A robust fuel cell operated on nearly dry methane at 500 °C enabled by synergistic thermal catalysis and electrocatalysis
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Ethylene is one of the largest building blocks in the petrochemical industry, mainly produced by steam cracking of ethane derived from naphtha or shale gas at high temperatures (>800 °C). Despite its technical maturity and economic competitiveness, the thermal steam cracking of ethane is highly energy-intensive. In this work, an electrochemically engineered direct conversion process of ethane to produce hydrogen and ethylene using a planar protonic ceramic membrane reactor with a bi-functional three-dimensional catalytic electrode is reported, with a single-pass ethane conversion of 40% and ethylene yield of 26.7% at 550 °C. Compared with the industrial ethane steam cracking, this method saves process energy input by 45.1% and improves process energy efficiency by 50.6%, based on comprehensive process simulation using Aspen Plus software. Further, steam electrolysis treatment under the solid oxide electrolysis cell mode can regenerate the system’s catalytic performance and significantly alleviate catalytic degradation by 74%, demonstrating high techno-economic viability.
Significant efforts have been devoted to develop processes for the conversion of biomass, an abundant and sustainable source of energy, to liquid fuels and chemicals, in order to replace diminishing fossil fuels and mitigate global warming. Thermochemical and biochemical methods have attracted the most attention. Among the thermochemical processes, pyrolysis and liquefaction are the two major technologies for the direct conversion of biomass to produce a liquid product, often called bio-oil. This chapter focuses on the liquefaction, a medium-temperature and high-pressure thermochemical process for the conversion of biomass to bio-oil. Water has been most commonly used as a solvent and the process is known as hydrothermal liquefaction (HTL). Fundamentals of HTL process, key factors determining HTL behavior, role of catalyst in HTL, properties of produced bio-oil, and the current status of the technology are summarized. The liquefaction of biomass by using organic solvents, a process called solvolysis, is also discussed. A wide range of biomass feedstocks have been tested for liquefaction including wood, crop residues, algae, food processing waste, and animal manure.
Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.
A method and system for membrane-assisted production of high purity concentrated dimethyl carbonate by the reaction of carbon dioxide and methanol is provided. Carbon dioxide is recovered from flue gas or other dilute streams from industrial processes by a membrane and subsequent conversion takes place to an intermediate methyl carbamate by reacting of carbon dioxide with ammonia and methanol. For high-purity carbon dioxide obtained by one of the carbon capture technologies or by a process (such as, for example, ethanol fermentation process) the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to methyl carbamate by reacting with ammonia and methanol. The methyl carbamate is further reacted with methanol for conversion to dimethyl carbonate. An integrated reactive distillation process using side reactors is used for facilitating the catalytic reaction in the subject method for producing high purity dimethyl carbonate.
The direct conversion in space of solar radiation into laser radiation for power transmission to earth, satellites, or deep space probes shows promise as a reasonably simple technology and may have cost advantage in deployment and greater reliability compared to other methods of space power generation and transmission. The main candidates for solar pumping are the gas dynamic, photochemical, and direct photoexcited lasers. Here consideration is given to the photochemical reaction of alkyliodides which predominantly excite the I(2P1/2) state which then lases at 1.315 microns. The iodine ground state is eventually lost to reconstituting the gas or in the formation of molecular iodine. The rates at which the gas is required to be recycled through the laser system are modest. The side exposure at 100-fold solar concentration of a 100-m long tube with a 1 sq m cross section is estimated to provide 20 kW of continuous laser output. Scaling laws and optimum operating conditions of this system are discussed.
This project is developing the centerpiece technology for a market-responsive, integrated biorefinery concept based on the conversion of renewable C1 intermediates (e.g., syngas, CO2, methanol) to a suite of fuels and co-products with improved carbon efficiency, reduced capital expense, and control of the product distribution to meet market demand. Advanced upgrading technologies of syngas are critically needed for the successful commercialization of fuel production at a scale relevant for biomass gasification. Research tasks within this project leverage complementary catalyst and process design for the conversion of CO2-rich syngas (15-20% CO2 in syngas) to achieve high carbon yields of gasoline and jet fuels as the major products. The conversion pathways generate high quality fuels (e.g., high octane gasoline with low aromatics, desirable jet-range hydrocarbons), and potential to achieve favorable cost targets by 2022. Research progress is compared against the Mobil Olefin to Gasoline and Distillate (MOGD) process, which also offers control over the gasoline and distillate products, as an industrial benchmark. The pathway for direct conversion of CO2-rich syngas to hydrocarbon fuels seeks to exceed the carbon efficiency of biomass-sourced MOGD (31.8%). Recent catalyst and process development achievements are highlighted by improvements in carbon-selectivity to fuels and carbon yields, along with evidence of incorporation of carbon from CO2 into the hydrocarbon products.
A critical challenge for the bioenergy research community has been producing drop-in hydrocarbon fuels and chemicals at yields sufficient to compete with their petroleum-derived counterparts. Biological production of highly reduced compounds poses fundamental challenges. Conversely, glucose, xylose, and sucrose can be fermented to ethanol at near-theoretical yields. Just as olefin crackers are often considered a gateway for petrochemical complexes that produce an array of downstream products, catalytic ethanol upgrading can potentially enable an entire biorefining complex able to produce renewable, low-carbon fuels and chemicals. By doping the Ta 2 O 5 /SiO 2 catalyst with different transition metals, we show herein that Ostromyslensky catalysts can be utilized for direct conversion of ethanol to varying ratios of 1,3-butadiene (1,3-BD), dietheylether (DEE), and ethylene. These results are integrated into the first comprehensive analysis of ethanol conversion to 1,3-BD, DEE, and ethylene that incorporates empirical data with chemical process modeling and life-cycle greenhouse gas (GHG) assessment. We find that the suite of products can replace conventional rubber, plastics, and diesel, achieving as much as a 150% reduction in GHG-intensity relative to fossil pathways (net carbon sequestration). Selecting the route with the greatest ethylene and DEE output can maximize total potential emission reductions.
The abundance of inexpensive, natural gas has transformed the energy landscape, whereby revealing new possibilities for sustainable chemical technologies or impacting those that have relied on traditional fossil fuels. The primary component, methane, is underutilized and wastefully exhausted, leading to anthropogenic global warming. Historically, the manipulation of methane remained “ clavis aurea ,” an insurmountable yet rewarding challenge and thus the focus of intense research. This is primarily due to an inability to dissociate C–H bonds in methane selectively, which requires a high energy penalty and is an essential prerequisite for the direct conversion of methane into a large set of value-added products. The discovery of such processes would promise an energy gainful use of natural gas benefiting several essential chemical processes associated with C1 chemistry. This first C–H bond dissociation step of the methane molecule appears in numerous catalytic mechanisms as the rate-determining step or most essential barrier sequence for all subsequent steps that follow in the production of C–C, C–O, or C x –H y –O z bonds found in value added products. A main goal is to catalytically reduce the energy barrier for the first C–H bond dissociation to be able to achieve the activation of methane at low or moderate temperatures. As such there is great value in understanding the fundamental nature of the active sites responsible for bond breaking or formation and thus be able to facilitate better control of this chemistry, leading to the development of new technologies for fuel production and chemical conversion. Surface science studies offer enhanced perspectives for a careful manipulation of bonds over the last layer atoms of catalyst surfaces, an essential factor for the design of atomically precise catalysts and unravelling of the reaction mechanism. With the advent of new surface imaging, spectroscopy, and in situ tools, it has been possible to decipher the surface chemistry of complex materials systems and further our understanding of atomic active sites on the surfaces of metals, oxides, and carbides or metal–oxide and metal–carbide interfaces. The once considered near impossible step of C–H bond activation is now observed at low temperatures with high propensity over a collection of oxide, metal–oxide, and metal–carbide systems in a conventional or inverse configuration (oxide or carbide on metal). The enabling of C–H activation at low temperature has opened interesting possibilities for the specific production of chemicals such as methanol directly from methane, a step toward facile synthesis of liquid fuels. We highlight the most recent of these results and present the key aspects of active site configurations engineered from surface science studies which enable such a simple reactive event through careful manipulation of the last surface layer of atoms found in the catalyst structure. New concepts which help in the activation and conversion of methane are discussed.
Natural gas (Methane) is currently the primary source of catalytic hydrogen production, accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However, the SMR process suffers with insufficient catalytic activity, low long-term stability, and excessive energy input, mostly due to the handling of large amount of CO 2 coproduced. With the demand for anticipated hydrogen production to reach 122.5 M tons in 2024, novel and upgraded catalytic processes are desired for more effective utilization of precious natural resources. In this review, we summarized the major descriptors of catalyst and reaction engineering of the SMR process and compared the SMR process with its derivative technologies, such as dry reforming with CO 2 (DRM), partial oxidation with O 2 , autothermal reforming with H 2 O and O 2 . Finally, we discussed the new progresses of methane conversion: direct decomposition to hydrogen and solid carbon and selective oxidation in mild conditions to hydrogen containing liquid organics (i.e., methanol, formic acid, and acetic acid), which serve as alternative hydrogen carriers. We hope this review will help to achieve a whole picture of catalytic hydrogen production from methane.
This article describes the recent progress GRC has made in the arena of long-life heat engines for power conversion. NASA has been interested in Stirling-cycle machines for power conversion since the 1970s. At that time, it was recognized that such a device could be designed to achieve long-life continuous operation with high reliability, by leveraging the free-piston configuration in favor of a kinematic engine. The free-piston variant eliminates the wear mechanisms associated with rolling-element bearings, piston rings, and connecting rods, typically found in kinematic Stirling engine designs. By restricting the moving components to linear motion only, there is no need to convert linear piston movement to rotating motion. With this, the moving components can be suspended within their cylinders by non-contacting bearings and seals can be effected with close clearances, also non-contacting. The use of a linear alternator attached directly to the piston enables direct conversion of heat, to mechanical, then to electrical energy, all in one hermetically sealed vessel, The electrical output only requires simple feedthroughs, and the complexity of sealed a rotating crankshaft is eliminated. In the free-piston variant, the displacer-to-piston phase is not implemented by a connection to a common rotating shaft. Instead, the pressure wave itself is used to drive the displacer. The displacer is designed to have a higher natural frequency of motion than the piston, which achieves a leading phase angle required for power production. The free-piston Stirling behaves like a spring-mass-damper system, with a forcing function created by the alternate heater and cooling of the working gas, and damping provided by the current flowing through the linear alternator. Two types of non-contacting bearings are available to designers: flexure and gas bearings. Flexure bearings consist of a spiral-cut disc of metal that has high radial stiffness but a deliberately engineering stiffness in the axial direction, to permit piston and displacer resonant motion. Gas bearings utilize a pressure source and precisely machined flow channels to provide a radial stiffness around the moving component. The pressure source can be supplied by the engine's pressure wave itself.
Materials that undergo a conversion reaction with lithium (e.g., metal fluorides MF{sub 2}: M = Fe, Cu, ...) often accommodate more than one Li atom per transition-metal cation, and are promising candidates for high-capacity cathodes for lithium ion batteries. However, little is known about the mechanisms involved in the conversion process, the origins of the large polarization during electrochemical cycling, and why some materials are reversible (e.g., FeF{sub 2}) while others are not (e.g., CuF{sub 2}). In this study, we investigated the conversion reaction of binary metal fluorides, FeF{sub 2} and CuF{sub 2}, using a series of local and bulk probes to better understand the mechanisms underlying their contrasting electrochemical behavior. X-ray pair-distribution-function and magnetization measurements were used to determine changes in short-range ordering, particle size and microstructure, while high-resolution transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) were used to measure the atomic-level structure of individual particles and map the phase distribution in the initial and fully lithiated electrodes. Both FeF{sub 2} and CuF{sub 2} react with lithium via a direct conversion process with no intercalation step, but there are differences in the conversion process and final phase distribution. During the reaction of Li{sup +} with FeF{sub 2}, small metallic iron nanoparticles (<5 nm in diameter) nucleate in close proximity to the converted LiF phase, as a result of the low diffusivity of iron. The iron nanoparticles are interconnected and form a bicontinuous network, which provides a pathway for local electron transport through the insulating LiF phase. In addition, the massive interface formed between nanoscale solid phases provides a pathway for ionic transport during the conversion process. These results offer the first experimental evidence explaining the origins of the high lithium reversibility in FeF{sub 2}. In contrast to FeF{sub 2}, no continuous Cu network was observed in the lithiated CuF{sub 2}; rather, the converted Cu segregates to large particles (5-12 nm in diameter) during the first discharge, which may be partially responsible for the lack of reversibility in the CuF{sub 2} electrode.
Low-current, high-impedance microelectronic devices can be affected by electric current shot noise more than they are affected by Nyquist noise, even at room temperature. An approach to implementing a sub-shot noise current source for powering such devices is based on direct conversion of amplitude-squeezed light to photocurrent. The phenomenon of optical squeezing allows for the optical measurements below the fundamental shot noise limit, which would be impossible in the domain of classical optics. This becomes possible by affecting the statistical properties of photons in an optical mode, which can be considered as a case of information encoding. Once encoded, the information describing the photon (or any other elementary excitations) statistics can be also transmitted. In fact, it is such information transduction from optics to an electronics circuit, via photoelectric effect, that has allowed the observation of the optical squeezing. It is very difficult, if not technically impossible, to directly measure the statistical distribution of optical photons except at extremely low light level. The photoelectric current, on the other hand, can be easily analyzed using RF spectrum analyzers. Once it was observed that the photocurrent noise generated by a tested light source in question is below the shot noise limit (e.g. produced by a coherent light beam), it was concluded that the light source in question possess the property of amplitude squeezing. The main novelty of this technology is to turn this well-known information transduction approach around. Instead of studying the statistical property of an optical mode by measuring the photoelectron statistics, an amplitude-squeezed light source and a high-efficiency linear photodiode are used to generate photocurrent with sub-Poissonian electron statistics. By powering microelectronic devices with this current source, their performance can be improved, especially their noise parameters. Therefore, a room-temperature sub-shot noise current source can be built that will be beneficial for a very broad range of low-power, low-noise electronic instruments and applications, both cryogenic and room-temperature. Taking advantage of recent demonstrations of the squeezed light sources based on optical micro-disks, this sub-shot noise current source can be made compatible with the size/power requirements specific of the electronic devices it will support.
Photoelectrochemical (PEC) conversion is a promising way to use methane (CH 4 ) as a chemical building block without harsh conditions. However, the PEC conversion of CH 4 to value-added chemicals remains challenging due to the thermodynamically favorable overoxidation of CH 4 . Here, we report WO 3 nanotube (NT) photoelectrocatalysts for PEC CH 4 conversion with high liquid product selectivity through defect engineering. By tuning the flame reduction treatment, we carefully controlled the oxygen vacancies of WO 3 NTs. The optimally reduced WO 3 NTs suppressed overoxidation of CH4 showing a high total C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol cm –2 h –1 . Scanning electrochemical microscopy revealed that oxygen vacancies can restrain the production of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates to CO 2 . Additionally, band diagram analysis and computational studies elucidated that oxygen vacancies thermodynamically suppress overoxidation. In conclusion, this work introduces a strategy for understanding and controlling the selectivity of photoelectrocatalysts for direct conversion of CH 4 to liquids.
The University of North Dakota (UND) Energy & Environmental Research Center (EERC), in collaboration with the UND Center for Process Engineering Research (CPER), conducted a project to validate two technologies capable of converting North Dakota lignite and lignite coal waste to high-quality graphite for fast-charging lithium-ion battery (LIB) anode. The project was conducted over about 3 years from April 7, 2022, to July 6, 2025. The two technological paths pursued in this project include path A – direct conversion of coal or coal waste to graphite by the upgraded carbon ores to products (UCOP) process being developed at the EERC and path B – lignite-derived coal tar pitch (CTP) conversion to graphite (CTP2G) process being developed at CPER. The results from this project validate the two technological approaches and are expected to be an integral part of a portfolio of emerging technologies for making high-quality graphite not only from North Dakota lignite, but from all ranks of U.S. domestic coal and coal waste resources. The quality of the graphite produced by these technologies is high enough for various applications, including batteries for the fast-growing electric vehicle industry, energy storage applications, electric arc furnace electrodes for steel production, and graphene production, among others. Although the two technologies can produce high-quality graphite, they are fundamentally different in that the UCOP technology provides a direct path to transform coal to graphite, while the CTP2G technology needs to go through a CTP intermediate and a coking process for the intermediate, which requires a special facility to accomplish. For application in the industry, the UCOP process is designed to be more flexible, with feedstock to include potentially any carbonaceous material such as all coal ranks and biochar, while the CTP2G process is designed to utilize CTP as the starting precursor. The key project accomplishments include the following: • Successful preparation of high-quality synthetic graphite from North Dakota lignite coal/coal wastes and lignite-derived CTP. • Patent application has been filed for the UCOP process and an internal invention disclosure has been filed for the CTP2G process. • The produced graphite performs better than a commercial battery-grade sample in LIB coin cells, especially fast-charging capability, stability, and long-duration cycling. • Coin-type Li-ion half-cells with CTP2G graphite showed excellent performance, with >370 mAh/g capacity, >90% initial coulombic efficiency, and 93%/67% retention at 1C/2C rate, which outperforms commercial graphite in charging speed, stability, and cycling. • Results of fabricated 18650 cells were consistent with the observations in coin cells. • Preliminary techno-economic analysis (TEA) estimates for the UCOP technology indicate a manufacturing cost of about $\$$39/kg based on 50-metric ton/year capacity. • Preliminary TEA estimates for the CTP2G technology indicate a market price of about $\$$7107/ton ($\$$7/kg) based on 22,000-ton/year production capacity.
Abstract not provided
The Characterization and Valorization of Aqueous Phases Derived from Liquefaction and Upgrading of Bio-Oils project developed processes to extract value from the organics within aqueous streams derived from biomass direct liquefaction processes. The focus of the project was twofold. First, we characterized a diverse set of aqueous streams from numerous processes and feedstocks. The characterization effort served to inform this project toward development around the most prevalent compounds to maximize versatility and impact. We analyzed diverse streams from hydrothermal liquefaction of lignocellulosic, algal, and waste feedstocks; catalytic fast-pyrolysis aqueous phases; fast-pyrolysis aqueous phases; and aqueous phases produced by hydroprocessing of fast-pyrolysis bio-oil. Second, thermochemical catalytic processes were developed to convert aqueous-phase organics into useful products. These processes focused mostly on organic acids and specifically acetic acid, which was found to be ubiquitous from the characterization effort. A La x Zr y O z catalyst was discovered and developed for the ketonization of acids to ketones in the condensed aqueous phase. A dual-bed steam reforming process was developed to convert acids and other organics to hydrogen for bio-oil hydroprocessing. The dual-bed reforming process consisted of a ketonization step followed by a steam reforming step with Co as the active metal. The dual-bed process significantly reduced the rate of coke deposition versus direct steam reforming of the organic acids and beneficially produced CH 4 below the equilibrium value. Finally, we demonstrated direct conversion of aqueous-phase organics to olefins over a Zn x Zr y O z catalyst. Each thermochemical catalytic process was demonstrated with process-derived aqueous mixtures. Model compounds were used to benchmark performance and optimize conditions, but emphasis was placed on utilizing “real” aqueous streams whenever possible. A liquid-liquid extraction process using methyl tert-butyl ether as the solvent was developed to segregate dissolved inorganic species and sugars from desirable light oxygenates such as acids and alcohols. Furthermore, a carbon treatment to remove color bodies was employed after it was found the presumably heavy organic chromophore species deactivated catalysts. These economic separation processes allowed for the successful demonstration of stable catalytic processing in the condensed-phase ketonization, dual-bed reforming, and direct olefin production processes for tens to hundreds of hours, which were limited only by the quantity of feed available. Techno-economic analysis of these processes demonstrated the impact possible when capturing “waste” organics as valuable products. The condensed-phase ketonization process for converting aqueous stream acids to ketones followed by reduction and dehydration to olefins sold as a co-product resulted in the reduction of the minimum fuel selling price by about 13% compared to the anaerobic-digestion, aqueous-phase treatment base case (3.74 to 4.29/GGE). The dual-bed reforming process was commensurate in price to the anaerobic digestion base case (4.24 versus 4.29/GGE). However, the need for external natural gas to produce hydrogen for bio-oil hydroprocessing was eliminated, thereby lowering the carbon impact of the process.
Direct conversion of preprocessed binary semiconductor NCs as template holds the key toward the shape control of hybrid perovskites. Here we report on an innovative route for realizing shape-controlled hybrid organohalide perovskite NCs from two-dimensional PbS NCs on solid substrates. Rectangular PbI 2 NCs are first synthesized by iodination of PbS NCs. Resultant PbI 2 NCs are subsequently transformed into the well-defined rectangular hybrid perovskite NCs upon controlled CH 3 NH 3 Br exposure. Structural analyses using X-ray absorption fine structure reveal transition of cubic lattice of PbS to hybrid perovskites with a mixture of cubic and tetragonal phases exhibiting a bimodal distribution of shorter Pb–Br and longer Pb–I bonds around an immediate neighboring lead absorber within the first coordination shell. Furthermore, this direct all anion exchange reaction route opens up new strategies for the fabrication of shape-controlled perovskite NCs on flexible substrates from suitable existing binary NCs as template for optoelectronic applications.