b 取向MFI分子筛膜的可控制备及其分离浓缩痕量TNT蒸气的性能研究

Reducing the reliance on the intrinsic sensitivity of a sensor by concentrating trace TNT vapor has been the focus of public security. To overcome the disadvantages of traditional explosives concentrating method through adsorption - thermal desorption, it is proposed that dense and continuous b-oriented MFI membranes could realize the one-step concentrating of trace TNT vapor selectively and rapidly. It is proposed that the cooperation of modification of porous substrate by TiO2 layer with self-assembling of the coffin shape MFI crystal seeds will make contributions to compact zeolite monolayers covered on the surface densely.. The in-plane growth of crystal seeds shall be adjusted by the growing dynamics factors. Application of detemplation in O3 atmosphere could obtain dense and continuous b-oriented MFI membranes with free channels. The MFI membranes is evaluated by testing the separation factor and permeation flux for TNT and N2. The influence of synthetic conditions on the membrane structure and the separation and enrichment performance could be analyzed. The determination of separation and enrichment performance by structure parameters could be revealed. This study will enrich the synthesis of b-oriented MFI membranes and provide reliable theoretical and experimental basis for concentrating trace TNT selectively employing zeolite membranes. Furthermore, it will extend the limit of sensor sensitivity and shed light on the design of TNT sensor.

浓缩痕量TNT蒸气，降低检测对传感器固有灵敏度的依赖程度，已成为公共安全领域关注的前沿性课题。为克服传统吸附-热脱附方式浓缩爆炸物的缺点，本项目设计合成连续致密、b取向的MFI分子筛膜实现一步选择性、快速分离浓缩空气中痕量TNT蒸气。拟通过多孔基底表面TiO2薄层修饰与棺材型MFI晶种自组装协同促进b取向单层的高度覆盖、紧密排列，调节二次生长动力学因素控制晶种层外延生长，结合低温臭氧脱模技术，制备出孔道通透、连续致密、b取向MFI分子筛膜。通过分子筛膜对TNT/N2混合气的分离系数和渗透通量评价分离浓缩性能，分析合成条件对膜结构及分离浓缩性能的影响，揭示结构参数与分离浓缩性能间的联系。此研究将丰富b取向MFI分子筛膜的制备方法，为分子筛膜选择性浓缩痕量TNT蒸气提供理论和实验依据，同时为爆炸危险品传感检测器件灵敏度的提高提供新的思路和技术途径。

本项目立足于提高爆炸物传感器件灵敏度，制备了连续致密取向性高的MFI和LTA分子筛膜,首次利用分子筛孔道直径与爆炸物2, 4, 6–三硝基甲苯（TNT）气体分子动力学直径的差异浓缩TNT气氛，实现了对TNT气氛的快速(20 s)、高效浓缩(浓缩系数为24.3和31.8)，对实时、超灵敏检测爆炸物分子具有重要意义，此方法具有普适性，通过选择合适孔径尺寸的分子筛膜，可实现其它低浓度爆炸物气氛的筛分浓缩。在研究中进一步发现，金属氧化物基化敏传感器检测TNT的灵敏度会受到水蒸气的交叉干扰，以对TNT气氛具有优异响应性能的TiO2纳米材料为对象开展了湿敏响应机理研究，氧空位缺陷造成了湿度对室温大气环境下TNT气氛检测的交叉干扰，因此，在敏感材料设计方面应采用降低缺陷而增加其比表面积的策略。同时，制备了具有有序晶格结构的异质结材料并实现了ppb H2S的的高检测限（1.7 ppb）、高选择性、快速（响应和恢复时间分别为78 s、70 s）检测，从能带结构、界面势垒高度及介晶孔结构研究敏感材料的响应增强机理及强抗干扰性。.项目在传感器灵敏度提高、湿度交叉干扰、传感材料设计方面的工作具有原创性，对于痕量TNT气氛及其它气氛如H2S等的检测具有一定的参考价值。相关成果发表在Sensors & Actuators, B: Chemical、Nanoscale Research Letters等材料领域知名期刊。