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At least 397 records · Page 22

Materials Data on CoH18C6SO10 by Materials Project

(CoC5H13SO9)2(CH2)2H2(H2O)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four hydrogen molecules, four methane molecules, four water molecules, and four CoC5H13SO9 clusters. In each CoC5H13SO9 cluster, Co2+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Co–O bond distances ranging from 1.81–2.35 Å. There are five inequivalent C+0.33+ sites. In the first C+0.33+ site, C+0.33+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.09 Å. The C–O bond length is 1.46 Å. In the second C+0.33+ site, C+0.33+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.09 Å. The C–O bond length is 1.47 Å. In the third C+0.33+ site, C+0.33+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.10 Å. The C–O bond length is 1.44 Å. In the fourth C+0.33+ site, C+0.33+ is bonded in a trigonal non-coplanar geometry to one H1+ and two O2- atoms. The C–H bond length is 1.10 Å. There is one shorter (1.42 Å) and one longer (1.43 Å) C–O bond length. In the fifth C+0.33+ site, C+0.33+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. There is one shorter (1.10 Å) and one longer (1.11 Å) C–H bond length. The C–O bond length is 1.43 Å. There are thirteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.44 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one C+0.33+ atom. S2- is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.49–1.70 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one S2- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one H1+ and one S2- atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Co2+ and two C+0.33+ atoms. In the fifth O2- site, O2- is bonded in a single-bond geometry to one H1+ and one O2- atom. The O–O bond length is 1.45 Å. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Co2+, one C+0.33+, and one O2- atom. In the seventh O2- site, O2- is bonded in a water-like geometry to one C+0.33+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Co2+, one C+0.33+, and one H1+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to one Co2+ and one C+0.33+ atom.

36 MATERIALS SCIENCE↗

Energy yields for hydrogen cyanide and formaldehyde syntheses - The HCN and amino acid concentrations in the primitive ocean

Simulated prebiotic atmospheres containing either CH4, CO, or CO2, in addition to N2, H2O, and variable amounts of H2, were subjected to the spark from a high-frequency Tesla coil, and the energy yields for the syntheses of HCN and H2CO were estimated from periodic (every two days) measurements of the compound concentrations. The mixtures with CH4 were found to yield the highest amounts of HCN, whereas the CO mixtures produced the highest yields of H2CO. These results model atmospheric corona discharges. From the yearly energy yields calculated and the corona discharge available on the earth, the yearly production rate of HCN was estimated; using data on the HCN production rates and the experimental rates of decomposition of amino acids through the submarine vents, the steady state amino acid production rate in the primitive ocean was calculated to be about 10 nmoles/sq cm per year.

Stribling, Roscoe↗

Magnesium and Carbon Dioxide - A Rocket Propellant for Mars Missions

A rocket engine for Mars missions is proposed that could utilize CO2 accumulated from the Martian atmosphere as an oxidizer. For use as possible fuel, various metals, their hydrides, and mixtures with hydrogen compounds are considered. Thermodynamic calculations show that beryllium fuels ensure the most impulse but poor inflammability of Be and high toxicity of its compounds put obstacles to their applications. Analysis of the engine performance for other metals together with the parameters of ignition and combustion show that magnesium seems to be the most promising fuel. Ballistic estimates imply that a hopper with the chemical rocket engine on Mg + CO2 propellant could be readily developed. This vehicle would be able to carry out 2-3 ballistic flights on Mars before the final ascent to orbit.

Shafirovich, E. IA.↗

Numerical Study of Contaminant Effects on Combustion of Hydrogen, Ethane, and Methane in Air

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NP, H2O, and a combustion of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamic effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

Lai, H. T.↗

Numerical study of contaminant effects on combustion of hydrogen, ethane, and methane in air

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NO, H2O, and a combination of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamically effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

Lai, H. T.↗

Prospects of hydrogen cogeneration and carbon dioxide utilization in electrochemical refineries for ethylene production via oxidative coupling of methane: A techno-economic assessment

Ethylene is recognized as one of the most significant chemicals globally. The projected ethylene production for 2023 stands at 227.6 million tonnes, with expectations of continued demand growth. The primary use of ethylene, accounting for over 76%, lies in the production of plastics such as polyethylene, polyvinyl chloride, and polystyrene. Despite the enduring carbon retention potential of plastics themselves, traditional ethylene feedstock production from fossil resources contributes substantially to greenhouse gas emissions, ranging from 0.29 to 2.29 kg CO2 /kg Ethylene depending on various factors like feedstock and process design. Various decarbonization strategies, including the utilization of hydrogen as a primary heat source, have been proposed to reduce the carbon footprint of ethylene production, but their efficacy remains limited, offering at best a 0–30% reduction in on-site CO 2 emissions.

09 BIOMASS FUELS↗

Photo-Reactive Amine-Based Direct Air Capture and Conversion of CO2

This study presents a novel photochemical approach to direct air capture (DAC) and CO2 conversion, utilizing a ruthenium-modified mesoporous TiO2 composite infused with linear polyethyleneimine (L-PEI) and enhanced by light absorbing and earth abundant titanium nitride (TiN). This light-activated system operates at ambient pressure and addresses long-standing challenges in conventional amine-based thermal reactive carbon capture (RCC), including amine degradation and CO2 slip. Our findings demonstrate that L-PEI effectively stabilizes CO2 adsorption and facilitates high-yield methanation over 50 cycles with a non-flammable forming gas mixture (approximately 5% H2). Comparatively, composites incorporating small-molecule amines exhibited poor stability under illumination, while highly mobilie branched PEI (B-PEI) formulations suffered from significant catalyst deactivation. A technoeconomic analysis suggests that methane synthesis via this platform could be achieved at costs below $5/kg under current electrocatalytic hydrogen pricing. These findings highlight the potential of this approach to enhance energy security by enabling decentralized, scalable fuel production from atmospheric CO2.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed.

Schryer, David R.↗

Spacecraft oxygen recovery system

A system which uses an electrochemical carbon dioxide concentrator to remove carbon dioxide from the cabin atmosphere and a Sabatier reactor to reduce carbon dioxide with hydrogen to form methane and water is described. Oxygen is recovered from water by means of a static-feed water electrolysis system. The hydrogen thus generated is reused in the carbon dioxide concentrator. The methane is a system byproduct. The CO2 removal reactions and the implementation of the CO2 concentration concept are discussed, and test results are examined.

Quattrone, P. D.↗

Venus - Lessons for earth

The old idea that Venus might possess surface conditions to those of an overcast earth has been thoroughly refuted by space-age measurements. Instead, the two planets may have started out similar, but diverged because of the greater solar flux at Venus. This cannot be proved, but is consistent with everything known. A runaway greenhouse effect could have evaporated an 'ocean'. The hydrogen would escape, and most of the oxygen would be incorporated into the crust. Without liquid water, CO2 would remain in the atmosphere. Chlorine atoms would catalyze the recombination of any free oxygen back to CO2. The same theories apply to the future of the earth, and to the explanation of the polar ozone holes; the analogies are striking. There is no likelihood that the earth will actually come to resemble Venus, but Venus serves both as a warning that major environmental effects can flow from seemingly small causes, and as a testbed for the predictive models of the earth.

Hunten, D. M.↗

Transport Cost for Carbon Removal Projects With Biomass and CO2 Storage

Strategies to remove carbon from the atmosphere are needed to meet global climate goals. Promising strategies include the conversion of waste biomass to hydrogen, methane, liquid fuels, or electricity coupled with CO 2 capture and storage (CCS). A key challenge for these projects is the need to connect geographically dispersed biomass supplies with geologic storage sites by either transporting biomass or CO 2 . We assess the cost of transport for biomass conversion projects with CCS using publicly available cost data for trucking, rail, and CO 2 pipelines in the United States. We find that for large projects (order of 1 Mt/yr CO 2 or greater), CO 2 by pipeline is the lowest cost option. However, for projects that send most of the biomass carbon to storage, such as gasification to hydrogen or electricity production, biomass by rail is a competitive option. For smaller projects and lower fractions of carbon sent to storage, such as for pyrolysis to liquid fuels, CO 2 by rail is the lowest cost option. Assessing three plausible example projects in the United States, we estimate that total transport costs range from $24/t-CO 2 stored for a gasification to hydrogen project traversing 670 km to $\$ 36$/t for a gasification to renewable natural gas project traversing 530 km. In general, if developers have flexibility in choosing transport mode and project type, biomass sources and storage sites can be connected across hundreds of kilometers for transport costs in the range of $20-40/t-CO 2 stored. Truck and rail are often viable modes when pipelines cannot be constructed. Distances of 1,000 km or more can be connected in the same cost range when shared CO 2 pipelines are employed.

09 BIOMASS FUELS↗

Materials Data on KP4(CO2)4 by Materials Project

KP4(CO)4(O2)2 crystallizes in the tetragonal I4_1/amd space group. The structure is two-dimensional and consists of eight hydrogen peroxide molecules and four KP4(CO)4 sheets oriented in the (0, 0, 1) direction. In each KP4(CO)4 sheet, K1+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All K–O bond lengths are 2.61 Å. C+1.25- is bonded in a 4-coordinate geometry to one C+1.25- and two equivalent P5+ atoms. The C–C bond length is 1.60 Å. Both C–P bond lengths are 1.75 Å. P5+ is bonded in a 1-coordinate geometry to two equivalent C+1.25- and one O2- atom. The P–O bond length is 1.49 Å. O2- is bonded in a distorted bent 120 degrees geometry to one K1+ and one P5+ atom.

36 MATERIALS SCIENCE↗

Cooperative Effects Associated with High Electrolyte Concentrations in Driving the Conversion of CO2 to C2H4 on Copper

Compared to a conventional electrolyte concentration of 1 M HCOOK, the use of a highly concentrated 7.1 M HCOOK electrolyte increases the Faradaic efficiency (FE) ratio of C2H4/CO from 2.2 +- 0.3 to 18.3 +- 4.8 at -1.08 V vs. reversible hydrogen electrode (RHE) on a Cu gas-diffusion electrode. Based on electrochemical analysis and ab initio molecular dynamics (AIMD) simulation, the identity and concentration of the cation and anion play more important roles in controlling the CO2R reaction pathway than the bulk CO2 solubility and the bulk pH of electrolytes. In situ attenuated reflectance surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) suggests that, unlike 1 M HCOOK, the *CO-bridge-binding mode on Cu is dominant in 7.1 M HCOOK electrolyte, which potentially results in less CO release and higher yield of C2H4. This study demonstrates that although we can tailor the electrolyte composition to shift product selectivity, the factors that control the product selectivity are numerous and cannot be distilled down into one correlated property-reactivity relationship.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Iron corrosion in the “inert” supercritical CO 2 , ab initio dynamics insights: How impurities matter

Metal corrosion from exposure to supercritical fluids is a long-standing challenge lacking atomistic understanding for effective corrosion prevention in diverse important applications. Here, in this work, reactions relevant to corrosion in supercritical CO 2 (sCO 2 ), with H 2 O and NO 2 as impurities, are revealed using ab initio molecular dynamics and enhanced sampling methods. While little reactivity is observed in bulk sCO 2 , the iron surface is found to play a crucial almost-catalytic role in its own corrosion, activating the inert CO2 and hence facilitating $\ast$HCO 3 – and $\ast$CO 3 2– formation at the interface. Moreover, the hydrogen bond network of $\ast$H 2 O assists the H shuttling to the activated CO 2 and impurities, forming reactive species observed in experiments. Such atomistic insight elucidates the reaction mechanisms of metal corrosion in aqueous and supercritical fluids and can point to possible remedies.

36 MATERIALS SCIENCE↗

Reaction Pathways over ZnZrO 2 -Based Catalysts and Catalytic Sorbents

Reactive capture and conversion (RCC) is a process intensification approach that integrates CO 2 capture and hydrogenation within a single unit, removing the CO 2 purification and storage steps of traditional process flow schemes. This alters the catalytic step from a traditional steady-state (SS) flow process to a transient capture and conversion cycle, which could lead to product distributions distinct from those observed in conventional SS experiments. Such differences are investigated in the combined capture and hydrogenation of carbon dioxide to methanol over a ZnZrO 2 catalyst and a ZnZrO 2 + NaNO 3 /Mg 3 AlO x catalytic sorbent (CS) using fixed-bed kinetic measurements, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and steady-state isotopic transient kinetic analysis-DRIFTS (SSITKA-DRIFTS). Under SS conditions, ZnZrO 2 produced methanol through sequential hydrogenation of HCOO* and CH 3 O* intermediates. On the contrary, CO was attributed primarily to CO 2 dissociation at oxygen vacancies, as supported by isotopic shifts and measured reaction orders. For the CS, isotopic switching experiments suggested that monodentate carbonate species (CO 3 2− , abbreviated as m-CO 3 2− ) act as active intermediates that can be hydrogenated to HCOO* and subsequently to CH 3 O. Under RCC conditions, in situ DRIFTS and isotopic experiments reveal that m-CO 3 2− species formed during the CO 2 capture step follow two competing routes upon H 2 exposure: (i) direct hydrogenation to methane on the sorbent domain or (ii) migration of m-CO 3 2− to the ZnZrO 2 domain, where they are hydrogenated to methanol through the HCOO pathway. Overall, RCC enables carbonate hydrogenation routes not observed under SS cofeed conditions. Thus, the reaction pathways and rates during RCC can be different from operation under conventional SS conditions, and the product distribution is determined here by competition between carbonate hydrogenation on sorbent sites and migration to ZnZrO 2 for methanol synthesis.

CCUS↗

Materials Data on Co(BrO3)2 by Materials Project

CoO4BrO2Br crystallizes in the monoclinic P2_1/m space group. The structure is one-dimensional and consists of two hydrobromic acid molecules; two hydrogen peroxide molecules; and one CoO4Br ribbon oriented in the (0, 1, 0) direction. In the CoO4Br ribbon, Co2+ is bonded in a linear geometry to four O2- atoms. There are two shorter (1.76 Å) and two longer (2.85 Å) Co–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Co2+ and two O2- atoms. There are one shorter (1.24 Å) and one longer (2.96 Å) O–O bond lengths. In the second O2- site, O2- is bonded in a water-like geometry to two equivalent Co2+ atoms. In the third O2- site, O2- is bonded in a single-bond geometry to one O2- atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to one O2- and one Br5+ atom. The O–Br bond length is 1.73 Å. Br5+ is bonded in a single-bond geometry to one O2- atom.

36 MATERIALS SCIENCE↗

Implementing Large-Scale CCS in Complex Geologic Reservoirs: Insights from Three Appalachian Basin Case Studies

This paper presents three design case studies for implementing large-scale geologic carbon storage in the Appalachian Basin region of the midwestern United States. While the Appalachian Basin has a challenging setting for carbon storage, the three case studies detailed in this article demonstrate that there are realistic options for implementing carbon storage in the basin. Carbonate rock formations, depleted hydrocarbon reservoirs, and moderate-porosity sandstones can be utilized as carbon-storage reservoirs in the Appalachian Basin. While these are not typical concepts for CO2 storage, the storage zones have advantages such as defined trapping mechanisms, multiple caprocks, and defined boundaries that are not always present in thick, permeable sandstones being targeted for many carbon-storage projects. The geologic setting, geotechnical parameters, and hydrologic setting for the three case studies are provided, along with the results of reservoir simulations of the CO2 injection-deployment strategies. The geological rock formations available for CO2 storage in the Appalachian Basin are more localized reservoirs with defined boundaries and finite storage capacities. Simulation results showed that accessing carbon-storage resources in these fields may require wellfields with 2–10 injection wells. However, these fields would have the capacity to inject 1–3 million metric tons of CO2 per year and up to 90 million metric tons of CO2 in total. The CO2 storage resources would fulfill decarbonization goals for many of the natural-gas power plants, cement plants, hydrogen plants, and refineries in the Appalachian Basin region.

Sminchak, Joel↗

Global Energy Policy to Achieve the United States’ Nationally Determined Contributions: Potential Pathway

In 2021, the United States declared its Nationally Determined Contribution (NDC) in preparation for the COP26 climate summit, setting goals to achieve zero emission electricity by 2035, and reducing net emissions by 50–52% compared to 2005 levels. The current U.S. energy policies were found to not be adequate to meet these goals, thus it is necessary to draft a pathway to achieving these goals through policy changes. This study focused on foreign energy policies to analyze the most effective policies in a host of sectors. By identifying the most ambitious and effective policies from around the world in each sector, this study was able to suggest a policy pathway that can potentially achieve both of goals set in the NDC. In guiding the development of the proposed policy pathway, this study analyzed policies from Australia, Canada, California, China, Denmark, France, Germany, Japan, Russia, South Korea, Sweden, the United Kingdom, and the United States. This study found that the most drastic CO2 reductions came from low-carbon electricity policy, but contributions were also made from carbon capture, reforestation, hydrogen, energy efficiency, and climate smart agriculture.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗