Synthesis, Characterization And Catalytic Reactivity Of Zirconium, Tungsten-doped SBA-15 Solid Acid For 1,4-Butanediol Esterification

3-butene-1-alcohol (BTO) with two functional groups of double bond and hydroxy, which is an important chemical intermediate. BTO is widely used in the synthesis of fine chemicals, such as medicine domain. Catalyzing for hydrolysis dehydration-coupling reaction of 1,4-butanediol monoacetate is model efficient synthesis of 3-butene-1-alcohol (BTO). Compared with BTO synthesis method reported in literatures,1, 4-butanediol monoacetate hydrolysis dehydration-coupling reaction model has the advantages of mild reaction conditions, easy separation from the product, and environmental friendly, which has great prospects for industrial application. And suitable catalyst selected plays an important role in BTO synthesis.In view of synthesis method of SBA-15 solid acid modified by hetero atoms, which has tunable acidity and pore structure and improve the characteristics of catalytic esterification activity. Research in this field has attracted many researchers attention. We propose a study to prepare catalyst via direct hydrothermal synthesis method, replaceing hydrochloric acid-water solvent with phosphotungstic acid-water solvent system, using PI23 as template, zirconium oxychloride as zirconium precursor, hosphotungstic acid as tungsten precursor, TEOS as siliceous precursor. All catalysts were characterized by XRD, TEM, and nitrogen adsorption-desorption, and the acid properties were detected by NH3-TPD, Py-IR spectroscopy. With the result, we can synthetic evaluation of catalyst performance for 1,4-butanediol esterification. When investigated zirconium or tungsten species as variables, we can conclude its influence on the structure, the acidity and catalytic esterification of SBA-15 as follows:1. The Zr-x-W-SBA-15 materials with different silicon/zirconium molar ratio were prepared via direct hydrothermal synthesis method under the condition of constant concentration of phosphotungstic acid aqueous solution. Studies have shown that Zr successfully entered the SBA-15 skeleton, within the appropriate scope of introduction, Zr can optimize Zr-x-W-SBA-15 of acidity and pore structure characteristics. With silicon/zirconium molar ratio ratio in the range of 25-50, the Zr-x-W-SBA-15 materials possessed ordered two-dimensional hexagonal mesostructures, which contains Lewis based acid catalyst acidic active. And its pore size is remained at 9.2 nm, pore volume remains at 0.99 cm3.g-1, while the surface area has decreased and the amount of acid increased. The Zr-x-W-SBA-15 materials obtained the maximum amount of acid and best mesoporous regularity at the ratio of 25 is given priority to with lewis acid characteristics of weak acid and acid.2. Under the condition of constant zirconium introduced (silicon/zirconium is 25), the W-x-Zr-25-SBA-15 materials were prepared via direct hydrothermal synthesis method under the condition of different concentration of phosphotungstic acid aqueous solution. Results show that within the appropriate amount of tungsten introduction, it can optimize W-x-Zr-25-SBA-15 of acidity and pore structure characteristics. With HPW doping amount increased from 0.1 g to 1.0 g, the W-x-Zr-25-SBA-15 materials could kept SBA-15 ordered two-dimensional hexagonal mesostructures, the pore size is remained at 10.1 nm, and pore volume remained at 0.96 cm3.g-1,and the specific surface area is slightly decreased. The W-x-Zr-25-SBA-1 materials aslo have Lewis based acid catalyst acidic active, and acquired the max of acid amount at the doping amount of 1.0 g.3. On the basis of exploring the synthesis, characterization and reactivity of tungsten-zirconium doped SBA-15 catalyst for esterification of 1,4-butanediol and acetic acid, we proposed the mechanism for catalytic 1, 4-butanediol esterification performance of mesoporous solid acid. As a result,1,4-butanediol monoacetate yield is mainly related to acid content of catalyst, and the catalyst selectivity for 1,4-butanediol monoacetate have something to do with the order degree of catalyst mesoporous structure. Therefore, W-1-Zr-25-SBA catalysts has the best physical and chemical properties, including high catalytic activity, high mesoporous ordered degree, large surface area, and strong acid strength, which showed highest catalytic performance in Synthesising 1,4-butanediol monoacetate, its yield and selectivity is 55% and 90% respectively.