添加成膜促进剂合成致密ZSM-5分子筛膜

Synthesis of Compact ZSM-5 Zeolite Membrane by Adding the Promoter NaCl

报道了一种添加氯化钠低温条件下合成出具有纳米尺寸的ZSM 5分子筛 ,并以其为晶种预吸附在多孔氧化铝载体上 ,再通过添加成膜促进剂氯化钠二次水热合成制备出高度致密ZSM 5分子筛膜的新方法 .通过考察添加的钠离子浓度对成膜的影响 ,认为在一定浓度范围内钠离子能够促进成膜 .SEM结果也验证了这一结论 ,分子筛膜主要是由孪生聚晶分子筛组成 .渗透结果显示 ,当添加量为x =10 0 (Al2 O3 ∶84SiO2 ∶10Na2 O∶xNaCl∶15TPABr∶3 5 0 0H2 O)时 ,在室温和 0 .1MPa的条件下 ,H2 /C3 H8的理想选择性最大值 2 3 .7,温度提高到 2 0 0℃时的选择性下降为 9.4,但仍然高于努森扩散值 (4 .69) 。

The compact ZSM-5 membranes was synthesized on porous alumina substrates by pre-coating narrosized ZSM-5 seeds and then employing the twice hydrothermal synthesis with adding the promoter NaCl. Effect of Na+ concentration on the formation of membrane was investigated in this work, indicating that adding a certain mount of NaCl can boost the growth of zeolite crystals on the substrates, thus forming the compact membrane consisted of highly intergrown crystals. The separating performance of zeolite membranes indicated that using a mixture with a composition of Al2O3: 84SiO(2): 10Na(2)O: 100NaCl: 15TPABr: 3500H(2)O as synthesis gel, the ideal selectivity of H-2/C3H8 could reach a maximum value of 23.7 at room temperature and pressure difference of 0.1 MPa, and the permselectivity decreased to 9.4 at testing temperature of 200 degreesC, which is still higher than the corresponding Knudsen diffusion value (4.69), suggesting that the membrane synthesized by this method was defect-free.