Synthesis Of Mesoporous Zirconia-based Solid Acid Catalyst And Its Application In Glycerol Acetylation With Acetic Acid

Sulfated zirconia provide both high activity and thermal stability have been recognized as one of the most important classes of solid acid catalysts. The traditional preparation method of sulfated zirconia is limited because of the low specific surface are a, irregular porosity, non-uniform pore size and so on. In this paper, the method of EISA was adopted to improve the pore structure properties of zirconia by compoundin g zirconia with other amphoteric oxide?TiO₂, SiO₂ and Al₂O₃?. Then mesoporous TiO₂-ZrO₂?MTZ?, SiO₂-ZrO₂?MSZ? and Al₂O₃-ZrO₂?MAZ? composite were synthesized by EISAT. After the mesoporous SO₄^2-/TiO₂-ZrO₂?STZ?, SO₄^2-/SiO₂-ZrO₂?SSZ?, SO₄^2-/Al₂O₃-ZrO₂?SAZ?, SO₄^2-/CeO₂-TiO₂-ZrO₂?SCTZ?, SO₄^2-/CeO₂-SiO₂-ZrO₂?SCSZ? and SO₄^2-/C eO₂-Al₂O₃-ZrO₂?SCAZ?solid acid catalysts were synthesized with impregnation method and characterized with XRD, BET, SEM and TEM. Finally, the above-mentioned catalysts are used for the acetylation reaction of glycerol with acetic acid to study catalyst performance and explore the optimal reaction conditions.Firstly, the MTZ, MSZ and MAZ with mesoporous structure and more uniform pore size distribution were synthesized by EISA. MTZ reveal a highly ordered and partial 2D hexagonal mesoporous structure when calcined at 400?. After calcined at 800?, the frameworks crystallize became to ZrTiO₄. MSZ owned worm-like channel, the high specific surface area of 402.3m²/g was observed, and the mean pore size was 4.5nm when calcined at 400?. MAZ sample also has a worm-like pore channel, but its mean pore size was larger?11.4nm? than MTZ and MSZ when calcined at 400?. After calcined at 800?, the frameworks crystallize turned to Al_0.16Zr_0.84O_1.92.Then, STZ, SSZ, SAZ, SCTZ, SCSZ, SCAZ samples were prepared by using the impregnation method. Small-angle XRD showed that all samples have mesoporous structure, as well as highly regularity. BET and TEM results showed that, SCTZ sample having a two-dimensional hexagonal mesoporous structure with long range order, the specific surface area of 160.8 m²/g, and an average pore diameter of 6.5nm after calcined at 400 ?. When the calcination temperature rise to 600 ?, SCTZ sample still maintain good orderliness, but the average pore diameter increased to 13.9nm, while specific surface area decreased to 102.2m²/g.Finally, the aforementioned catalysts were applied into the acetylation reaction of glycerol with acetic acid. The different calcination temperature and Ti/Zr?mole ratio? of catalysts have been inspected. The diverse parameters such as reaction temperature, reaction time, different molar ratio of acetic acid with glycerol and different catalyst dosage were studied over SCTZ? calcined at 400?? to explore the optimal reaction conditions of glycerol with acetic acid. The results shows the optimized reaction conditions were 120? reaction temperature, 2h reaction time, 2h reaction time, 9:1 acetic acid to glycerin mole ratio and 5wt% catalyst to glycerol over SCTZ catalyst was calcined at 600 ? and Ti/Zr?molar ratio?=5:5. the conversion of glycerol was 100%, the selectivity of monoacetate, diacetate and triacetate were 22.1%, 59.5% and 18.4%, respectively. Finally, the stability of reusability of SCTZ catalyst was studied.