Preparation Of Zn-based Composite Metal Oxide Catalyst And Study On The Performance Of Acetylation Of P-anisole

Friedel-Crafts acylation is an important reaction in chemical production.Among them,the acetylation product of anisole:P-methoxyacetophenone(P-MAP),is widely used in pesticides,drugs,perfumes and dyes.Generally speaking,traditional metal halide catalysts and proton acid catalysts are still used in existing processes,but there are many shortcomings,such as corrosion,environmental pollution and non-recyclability.Therefore,it is necessary to replace traditional homogeneous acid catalysts with environmentally friendly catalysts.Among them,composite metal oxides are widely used in academic and industrial fields due to their advantages of simple preparation,diverse structures,and low cost.Different structural characteristics make composite metal oxides exhibit different catalytic properties in the fields of light,electricity and thermal catalysis.In addition,the interaction between different oxides can adjust the p H and active sites of the catalyst surface,showing better catalytic activity than other catalysts.In this paper,a series of bimetal oxide catalysts were synthesized by co-precipitation,sol-gel and MOFs template method and applied to the acetylation reaction of anisole.Main contents are as follows:A series of composite metal oxide catalysts with different Zn/Cu molar ratios were prepared by co-precipitation method,which Zn Cu₃O_x catalyst has the highest catalytic activity.Interestingly,Zn O plays an important role in promoting the dispersion of active sites and adjusting the surface structure and coordination.With the dispersion of Zn O in Cu O crystal phase to varying degrees,part of the tetrahedral coordinated divalent copper ion transforms into the octahedral coordinated divalent copper ion with lower binding energy and more stable.When Zn O is completely dispersed in the Cu O lattice,the content of octahedral coordinated divalent copper ions is the most.Because of its strong Lewis acidity,the catalyst has the highest activity,which accelerates the reaction.All in all,the outstanding catalytic performance of Zn-Cu composite metal oxide catalysts come from the synergistic effect of octahedral coordinated divalent copper ions and fully dispersed Zn O.A series of composite metal oxide catalysts with different Zn/Al molar ratios were prepared by the sol-gel method.It is worth noting that when the Zn/Al molar ratio is 1:2,Zn Al₂O₄ spinel-type oxides were successfully prepared.It has the highest catalytic activity in this catalytic reaction.A series of characterizations show that this is not only because the strong Lewis acidity and acid sites of the spinel catalyst,which can activate the acetyl chloride,but in addition,the formation of the spinel structure makes it has the highest surface active oxygen vacancies.And more importantly,the formation of the spinel structure makes it has a larger specific surface area than any other catalyst,which also plays a strong role in promoting the occurrence of the reaction.Several bimetallic composite oxide catalysts with different Zn/Co molar ratios were synthesized by MOFs template method and successfully applied to the acetylation reaction of anisole.Zn Co₂Ox bimetallic composite oxide catalyst was prepared when the Zn/Co molar ratio is 1:2 and it has good catalytic activity.Through a series of characterization,we found that the excellent catalytic performance of the Zn Co₂Ox catalyst may be derived from the change of structure,resulting in transformation of the three-dimensional structure of MOFs to the two-dimensional oxide structure during the preparation of the catalyst.After the catalyst is heat-treated,a larger specific surface area and pore structure are formed,which is conducive to the progress of the reaction.In addition,the internal defects caused by Co²⁺can also provide more active sites for the reaction,and the existence of strong acidity is the indispensable factor for the reaction.