl acrylate,10 mL DMF,6 mmol ethylamine, 0.5 ml of dodecane,120?. Iodobenzene conversion reached 99.34% for 1 h. 1 wt%Pd3wt%Cu/ZIF-8@Si02@Fe3O4 could be reused for 5 times.The best Co loading amount of bimetallic PdCo catalyst containing 1 wt%Pd was 5wt%.0.01 g bimetallic 1wt%Pd5wt%Co/ZIF-8@SiO2@Fe3O4 catalyst was used as catalyst for Heck reaction under the same conditions above. Iodobenzene conversion reached 99.17% for 2 h. lwt%Pd5wt%Co/ZIF-8@SiO2@Fe3O4 could be reused for 2 times. By comparison, lwt%Pd3wt%Cu/ZIF-8@SiO2@Fe3O4 is the best catalyst with the highest catalytic activity and the best performance for repeated use.