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Full-Text Articles in Engineering
Phosphorus-Containing Zeolites For Biofuel Production, Jason Gulbinski
Phosphorus-Containing Zeolites For Biofuel Production, Jason Gulbinski
Doctoral Dissertations
Fossil fuel consumption increases 2% a year due to transportation fuels and specialty chemicals for plastics and synthetic fibers such as p-xylene, a monomer of polyethylene terephthalate. p-Xylene demand was over 50 million tons in 2021 and will increase by 5% a year through 2026. Therefore, sustainable p-xylene production is desired. p-Xylene is produced renewably through Diels-Alder cycloaddition of biomassderived 2,5-dimethylfuran (DMF) with ethylene from bio-ethanol and dehydration over an acid catalyst. Industrial aluminosilicate zeolite catalysts achieve a selectivity of 75%, with loss to side products and coking. A new class of catalysts, phosphoric acid-containing aluminum-free zeolites, P-zeosils, like dealuminated …
Spectroscopic Investigations Of Zeolite-Catalyzed Carbenium Ion Chemistry, Eric David Hernandez
Spectroscopic Investigations Of Zeolite-Catalyzed Carbenium Ion Chemistry, Eric David Hernandez
Doctoral Dissertations
The catalytic conversion of methanol to olefins on zeolites is an industrially important process, yet the mechanistic details remain unresolved. Enylic cations (unsaturated carbenium ions) are active intermediates in the production of olefins and aromatics. However, these long-lived species are also precursors to carbonaceous deposits, the accumulation of which is responsible for catalyst deactivation. The aim of this work is to develop a mechanistic understanding that will ultimately allow steering the surface chemistry toward active intermediates. An in situ spectroscopic approach is applied to determine the nature of the relevant surface species and to track their transformations. The UV–vis and …
3d-Printed Adsorbents For Gas Separations: A Material Development, Kinetic Assessment, And Process Performance Investigation, Shane Lawson
3d-Printed Adsorbents For Gas Separations: A Material Development, Kinetic Assessment, And Process Performance Investigation, Shane Lawson
Doctoral Dissertations
“Adsorbent materials are promising for various gas purification processes, however, forming them into structured contactors is paramount in enhancing mass transfer properties and reducing pressure losses. In this research, various adsorbents were engineered into structured contactors with 3D printing. The overall goal of this research was to improve the formulation methods of 3D-printed adsorbents and understand their performances in gas separation processes. The specific objectives were to 1) develop new adsorbent 3D-printing strategies, 2) understand the kinetic properties of printed adsorbent monoliths, and 3) assess their process performances. Objective one was addressed by developing five 3D printing techniques: i) oxide …
Engineering Advanced Adsorbent Materials For Co₂ Capture Applications, Harshul Thakkar
Engineering Advanced Adsorbent Materials For Co₂ Capture Applications, Harshul Thakkar
Doctoral Dissertations
"Global climate change due to the increasing CO2 concentration in the atmosphere is primarily associated with anthropogenic CO2 emissions. CO2 capture technologies using adsorbents have not been implemented commercially due to lack of scalable, practical and cost-effective strategies and are still under development. Moreover, the use of conventional configurations such as pellets and beads for the removal of CO2 from enclosed environments have been shown to impose limitations to the removal efficiency and system performance. In this dissertation, engineering of advanced and efficient structured adsorbents for practical and scalable CO2 capture technologies and their use …
Study Of The Self-Assembly Process Of Microporous Materials Using Molecular Modeling, Mohammad Navaid Khan
Study Of The Self-Assembly Process Of Microporous Materials Using Molecular Modeling, Mohammad Navaid Khan
Doctoral Dissertations
Zeolites are an important class of materials in modern technology with applications in catalysis, separations, biosensing and microelectronics. There are over 200 different zeolite frameworks reported in literature, but only a handful have been used commercially. Understanding their self-assembly process would assist in the fabrication of new zeolites through the control of their pore size/shape, and surface area for advanced applications. With our research we aim to elucidate aspects of zeolite formation using molecular simulations. We have extended the lattice model of silica tetrahedra developed by Jin et al. [L. Jin, S. M. Auerbach and P. A. Monson J. Chem. …
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Modeling The Self-Assembly Of Ordered Nanoporous Materials, Szu-Chia Chien
Doctoral Dissertations
Porous materials are of great importance in many fields due to their wide applications. An ongoing theme in this area is the tailoring of materials for specific applications. With a better understanding of the formation mechanisms, tailoring and controlling the pore structure may be achieved. The objective of this research is acquiring further understanding of the fundamental physics that govern the formation of these materials using molecular simulations. We are aiming to unravel the assembly process of silica porous materials using a semi-rigid silica tetrahedral model. This model together with reaction ensemble Monte Carlo simulations allows us to study the …
Transport Limitations In Zeolites And Biomass Pyrolysis, Andrew Robert Teixeira
Transport Limitations In Zeolites And Biomass Pyrolysis, Andrew Robert Teixeira
Doctoral Dissertations
Biomass pyrolysis has been widely explored for its potential to generate a sustainable chemical source capable of producing synthetic fuels and chemicals. Lignocellulosic biomass is the carbon rich, inedible fraction of wood that is comprised of long oxygenated biopolymers, primarily cellulose, hemicellulose and the highly aromatic lignin. High temperature thermal conversion of biomass to bio-oil (pyrolysis oil) occurs on the order of milliseconds and converts long chain biopolymers to a carbon-rich liquid crude. The chemistry of biomass pyrolysis is greatly complicated by significant heat and mass transport challenges. The complex fluid dynamics of the reactive liquid intermediate are examined in …