Prins Condensation Between Formaldehyde And Isobutene Catalyzed By Various Metals Modified MCM-41

3-methyl-3-butene-1-ol（MBO）is a profitable organic synthesis intermediate,which has extensive applications in many fields such as pesticide,medicine,perfume,architecture material.MBO is synthesized normally by Prins condensation of formaldehyde and isobutene,which can utilize the excessive isobutene efficiently in petrochemical industry.The solid acidic catalyst is considered to be effective for this reaction,of which Lewis acidic catalyst may be more suitable due to the moderate acid strength.In this thesis,a series of MCM-41 modified with different metals were prepared by mechanical mixing method,and their catalytic performances were evaluated.The relationship between performance,structure and acidity of M/MCM-41 were systematically investigated.Their stability and regeneration performance were also examined.The main results are as follows:（1）Zn/MCM-41 with different Zn loadings were prepared by mechanical grinding method,and their catalytic performances in Prins condensation between formaldehyde and isobutylene were evaluated.The structure and acidity of Zn/MCM-41 were characterized by means of XRD,NH₃-TPD and UV-vis spectra.It is found that the conversion of formaldehyde increases to 99%and MBO yield is up to 88%on Zn/MCM-41 catalyst under the optimized reaction temperature of240℃,isobutene/formaldehyde molar ratio of 6 and 4 h of reaction.The proper ratio of isolated to clustered zinc oxide and appropriate amount of acidic sites are beneficial to the catalytic performance.Moreover,this catalyst has regeneration capability to a certain extent.After five successive regeneration cycles,MBO yield was reduced from 88%to 65%.（2）A series of single metal modified M/MCM-41（M=Zn、Zr、Al、Cu、Y、Ce、Sn、Ni）catalysts were prepared for the Prins condensation reaction between formaldehyde and isobutene to MBO.Under optimal reaction conditions,it is founded that Cu/MCM-41 and Al/MCM-41 have better performances than the others.The conversions of formaldehyde on Cu/MCM-41 and Al/MCM-41are 92%and 97%,and MBO yields are 89%and 94%,respectively.The coke contents on the spent Cu/MCM-41 and Al/MCM-41are 14%and 18%,respectively,which are less than the other catalysts.While other catalysts have poor Prins condensation reaction performances,for instance,Y/MCM-41 and Ce/MCM-41 catalysts have low conversion of formaldehyde,which are 79%and 83%,respectively.Zr/MCM-41,Sn/MCM-41 and Zn/MCM-41 catalysts have low MBO selectivity.The coke contents of Y/MCM-41,Ce/MCM-41 and Ni/MCM-41 are higher,which are 32 wt%,27 wt%and 26 wt%,respectively.（3）It is found that the conversion of formaldehyde increases to 100%and MBO yield is up to98%on bimetal modified Cu-Al（1:1）/MCM-41 catalyst,which is higher than the single metal supported catalyst under the optimized reaction condition.The structure and acidity of Cu-Al（1:1）/MCM-41 were characterized by means of XRD,NH₃-TPD,BET and UV-vis spectra,and the influences of the quantity ratio of the catalyst and the synergistic effect on Prins reaction performance was explored.Moreover,this catalyst has regeneration capability to a certain extent.After three successive regeneration cycles,MBO yield decreses to 64%.Its BET surface area and pore volume decrease obviously after regeneration.The aggregation of the active sites may lead to the decrease in the amount of acid sites,especially the middle-strong and strong acid sites,which is the main reason for the catalyst deactivation in Prins reaction.