十二烷基苯磺酸钠辅助合成梯级孔丝光沸石的研究

Study on the Synthesis of Hierarchical Mordenite by Using Sodium Dodecyl Benzene Sulfonate as Soft Template

摘要:

丝光沸石 (MOR) 是二甲醚 (DME) 羰基化反应的高效催化剂，采用添加模板剂的方法合成具有介孔结构的丝光沸石是进一步提高其催化性能的重要方法。本文采用无溶剂法，以十二烷基苯磺酸钠(SDBS)为软模板剂合成了具有微介复合结构的丝光沸石分子筛。采用X射线粉末衍射、N2吸附-脱附、NH3吸附-脱附、吡啶红外等方法对制备的丝光沸石进行了表征。表征结果表明，提高SDBS添加量能提高样品的相对结晶度，SDBS的加入显著提高了样品比表面积、介孔孔容和总孔容，提高了反应的传质效率。此外，SDBS在合成过程中能够诱导Al原子优先进入8元环孔道形成强酸和中强酸中心，从而增加羰基化反应的活性中心数量。在200 ℃、0.5 MPa、GHSV=2000 mL/(g·h) 、DME:CO=97.5:2.5(mol)的条件下进行二甲醚羰基化反应评价，结果表明，添加4%SDBS的样品在保持乙酸甲酯 (MA) 高选择性的前提下，DME最高转化率提高了将近1.8倍，具有最佳的反应性能。

Abstract:

Mordenite (MOR) is an efficient catalyst for dimethyl ether (DME) carbonylation reaction. The synthesis of hierarchical Mordenite by using soft templates is an important method to further improve its catalytic performance. In this paper, a solvent-free method was used to synthesize Mordenite with hierarchical structure using sodium dodecyl benzene sulfonate (SDBS) as a soft template. The as-synthesized samples are characterized by X-ray powder diffraction, N2 adsorption desorption, NH3 adsorption desorption, pyridine infrared spectroscopy and other methods. The characterization results indicate that the addition of SDBS could improve the relative crystallinity of the sample, and the addition of SDBS significantly increases the specific surface area, mesoporous volume, and total pore volume of the sample, and improves the mass transfer efficiency of the reaction. Besides, SDBS can induce Al atoms to preferentially enter the 8-member ring channel to form strong acid and medium-strong acid sites during the synthesis process, thereby increasing the number of active sites for carbonylation reactions. The carbonylation reaction of DME was evaluated at 200 °C, 0.5 MPa, GHSV = 2000 mL / (g·h), DME : CO = 97.5 : 2.5 (mol). The results demonstrated that the highest conversion of DME increased by nearly 1.8 times with the addition of 4% SDBS under the premise of maintaining high selectivity of methyl acetate (MA), which exhibited the best carbonylation performance.