Preparation of Sulfated Zirconia-modified Mesoporous SBA-15 and Catalytic Performance in Synthesis of Methyl Paimitate

摘要

Sulfated zirconia-modified mesoporous SBA-15 molecular sieves(ZS/SBA-15) had been prepared by homogeneous urea hydrolysis method. The modified materials were characterized by X-ray diffraction (XRD), transmission electron micrographs (TEM), nitrogen adsorption. XRD results exhibit that ZS/SBA-15 remains the highly order mesoporous channels with hexagonal structure. The average diameter of the pore decreases from 5.60 to 4.70 nm after addition of ZrO_2 and SO_4~(2-) to SBA-15. The acid strength(0.80 < H_0 < 0.99)on catalyst surface was determined by mean of Hammett indication method, and the total amount of acid (1.42 mmolg~(-1)) was estimated by TPD of NH3. The catalyst (ZS/SBA-15) show best catalytic activity in synthesis of methyl paimitate.The optimum conditions of the esterification by orthogonal experiments were studied: the molar of methanol to palmitic acid 15: l,the amount of catalyst 0.8 g, reaction time 8h .The conversion of methyl paimitate could reach 90.3% under the optimum conditions.