面向乙酸脱水高性能沸石分子筛膜微结构的调控与优化

Dehydration of acetic acid using efficient and energy-saving membrane technology is urgent needs for national energy conservation, environmental protect and sustainable development. The development of high performance membranes for dehydration of acetic acid is a big challenge imposed by the inherent physical and chemical properties of acetic acid molecules for the membrane community. Membranes developed so far for this purpose are of low acid resistance, low permeation flux, low selectivity. To this key question, in the project, a new strategy to manipulate both the hydrophilicity and acid resistance of zeolite membranes is proposed. Using Fluoride ions and hydroxide ions as co-mineralizing agents, microstructure control and optimization of both framework Sicon over Aluminium atom ratio (Si/Al ratio ) and microscopic distribution of Silicon and Aluminium atom within the membrane layer is carried out, aiming at achievement of a ZSM-5 membrane with high acid resistance,selectivity and permeation flux. Besides, the evolution mechanism of the two kind microstructures will be investigated. Furthermore, the structure-property relevance between the two kind micostructures and the acid resistance,selectivity and permeation flux will be explored. The study on the proposed project is of great academic significance because the related findings obtained from the project will promote the development of zeolite membrane science and technology, the zeolite catalytic science and as well as adsorption science of zeolite. Meanwhile, the obtained findings provide technical support for the industrilization of dehydration of acetic acid using membrane technology and of great practial value.

高效、节能膜技术乙酸脱水是国家节能减排、可持续发展的迫切需求。乙酸分子固有的物理化学性质使高性能乙酸脱水膜的研制成为膜科学界的难题。针对乙酸脱水分离膜低耐酸性、低通量、低选择性的关键技术难题，本项目构建了一种调控沸石膜的亲水性与耐酸性的新策略，提出采用氟离子F-与氢氧根OH-共矿化剂的合成路线，调控优化ZSM-5沸石分子筛膜的Si/Al比、硅铝元素微观分布这两微观结构因素，探讨ZSM-5沸石膜这两微观结构的演化机制，揭示ZSM-5沸石分子筛膜Si/Al比、硅铝元素微观分布这两微观结构与膜耐酸性与分离性能间的构效关系，制备具有高耐酸性、高通量、高选择性"三高"乙酸脱水ZSM-5沸石分子筛膜。本项目的相关研究成果将对沸石分子筛膜科学、沸石分子筛催化科学、吸附科学有促进作用，具有重要的学术价值；同时为膜技术乙酸脱水工业化提供技术支撑，具有重要的工业价值。

乙酸是一种基本的化学品，高效、低能耗新技术乙酸脱水浓缩精制是现有工业生产法、生物质制乙酸等工程的迫切需求。针对乙酸脱水分离膜低耐酸性、低选择性、低通量的技术问题，本项目提出对ZSM-5沸石分子筛膜的Si/Al比、硅铝元素微观分布这两微观结构因素进行调控与优化，探讨ZSM-5沸石膜这两微观结构的演化机制，弄清ZSM-5沸石分子筛膜Si/Al比、硅铝元素微观分布这两微观结构与膜耐酸性与分离性能间的构效关系，制备具有高耐酸性、高选择性、高通量“三高”乙酸脱水ZSM-5沸石分子筛膜。主要内容如下：. (2) 针对ZSM-5沸石膜材料的耐酸性与亲水性矛盾的关系，提出调控膜层中硅铝原子空间分布微结构的策略，以OH—与F—作为共矿化剂，在无有机模板剂条件下制备ZSM-5沸石膜。深入探究了有无有机模板剂对ZSM-5沸石膜Al原子空间分布的影响。结果表明，在无有机模板剂条件下，有利于制备Al原子空间分布均匀的ZSM-5沸石膜，而在含有机模板剂（TPAOH）条件下，制备的ZSM-5沸石膜表层出现富铝现象，Al原子空间分布不均一。.(3) 通过研究ZSM-5沸石膜层中硅铝原子的空间分布与乙酸脱水分离性能的构效关系，发现调控硅铝原子微观空间分布是构筑耐酸性和亲水性兼优ZSM-5沸石膜的有效策略。在此基础上，研制出具有低Si/Al摩尔比同时膜层中硅铝原子空间分布均匀的ZSM-5沸石膜，得到了高性能ZSM-5沸石膜。在75 °C下，渗透蒸发分离90 wt.% AcOH/H2O混合物的渗透通量为1.13 kg•m-2•h-1，相应的分离系数为∞，且具有良好的耐酸稳定性。.本项目的相关研究成果不仅对沸石分子筛膜科学、而且对沸石分子筛催化科学、吸附科学有促进作用，具有重要的学术价值，同时高性能乙酸脱水膜的研制是膜技术乙酸脱水的关键技术问题，是国家节能减排、可持续发展的迫切需求，具有重要的工业应用意义。