Download Free Cerium Oxide Ceo2 Promoted Oxygen Carrier Development And Scale Modeling Study For Chemical Looping Combustion Book in PDF and EPUB Free Download. You can read online Cerium Oxide Ceo2 Promoted Oxygen Carrier Development And Scale Modeling Study For Chemical Looping Combustion and write the review.

This book presents ongoing research activities of currently available renewable energy technologies and the approaches towards clean technology for enabling a socio-economic model for the present and future generations to live in a clean and healthy environment. The book provides chapter wise implementation of research works in the area of green energy technologies with proper methods used with solution strategies and energy efficiency approaches by combining theory and practical applications. Readers are introduced to practical problems of green computation and hybrid resources optimization with solution based approaches from the current research outcomes. The book will be of use to researchers, professionals, and policy-makers alike.
In last decades, significant concerns have been raised regarding the global warming effects. To date, about one - third of the total anthropogenic CO2 emission results from power generation using fossil based fuel and CO2 is regarded as 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 it facilitates the combustion process in absence of N2 diluted air. Therefore, the combustion products (CO2 and water) are easily separable without any extra downstream processing cost involved in other available alternatives. However, the non- vailability of suitable oxygen carriers still hinders the commercialization of CLC. This study, thus, deals with the development of a new mixed metallic oxygen carrier, Ni-Co/La-?-Al2O3. Several characterization techniques are used to evaluate the reactivity and stability of the prepared oxygen carriers under the industrial-scale conditions of a CLC processes. Apart from the beneficia l effects of La and Co, the reducibility and the structural properties of the prepared oxygen carriers are found to be influenced significantly by the different preparation methods used. N2 adsorption isotherms show that?-Al2O3 retains its structural int egrity under some specific preparation conditions. Reducibility as determined by consecutive temperature programmed techniques resembles the chemical properties of? - and?-Al2O3 for the other preparation techniques. However, no bulk phase change is detected for all the oxygen carriers studied using XRD. The SEM/EDX and H2 chemisorption analyses show the absence of metal agglomeration and suggest that the prepared oxygen carriers are highly stable under CLC operating conditions. The prepared oxygen carriers are also tested for reactivity, stability and fluidizability in the CREC Riser Simulator using multiple reduction/oxidation cycles with CLC fuel. Results obtained show expected reducibility, oxygen carrying capacity and stability. The solid-state kinetics of the reduction processes are developed using nucleation and nuclei growth model (NNGM) and unreacted shrinking core model (USCM). The NNGM model shows better adequacy over USCM in describing the mechanism of reduction process.
Cerium Oxide (CeO2): Synthesis, Properties and Applications provides an updated and comprehensive account of the research in the field of cerium oxide based materials. The book is divided into three main blocks that deal with its properties, synthesis and applications. Special attention is devoted to the growing number of applications of ceria based materials, including their usage in industrial and environmental catalysis and photocatalysis, energy production and storage, sensors, cosmetics, radioprotection, glass technology, pigments, stainless steel and toxicology. A brief historical introduction gives users background, and a final chapter addresses future perspectives and outlooks to stimulate future research. The book is intended for a wide audience, including students, academics and industrial researchers working in materials science, chemistry and physics. Addresses a wide range of applications of ceria-based materials, including catalysis, energy production and storage, sensors, cosmetics and toxicology Provides the fundamentals of ceria-based materials, including synthesis methods, materials properties, toxicology and surface chemistry Includes nanostructured ceria-based materials and a discussion of future prospects and outlooks
Chemical-looping (CL) is a novel and promising technology for several applications including oxy-combustion for carbon capture, hydrogen production and CO2 reuse. In this process, oxygen carriers are utilized to cyclically adsorb and release oxygen producing two separated exhaust streams with desirable products. A rotary reactor design with micro-channel structure was developed in the Reacting Gas Dynamics Lab (RGDL) at MIT, which exhibits superior performance over conversional designs. Preliminary simulation identified OC redox kinetics and material characteristics as keys to the success of CL technology. This thesis examines the fundamentals of the reduction and oxidation (redox) processes with the aim of achieving fast and reliable reaction kinetics for CL applications. Experiments are conducted in a button-cell fixed-bed reactor with an on-line mass spectrometer. The timeresolved kinetics are modeled with consideration of thermodynamics, surface chemistry, transport mechanism, and structural evolution. Our approach, combining well-controlled experiment and detailed kinetics modeling, enables a new methodology for identifying the rate-limiting mechanism, examining the defect electrochemistry, and designing alternative materials for chemical-looping technology. Redox study with nickel thin foils reveals that structural evolution is the determining factor. Nickel oxidation starts via nucleation of oxide grains, which overlap and annihilate the fast diffusion paths. The model shows that the reaction is limited by the decreasing ionic diffusivity. To achieve practical redox repeatability, NiO fine particles supported on YSZ nanopowder is tested, and superior kinetics and cyclic stability are observed. Fast oxygen exchange is achieved from 500 to 1000°C with sufficient utilization of the carrying capacity within 1 min. Improvement is attributed to the enhanced ionic diffusivity with YSZ. The use of ceria nanopowder exhibits an order of magnitude H2 production rate improvement as compared to the state-of-the-art. Ceria reduction is slow with a threshold temperature of 700°C. The model reveals that the charge transfer is the rate-determining step for H2 production. Improving H2 splitting requires: (i) reducing the defect formation enthalpy, and (ii) accelerating charge-transfer. The addition of Zr lowers the threshold temperature to 650°C with 60% improvement in the rates, resulting from 40% decrease in the defect formation enthalpy. Doping ceria with Pr 3+ further lowers the threshold temperature to 600°C while doubling the peak rate. The model reveals that the high concentration of surface defects achieved from either approach promotes adsorbate formation, thus accelerating the splitting steps. Similar conclusions are obtained for CO2 splitting. Using the derived kinetics, H2-syngas co-production with CH4 as fuel is examined. Two important stages are identified: the formation of the complete products on oxidized surface, and syngas on the reduced surface. CH4 reduction is found to be rate-limited by the slow fuel cracking reaction. To accelerate the kinetics, a novel perovskite-nickel composite OC is examined, in which nickel effectively catalyzes reduction, leading to an order of magnitude faster kinetics at 600-700°C. This project has clearly demonstrated that using novel materials, CL technology can provide an efficient solution to oxy-combustion based CO2 capture, and H2/syngas co-production. Specifically, the use of NiO/YSZ achieves fast kinetics, robust stability and sufficient OC utilization from 500 to 1000°C, enabling complete CO2 capture with minimum energy penalty. The ceria-, and perovskite-based OCs exhibit over an order-of-magnitude faster kinetics compared to the state-of-the-art, enabling improved H2 production/CO 2 reduction efficiency isothermally at 600-700°C. In-depth understanding gained on the redox fundamentals will shed light on the design and fabrication of new materials as well as optimization of the CL applications.
This comprehensive and up-to-date handbook on this highly topical field, covering everything from new process concepts to commercial applications. Describing novel developments as well as established methods, the authors start with the evaluation of different oxygen carriers and subsequently illuminate various technological concepts for the energy conversion process. They then go on to discuss the potential for commercial applications in gaseous, coal, and fuel combustion processes in industry. The result is an invaluable source for every scientist in the field, from inorganic chemists in academia to chemical engineers in industry.
The focus of this work is to investigate the feasibility of oxygen extraction from CO2 by doped ceria in chemical looping process. In order to increase the oxygen capacity and oxygen release rates, Cerium- based oxygen carriers are doped with ZrO2. Additionally, the zirconia-doped ceria is modified by iron and copper to boost the oxygen release in the fuel reactor. It should be noted that the level of doping allows the solids to maintain the cubic fluorite structure of CeO2. The redox activity of oxygen carriers is studied in order to determine the most promising material due to the oxygen transfer capacity and methane conversion. The chemical looping dry reforming in a quartz fixed-bed reactor is carried out in two steps. In the first step, the oxygen carriers are reduced by methane through the combustion reaction. In the second step, CO2 is used for oxidation of reduced metal oxides. The obtained results at different doping levels were compared to determine the optimal oxygen carrier. The results indicate that doping ceria can boost the reactivity with methane and enhance the methane conversion during combustion reaction. CeO2 modified by Fe presents a progress in both oxygen release and uptake with an increase in oxygen capacity of metal oxide. However, zirconia and copper ceria show different effect on reduction and oxidation. This means that zirconia doped ceria results in an increase in oxygen release during reduction and decrease in oxygen uptake during oxidation with CO2. In contrast, addition of copper to ceria metal oxides shows a negative effect on oxygen release, while it enhances the ability of oxygen uptake. Out of all mixed cerium oxides investigated in this study, cerium oxide containing 10% mole iron is determined as the most promising oxygen carrier for CLDR due to the methane conversion, facilitating oxygen release, increasing the level of reduction and improving the oxidation uptake of the metal oxide in the reaction with CO2.
Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO2 capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This topical report discusses the results of four complementary efforts: (5.1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (5.2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification; (5.3) the exploration of operating characteristics in the laboratoryscale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability; and (5.4) the identification of kinetic data for copper-based oxygen carriers as well as the development and analysis of supported copper oxygen carrier material. Subtask 5.1 focused on the development of kinetic expressions for the Chemical Looping with Oxygen Uncoupling (CLOU) process and validating them with reported literature data. The kinetic expressions were incorporated into a process model for determination of reactor size and oxygen carrier circulation for the CLOU process using ASPEN PLUS. An ASPEN PLUS process model was also developed using literature data for the CLC process employing an iron-based oxygen carrier, and the results of the process model have been utilized to perform a relative economic comparison. In Subtask 5.2, the investigators studied the trade-off between modeling approaches and available simulations tools. They quantified uncertainty in the high-performance computing (HPC) simulation tools for CLC bed applications. Furthermore, they performed a sensitivity analysis for velocity, height and polydispersity and compared results against literature data for experimental studies of CLC beds with no reaction. Finally, they present an optimization space using simple non-reactive configurations. In Subtask 5.3, through a series of experimental studies, behavior of a variety of oxygen carriers with different loadings and manufacturing techniques was evaluated under both oxidizing and reducing conditions. The influences of temperature, degree of carrier conversion and thermodynamic driving force resulting from the difference between equilibrium and system O2 partial pressures were evaluated through several experimental campaigns, and generalized models accounting for these influences were developed to describe oxidation and oxygen release. Conversion of three solid fuels with widely ranging reactivities was studied in a small fluidized bed system, and all but the least reactive fuel (petcoke) were rapidly converted by oxygen liberated from the CLOU carrier. Attrition propensity of a variety of carriers was also studied, and the carriers produced by freeze granulation or impregnation of preformed substrates displayed the lowest rates of attrition. Subtask 5.4 focused on gathering kinetic data for a copper-based oxygen carrier to assist with modeling of a functioning chemical looping reactor. The kinetics team was also responsible for the development and analysis of supported copper oxygen carrier material.
Development of a model that can be used to predict oxidation rates of copper to cuprous and cupric oxide (Cu2O and CuO, respectively) in the air reactor of a Chemical Looping Combustion (CLC) system is the primary focus of this thesis. The proposed oxidation model, which is based in Wagner Theory and defect chemistry, describes the fundamental processes occurring during copper oxidation. Consequently, it provides better predictive capabilities over a wide range of temperatures and pressures, as well as characteristic particle geometries (spheres, cylinders and plates) than the phenomenological models that are currently being used to predict oxidation rates of copper-based oxygen carriers used in CLC systems. In addition to developing this oxidation model, cuprous and cupric oxide reduction experiments with gaseous fuels like carbon monoxide, hydrogen and methane, and solid fuels like char, wyodak coal, and corn stover, were performed to characterize reaction rates in the fuel reactor of CLC systems. Oxidation rates obtained from the oxidation model, and measured rates from the reduction experiments were used to estimate the size and oxygen carrier loading for a 10 MWth CLC system.
This book focuses on the chemical structure and applications of CeO2. It covers the recent developments in a wide range of CeO2 applications, particularly catalysis corrosion protection, fuel cells, sensors, and UV-blocking. It also provides a concise but thorough coverage of the chemical structure and applications of CeO2. Thus, this book provides an overview of chemical structure, applications, and recent attributes of CeO2 for a broad audience, including beginners, graduate students, and specialists in both academic and industrial sectors.