Engineering Commons^™

Insights Into Rational Catalysts Synthesis, Abolfazl Shakouri

Theses and Dissertations

Atomically distributed metal centers with maximized atom utilization efficiency called single-atom catalysts (SACs) have attracted significant attention in catalysis. SACs with the advantages of both homogeneous and heterogeneous catalysts have been rising as a new frontier in the field of catalysis. New catalytic technologies are ever-growing, considering 90% of all chemical processes employ catalysts, securing modern society’s sustainable future. A classical field in catalysis has been dedicated to catalysis by supported metals. Recently, a vast effort has been devoted to smaller catalyst particles where size is restricted to a single atom on a surface. Single atoms supported or embedded on …

From The Surface To The Reactor: Identifying The Active Sites For Propane Dehydrogenation On Platinum-Based Catalysts Through Density Functional Theory, Experimental Data, And Uncertainty Quantification, Charles Henry Fricke

Theses and Dissertations

Propane dehydrogenation is a critical process of producing propylene, an important feedstock for the chemical industrial. There are multiple key processes to produce propylene in this manner, but one of the largest processes involves non-oxidative dehydrogenation on a platinum-tin alloy based catalyst. In general, these reactions and catalytic particles are complex, with many dehydrogenation, cracking, and reforming reactions taking place during these processes on multiple surfaces. With this in mind, ab initio computational catalysis models are used to generate further insight into these catalytic processes. In this dissertation, there are three aims to be solved: identifying the most likely active …

Recent Advances In Catalytic Ethylene Epoxidation: Synthesis, Characterization, And Evaluation, Benjamin Thomas Egelske

Theses and Dissertations

First synthesized in 1859 by French chemist Charles-Adolphe Wurtz, ethylene oxide (EO) is produced from the direct epoxidation of ethylene and molecular oxygen over a low surface area α-Al₂O₃ supported silver (Ag) catalyst [1-6]. With a production capacity over 35 Mt/year, EO is the largest chemical by volume synthesized from a heterogeneously catalyzed process and is used in the production of ethylene glycol, ethoxylates, and ethanolamines [6, 7]. State-of-the-art catalyst formulations contain high loadings of Ag, typically 12-30wt%, required to recover activity in the presence of promoter elements which increase EO selectivity from ~75% for unsupported Ag to 80% for …

Modified Electrode Surfaces With Hydrogen Evolution Reaction Catalysts Derived From Electropolymerized Complexes With Redox Active Ligands., Amanda Mae Arts

Electronic Theses and Dissertations

The demand for energy is growing exponentially, and to keep up with these demands new technologies for renewable energy have received increased attention. Hydrogen is one of the most promising energy sources for the future and plays a vital role in water electrolysis and fuel cells, as the hydrogen evolution reaction (HER) is the main step in the water splitting process. To increase the reaction rate and improve efficiency for the water electrolysis, catalysts are used to minimize the overpotential.

Most of the current electrocatalysts for HER are heterogeneous in nature and are dominated by platinum and other precious metals …

Mixed Metal Oxide Nanowires Via Solid State Alloying., Veerendra Atla

Electronic Theses and Dissertations

Mixed metal oxide materials with composition control find applications in energy conversion and storage processes such as heterogenous catalysis, photoelectrochemical catalysis, electrocatalysis, thermal catalysis, and lithium-ion batteries. Mixed metal oxides and/or complex oxides with composition control and in one-dimensional form as nanowires could be interesting to various catalysis applications due to control on single crystal surfaces, active sites, acidity versus basicity site density, and oxygen vacancies. The major challenge is to synthesize mixed metal oxide nanowires beyond binary oxides with composition control. In this dissertation, solid state alloying of binary oxide nanowires with solid and liquid precursors is studied to …

Solvent Effect Modeling In Heterogenous Catalysis, Mehdi Zare

Theses and Dissertations

In recent years, the biorefining industry and biofuels have emerged as a major American energy sector. Biofuels are fuels produced from plant and animal material, also referred to as biomass. This includes wood products, manure, and corn, among other materials. Compared to fossil fuels, biofuels are significantly more environmentally friendly and thus pose less of a threat to environmental health. In 2019, the United States consumed around 14.54 billion gallons of ethanol and around 1.81 billion gallons of biodiesel. By 2030, the United States is expected to consume around 95 Mtoe of biofuels. In order to meet current demand and …

Degradation Of Antibiotics In Aqueous Phase Using Pms Catalytic Decomposition With Zero-Valent Iron Nanoparticles Immobilized In Sba-15, Ahdee Bluma Zeidman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Zero-valent iron nanoparticles (nZVI) have been studied as an option for soil remediation and water treatment for many years. The capability of nZVI to produce oxidation/reduction processes, depending on the reaction conditions, has attracted great interest with their major drawback being reactivity loss through agglomeration. The loss in nZVI surface area has been reported to be prevented through immobilization onto a porous media (e.g., SBA-15, MCM-41, or zeolites). In this work, a mesoporous silica structure (SBA-15) is used as an nZVI supporting material to enhance its reactivity and promote peroxymonosulfate (PMS) catalytic decomposition for the degradation of antibiotics in aqueous …

Conversion Of Lignocellulose Biomass From Date Palm Waste To High Value Chemicals, Emmanuel Galiwango

Dissertations

Lignocellulose biomass has gained growing popularity because of its low cost of production compared to food crops, it solves problems of food and energy security, can grow in various climates and land, and it is CO₂ neutral. Date palm trees produce large amounts of fibrous wastes that are good sources of lignocellulose. There are over 40 million date palm trees in UAE and most of their lignocellulosic wastes (i.e., leaves, surface fibers, bunches, etc.) are currently used for low value applications such as compost or electric generation. However, the lignocellulosic components of this waste stream have the potential to …

Simultaneous Activation Of Stable Molecules- Methane And Nitrogen- Using Microwave Reactor With And Without Plasma- To Produce Ethylene And Ammonia, Sarojini Tiwari

Graduate Theses, Dissertations, and Problem Reports

The discovery of stranded natural gas around the world has made shale gas cheaper and widely accessible. This has driven the relevant research towards the direct utilization of Methane (CH4), a major component of natural gas. CH4 is a highly stable molecule, hence its activation and consequent formation of value-added chemicals in a direct and efficient manner is a relevant problem of the 21st century. All the commercial processes convert natural gas to chemicals indirectly, via the formation of syngas followed by several reactions. The conventional systems are energy intensive and one of the major contributors to green-house gas emissions. …

Cyclic Sequential Adsorption Desorption/Thermal-Catalytic Oxidation Of Volatile Organic Compounds: Material Development, Process Advancement/Improvement, And Numerical Modeling, Simulation And Optimization, Busuyi Ojo Adebayo

Doctoral Dissertations

"Volatile organic compounds (VOCs) are a group of useful organic chemicals but when emitted have contributed to air pollution. They affect human health, cause environmental degradation and contaminate our waters and soils, so they need to be controlled. When they exist in dilute concentrations, abatement becomes challenging, thus requiring advanced abatement methods, e.g., sequential adsorption desorption/thermal-catalytic oxidation process. The overall goal of this research was to abate dilute streams of VOCs via the process. The specific objectives were to 1) develop novel adsorbent/catalyst dual-function materials (DFMs) for the process, 2) improve the operability of a one-bed-one-column reactor configuration for the …

Microwave-Assisted Natural Gas Conversion To Value-Added Chemicals, Xinwei Bai

Graduate Theses, Dissertations, and Problem Reports

Stranded gas is a raw gas mixture of volatile hydrocarbons where the main composition is methane. The producers flare the stranded gas at the site because the cost of collecting and transporting the gas is higher than the value of the gas itself. To reduce the waste of this natural resource, it is worthwhile to utilize the on-site stranded natural gas as feedstock to produce value-added chemicals without emitting greenhouse gas. Direct natural gas conversion process is more desirable because of lower capital investment. Methane and ethane, the two major components of natural gas, are very stable molecules that usually …