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Smith, Mark W.

Publications and source records attributed to Smith, Mark W..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Electromagnetic field-assisted method for chemical conversion

Embodiments relate to methods for enhancing chemical conversions. One or more embodiments relate to a method for enhancing a multi-step chemical conversion reaction. The method includes providing a reactant mixture comprising one or more reacting specie(s); and providing a catalyst or sorbent comprising one or more support materials and one or more deposited catalytically active materials. The method further includes applying an electromagnetic field with a prescribed power, frequency, and pulsing strategy specific to interactions of reactant species and an electromagnetic field with at least one of the support materials, sorbent, and catalytically active materials in a particular chemical reaction.

Shekhawat, Dushyant↗
DOE OSTI2023

Activated carbon supported Ni, Fe, and bimetallic NiFe catalysts for CO x -free H 2 production by microwave methane pyrolysis

The goal of this study was to test the effect of metal-impregnated carbon-based catalysts on the conversion of methane to hydrogen gas and solid carbon using microwave reactor technology. Monometallic and bimetallic catalysts on activated carbon supports (Ni/AC, Fe/AC, Ni-Fe/AC) are compared during methane pyrolysis testing. Catalytic methane pyrolysis was carried out in a microwave reactor at reaction temperatures of 600 °C and 800 °C. For comparison, one of the catalysts (Ni-Fe/AC) was tested in a conventionally heated reactor at 800 °C. The prepared catalysts were characterized by X-ray diffraction (XRD), while post-reaction catalysts were characterized by XRD and SEM. During reaction testing, the monometallic Ni/AC catalyst exhibited the best catalytic activity (CH 4 conversion: 46.0 and H 2 yield: 46.9%) when reacted in the microwave reactor, however, it suffered from rapid deactivation from carbon deposition (carbon yield: 0.39 gC/g catalyst). The bimetallic Ni-Fe/AC catalyst was slightly less active (CH 4 conversion: 36.9 and H 2 yield: 40.5%) but it was more resistant to carbon formation (carbon yield: 0.27 gC/g catalyst) suggesting it may have greater long-term stability. The Ni-Fe/AC catalyst was also the most energy efficient as it required the least microwave power to maintain the 800 °C reaction temperature compared to the other catalysts tested. Methane conversion of the bimetallic Ni-Fe/AC at 800 °C under microwave irradiation was three times the conversion under conventional heating at the same reaction temperature. Finally, this work demonstrates the use of microwave-specific catalysts for catalytic methane pyrolysis in a microwave reactor, and can be used as a foundation for further methane pyrolysis process and catalyst optimization for CO x -free H 2 production.

08 HYDROGEN↗
DOE OSTI2023

Broadband differential absorption sensor for detecting gaseous species

A remote sensor system comprising a laser transmitter that emits a pulse of broadband laser illumination comprising a plurality of wavelengths and a receiver configured to detect laser illumination backscatter. The sensor system further includes a computing system configured to determine a plurality of species number densities along a travel path of the laser illumination. Determining the plurality of species number densities includes determining a first number density of a first species based on a first set of optical transmission values from the backscatter data for a first subset of wavelengths of the plurality of wavelengths and a first attenuation cross-section of the first species. Additional species are determined based on additional sets of optical transmission values from the backscatter data for additional subsets of wavelengths of the plurality of wavelengths and additional cross-sections of additional species.

Smith, Mark W.↗
DOE OSTI2022

Cooperative Research and Development Agreement between National Energy Technology Laboratory and Princeton University (Abstract)

The National Energy Technology Laboratory (NETL) and Princeton University will collaborate in the development of microwave-plasma technology to convert methane into hydrogen and valuable solid carbon materials. The effort will combine NETL’s vast resources for microwave-enhanced process development, characterization, and design with Princeton University’s extensive expertise in the study of non-equilibrium plasmas employing supersonic nozzles. Lab-scale experiments will be conducted for different conditions to convert and compare their respective performance in hydrogen production. Computational modeling will be performed to verify results from experimental studies conducted in both labs.

08 HYDROGEN↗
DOE OSTI2021

Mixed-metal oxide based catalysts

One or more embodiments relates to a method of catalytically converting a reactant gas mixture for pollution abatement of products of hydrocarbon fuel combustion. The method provides substituted mixed-metal oxides where catalytically active metals are substituted within the crystal lattice to create an active and well dispersed metal catalyst available to convert the reactant gas mixture. Embodiments may be used with gasoline and diesel fueled internal combustion engine exhaust, although specific embodiments may differ somewhat for each.

Berry, David A.↗
DOE OSTI2020

Microwave-induced selective decomposition of cellulose: Computational and experimental mechanistic study

Understanding microwave-material interactions will help facilitate the utilization of microwave technology in gasification and renewable energy production. In this study, cellulose was used as a model compound to simulate the organic matter in biomass, and its catalytic decomposition under a microwave (MW) field was studied to identify structural changes from the reaction. The study was conducted using a MW source coupled to a fixed-bed gas-flow reactor, mass spectroscopic, and Fourier transform infrared spectroscopy post-reaction analysis. Zeolite 13X was chosen as a microwave absorber to study the catalytic enhancement of the decomposition of cellulose. Density functional theory (DFT) was used to gain insights into the molecular transformations occurring in the presence of a static electric field, which was used to simulate the electric field component of the microwave electromagnetic radiation. Theoretical calculations demonstrated that both the positive and negative portion of the electric field interact with the permanent dipoles of the cellulose effecting the decomposition through the glycosidic bond breaking mechanism. The theoretical result was verified using infrared spectroscopic analysis of the pure cellulose during microwave heating. The theoretical calculations suggest only the positive electric field component may be active for the cellulose decomposition in the presence of Zeolite 13X. Physically mixing Zeolite 13X with the cellulose led to a significant enhancement in the decomposition rate of the glycosidic bond. Zeolite 13X enhanced the glycosidic O-C decomposition at lower MW power (lower temperatures), whereas the O-H functional group required higher MW power (higher temperature) for its decomposition. The DFT study coupled with the reaction studies revealed that the electric field polarizability is dependent upon both the direction and the orientation of the cellulose. Gas products revealed that applying 250 W of MW power led to the production of CO, H 2 , along with some CO 2 , CH 4 , and benzene at 305 °C. Finally, reaction under 500, 750, and 1000 W of power at constant temperature (305 °C) revealed that higher power led to the complete decomposition of cellulose to mostly CO, H 2 , and CO 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Method of exhaust cleanup from combustion processes using mixed-metal oxide based catalysts

One or more embodiments relates to a method of catalytically converting a reactant gas mixture for pollution abatement of products of hydrocarbon fuel combustion. The method provides substituted mixed-metal oxides where catalytically active metals are substituted within the crystal lattice to create an active and well dispersed metal catalyst available to convert the reactant gas mixture. Embodiments may be used with gasoline and diesel fueled internal combustion engine exhaust, although specific embodiments may differ somewhat for each.

02 PETROLEUM↗
DOE OSTI2019

Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

Chemical-looping combustion with oxygen uncoupling (CLOU) is a process using gaseous or solid hydrocarbon fuels and is a promising carbon capture and storage (CCS) technology. In CLOU, combustion of the fuel is achieved through the release of gaseous O 2 from an oxygen carrier material such as CuO and is favored at high temperatures and low O 2 partial pressures. The primary objectives of this study were to (1) compare values for the apparent rate constant k ov ( T ) for the overall rate of reduction of a CuO carrier, either alone or in the presence of coal char obtained from the pyrolysis of Powder River Basin (PRB) coal, and (2) develop and validate a computational fluid dynamics (CFD) model for the CuO/PRB coal char system based on known kinetics of the individual CuO and Cu 2 O reduction, combustion, and gasification reactions. Two oxygen carriers consisting of 20 wt % CuO/Al 2 O 3 and 9 wt % CuO/Al 2 O 3 were prepared by physical mixing and by incipient wetness impregnation (IWI), respectively. Kinetic analyses were conducted in the temperature range of 850–1100 °C. The CFD model typically reproduced experimental values of k ov ( T ) to within ±10%. We note the increase in k ov ( T ) caused by addition of only 0.075 g of PRB char per gram of CuO was modest at 1100 °C, but was more than 3-fold at 850 °C. Combustion and gasification of the coal char not only produced CO, opening another pathway for CuO reduction in addition to the CLOU reaction, but also resulted in the over-reduction of Cu 2 O to the undesired metallic Cu. Production of Cu metal increased with respect to char loading.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Effect of Microwave and Thermal Co-pyrolysis of Low-Rank Coal and Pine Wood on Product Distributions and Char Structure

Direct conversion of a low-rank coal into valuable chemicals or improving its char’s coking value became very demanding aims in coal utilization strategies. Here, the co-pyrolysis of a low-rank lignite coal and pine wood sawdust biomass blended at a 3:1 coal-to-biomass ratio was investigated along with original coal and biomass samples by microwave-assisted and conventional thermal methods at 550 °C under nitrogen and ambient pressure. The carbon structure and its reactivity in generated chars and the product distributions were greatly affected by the applied heating mechanism and the presence of biomass during coal pyrolysis. High gas and low tar yields were observed for all microwave chars in comparison to thermal chars, regardless of composition. The addition of biomass to coal increased the tar yield under both methods and to a higher extent under the microwave. This agrees with the high gas yield and high aromatic-to-aliphatic fraction observed under the microwave and the presence of biomass. The high O/C ratio and low fixed carbon content in a biomass structure relative to coal affect the product distribution during microwave pyrolysis. This could selectively heat the biomass in the sample, remove its polar groups, and convert it into an efficient microwave absorber biochar that can decompose coal efficiently during co-pyrolysis. The aromatic carbon stacking and its ordering in the generated chars were investigated by powder X-ray diffraction, Raman spectroscopy, dielectric property measurements, and electron spin resonance techniques. A synergistic effect was observed upon biomass addition during microwave coal pyrolysis. Electron spin resonance spectroscopy revealed that the microwave coal/biomass char is the most stable char with the lowest free radical concentration. Furthermore, this agrees with the highest I G /I all band area ratio calculated from Raman analysis revealing a more graphitic nature for carbon in this char. Similarly, the dielectric properties confirmed that the addition of biomass to coal under the microwave has the highest loss tangent, indicating a high graphitic nature compared to pure biochar or coal char.

09 BIOMASS FUELS↗
DOE OSTI2019

Extended cavity laser absorption spectroscopy

Technologies for detecting absorption of electromagnetic radiation traveling through a measurement volume of interest are described herein. In a general embodiment, a laser is used to emit electromagnetic radiation through the measurement volume where absorption is desirably detected. An optical collector receives a portion of the radiation and directs a first fraction of the portion back to a gain medium of the laser, where the radiation is amplified and emitted again, and directs a second fraction to an optical sensor that can detect absorption in the measurement volume based upon attenuation of energy of the radiation. As the radiation feeds back to the gain medium and is emitted again, energy at attenuated wavelengths is amplified less than at other wavelengths. Thus, attenuation of energy of the radiation due to absorption in the measurement volume is cumulative, and relatively small absorptions are amplified, allowing smaller absorptions to be detected more easily.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Examining and Modeling Oxygen Uncoupling Kinetics of Cu-Based Oxygen Carriers for Chemical Looping with Oxygen Uncoupling (CLOU) in a Drop Tube Fluidized Bed Reactor

Chemical looping combustion with oxygen uncoupling (CLOU) is a promising carbon capture and storage (CCS) technology for conversion of gaseous and solid hydrocarbon fuels where the release of gaseous O 2 from an oxygen carrier is favored at high temperature and low O 2 partial pressure. One promising CLOU material is the copper oxide redox system (CuO–Cu 2 O). The primary objective of this study was to examine the use of a drop tube fluidized bed reactor (DT-FBR) for evaluating the kinetics of oxygen uncoupling with Cu-based oxygen carriers. Appropriate rate expressions from redox experiments are needed to model and scale up CLOU systems. Additionally, the determined oxygen uncoupling kinetic parameters were validated using a computational fluid dynamic model. Two oxygen carriers consisting of 20 wt % CuO/Al 2 O 3 and 9 wt % CuO/Al 2 O 3 were prepared by physical mixing. A third oxygen carrier sample was prepared at 9 wt % CuO/Al 2 O 3 by incipient wetness impregnation. The reaction rates of the copper oxide redox system are strongly dependent on thermodynamic effects of the oxygen partial pressure relative to the equilibrium oxygen partial pressure. The results presented in this paper offer an alternative and simplified kinetic analysis compared to that traditionally presented in the literature for the thermal reduction of copper oxide or other CLOU oxygen carriers. The reactor system used in this study allows for operating parameters to be adjusted, minimizing thermodynamic and mass transfer limitations, which eliminates the need for more complex kinetic/thermodynamic reaction models. The reaction kinetics measured in this study is compared based on the preparation method and the CuO weight percent loading. These results may aid in the development of CLOU technologies during reactor design and process modeling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗