Collaborative Research: Advanced Zeolite-Composite Adsorbents with Fine-Tuned Pore Sizes for Molecular Sieving Separations

项目编号：1402772 / 1402122标题：用于分子筛分离的先进分子筛-复合吸附剂混合物分离是工业过程中一个庞大而昂贵的组成部分。各种分离技术，如蒸馏、萃取、吸附和膜分离，已经发展到利用混合物中不同性质的组分来分离混合物。其中，以变压吸附（PSA）和变温吸附（TSA）为基础的吸附分离技术在工业上得到了广泛的应用。更节能的吸附气体分离工艺的发展强烈依赖于改进的多孔吸附剂的发展，具有良好吸附等温线和选择性的多孔吸附剂一直是基于吸附的分离工艺的重点。分子筛由于具有均匀的分子孔径和较高的化学稳定性、热稳定性和机械稳定性，是在苛刻的分离条件下实现真正分子筛分离的最有前途的吸附剂之一。尽管有大量的沸石/分子筛可供选择，也有调整其孔径的技术，但并不是所有理想的孔径都能用于目标分离，特别是对于尺寸非常接近的分子，如N2（动力学直径：0.364 nm）/CH4 （0.38 nm）、O2 (0.346 nm)/N2和石蜡/烯烃。因此，迫切需要开发新的策略来进一步微调沸石基材料的孔径，填补不同沸石之间的孔径差距。本研究的目标是通过沉积超薄微孔涂层来微调沸石的孔入口，以实现传统沸石难以分离的工业重要混合物的有效分离。利用分子层沉积技术（MLD）在沸石上沉积超薄微孔涂层，以填补不同沸石之间的孔径间隙，从而增强对沉积机制和涂层与沸石基质相互作用的基本理解。具体而言，本研究的目标是：(1)开发一种可靠且可重复的MLD工艺，在沸石衬底上沉积超薄有机/无机杂化膜（具有精确控制的性能），并对影响MLD涂层质量的因素有一个基本的了解；(2)阐明和了解复合MLD涂层在不同条件下的分解和成孔机理；(3)表征沸石-复合吸附剂的有效孔径，建立基本的涂层性能-孔径关系；(4)合理设计具有理想孔径的沸石复合吸附剂，考察其对目标混合物的分离性能。这一全新的概念可能导致难以分离的混合物的有效吸附分离。这项研究预计将对纳米结构沸石复合吸附剂的合成产生重大的科学和技术影响，这些吸附剂具有微调孔径，可用于混合物分离和潜在的选择性催化。如果成功，该项目将大大有利于基于吸附的分离工艺。这将在合理设计沸石基吸附剂方面取得重大进展。所提出的研究对工业上重要气体混合物的分离具有重要的实际意义。期望本研究能为吸附分离过程中高级吸附剂的合理设计提供参考。pi有明确的计划，以吸引广泛的学生学习纳米材料和分子筛。少数族裔的特殊机会将在夏季通过有针对性的奖学金和项目获得资助。两所大学的pi都积极开展面向K-12学生的外展项目，这些学生主要是两所大学所在地区代表性不足的人群。

PI: Yu, Miao / Liang, XinhuaProposal Number: 1402772 / 1402122Title: Collaborative Research: Advanced Zeolite-Composite Adsorbents with Fine-Tuned Pore Sizes for Molecular Sieving Separations Mixture separation constitutes a large and costly component of industrial processes. Various separation technologies, such as distillation, extraction, adsorption, and membrane separation, have been developed to separate mixtures utilizing different properties of components in the mixture. Among these technologies, separation processes based on adsorption, such as pressure swing adsorption (PSA) and temperature swing adsorption (TSA), have been widely used in industry. Development of more energy-efficient adsorptive gas separation processes strongly depends on the development of improved porous adsorbents, and porous adsorbents with favorable adsorption isotherms and selectivity for the separation of interest are always the focus of adsorption-based separation processes. Zeolites are one of the most promising adsorbents that may realize true molecular-sieving separation under harsh separation conditions, attributing to their uniform, molecular-sized pores and high chemical, thermal and mechanical stabilities. Despite of a large selection pool of zeolites/molecular sieves and available techniques to adjust their pore sizes, not all desired pore sizes can be obtained for target separations, especially for separation of molecules with very close sizes, such as N2 (kinetic diameter: 0.364 nm)/CH4 (0.38 nm), O2 (0.346 nm)/N2, and paraffin/olefin. Therefore, it is highly desirable to develop new strategies to further fine-tune the pore sizes of zeolite-based materials and fill the pore size gaps between different zeolites. The goal of this proposed research is to fine-tune the pore entrance of zeolites by depositing ultrathin microporous coatings to achieve effective separation for industrially important mixtures that traditional zeolites have difficulty to separate. Ultrathin microporous coatings will be deposited using molecular layer deposition (MLD) on the zeolites to fill the pore-size gaps between different zeolites an obtain enhanced fundamental understanding of deposition mechanisms and coating interactions with zeolite substrates. Specifically, the objectives of the proposed research are: (1) To develop a reliable and reproducible MLD process to deposit ultrathin organic/inorganic hybrid films (with precisely controlled properties) on zeolite substrates and obtain a fundamental understanding on the factors that affect the quality of MLD coatings; (2) To elucidate and understand the decomposition of hybrid MLD coating and pore-generation mechanisms under different conditions; (3) To characterize effective pore sizes of zeolite-composite adsorbents and establish the fundamental coating property-pore entrance size relationship; and (4) To rationally design zeolite composite adsorbents with desired pore sizes and investigate separation performance for target mixtures. This completely new concept may lead to effective adsorptive separation of difficult-to-separate mixtures.This proposed research is expected to have great scientific as well as technological impact on the synthesis of nanostructured zeolite-composite adsorbents with fine-tuned pore sizes for mixture separations and potentially for selective catalysis. If successful, the project will greatly benefit adsorption-based separation processes. It will represent a significant advance in the rational design of zeolite-based adsorbents. The proposed research has significant practical implications on industrially important gas mixture separations. It is anticipated that this study could serve as a model for the rational design of advanced sorbents for adsorption-based separation processes.The PIs have specific defined plans to engage a broad range of students in learning about nanomaterials and molecular sieves. Specific opportunities for minorities will be funded through targeted scholarships and projects during the summer. Both PIs are active in outreach programs for K-12 students in mainly underrepresented populations in the areas of both universities.