介孔分子筛Al-MCM-41接枝三甲基氯化锡的合成、表征及催化性能

将三甲基氯化锡与Al-MCM-41介孔分子筛在N2气气氛中135 ℃回流4.5 h，得到表面键合有机锡的分子筛(CH3)3Sn-O-MCM-41[(CH3)3SnM]。 采用电感耦合等离子体质谱（ICP-MS）、有机元素分析、红外光谱、N2吸附-脱附、热重分析（TG）、NH3程序升温脱附（NH3-TPD）、X射线多晶衍射（XRD）和透射电子显微镜等测试技术对样品的组成、结构和表面物理化学性质进行表征。 结果表明，有机锡接枝率可达14.44%；接枝前后分子筛的NH3-TPD表面酸量(NH3)由0.652 6 mmol/g增加至1.294 4 mmol/g。 接枝后分子筛的比表面积减小，孔容变大，孔径变小，仍保持六方介孔结构；接枝分子筛(CH3)3SnM用于催化合成乙酸异戊酯，当n(异戊醇)∶n（冰乙酸）=1.0∶1.0，w（催化剂）=5%，138 ℃，回流5 h，反应转化率为96%；催化剂重复使用5次，酯化转化率仍可达到86%。

Synthesis and Characterization of the Trimethyltin Chloride Tethered on Mesoporous Molucular Sieve Al-MCM-41 and Its Catalytic Performance

Trimethyltin chloride and mesoporous molecular sieve Al-MCM-41 were heated at 135 ℃ for 4.5 h under stirring conditions and nitrogen atmosphere, to obtain (CH3)3Sn-O-MCM-41[(CH3)3SnM]. The composition, structure, and physical and chemical surface properties of the resulted solid were characterized by inductively coupled plasma mass spectrometry(ICP-MS), Fourier transform infrared spectroscopy(FTIR), N2 adsorption-desorption, NH3 chemisorption(NH3-TPD), X-ray diffraction(XRD), and transmission electron microscopy(TEM). The results showed that the grafting yield was 14.44% for Sn in mass fraction. TPD acid (NH3) of Al-MCM-41 before and after reaction with trimethyltin chloride increased from 0.652 6 mmol/g to 1.294 4 mmol/g. (CH3)3-SnM resulted in a decrease of the surface areas and the pore size and an increase of the mesopous volume and surface acidity compared to Al-MCM-41. The thermal stability for the sample grafted with organotin was improved. The sample that was grafted with organotin on the Al-MCM-41 had the ordered hexagonal mesopore structure. The conversion rate is 96% when n(isoamyl alcohol)∶n(acetic acid)=1.0∶1.0, w((CH3)3SnM)=5%, 138 ℃ for 5 h, and the catalyst can be reused. A conversion rate of 86% can be attained when catalyst was reused five times under the same catalytic conditions.