Engineering Commons^™

Multi-Objective Optimization Of Industrial Ammonia Synthesis, Stanislav Ivanov

Electronic Thesis and Dissertation Repository

The thesis describes modelling and optimization work of an industrial ammonia synthesis. Author developed first-principle mathematical model of the commercial converter based on gas-solid reaction and heat transfer within the system. The model is validated with industrial data and showed satisfactory accuracy. Further, optimization study is performed in multi-objective manner to intensify ammonia production and decrease heat duty of the process. Result have revealed a potential to improve current operating condition int terms of both objectives.

Supercritical Fluid Extraction Of Valuable Chemicals: Application Of Microalgae And Pyrolysis Oil As Feedstocks, Osariemen Ogbeide

Electronic Thesis and Dissertation Repository

In this dissertation, pure and modified carbon dioxide were used as non-conventional solvents for the investigation of lutein, chlorophyll a, chlorophyll b extraction from microalgae and for caffeine extraction from the pyrolysis oil of spent coffee grounds. The use of toxic organic solvents in supercritical fluid extraction has propelled research efforts to develop new solvents that are environmentally friendly and provide faster extraction compared to conventional extraction processes. For this reason, phosphatidylethanolamine (PE), a major phospholipid consisting of 14% of the entire soybean lecithin was acetylated with acetic anhydride, providing a surfactant (N-A-PE).

Then, the synthesized N-A-PE was employed as …

Sulfur Species Selective Adsorption Using A New Offretite Based Additive, Yira Yorsirys Aponte Torrealba

Electronic Thesis and Dissertation Repository

Fluid Catalytic Cracking (FCC) unit is one of the most important conversion processes used in petroleum refineries. Nowadays, petroleum refineries, and specifically FCC units, have to be improved. New technologies must be developed to increase the refineries revenues as well to comply with environmental regulations. One area of significant concern is the necessary in-situ FCC gasoline sulfur reduction.

In this respect, this PhD dissertation proposes a new Zn-Offretite (Zn-OFF) additive for gasoline sulfur reduction via selective adsorption in FCC units. The PhD research developed covers the preparation of the Zn-OFF zeolites and their physicochemical characterization. This physicochemical …

Esterification Of Free Fatty Acid By Selected Homogeneous And Solid Acid Catalysts For Biodiesel Production, Mohamed Kaddour

Electronic Thesis and Dissertation Repository

Biodiesel, derived from plant oils and animal fats is an attractive alternative fuel to fossil-based diesel as it is biodegradable, non-toxic, renewable, and has a low emission profile. Industrial production of biodiesel faces major challenges including limited supply of raw material and high cost of feedstock, which accounts for 60-80% of total production cost. Economic feasibility for biodiesel can be improved by using inexpensive raw materials such as waste frying oils and non-edible oils. However, these low quality feedstocks contain significant amounts of free fatty acids (FFA) which reacts with a base to produce soap hindering product separation and reduce …

Reactor Performances And Hydrodynamics Of Various Gas-Solids Fluidized Beds, Jiangshan Liu

Electronic Thesis and Dissertation Repository

The reactor performances and hydrodynamics were systematically studied in a multifunctional fluidized-bed system which included a bubbling fluidized bed (BFB), a turbulent fluidized bed (TFB) as well as a newly identified circulating turbulent fluidized bed (CTFB) using the same batch of activated FCC particles. Catalytic ozone decomposition was employed as the model reaction to experimentally investigate the reactor performances of BFB, TFB and CTFB. The complete mappings of ozone concentration were obtained in these fluidized beds, showing close relationship with the solids holdup distributions. In the BFBs and TFBs, the study of scale-up effect revealed that the static bed height …

Evaluation Of Voc Degradation In Photo-Catalytic Air Reactors: Tio2 Immobilization, Energy Efficiency And Kinetic Modeling, Cristina S. Lugo Vega

Electronic Thesis and Dissertation Repository

The high VOC emissions from anthropogenic sources are detrimental to both the environment and humans, contributing with ground-level ozone and particle matter formation. Heterogeneous photocatalysis provides significant potential for VOC degradation. However, the approaches to be used for photocatalyst immobilization in scaled and highly efficient photoreactors are still not well established. Furthermore, there is a lack of reported photonic efficiencies and a shortage of required methods to establish these efficiencies.

To address these issues, this PhD Dissertation reports the study of photonic efficiencies, TiO₂ immobilization on a stainless steel mesh and kinetic models in a scaled-up Photo-CREC-Air Reactor. Acetone …

Catalytic Conversion Of Fructose, Glucose And Industrial Grade Sugar Syrups To 5-Hydroxymethylfurfural, A Platform For Fuels And Chemicals, Sadra Souzanchi

Electronic Thesis and Dissertation Repository

5-hydroxymethylfurfural (HMF) as a versatile and polyfunctional compound derived from dehydration of biomass has attracted increasing attentions in research over the past decades. HMF is an important intermediate and platform chemical, which can be converted into different useful chemicals as well as the promising biofuels. It can be obtained from acid-catalyzed dehydration of different C₆-based carbohydrates such as glucose, fructose, sucrose and cellulose.

In this thesis, a cost-effective process for catalytic conversion of simple sugars (particularly glucose and fructose) and industrial grade sugar syrups to HMF was studied in a novel biphasic continuous-flow tubular reactor using inexpensive heterogeneous …

Microwave And Ultrasound Assisted Zeolitization Of Coal Fly Ash, Syed Salman Raza Bukhari

Electronic Thesis and Dissertation Repository

Coal fly ash (CFA) is a major bi-product of coal fired power plants and is a liability for coal power industry. Coal fly ash has been accumulating rapidly around the globe and has been known to be accident prone, resulting in $1.65 billion in clean-up costs and fines. Given the environmental damage CFA is capable of causing, it is a great interest for scientists to recycle this material. Utilization of novel energy such as microwave and ultrasound has been of research interest for the zeolitization of coal fly ash.

This research produced zeolites from CFA utilizing microwave and ultrasound power. …

Mechanism Of Ethanol Partial Oxidation Over Titania Supported Vanadia Catalysts: Geometric And Electronic Structure Consequences On Reaction Kinetics, Dongmin Yun

Electronic Thesis and Dissertation Repository

Supported vanadium oxide catalysts (VO_x) are used for a wide range of industrial processes. A significant amount of research has been carried on this specific system with the aim to identify the critical parameters involved in catalytic activity. The results on this relative large body of research indicate that the catalyst support plays a critical role in determining the catalytic activity of vanadia and the use of titanium dioxide as support renders a catalyst with superior activity. Studies on supported vanadia on titanium oxide (VO_x/TiO₂) have provided an understanding on support interactions that result …

Particle Entrainment Studies From Dry And Wet Bed, Saber Ayatollahi

Electronic Thesis and Dissertation Repository

During the Fluid Coking Process™ bitumen is sprayed into a fluidized bed of hot coke particles. The bitumen undergoes thermal cracking and is converted into gasses, condensable vapors, and solid coke, which deposits on the coke particles. These vapors rise through the vessel and result in entrainment of coke particles. Wet fine coke particles from the freeboard region enter the cyclone and contribute to the fouling of the Coker cyclones which can lead to the premature shut-down of Fluid Cokers.

The primary objective of this research is to determine how bed wetness affects entrainment.

First, a new fluidized bed was …

Visible Light Driven Photocatalysis For Degradation Of Diclofenac, Noshin Hashim

Electronic Thesis and Dissertation Repository

Diclofenac (DCF), a widely used non-steroidal anti-inflammatory drug (NSAID), is a commonly detected substance that readily accumulates in tissues of aquatic fish and poses a threat to wildlife and freshwater quality. Advanced Oxidation Processes (AOPs) have been explored as an alternative method for complete mineralization of DCF as conventional treatment methods are inadequate for treatment of trace contaminants.

This study employs a semi-batch, swirl-flow, monolithic type photocatalytic reactor to determine intrinsic kinetic parameters of DCF mineralization, in an immobilized system under both UV and visible radiation. The goal of this work to determine true kinetics of DCF, after correcting for …

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO₂), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO₂ at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a …

Enhanced Solar Photocatalytic Hydrogen Generation And Water Treatment Using Hetero-Structure Photocatalysts, Ghodsieh Malekshoar

Electronic Thesis and Dissertation Repository

Among different approaches to overcome current environmental concerns, heterogeneous photocatalysis is recognized as a promising one. While there are various applications of photocatalysis including water splitting and water treatment, the overall efficiency of this process is still fairly low due to the two dominant drawbacks of current semiconductors, namely wide band gap and fast recombination of photo-generated charges, which restrict the photocatalytic reactions. Designing a hybrid photocatalyst composed of semiconductor hetero-junctions is a viable approach to address these challenges.

The objective of this research project is developing efficient photocatalysts via simple and practical synthesis methods in order to enhance the …

Catalytic Conversion Of Glycerol To Value-Added Chemical Products, Malaya Ranjan Nanda

Electronic Thesis and Dissertation Repository

Rapid expansion of biodiesel industry has generated a huge amount of crude glycerol. This thesis aimed to explore utilization of glycerol for the production of solketal as an oxygenated fuel additive and 1, 2-propanediol as a pre-polymer via catalytic conversion.

The thesis work may be divided into two major parts. In the first part, the thermodynamics and kinetics of the glycerol ketalization for the synthesis of solketal were investigated in a batch reactor. From this information, a continuous-flow process was designed, developed and optimized using pure glycerol. Crude glycerol (13 wt% purity) was successfully upgraded into a purified crude glycerol …

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 …

Application Of Mechanically Fluidized Reactors To Lignin Pyrolysis, Valentina Lago

Electronic Thesis and Dissertation Repository

Lignin has great potential for the production of aromatics currently derived from petroleum, since it is the most abundant source of aromatics in nature. At present, Kraft lignin is used as fuel within the pulping process but, alternatively, it could be converted to high-value chemicals using thermochemical processes such as pyrolysis. Kraft lignin, however, is a very cohesive and thermally sensitive powder with foaming and agglomerating tendency under reaction conditions. Therefore, new reactor designs are necessary to efficiently process this raw material.

Consequently, a novel reactor design, designated as Mechanically Fluidized Reactor (MFR) has been developed to successfully process Kraft …

Towards Intensified Protein Refolding And Purification On Size Exlusion Chromatography: Fundamental Studies And Mathematical Modelling, Pegah Saremirad

Electronic Thesis and Dissertation Repository

For industrial recombinant-protein processes, protein refolding and purification are crucial steps towards the recovery of considerable numbers of active and safe therapeutic products. In this thesis, intensification strategies for protein refolding and purification processes are explored. Development of an intensified process aims at simultaneous optimization of process performance indicators, namely: refolding yield, product purity, volumetric productivity and solvent consumption which in turn decrease the cost and time constraints to market.

The first strategy investigated related to multivariable experimental work using size exclusion chromatography (SEC) as a refolding method and a denatured/reduced model protein (lysozyme). SEC was selected due to its …

Disinfection And Advanced Oxidation Of Highly Absorbing Fluids By Uv/Vuv Light: Process Modeling And Validation, Ferdinando Crapulli

Electronic Thesis and Dissertation Repository

One of the limitations in treating highly absorbing fluids with ultraviolet photoreactors is the short light penetration into the fluid leading to the following issues: (a) if not engineered properly, ultraviolet photoreactors dealing with highly absorbing fluids are likely to be energy-inefficient due to a non-ideal use of emitted photons and non-uniform dose distribution (b) the quantification of photo-chemical rate constants could be a challenging task due to the severe mixing-limited conditions of the experimental apparatus used during the investigation. As a result, new lab-scale apparatus (alternative to the conventional collimated beam system) and modeling approaches are needed in order …

Solar Photocatalytic Reduction Of Zn2+ Using Graphene-Based Tio2 Composite Catalyst For Application To Cso Treatment, Gloria Kumordzi

Electronic Thesis and Dissertation Repository

The improvement of photocatalyst efficiency in utilizing the majority of wavelengths in the solar spectrum, an abundant natural resource, presents the next step in the large scale application of photocatalysis for the treatment of dissolved organic and inorganic pollutants in wastewater. In this study, a composite catalyst of TiO₂ and Graphene synthesized by a hydrothermal treatment method is used to photo-reduce Zn²⁺, the most abundant heavy metal found in combined sewer overflows (CSOs). The performance of this composite catalyst was assessed under various process conditions such as pH, light intensity, catalyst loading and light source. The TiO …

Cluster Fluid Dynamics In Down Flow Reactors: Experimental And Modeling Study, Angel Virgilio Lanza Soto

Electronic Thesis and Dissertation Repository

Gas–solid concurrent downers possess unique features when compared to other gas–solid systems. Establishing their fluid dynamic properties requires both experimental measurements of gas-solid flow properties and computational modeling.

Measuring gas-solid flow properties such as cluster solid concentrations, individual cluster slip velocities, and cluster sizes, involves the use of specialized optical equipment, as well as a rigorous data analysis methodology. In addition, the modeling of the fluid dynamics of gas-solid flows in downer units offers special challenges such as establishing a proper drag model, cluster configuration and sizes, sphericity, boundary conditions, among other issues.

In this PhD dissertation, the fluid dynamics …

Scale-Up Methodology For Bench-Scale Slurry Photocatalytic Reactors Using Combined Irradiation And Kinetic Modelling, Patricio J. Valades Pelayo

Electronic Thesis and Dissertation Repository

The present study focuses on developing a predictive methodology to scale-up a slurry annular photoreactor using a TiO₂ Degussa P25 from the bench-scale to a pilot-plant scale. The bench-scale photoreactor is a Photo-CREC-Water II, a 2.65 L internally-irradiated slurry annular photocatalytic reactor. The pilot-plant scale photoreactor is a Photo-CREC Water Solar Simulator, a 9.8 L pilot-plant photoreactor, externally irradiated by eight lamps.

The adopted methodology allows the independent validation of radiative and kinetic models avoiding cross-correlation issues. The proposed approach involves two Monte Carlo methods, to model the Radiative Transfer Equation (RTE) inside each photoreactor. With this end, a …

Reductive Depolymerization Of Kraft Lignin For Chemicals And Fuels Using Formic Acid As A In-Situ Hydrogen Source, Shanhua Huang

Electronic Thesis and Dissertation Repository

In this thesis work, formic acid (FA) proved to be an effective in-situ hydrogen donor for the reductive de-polymerization of kraft lignin (KL). At the optimum conditions without catalysts, i.e., 300 ^oC, 1 h, 18.6 wt.% substrate concentration, 50/50 (v/v) water-ethanol medium at a FA-to-lignin mass ratio of 0.7, KL (M_w ~10,000 g/mol) was effectively de-polymerized, producing de-polymerized lignin (DL, M_w 1, 270 g/mol) at a yield of ~90 wt.% and wt.% yield of solid residue (SR). The effects of heterogeneous catalysts on KL reductive de-polymerization in 50/50 (v/v) water-ethanol medium were also investigated. At all conditions, …

Steam Gasification Of Biomass Surrogates: Catalyst Development And Kinetic Modelling, A S M Jahirul Islam Mazumder

Electronic Thesis and Dissertation Repository

This study reports a new fluidizable La₂O₃ promoted Ni/γ-Al₂O₃ catalyst. Prepared catalysts are characterized using BET specific surface area, XRD, TPR, TPO, H₂-pulse chemisorptions, Pyridine FTIR, NH₃-TPD and CO₂-TPD. Catalytic steam gasification of biomass surrogates (glucose and 2-methoxy-4-methylphenol) are conducted in a CREC Riser Simulator under the expected conditions of a twin circulating fludized bed gasifier.

Catalyst structure-property and structure-reactivity relationships are established using characterization and gasification results. Gasification performance of a catalyst is found to be well-correlated as a function of its Ni dispersion and basicity/acidity ratio. …

A Comprehensive Study Of Cd(Ii) Removal From Aqueous Solution Via Adsorption And Solar Photocatalysis, Samindika Athapaththu

Electronic Thesis and Dissertation Repository

As the increase in industrial technology continue to progress, it results in the increase in heavy metal pollution, creating harmful effects on humans, plants, and animals. Since toxic metals do not degrade easily, they accumulate over time, posing greater danger to living organisms. Removal of these heavy metals is therefore, of great importance. Though many research studies successfully utilized UV photocatalysis with TiO₂ catalyst for the removal of Cd²⁺, none have performed the photoreduction of Cd²⁺ under visible light using eosin-y dye-sensitized TiO₂. The objective of the present research is to study the photocatalytic …

Oxygen-Free Propane Oxidative Dehydrogenation Over Vanadium Oxide Catalysts: Reactivity And Kinetic Modelling, Sameer Ali Al-Ghamdi

Electronic Thesis and Dissertation Repository

Propane conversion to propylene has been the subject of intensive researches. This is due to the increasing demand for propylene. Current propylene production processes suffer from several limitations. Oxidative dehydrogenation (ODH) is a promising alternative technology for propylene production overcoming the drawbacks of current processes. However, selectivity control in ODH is still a challenge preventing it from an industrial application. This is due to the formation of undesired carbon oxides. Thus, the development of a selective catalyst is crucial for the commercialization of ODH. Vanadium oxide catalysts have been proposed as the most active and selective catalyst for propane ODH. …

Optimisation Of The Transesterification Stage Of Biodiesel Production Using Statistical Methods, Arnold Paintsil

Electronic Thesis and Dissertation Repository

The present research examines solely the transesterification stage of the biodiesel production process. Six process variables that affect the yield of biodiesel at this stage are examined using the 12 run Plackett-Burman Design. To study the effect of FFA[1] and to replicate real life situations where oil (feedstock) contain varying amounts of FFA, linoleic acid is used as FFA and intentionally added to high oleic acid canola oil containing less than 0.07% FFA. The process is catalyzed with potassium carbonate and evaluated at varying temperatures, stirring rates, reaction times and methanol oil ratios. The yields at the end of …

Upgrading Pyrolysis Oil To Produce Liquid Transportation Fuels, Ehsan Reyhanitash

Electronic Thesis and Dissertation Repository

The effects of stabilizing fast pyrolysis oil via catalytic alcohol pretreatment on upgrading via hydrodeoxygenation or thermal treatment was studied by comparing the properties of upgraded-stabilized oils with those of upgraded-non-stabilized oils (benchmarks). The major expected effect was reduction in molar mass of upgraded oils, as stabilization was expected to reduce the reactivity of fast pyrolysis oil, thereby reducing polymerization. It was observed that molar mass reduction was induced by dilution effect of the alcohol rather than reactivity reduction due to stabilization. Also, the effects of different alcohols on stabilization and subsequent upgrading were examined at minimized dilution effect conditions. …

Treatment Of Aqueous Biomass And Waste Via Supercritical Water Gasification For The Production Of Ch4 And H2, Izad Behnia

Electronic Thesis and Dissertation Repository

The present study targets to convert aqueous fraction of fast pyrolysis oil into methane and hydrogen gases via supercritical water gasification (SCWG). Water above its critical point is referred to as supercritical water, which has unique properties such as a loss of hydrogen bonding, becoming an excellent solvent for organic compounds. In this thesis, SCWG was used to gasify slurry materials into high calorific gases including CH₄ and H₂. Production selectivity towards more methane or hydrogen was affectively controlled by operational conditions. However, in the absence of catalyst (bank test), gas formation was very minimal. SCWG of …

High Density Gas-Solids Circulating Fluidized Bed Riser And Downer Reactors, Chengxiu Wang

Electronic Thesis and Dissertation Repository

A systematic and comprehensive study of hydrodynamics and reactor performance was conducted in a 76 mm i.d., 10 m high riser and a 76 mm i.d., 5.8 m high downer reactor under high density/flux operating conditions using fluid catalytic cracking (FCC) catalyst particles. An optical fiber probe was used to obtain a complete mapping of local solids holdup and particle velocity. Catalytic ozone decomposition reaction was employed to study the characteristics of reactor performance in the CFB riser and downer. The superficial gas velocity (U_g) and the solids circulation rate (G_s) were 3-9 m/s …

A Novel Mixed Metallic Oxygen Carrier For Chemical Looping Combustion: Preparation, Characterization And Kinetic Modeling, Mohammad Rezwanul Quddus

Electronic Thesis and Dissertation Repository

In last decades, significant concerns have been raised regarding the global warming effect. To date, about one-third of the total anthropogenic CO₂ emission results from power generation using fossil based fuel and CO₂ is the main contributor to global warming. Therefore, technologies for efficient capture of CO₂ are becoming of great value. In this respect, Chemical-Looping Combustion (CLC) has received significant attention as a promising technology facilitating concurrent CO₂ capture and power generation. This non-conventional technique employs a solid carrier, known as oxygen carrier, to supply oxygen and facilitates combustion process in absence of N_{2 …}