Engineering Commons^™

Upgrading Biomass To Bio-Oil: Catalytic Hydrodeoxygenation And Pyrolysis Of Vanillin And Anisole Biomass Model Compounds, Ahmad J. Yaghi

Theses

The purpose of this project is to investigate capacity of selected formulations of catalysts toward the hydrodeoxygenation (HDO) of biomass model compounds in the gas phase with the underlying aim to produce hydrocarbon cuts that can be directly used as transportation fuels. The first part of this project is to devoted to illustrate procedures for the synthesis of potent (HDO) catalysts. Synthesized catalysts encompass nickel (Ni), cobalt (Co) and palladium (Pd) supported on zeolite, cerium oxide (CeO₂) or alumina (Al₂O₃). Various characterization techniques such as X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR) were deployed …

New Perspectives And Insights Into Direct Epoxidation Of C3H6 Using O2 And Ag Based Catalysts And Measurement Of Active Ag Site Concentration Of Promoted Ag Catalyst For C2H4 Epoxidation By H2 Pulse Titration Over Oxygen Pre-Covered Surface, Md Masudur Rahman

Theses and Dissertations

Direct epoxidation of C₃H₆ using molecular O₂ and Ag catalysts to produce propylene oxide (PO) selectively is a long-sought goal in the field of heterogeneous catalysis. In the early 1990’s Scientists at ARCO reported promising results of 58 – 59% selectivity to PO at 3.2% conversion of C₃H₆ over an unusual composition of 54.0 wt% Ag, 2.0 wt% K⁺, 0.5 wt% Mo and balance CaCO₃. Feed additives of ethyl chloride (EtCl), nitric oxide (NO) and CO₂ were stated necessary to achieve the claimed high PO selectivities. The roles …

Structural Evolution During Synthesis And Annealing Of Platinum-Nickel Bimetallic Nanoparticles, Xiner Lu

All Theses

In the past years, there has been an increasing interest in synthesizing Pt alloy nanocrystals to achieve high catalytic performance for energy-related applications. Pt-Ni nanoparticles (NPs) have shown high electrocatalytic activity for electrocatalysis and thermal catalysis. However, the stability of surface structures and compositions still needs to be improved to obtain better long-term catalytic stability. It is noted that thermal annealing can adjust the surface structures and compositions to improve the stability. Transmission electron microscopy (TEM) plays a vital role in characterizing the morphology, structure, and composition of nanoparticles. Specifically, the utilization of in situ TEM can allow for observing …

Development Of Porous Solid Acid Catalysts For Lignocellulose And Plastic Upcycling., Mohammad Shahinur Rahaman

Electronic Theses and Dissertations

My goal is to develop chemical processes for transforming waste to solve environmental problems and enhance sustainability. Environmental problems such as pollution and massive amounts of waste are the main drivers that stimulate my research ideas. I focused on creating novel, efficient catalytic processes for converting polymeric waste "feedstocks" into high-value chemicals by integrating my expertise in catalysis, materials science, and synthetic chemistry to develop porous solid catalytic materials. During my Ph.D., I focused on two polymeric feedstocks, lignocellulose, and discarded plastic.

Early in my Ph.D. journey, I focused on catalytic upcycling of lignocellulose. Lignocellulosic biomass is cost-effective, abundant, and …

The Controlled Synthesis Of Hydrogen Electrocatalysts For Alkaline Exchange Membrane Fuel Cell And Electrolysis Applications Via Chemical Vapor Deposition, Stefan Thurston Dubard Williams

Doctoral Dissertations

The development of catalysts for the electrochemical processes of hydrogen systems (e.g., fuel cells and electrolyzer systems) continues to be an attractive area of research for renewable energy technologies. One significant challenge has been developing hydrogen catalysts suitable for alkaline environments, mainly due to the sluggish kinetics of hydrogen reactions. In alkaline environments, the kinetics are decreased by two orders of magnitude when compared to acidic environments. Chemical vapor deposition (CVD) is a conventional method used to synthesize these types of catalysts. This effort discusses extending work being done using a modified CVD process known as “Poor Man’s” CVD (PMCVD) …

Improving Boron For Combustion Applications, Kerri-Lee Annique Chintersingh

Dissertations

Boron has received much attention as a potential additive to explosives and propellants due to its high theoretical gravimetric and volumetric heating values. The challenge, however, is that boron particles tend to agglomerate, have lengthy ignition delays and very low combustion rates. Prior research indicates that boron’s long ignition delays are due to its inhibiting naturally occurring oxide layer, impeding the diffusion of reactants for oxidation. For combustion, current studies report that boron particles have two consecutive stages, but the actual reaction mechanism is poorly understood. Despite many years of relevant research, quantitative combustion data on micron-sized boron particles are …

Nanowire Based Adsorbents/Catalysts For Co2 Capture And Utilization., Apolo Nambo

Electronic Theses and Dissertations

Even today, the major energy source is fossil fuels, which release CO₂, a greenhouse gas that contributes to global warming. CO₂ capture, storage (CCS) and/or utilization (CCU) technologies are two routes to mitigate this problem. Sorbents are being investigated in either temperature swing or pressure swing absorption approaches for carbon capture from flue gases. Solid sorbent based technology is a promising one but suffers from slow kinetics, low capacity and need for high temperatures. Thus, new sorbent materials that can have good CO₂ sorption capacity, recyclability are sought. Similarly, one of the utilization approaches for CO …

Design, Synthesis, And Characterization Of Monometallic And Bimetallic Catalysts, Sonia Eskandari

Theses and Dissertations

Supported catalysts are used extensively in a variety of heterogeneously catalyzed reactions for industrial processes. Techniques for preparing supported noble metal catalysts are typically chosen to achieve high metal dispersions in order to obtain high activity for a given metal loading. Enhancing the catalytic performance of heterogeneous catalysts can be done by increasing active site count as well as modification of the physico-chemical characteristics of the catalyst material. For supported metal nanoparticles this can be achieved by decreasing particle size, thus increasing dispersion or metal utilization on the surface of the particles, while modification of metal properties can be attained …

Ceria Nanostructured Catalysts For Conversion Of Methanol And Carbon Dioxide To Dimethyl Carbonate, Jawad Hassan A Al Drwish

Masters Theses

"In this study, three different shapes of ceria (CeO₂) nanostructures (e.g., nanooctahedra, nanocubes and nanorods) were synthesized via the hydrothermal method and screened for carbonylation reaction. Of these three shapes of nanostructures, the nanorod was doped with metals such as Ca, Ni, Cu, and Co by wet impregnation method. All materials were characterized by XRD, NH₃/CO₂-TPD, XRF, FTIR and N₂ physorption to determine the crystal size and phases, acid-base properties, metal loading, and surface properties. The obtained materials were employed as catalysts for the activation of Carbon Dioxide (CO₂) and methanol …

Hydrodeoxygenation Of Acetic Acid Using Monometallic And Bimetallic Catalysts Supported On Carbon, José Luis Contreras Mora

Theses and Dissertations

Heterogeneous catalytic hydrodeoxygenation (HDO) of biomass-derived feeds is a deoxygenation process that is of highly interest. Carboxylic acids are one of the main components of bio-oils and acetic acid is one of the most abundant of these carboxylic acids. This acid is rich in oxygen, therefore a lot of research to produce fuel and other valuable chemicals such as ethanol is of interest.

This dissertation explores the gas-phase catalytic HDO of AA over catalysts supported on activated carbon (Cp-97). Temperature-dependent conversion and selectivity were studied at 1 atm from 200-400⁰C with an AA concentration of 1.1% and 20% …

Three-Way Catalysts In Passive Selective Catalytic Reduction Systems, Calvin Thomas

Theses and Dissertations

Conventional gasoline-powered engines operate with a stoichiometric air-fuel ratio (AFR), but greater fuel economy is achieved in lean burn engines by increasing the AFR. The primary drawback to these engines is the nitrogen oxide (NOX) emissions, which cannot be reduced over a conventional three-way catalyst (TWC). Passive selective catalytic reduction (SCR) is a promising approach for the control of NOX emissions in lean burn systems. By periodically decreasing the AFR to fuel-rich levels, ammonia (NH3) can be produced over a TWC and stored on a downstream SCR catalyst for the reduction of NOX during normal lean operation. While passive SCR …

The Rational Synthesis Of Bimetallic Catalysts On Oxide Supports, Andrew Phillip Wong

Theses and Dissertations

Catalysts play an important role in many chemical reactions. However, simple impregnated monometallic catalysts are often limited in their function. One way to overcome this limitation is through the incorporation of a secondary metal to the catalysts. These bimetallic catalysts often have synergistic benefits not observed in the monometallic analogues. Here, we focused on the synthesis of bimetallic catalysts using rational methods in order to improve catalyst function; specifically by tuning the particle size, morphology, and composition. The two methods of interests were Strong Electrostatic Adsorption (SEA) and Electroless Deposition (ED). An adaptation of SEA to bimetallic catalysts (coSEA) was …

Production Of Bio-Oil With Different Oxygen Content And Characterization Of Catalytic Upgrading To Transportation Fuel, Mubarak Mohammed Khlewee

Electronic Theses and Dissertations

The world’s increasing population requires an increase in transportation fuel production. The lack of production of transportation fuels due to the shortage of fossil fuel resources combined with concerns about global emissions of carbon dioxide from fossil fuel combustion are the two major issues that have driven researchers to actively pursue alternative sources for oil production. Biomass is being considered as an alternative feedstock to produce fuel and chemicals due to its abundance and renewability. It has many features that make it suitable as a source of transportation fuel production. However, the bio-oil produced by the fast pyrolysis process has …

Development Of Heterogeneous Catalysts For Upgrading Biomass Pyrolysis Bio-Oils Into Advanced Biofuels, Shouyun Cheng

Electronic Theses and Dissertations

The massive consumption of fossil fuels and associated environmental issues result in an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two most promising bio-oil upgrading techniques for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although some progresses have been made, the cost and effectiveness of catalysts still remain challenges. The main objective of this study was to develop efficient heterogeneous catalysts for upgrading bio-oils into advanced hydrocarbon biofuel with low costs. In catalytic cracking, …

Rational Synthesis Of Catalysts For Biomass Conversion, Qiuli Liu

Theses and Dissertations

With climate change due to global warming, the production of hydrocarbon fuels and chemicals from renewable biomass resource has become more pressing in recent decades. The biggest challenge in biomass conversion is to develop active, selective and stable catalysts for particular applications. The objective of this research is to optimize catalytic performance for hydrodeoxygenation (HDO) and hydrogenation reactions by enhancing the stability of the support, tuning metal particle size, and controlling surface composition.

The high content of water in bio-oil and the aqueous environment of the upgrading process requires a hydrothermally stable catalyst. The hydrothermal stability has been effectively improved …

Rational Design And Synthesis Of Pt/Silica-Alumina Metal-Acid Bifunctional Catalysts, Jadid Ettaz Samad

Theses and Dissertations

In the domain of rational catalyst design and synthesis, Strong Electrostatic Adsorption (SEA) has been applied with tremendous potential and use. In this study, SEA method has been advanced to thick slurries as well as to mixed oxide systems with a view to synthesizing stable, active and selective catalysts fine-tuned for specific applications.

The main objective was to synthesize metal-acid bifunctional catalysts with controlled ratio and proximity between metal and acid sites in order to analyze their effects on a bifunctional reaction. At first, the difference in charging behavior of silica and alumina in solution was used to selectively deposit …

Rational Synthesis To Optimize Ruthenium-Based Biomass Conversion Catalysts, Shuo Cao

Theses and Dissertations

With worldwide petroleum resources dwindling and greenhouse gas emissions rising, it is urgent to find renewable replacements for petroleum-derived products. A biomass-derived chemical with high potential as a platform intermediate, γ-valerolactone (GVL) can be readily synthesized by hydrogenation of levulinic acid (LA), itself a common biomass intermediate, using supported Ru catalysts. Overall, vapor phase hydrogenation is more energy sensitive as the higher boiling point of LA (~245°C) and requires a high energy input, comparable to liquid phase hydrogenation, which is more economical. To date the literature on many novel biomass conversion processes such as the hydrogenation of LA to GVL …

Hydrotreatment Of Lignin Into Green Fuels And Chemicals, Matthew Tymchyshyn

Electronic Thesis and Dissertation Repository

Concerns about declining non-renewable fossil resources, energy security, climate change and sustainability are increasing worldwide. This has resulted in an increased interest in the development of alternatives to fossil resources not only for energy, but particularly for chemical production on a global level. There are a number of promising alternatives to fossil resources, however, lignocellulosic biomass such as forestry residues and wood waste (limbs, bark, sawdust, etc.) seem to be the most promising. They are widely available, renewable and a non-food resource. Therefore woody biomass holds the promise of being a sustainable resources for both energy and chemical production.

The …

Hierarchical Porous Structures With Aligned Carbon Nanotubes As Efficient Adsorbents And Metal-Catalyst Supports, Hema Vijwani

Browse all Theses and Dissertations

The overall goal of this study is two-fold: synthesis of multiscale nanostructures by growing aligned carbon nanotubes on porous foam substrates and investigation of their applicability as adsorbents and catalyst supports for environmental remediation applications. High purity, vertically-aligned arrays of carbon nanotubes (CNT) are grown on open-cell interconnected porous carbon foams by pre-activating them with an oxide buffer layer followed by chemical vapor deposition (CVD). This type of hierarchical morphology provides the capability of increasing surface area by several orders of magnitude, while tuning its morphology for targeted applications. Analytical models are also proposed in this study for specific surface …

Perovskite Catalysts Enhanced Combustion On Porous Media And Thermoelectric Power Conversion, Manuel Robayo

Electronic Theses and Dissertations

A combustion chamber incorporating a high temperature porous matrix was design and tested. The effects and merits of combining combustion on porous media and catalytic enhancement were explored, in addition to the proof of concept of integrating these technologies with simple heat engines, such as thermoelectric generators, to generate efficient and reliable power. The direct observation of the flame during the combustion becomes possible due to a specially designed stainless steel chamber incorporating a quartz window where the initiation and propagation of the combustion reaction/flame was directly visible. The simple design of the combustion chamber allowed for a series of …

Advanced Nanostructured Electro-Catalysts For Electricity Generation And Biorenewable Alcohol Conversion, Zhiyong Zhang

Dissertations, Master's Theses and Master's Reports - Open

In my Ph.D research, a wet chemistry-based organic solution phase reduction method was developed, and was successfully applied in the preparation of a series of advanced electro-catalysts, including 0-dimensional (0-D) Pt, Pd, Au, and Pd-Ni nanoparticles (NPs), 1-D Pt-Fe nanowires (NWs) and 2-D Pd-Fe nanoleaves (NLs), with controlled size, shape, and morphology. These nanostructured catalysts have demonstrated unique electro-catalytic functions towards electricity production and biorenewable alcohol conversion.

The molecular oxygen reduction reaction (ORR) is a long-standing scientific issue for fuel cells due to its sluggish kinetics and the poor catalyst durability. The activity and durability of an electro-catalyst is strongly …

Energetic Nanoparticles As Fuel Additives For Enhanced Performance In Propulsion Systems, Srinibas Karmakar

LSU Doctoral Dissertations

Biofuels are currently being explored as a carbon-neutral fuel alternative to petroleum-based fuels. However, biofuels such as ethanol has lower energy density (~27MJ/kg) relative to petroleum fuels (~ 45 MJ/kg). Adding high-energy density particles (such as boron with heating value of ~ 58.5 MJ/kg) to biofuels can generate fuel slurry with higher energy density than the base fuel, and represents a potential strategy toward making biofuels more viable. However, the combustion of boron is inhibited (specifically, the ignition is delayed) by the initial presence of an oxide layer, and its high evaporation and boiling temperatures. The present study investigates the …

Synthesis And Characterization Of Catalysts For The Selective Transformation Of Biomass-Derived Materials, Isaac Tyrone Ghampson

Electronic Theses and Dissertations

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silicasupported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, …

Super-Adiabatic Combustion In Porous Media With Catalytic Enhancement For Thermoelectric Power Conversion, Kyle Thomas Mueller

Electronic Theses and Dissertations

The combustion of ultra-lean fuel to air mixtures provides an efficient way to convert the chemical energy of hydrocarbons into useful power. Conventional burning techniques of a mixture have defined flammability limits beyond which a flame cannot self-propagate due to heat losses. Matrix stabilized porous medium combustion is an advanced technique in which a solid porous matrix within the combustion chamber accumulates heat from the hot gaseous products and preheats incoming reactants. This heat recirculation extends the standard flammability limits and allows the burning of ultra-lean fuel mixtures, conserving energy resources, or the burning of gases of low calorific value, …

Investigation Of Titanium Nitride As Catalyst Support Material And Development Of Durable Electrocatalysts For Proton Exchange Membrane Fuel Cells, Bharat Avasarala

Legacy Theses & Dissertations (2009 - 2024)

The impending energy and climatic crisis makes it imperative for human society to seek non-fossil based alternative sources for our energy needs. Although many alternative energy technologies are currently being developed, fuel cell technology provides energy solutions, which satisfy a wide range of applications. But the current fuel cell technology is far from its target of large scale commercialization mainly because of its high cost and poor durability. Considerable work has been done in reducing the cost but its durability still needs significant improvement. Of the various materials in a PEM fuel cell, the degradation of electrocatalyst affects its durability …

Dry Reforming Of Methane On Rhodium And Nickel Substituted Pyrochlore Catalysts, Sarthak Gaur

LSU Master's Theses

Dry reforming of methane (DRM) has been widely investigated, with most studies showing rapid deactivation due to carbon deposition. This suggests a need to develop catalysts that limit carbon formation while avoiding structural changes at the elevated temperatures typical of this reaction. Here, we report CO2 reforming of methane on four pyrochlore catalysts. First, Rh was partially substituted for Zr in lanthanum zirconate (La2Zr2O7) to give La2Zr2-xRhxO7.5 (LRZ, x=0.112, 2 wt% Rh) pyrochlore. A second pyrochlore catalyst was synthesized in which Ca was further substituted into the La-site to give La1.95Ca0.05Zr2-xRhxO7 (LCRZ, x=0.055, 1 wt% Rh). A third catalyst was …

Screening Of Tar Cracking Catalysts For Syngas Produced By Biomass Gasification, Bijeet Mukherjee

LSU Master's Theses

The gasification of biomass produces tars and particulates. These tars and particulates create problems in the gasification systems. Tars condense on surfaces at lower temperatures, such as exit pipes and on particulate filters, leading to blockages and clogged filters. Tars also have varied impacts on other downstream processes. Due to these reasons, syngas containing significant concentrations of tars cannot be used in internal combustion engines. Thus the processes through which tars can be removed have been subject to considerable research. The objective of this research was to identify the best catalyst for for down-draft gasifiers, including the LSU AgCenter down-draft …

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …

Investigation Into The Hydrothermal Treatment Of Sugarcane Bagasse Under Near- And Supercritical Conditions, John E. White

LSU Doctoral Dissertations

Processing biomass in near- and supercritical water has garnered increasing attention because of its ability to accept a variety of wet feedstocks, energy efficiency, and ability to regulate the solubility and separation of components. Very few studies of biomass hydrothermal conversion provide a comprehensive evaluation of multiple process parameters and various additives and their effects on a single product phase. This research examined the influence of temperature, residence time, biomass concentration, and particle size on volatiles production from the hydrothermal conversion of sugarcane bagasse. Temperature had the greatest impact on volatile yields with the largest increase (23 wt %) occurring …

Predictions Of Catalyst Utilization With Continuous Replacement In Multistage Continuous Reactors From Batch Reactor Data, Norman M. Feinberg

Theses

This thesis presents a new equation for predicting catalyst utilization with continuous replacement in multistage continuous reactors from batch reactor data.

An equation is derived from experimental data for a. no-replacement system which predicts catalyst activity as a function of time. The assumption of constant inventory, constant replacement rate and perfect mixing permit the calculation of catalyst age distribution. By combining age distribution with a measure of catalyst productivity, as determined from activity as a function of time, an equation for catalyst utilization was derived. The case used to prepare this equation was where the activity decline curve appears as …