The Preparation And Research Of Water Tolerant Solid Acid Catalysts In Esterification Of Acrylic Acid

Water-tolerant solid acid catalysts are attracted much attention because they have excellent catalytic activity, selectivity and hydrophobicity, short reaction time, simple final treatment, low reaction temperature, ease of separation and reusability in water-concerning reactions. The detailed results of the research work are presented as follows.Novel hydrophobic solid acid catalysts ZS/HZSM-5were prepared by supporting Zirconium sulfate on HZSM-5and utilized esterificaton of acrylic acid with n-butanol as a model reaction to assess catalysts. The preparation conditions were optimized. The catalysts ZS/HZSM-5were characterized by XPS, XRD, FTIR, DTA-TQ BET, and FTIR in situ. The results showed that new interaction chemical bands formed between ZS and HZSM-5, which resulted in ZS low water solubility. The maximum conversion of AA was98.98%, and ZS/HZSM-5exhibits good hydrophobicity and activity for esterification.Activated carbon supported zirconium sulfate were also studied. ZS/AC had not only high activities and selectivity, the conversion of AA was98.87%, but also good hydrophobicity due to low water solubility, the conversion of AA kept86.02%after ZS/AC was recycled successive4times. Therefore ZS/AC was stable and anti-leaching in water and easy to recycle.Zirconium sulfate supported on silica were also prepared. ZS/SiO2had high activities, the highest conversion of AA was98.1%. These catalysts were characterized by FTIR, XRD and their acidity was measured by in situ FTIR.ZS/HZSM-5(20%ZS,110℃,2h), ZS/AC (30%ZS,110℃,2h) and ZS/SiO2(25%ZS,200℃,2h) were used as catalysts in the esterification of acrylic acid and n-butanol. These catalysts were recycled4times, and compared their catalytic activity and stability. Experimental results indicated that the catalytic activity and stability of ZS/AC were the best, the second was ZS/HZSM-5, and the last was ZS/SiO2.H3PW12O40(HPW) supported on HZSM-5, as a novel solid acid catalyst was prepared for esterification of acrylic acid (AA) with n-butanol. The effects of SiO2/Al2O3, HPW loading on HZSM-5and calcination temperature were optimized. The maximum conversion of AA is96.44%. After reused4times, the conversion of HPW/HZSM-5is still stain71.98%. These catalysts were characterized by FTIR, XRD and their acidity was measured by in situ FTIR. The results indicated that HPW was well dispersed on the support surface. The bands assigned acid sites at1525cm-1and1686cm-1were observed in in situ FTIR of HPW/HZSM-5after adsorbing ammonia, indicating HPW/HZSM-5had Lewis acid sites and Br(?)nsted acid sites. HPW/HZSM-5(40%HPW,180℃,2h) and ZS/HZSM-5(20%ZS,110℃,2h) were used as catalysts in the esterification of acrylic acid and n-butanol. These catalysts were recycled4times, and compared their catalytic activity and stability.