Chemical Engineering Commons^™

Theoretical Investigation Of The Catalytic, Liquid-Phase Hydrodeoxygenation Of Organic Acids And Esters, Sina Behtash

Theses and Dissertations

With worldwide fossil fuel resources dwindling and greenhouse gas emissions rising, it is urgent to find renewable liquid fuel alternatives from e.g. biomass to meet the world’s growing energy demand. Lipid feedstocks and pyrolysis oils from woody biomass can be utilized for the production of second-generation biofuels via a catalytic hydrodeoxygenation (HDO) process. The conversion of fatty acids and esters plays an important role in the activity and selectivity of these processes. Understanding the HDO reaction mechanism of organic acids and esters on metal surfaces is a prerequisite for the rational design of new HDO catalysts specifically designed for upgrading …

Gasification Of Biomass, Coal, And Petroleum Coke At High Heating Rates And Elevated Pressure, Aaron D. Lewis

Theses and Dissertations

Gasification is a process used to convert any carbonaceous species through heterogeneous reaction to obtain the desired gaseous products of H2 and CO which are used to make chemicals, liquid transportation fuels, and power. Both pyrolysis and heterogeneous gasification occur in commercial entrained-flow gasifiers at pressures from 4 to 65 atm with local gas temperatures as high as 2000 °C. Many gasification studies have been performed at moderate temperatures, heating rates, and pressures. In this work, both pyrolysis and char gasification experiments were performed on coal, petroleum coke, and biomass at conditions pertinent to commercial entrained-flow gasifiers. Rapid biomass pyrolysis …

Theoretical Investigation Of Heterogeneous Catalysis At The Solid–Liquid Interface For The Conversion Of Lignocellulosic Biomass Model Molecules, Muhammad Faheem

Theses and Dissertations

Catalytic conversion of biomass-derived oxygenates to fuels and value-added chemicals is a promising strategy in the search for renewable and sustainable energy sources. Most relevant catalytic processes are carried out in an aqueous environment using supported transition metal catalysts. The reaction network consists of multiple series and parallel pathways leading to formation of hydrogen, alkanes, and lighter oxygenates. The final product distribution ultimately depends on the sequence and competition of C−C, C−O, C−H, and O−H bonds scissions. Ethylene glycol (EG) is the simplest model molecule of various biomass-derived polyols that has a C:O stoichiometry of 1:1 and contains all relevant …

Gas-Phase, Catalytic Hydrodeoxygenation Of Propanoic Acid Over Supported Group Viii Noble Metals, Yuliana K. Lugo José

Theses and Dissertations

Recent advances for the deoxygenation of biomass, have demonstrated that hydrodeoxygenation (HDO) is one of the most promising route for the upgrading pyrolysis bio-oils. Catalytic hydrodeoxygenation of pyrolysis bio-oil have shown to be an efficient and economical process, since the raw materials consist mainly of waste. Propanoic Acid (PAc) is considered as one of the main constituents of pyrolysis bio-oils. However, these carboxylic acids are extremely corrosive and difficult to deoxygenate. Therefore, much effort have been given to the development of novel catalytic techniques, to improve the activity, stability and selectivity for the HDO of carboxylic acids.

This dissertation explores …

The Role Of Surface Area In Catalytic Gasification Of Biomass, Elizabeth A. Wachs, Nitish Kumar, Indraneel Sircar, Prithviraja Basak, Jay P. Gore Phd

The Summer Undergraduate Research Fellowship (SURF) Symposium

Gasification of biomass has the potential to provide a carbon-negative source of liquid fuels. The current limited use of gasification is due in part to the high temperatures necessary to achieve high conversion levels. These temperatures can be lowered by the use of catalysts, but the mechanisms by which catalysts affect the reaction rate are not fully understood. Here, the structural component of potassium carbonate’s role in the gasification process was examined. Samples of pinewood sawdust were impregnated with potassium carbonate, then pyrolyzed with N2 in a fixed bed reactor at 750°C (heater thermocouple reading). Half of the char was …

Co2 Char Gasification Rates Of Sawdust, Switchgrass, And Corn Stover In A Pressurized Entrained-Flow Reactor, Thomas H. Fletcher, Aaron D. Lewis, Emmett G. Fletcher

Faculty Publications

An entrained-flow flat-flame burner reactor was used to measure apparent CO2 gasification rates of near-spherical biomass chars of poplar sawdust, switchgrass, and corn stover using particle residence times1258−1891 K and 6.1− 13.5 atm, respectively. A new method was developed to produce near-spherical particles from nonspherical biomass chars. The apparent CO2 gasification rates for the three biomass chars with mean diameters near 100 μm were fit to a global first-order model, and the optimal kinetic parameters are reported. The measured gasification rate of poplar sawdust was about 3.9 times faster than that of switchgrass char, but only about 20% faster than …

Pretreatment Of Cellulosic Biomass By Iron-Containing Magnetic Ionic Liquid Dissolution, Christopher Roth Riley

Electronic Theses and Dissertations

The focus of this project is to determine the effectiveness in the preprocessing of biomass when magnetic ionic liquids (MIL) (1-butyl-3-methylimidazolium tetrachloroferrate (Bmim[FeCl4]) and 1-ethyl-3-methylimidazolium tetrachloroferrate (Emim[FeCl4])) are used as a green solvent. Lignocellulose is a promising starting material for a plethora of products, ranging from biofuels to custom chemicals; however, lignocellulose is resistant to enzymatic degradation. Various biomass-preprocessing techniques such as microbial, mechanical, and chemical pretreatment are used for enhancing the digestibility of biomass to sugars for ethanol production. Varieties of ionic liquids have demonstrated the ability to fragment lignocellulose. However, after fragmentation, separation of biomass and ionic liquids …

Electrocatalytic Processing Of Renewable Biomass-Derived Compounds For Production Of Chemicals, Fuels And Electricity, Le Xin

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

The dual problems of sustaining the fast growth of human society and preserving the environment for future generations urge us to shift our focus from exploiting fossil oils to researching and developing more affordable, reliable and clean energy sources. Human beings had a long history that depended on meeting our energy demands with plant biomass, and the modern biorefinery technologies realize the effective conversion of biomass to production of transportation fuels, bulk and fine chemicals so to alleviate our reliance on fossil fuel resources of declining supply. With the aim of replacing as much non-renewable carbon from fossil oils with …

Lab-Scale Fast-Hydropyrolysis And Vapor-Phase Catalytic Hydrodeoxygenation For Producing Liquid Fuel Range Hydrocarbons From Intact Biomass, Vinod Kumar Venkatakrishnan

Open Access Dissertations

Liquid transportation fuels are primarily produced from petroleum-based non-renewable carbon sources. Sustainably available lignocellulosic biomass, as a renewable form of atmospheric carbon, could be utilized to produce hydrocarbon-based fuels with high energy density. One of the process options for this conversion is the H2Bioil process, where biomass is rapidly heated in a hydrogen environment to produce fast-hydropyrolysis vapors that are catalytically upgraded in downstream hydrodeoxygenation (HDO) to produce hydrocarbons. This process has been modeled to have high carbon and energy efficiencies of ~70% and ~75%, respectively.

This dissertation presents the results of a lab-scale experimental proof-of-concept for the H2Bioil process …

Solvent Selection For Liquid-Liquid Extraction Of Acetic Acid From Biomass Hydrolysate, Emma A. Barber, Mahdieh Aghazadeh, Abigail Engelberth

The Summer Undergraduate Research Fellowship (SURF) Symposium

Biofuels are one of the most hopeful alternative energy sources to fossil fuels. However, the processing and production of biofuels needs improvement to be economically competitive in the current market. One drawback is the presence of naturally occurring compounds that decrease the bioethanol production rate and yield; these are called inhibitors. A resolution to this problem is to remove the inhibitors from biomass fermentation broth prior to fermentation. This project examined liquid-liquid extraction (LLE) for removal of acetic acid, a major inhibitor. Initially, a stock solution of glucose, xylose, acetic acid, and water was combined with an additional organic solvent …

Energy Systems Analysis For A Solar Economy, Dharik Sanchan Mallapragada

Open Access Dissertations

The use of solar energy for human needs faces challenges owing to its relatively low energy intensity and intermittent availability, coupled with the constrained availability of renewable carbon and land resources. This study uses systems analysis tools to identify carbon and energy efficient transformations of solar energy for different purposes, including transportation fuels and grid-scale energy storage. These efforts have been complemented with a feasibility analysis of existing fossil-energy and other hybrid pathways.

In an era of limited fossil resources, liquid fuels from sustainably available (SA) biomass could meet the energy needs of the transportation sector. We present a method …

Application Of One Dimensional Turbulence (Odt) To Model Fire Spread Through Biomass Fuel Bed, Abinash Paudel

Theses and Dissertations

Each year fires destroy millions of acres of woodland, lives, and property, and significantly contribute to air pollution. Increased knowledge of the physics and properties of the flame propagation is necessary to broaden the fundamental understanding and modeling capabilities of fires. Modeling flame propagation in fires is challenging because of the various modes of heat transfer with diverse fuels, multi-scale turbulence, and complex chemical kinetics. Standard physical models of turbulence like RANS and LES have been used to understand the flame behavior, but these models are limited by computational cost and their inability to resolve sub-grid scales. Application of several …

Characterization And Quantification Of Monomers, Oligomers, And By-Products From Xylan During Biomass Pretreatment, Ching-Shuan Lau

Graduate Theses and Dissertations

Biomass pretreatment generates inhibitory products, which reduce the overall yield of xylose for ethanol production. Understanding of hemicellulose depolymerization into xylose is essential to identify the pretreatment conditions that maximize xylose formation, but minimize the generation of these inhibitory products, such as formic acid and furfural. Thus, the goal of this project is to understand how dilute acid pretreatment parameters affect hemicellulose depolymerization, maximize xylose concentrations, and minimize by-products formation.

To progress towards this goal, rates and mechanisms of hemicellulose release must be determined. Birchwood xylan was used as the starting material to produce xylose oligomers. The hydrolyzed birchwood xylan …

Optimization Of A Dynamic Hot Water Pretreatment Of Switchgrass Using Catalysis By Carbonation To Maximize Carbochemical Yields, Rohit Tanaji Dhamdere

Graduate Theses and Dissertations

A bio-refinery is a facility that converts renewable bio-resources into value-added chemicals and products. In this context of a bio-refinery, the production of the carbochemicals such as HMF, furfural and organic acids illustrate that multiple products can be produced from a renewable source such as lignocellulosic biomass (switchgrass). Traditionally, carbochemicals such as furfural and HMF are produced using inorganic acids such as H2SO4, HCL, and H3PO4. The use of such acids requires the application of high cost materials of construction such as Hastelloy-C, titanium etc.

The objective of this study is to develop a semi-continuous process for the conversion of …

Prediction Of Tar And Light Gas During Pyrolysis Of Black Liquor And Biomass, Thomas H. Fletcher, Harland R. Pond, Jarom Webster, Judson Wooters, Larry L. Baxter

Faculty Publications

A generalized model for describing the pyrolysis behavior of low-grade fuels is being developed for incorporation into larger combustion simulation models. Light gas and tar yields from black liquor or biomass pyrolysis can be predicted using the chemical percolation devolatilization (CPD) model originally developed for coal. The initial approach is to measure the average chemical structures in a black liquor sample using 13C NMR spectroscopy. These chemical structures are then used in pyrolysis model predictions. With few changes from the coal-derived kinetic parameters, the model describes the organic pyrolysis behavior of black liquor samples obtained in a nitrogen-purged furnace. It …

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 …

Preprocessing Of Biomass Using Mechanical, Chemical And Microbial Techniques, Swetha Mahalaxmi

Electronic Theses and Dissertations

Biomass-derived fuels have acquired a lot of attention recently due to increasing emphasis on energy independence, efforts to utilize abundance of green resources and mitigation of greenhouse gas emissions. Grasses, agricultural residues, animal residues and waste, used oils, etc., can be used as starting materials in the production of biofuels. Various preprocessing techniques used in the preprocessing of biomass, such as microbial preprocessing, mechanical preprocessing and chemical pretreatment, are used for enhancing the digestibility of biomass to sugars for ethanol production. In this work, studies were conducted to improve the microbial, chemical and mechanical preprocessing of switch grass by decreasing …

Life Cycle Assessment Of Biofuels Produced By The New Integrated Hydropyrolysis-Hydroconversion (Ih2) Process, Edwin Maleche

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

Biofuels are alternative fuels that have the promise of reducing reliance on imported fossil fuels and decreasing emission of greenhouse gases from energy consumption. This thesis analyses the environmental impacts focusing on the greenhouse gas (GHG) emissions associated with the production and delivery of biofuel using the new Integrated Hydropyrolysis and Hydroconversion (IH²) process. The IH² process is an innovative process for the conversion of woody biomass into hydrocarbon liquid transportation fuels in the range of gasoline and diesel.

A cradle-to-grave life cycle assessment (LCA) was used to calculate the greenhouse gas emissions associated with diverse feedstocks …

A Cfd Model For Thermal Conversion Of Thermally Thick Biomass Particles, Ramin Mehrabian, Selma Zahirovic, Robert Scharler, Ingwald Obernberger, Stefan Kleditzsch, Siegmar Wirtz, Victor Scherer, Hong Lu, Larry L. Baxter

Faculty Publications

A one-dimensional model for the thermal conversion of thermally thick biomass particles is developed for the simulation of the fuel bed of biomass grate furnaces. The model can be applied for cylindrical and spherical particles. The particle is divided into four layers corresponding to the main stages of biomass thermal conversion. The energy and mass conservation equations are solved for each layer. The reactions are assigned to the boundaries. The model can predict the intra-particle temperature gradient, the particle mass loss rate as well as the time-dependent variations of particle size and density, as the most essential features of particle …

Analysis Of Biomass/Coal Co-Gasification For Integrated Gasification Combined Cycle (Igcc) Systems With Carbon Capture, Henry A. Long Iii

LSU New Orleans Theses and Dissertations

In recent years, Integrated Gasification Combined Cycle Technology (IGCC) has become more common in clean coal power operations with carbon capture and sequestration (CCS). Great efforts have been spent on investigating ways to improve the efficiency, reduce costs, and further reduce greenhouse gas emissions. This study focuses on investigating two approaches to achieve these goals. First, replace the subcritical Rankine steam cycle with a supercritical steam cycle. Second, add different amounts of biomass as feedstock to reduce emissions. Finally, implement several types of CCS, including sweet- and sour-shift pre-combustion and post-combustion.

Using the software, Thermoflow®, this study shows that utilizing …

Numerical Computation Of Hydrodynamic Behavior Of Biomass Particles In Circulating Fluidized Beds, Afsin Gungor Dr.

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

A model using a particle based approach is developed to accurately predict the hydrodynamic behavior of biomass particles in CFBs. Generally, the change in the pressure gradient with height in CFB riser is small. Numerical results are in good agreement with experiments, both in form and magnitude.

Desulfurization And Tar Removal From Gasifier Effluents Using Mixed Rare Earth Oxides, Sumana Adusumilli

LSU Master's Theses

Biomass gasification is a promising source of fuels. However, hydrogen sulphide, tars and other by-products must be removed from the raw gas because they deactivate downstream reforming and water gas shift catalysts. The goal of this project is to find the best REO combination for simultaneous tar cracking and desulfurization of gasifier effluents and to find the sorbents that are stable at high operating temperatures of gasifiers. Simultaneous tar cracking and H2S removal from a simulated gasifier effluent was tested using different rare earth mixed oxide (REO) catalysts/sorbents based on Ce/LaOx, Ce/La/MOx and Ce/La/M2Ox/Al2O3 where M is a transition metal …

Historical And Recent Developments In The Enzymatic Hydrolysis Of Brazilian Feedstocks For Ethanol Production, Elba P.S. Bon

Bioenergy - II: Fuels and Chemicals from Renewable Resources

N/A

Simulation Of Corn Stover And Distillers Grains Gasification With Aspen Plus, Ajay Kumar, Hossein Noureddini, Yaşar Demirel, David Jones, Milford Hanna

Yaşar Demirel Publications

A model was developed to simulate the performance of a lab‐scale gasifier and predict the flowrate and composition of product from given biomass composition and gasifier operating conditions using Aspen Plus software. Mass balance, energy balance, and minimization of Gibbs free energy during the gasification were applied to determine the product gas composition. Carbon conversion efficiency and tar content were provided to the model as inputs as these could not be predicted by the model based on minimization of Gibbs free energy. Experiments for validation of the model were performed on a lab‐scale fluidized bed gasifier using corn stover and …

The Effects Of Inorganic Solids And Certain Gases On The Thermal Decomposition Of Catechol, Jerome Apilan Robles

LSU Doctoral Dissertations

In order to investigate the effects of calcium carbonate and iron oxide on the thermal decomposition of solid fuels, we have constructed an isothermal flow reactor to perform experiments on the model compound catechol (ortho-dihydroxybenzene), a phenol-type compound representative of coal, wood and biomass. Calcium carbonate and iron oxide are inorganic components of coal and wood, which have demonstrated catalytic properties in thermal reactions and are commercially used to enhance the conversion of solid fuels. In this study, the effects of the inorganic solids on pyrolysis and combustion are conducted through identification and quantification of the products formed after subjecting …

Mechanistic Investigation Of Ash Deposition In Pulverized-Coal And Biomass Combustion, Shrinivas Sadashiv Lokare

Theses and Dissertations

This investigation details the effects of fuel constituents on ash deposition through systematic experimental and theoretical analyses of fundamental particle experiments and a suite of fuels with widely varying inorganic contents and compositions. The experiments were carried out in the Multifuel Flow Reactor (MFR) at Brigham Young University. Fuels included several biomass fuels (straw, sawdust and mixtures of straw-sawdust with other additives such as Al(OH)3, CaCO3, etc.) and four commercially-used coals (Illinois#6, Powder River Basin – Caballo and Cordero, Blind Canyon, and Lignite – Beulah Zap). The data from the series of experiments quantitatively illustrate the effects of fuel properties, …

Fast Pyrolysis Of Biomass In A Circulating Fluidised Bed, Manon Van De Velden, Xianfeng Fan, Andy Ingram, Jan Baeyens

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

CFB biomass pyrolysis produces mostly bio-oil. Reaction rates are fast (k > 0.5 s-1). Yields exceed 60 wt% of bio-oil at 500 °C and at a residence time for oil and char t < 2.5 s. as achieved in plug flow CFB-mode, shown by PEPT to occur at U > (Utr + 1) m/s and G > 200 kg/m² s.

Thermal Conversion Of Biomass And Waste, Liban Yassin, Paola Lettieri, Stefaan Simons, Antonino Germanà

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

This paper investigates the process designs of 2 fluidized bed gasification plants utilizing clean biomass. Energy and mass balances for each process were carried out and ChemCAD was used to evaluate the energy recovery process by simulating the operation of a steam turbine and a combined cycle gas turbine (CCGT).

H2-Rich Syngas From Renewable Sources By Dual Fluidized Bed Steam Gasification Of Solid Biomass, Christoph Pfeifer, Tobias Pröll, Bernhard Puchner, Hermann Hofbauer

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Steam gasification of solid biomass yields high quality producer gases that can be used for efficient combined heat and power production (CHP) and as a renewable resource for chemical syntheses. The dual fluidized bed steam gasification technology provides the necessary heat for steam gasification by circulating hot bed material that is heated in a second fluidized bed reactor by combustion of residual biomass char. The hydrogen content in producer gas of such gasifiers is about 40 vol% (dry basis). Addition of carbonates to the bed material and adequate adjustment of operation temperatures in the reactors allow selective transport of CO2 …

Experimental And Modeling Investigations Of Biomass Particle Combustion, Hong Lu

Theses and Dissertations

This investigation provides a comprehensive analysis of entrained-flow biomass combustion processes. Experimental and theoretical investigations indicate how particle shape and size influence biomass combustion rates. Experimental samples include flake-like, cylinder-like, and equant (nearly spherical) shapes with similar particle masses and volumes but different surface areas. Samples of small (less than 500 µm) particles were passed through a laboratory entrained-flow reactor in a nitrogen/air atmosphere and a maximum reactor wall temperature of 1600 K, while large samples were reacted in suspension in a single particle furnace operated at similar conditions as the entrained-flow reactor. A separately developed computer and image analysis …