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Author ORCID Identifier

https://orcid.org/0000-0002-9808-0998

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemical Engineering

Year Degree Awarded

2021

Month Degree Awarded

February

First Advisor

Wei Fan

Subject Categories

Catalysis and Reaction Engineering | Membrane Science | Polymer Science

Abstract

Global industrial and economic development over the past century has largely relied on combustion of non-renewable fossil fuels, such as petroleum, coal, and natural gas, which are also harmful to environment because of the release of CO2, responsible for global warming and climate change. Establishing eco-friendly, energy-efficient and cost-effective processes to reduce environmental impact is currently one of the most urgent issues for the sustainable development of our society. Inorganic porous materials have found applications in the fields of renewable energy and environmental protection such as biomass conversion, fuel cells, thermal energy storage, CO2 capture and conversion, air pollution remediation, water purification, etc. Their advantages such as high surface area, tunable properties and stability at high temperatures and high pressures make them potential candidates as solutions to the sustainability issues in our society. In this thesis, we synthesized inorganic porous materials, namely zeolites and mesoporous carbons, by tuning their morphology, hydrophobicity and micro- and mesopore structure.

Mesoporous carbons with functional surface groups have recently received significant attention as catalysts for cellulose hydrolysis and as adsorbents for sugars due to their low cost, hydrothermal stability and ability of their graphitic domains to bond with sugars with CH-�� interactions. In the first part of this thesis, a three-dimensionally ordered mesoporous (3DOm) carbon was synthesized as a potential adsorbent for the recovery of glucose obtained from cellulose hydrolysis in molten salt hydrate. Lanthanum-embedded silica nanoparticles were used as a template and ethylene was used as a carbon source to achieve a graphitic structure.

Zeolites (microporous aluminosilicates) are normally synthesized under hydrothermal conditions in a sealed autoclave, which involves the use of a large amount of water as a solvent leading to high autogenous pressures, and safety and environmental issues. In the second part of this thesis, the role of water and autogenous pressure in vapor-phase transport method for zeolite (silicalite-1) synthesis was investigated.

About one third of the CO2 emissions in the U.S. come from the electric power sector, a major fraction of which come from coal power plants. A hydrogen-selective membrane reactor can replace the energy-intensive solvent-based process used for CO2 capture in an IGCC power plant. ITQ-1(P), a two-dimensional layered zeolite with MWW framework is an excellent candidate for fabrication of such a membrane. The MWW framework contains six-membered ring (~0.3 nm) apertures that can allow the passage of H2 but restrict the passage of CO2. The current challenge is to develop a facile method for exfoliation of ITQ-1(P), to obtain high aspect-ratio MWW nanosheets. The other challenge is to form a uniformly oriented, defect-free coating of these nanosheets on a porous support, while minimizing the film-thickness to achieve high flux. In the third part of this thesis, a successful room temperature self-exfoliation of swollen ITQ-1(P) in commercially available liquid hydroxyl-terminated polybutadiene (HTPB) was achieved, and high-aspect ratio nanosheets were obtained. A uniform coating of MWW nanosheets on a sintered silica fiber (SSF) support was achieved by vacuum filtration. A successful gel-free secondary growth was performed on this coating by preserving its preferred orientation. The effects of framework aluminum and nature of organic structure directing agent (OSDA) in the interlayer on exfoliation were studied. The polymer-zeolite interactions were studied using rheology, highlighting the role of polymer end-groups in exfoliation.

DOI

https://doi.org/10.7275/20234514

Available for download on Thursday, November 18, 2021

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