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

项目编号：1402772/1402122标题：合作研究：用于分子筛分离的孔径可调的高级沸石-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。已开发出各种分离技术，如蒸馏、萃取、吸附和膜分离，以利用混合物中不同性质的组分来分离混合物。其中，变压吸附(PSA)和变温吸附(TSA)等基于吸附的分离工艺在工业上得到了广泛的应用。更节能的吸附气体分离过程的发展在很大程度上依赖于改进的多孔吸附材料的开发，而具有良好的吸附等温线和对目标分离的选择性的多孔吸附材料一直是吸附分离技术的研究重点。沸石分子筛具有均匀的、分子尺寸的孔结构和较高的化学稳定性、热稳定性和机械稳定性，是在恶劣的分离条件下实现分子筛分离的最有前途的吸附剂之一。尽管有大量沸石/分子筛的选择池和可用来调整其孔径的技术，但对于目标分离，特别是对于尺寸非常接近的分子，例如N_2(动力学直径：0.364 nm)/CH_4(0.38 nm)、O_2(0.346 nm)/N_2和烷烃/烯烃，并不能获得所有所需的孔尺寸。因此，开发新的策略来进一步微调沸石材料的孔径，填补不同沸石之间的孔径差距是非常有必要的。这项研究的目的是通过沉积超薄的微孔涂层来微调沸石的孔入口，以实现对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)在沸石上制备超薄微孔涂层，填补不同沸石之间的孔隙，加深对沉积机理和涂层与沸石基质相互作用的基本认识。具体地说，这项研究的目标是：(1)开发一种可靠且可重复使用的MLD工艺，在沸石衬底上沉积超薄的有机/无机杂化薄膜(具有精确控制的性质)，并对影响MLD涂层质量的因素有一个基本的了解；(2)阐明和了解不同条件下杂化MLD涂层的分解和成孔机理；(3)表征沸石-复合吸附剂的有效孔径，并建立基本的涂层性能-孔入口尺寸关系；以及(4)合理设计具有所需孔径的沸石复合吸附剂，并研究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。这项拟议的研究有望对合成具有微调孔径的纳米沸石-复合吸附剂产生重大的科学和技术影响，用于混合物分离和潜在的选择性催化。如果成功，该项目将极大地有利于基于吸附的分离过程。这将标志着沸石基吸附剂的合理设计取得重大进展。该研究对工业上重要的混合气体分离具有重要的实际意义。预计这项研究可以作为合理设计基于吸附的分离过程的先进吸附剂的模型。PI已经制定了具体的计划，让广泛的学生学习纳米材料和分子筛。针对少数群体的具体机会将在夏季期间通过有针对性的奖学金和项目提供资金。这两个私人投资机构都积极参与两所大学地区主要代表人数较少的K-12学生的外展计划。

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.