Conversion of Methane to Graphite-Like Carbon Nanoparticles Using a Low-Temperature Dusty Plasma
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Results for “Conversion”
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Stacking Independence and Resonant Interlayer Excitation of Monolayer WSe 2 /MoSe 2 Heterostructures for Photocatalytic Energy Conversion
Here, we report a comparison of the photocatalytic performance of WSe 2 -on-MoSe 2 and MoSe 2 -on-WSe 2 heterostructures. While built-in electric fields exist in these heterostructures on the order of 100 kV/cm due to band offsets between these two materials, the photocatalytic performance (i.e., photocurrent) is independent of the stacking order of the two materials. Solving Poisson’s equation under these conditions, we find that the built-in electric field produced in the heterostructure is at least 1 order of magnitude smaller than that produced in the electrochemical double layer (i.e., Helmholtz layer). Mott–Schottky measurements indicate that transition metal dichalcogenides (TMDCs) on ITO electrodes have similar capacitance to that of bare ITO, providing further evidence that the interfacial electric fields produced in the solid state heterostructure are negligible compared to the fields generated by the ions in solution. The photocatalytic performance of these heterostructures provided the largest relative enhancement in the heterojunction region under 920 and 785 nm irradiation compared with 532 and 633 nm wavelength excitation. Here, the 920 nm (1.35 eV) photons lie below the band gaps and produce very little photocurrent in the constituent monolayer materials but resonantly excite the interlayer optical transition in the heterostructure, producing a 5-fold enhancement in the measured photocurrent.
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Understanding Limitations in Electrochemical Conversion to CO at Low CO 2 Concentrations
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32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Highly Efficient Anisotropic Chiral Plasmonic Metamaterials for Polarization Conversion and Detection
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New Strategies for Direct Methane-to-Methanol Conversion from Active Learning Exploration of 16 Million Catalysts
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New up-conversion luminescence in molecular cyano-substituted naphthylsalophen lanthanide(iii) complexes
A new naphthylsalophen and its 3:2 ligand-to-lanthanide sandwich-type complexes were isolated. Here, when excited at 380 nm, the complexes display the characteristic metal-centred emission for Nd III , Er III and Yb III . Upon 980 nm excitation, in mixed lanthanide and the Er complexes, Er-centred upconversion emission at 543 and 656 nm is observed, with power densities as low as 2.18 W cm –2 .
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Fast microflow kinetics and acid catalyst deactivation in glucose conversion to 5-hydroxymethylfurfural
5-Hydroxymethyl furfural (HMF) is an important platform chemical because it can be upgraded to various drop-in and performance-advantaged products. The cascade reaction of HMF production from glucose over a Lewis acid (CrCl 3 ) and a Brønsted acid (HCl) catalyst in aqueous media is investigated in a microreactor at short residence times and high temperatures. We study the formation of various chromium species using UV-visible spectrophotometry and elucidate the Cr(III) speciation. The catalyst reactivity increases sharply at short residence times, and then drops at long times. This indicates that the catalyst treatment plays a vital role in getting optimal reactivity, and recording the catalyst history is necessary. We develop a kinetic model to describe the catalyst speciation as well as the Lewis and Brønsted acid-catalyzed reaction kinetics using a hierarchical approach. Here, the model is in good agreement with experiments. We demonstrate the benefits of tandem Lewis-external added Brønsted acid catalysis in processing time, productivity, and catalyst stability. We apply this model to optimize the HMF yield and obtain ~36% yield at 200 °C in 7 min and report the highest productivity of ~15% yield per min, demonstrating the opportunity of reaching high productivity at short residence times.
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Integrated low carbon H 2 conversion with in situ carbon mineralization from aqueous biomass oxygenate precursors by tuning reactive multiphase chemical interactions
Meeting our rising demand for clean energy carriers such as H 2 from renewable biomass resources is challenged by the co-emission of CO 2 and CH 4 . To address this challenge, we design novel reactive separation pathways that integrate multiphase chemical reactions by harnessing Ca and Mg bearing minerals as a sorbent to capture CO 2 released during the hydrothermal deconstruction of aqueous biomass oxygenates to produce H 2 and solid carbonates via low temperature aqueous phase reforming and thermodynamically downhill carbon mineralization. Earth abundant catalysts such as Ni/Al 2 O 3 are effective in producing H 2 yields as high as 79% and 74% using ethylene glycol and methanol in the presence of Ca(OH) 2 as an alkaline sorbent, without contaminating or deactivating the catalyst. H 2 yields with in situ carbon mineralization using a Ni or Pt/Al 2 O 3 catalyst are enhanced based on the following order of reactivity: acetate < glycerol < methanol < formate < ethylene glycol. These studies demonstrate that the multiphase chemical interactions can be successfully tuned to enhance H 2 yields through the selective cleavage of C–C bonds using Ni/Al 2 O 3 catalysts to deconstruct biomass oxygenates for producing H 2 and CO 2 , and in situ carbon mineralization by harnessing abundant alkaline materials, as demonstrated using ladle slag. This approach unlocks new scientific possibilities for harnessing multiple emissions including abundant organic-rich wastewater streams and alkaline industrial residues to co-produce low carbon H 2 and carbonate-bearing materials for use in construction by using renewable solar thermal energy resources.
09 BIOMASS FUELS↗
Heat Transport and Power Conversion of the Kilopower Reactor Test
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21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Metamorphic Epitaxy Solutions for Thermophotovoltaic and Laser Power Conversion Applications
Metamorphic GaInAs enables photovoltaic devices optimized for a wide range of bandgaps between 0.35 and 1.41 eV. We have developed compositionally graded buffers made of GaInP and AlGaInAs to enable growth of these devices on GaAs substrates with low dislocation densities and high performance. We present results for devices grown on both graded buffer materials with device bandgaps in the range 0.58-1.41 eV and compare the benefits and drawbacks of each material system. These results enable high performance for applications such as thermophotovoltaics and optical power transmission using high power lasers.
III-V↗
Data for Catalytic Strategy for Conversion of Triacetic Acid Lactone to Potassium Sorbate
This study shows a new route to produce potassium sorbate (KS) from triacetic acid lactone (TAL), which is a chemical platform that can be biologically synthesized from natural sources. Sorbic acid and its potassium salt (KS) are widely used as preservatives in foods and pharmaceuticals. Three steps are used to produce KS from TAL: 1) hydrogenation of TAL into 4-hydroxy-6-methyltetrahydro-2-pyrone (HMP), 2) dehydration of HMP to parasorbic acid (PSA), and 3) ring-opening and hydrolysis of PSA to KS. TAL can be fully hydrogenated over Ni/SiO2 to give near quantitative yields of HMP. A three-step reaction kinetics model was developed for dehydration of HMP into PSA. This model was used to show that the highest PSA yield occurs at low temperatures. An experimental PSA yield of 84.2% with respect to TAL was obtained which agreed with the prediction of the reaction kinetics model. KOH was used as a coreactant for the ring-opening hydrolysis of PSA to produce >99.9% yield of KS from PSA. Tetrahydrofuran (THF) was used to purify the TAL derived-KS (TAL-KS). The TAL-KS had a KS purity of 95.5%. The overall yield of TAL-KS with respect to TAL was calculated to be 77.3%. TAL-KS produced in this study had similar antimicrobial activities as commercial KS.
Catalysis↗
Data for Complete and Efficient Conversion of Plant Cell Wall Hemicellulose into High-Value Bioproducts by Engineered Yeast
Plant cell wall hydrolysates contain not only sugars but also substantial amounts of acetate, a fermentation inhibitor that hinders bioconversion of lignocellulose. Despite the toxic and non-consumable nature of acetate during glucose metabolism, we demonstrate that acetate can be rapidly co-consumed with xylose by engineered Saccharomyces cerevisiae . The co-consumption leads to a metabolic re-configuration that boosts the synthesis of acetyl-CoA derived bioproducts, including triacetic acid lactone (TAL) and vitamin A, in engineered strains. Notably, by co-feeding xylose and acetate, an engineered strain produces 23.91 g/L TAL with a productivity of 0.29 g/L/h in bioreactor fermentation. This strain also completely converts a hemicellulose hydrolysate of switchgrass into 3.55 g/L TAL. These findings establish a versatile strategy that not only transforms an inhibitor into a valuable substrate but also expands the capacity of acetyl-CoA supply in S. cerevisiae for efficient bioconversion of cellulosic biomass.
Conversion↗
Data for Conversion of High-Solids Hydrothermally Pretreated Bioenergy Sorghum to Lipids and Ethanol Using Yeast Cultures
Glucose and xylose are the major sugars present in cellulosic hydrolysates. The cellulosic sugars can be used for the production of platform chemicals. In this study, productions of lipid and ethanol by yeasts were compared for concentrated bioenergy sorghum syrup. Bioenergy sorghum was hydrothermally pretreated at 50% w/w solids in a continuous industrial reactor and sequentially mechanically refined using a burr mill to improve biomass accessibility for hydrolysis. Fed-batch enzymatic hydrolysis was conducted with 50% w/v solids loading and cellulase cocktail (50 FPU/g biomass) to achieve 230 g/L sugar concentration. Various strains of Rhodosporidium toruloides were evaluated for converting sugars into lipids, and strain Y-6987 had the highest lipid titer (9.2 g/L). The lipid titer was improved to 19.0 g/L by implementing a two-stage culture scheme, where the first stage was optimized for yeast growth and the second for lipid production. For ethanol production, the engineered Saccharomyces cerevisiae SR8ΔADH6 was used to coferment glucose and xylose. Ethanol fermentation was optimized for media nutrients (YP, YNB/urea, and urea), cellulosic sugar concentration, and sulfite conditioning to maximize the ethanol concentration from sorghum syrups. Fermentation of 70% v/v concentrated hydrolysate conditioned with sulfite produces 50.1 g/L ethanol from 141 g/L of sugars.
Conversion↗
A Modular Heat Engine for the Direct Conversion of Natural Gas to Hydrogen and Power using Hydrogen Turbines (Phase I Final Report)
This report describes a novel, modular heat engine comprising of a one-step hydrogen production from natural gas with in-situ CO 2 separation which is amenable for re-use or sequestration. Combining with a hydrogen turbine subsystem, a distributed or central power generation system is conceived. An added hydrogen storage subsystem enables load-following capability. The techno-economics of the overall system compared favorably against current state-of-the-art natural gas combined cycle plants with post-combustion CO 2 capture.
01 COAL, LIGNITE, AND PEAT↗
Design and Optimization of Structured Multi-Functional Trapping Catalysts for Conversion of Hydrocarbons and NOx from Diesel and Advanced Combustion Engines
Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO 2 ) commonly referred to as NOx, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NOx is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NOx in the presence of excess O 2 . Vehicular emission control catalysts are ineffective in eliminating CO, hydrocarbons, and NOx during engine cold-start when exhaust temperatures are below 200°C. The objective of the project was to develop and demonstrate a multi-functional, catalyzed trap that enables vehicles with advanced combustion strategies to meet Tier 3 emissions standards while achieving the 150 °C challenge for sustained co-oxidation of HCs and CO and ≥90% NO trapping and release during warmup. Specifically, the multi-functional Lean HC+NOx (LHCNT) was developed for application in the exhaust aftertreatment of conventional diesel engines and engines having low temperature combustion (LTC) regimes. Activities included the design and synthesis of adsorbents and catalysts, screening and evaluation. Passive NOx absorbers (PNA), hydrocarbon (HC) traps, and oxidation catalysts (OC) were evaluated for use in series or as integrated devices. Predictive tools were developed utilizing the characterization and analysis of these materials, and an emission system was designed and optimized utilizing the catalyst systems. Microkinetic models were developed for the PNA for the simple NO-only feed and complex feed containing CO, H 2 , and model hydrocarbons (ethylene and dodecane). A first-principles, mechanistic-based model of the PNA was developed which utilized molecular-scale estimates (density functional theory) of energy barriers, mechanistic-based kinetics and realistic treatments of the flow and transport processes. Two new oxidation catalysts were developed (PdCu alloy, mixed copper-ceria-cobalt oxide), both of which significantly lessened the detrimental inhibition by CO on hydrocarbon and NO oxidation. A method for lessening the detrimental impact of CO on PNA activity was developed that involves use of an oxidation catalyst upstream of the PNA. The SwRI Ectolab TM burner system was applied to evaluate the baseline PNA material and confirmed performance comparable to the benchflow PNA studies using simulated exhaust. Spatially-resolved mass spectrometry (SpaciMS) was used to measure the transient spatial profiles of reacting species spanning the length of a three-function LHCNT containing PNA, HCT, and OC. The findings from this study provide diesel vehicle and catalyst companies valuable information to develop more cost effective emission control catalysts which helps to expand the use of more fuel efficient diesel power. The fundamental modeling and experimental tools and findings from this project can be applied to catalyst technologies used in the energy and chemical industries. The project led to 14 publications in the peer-reviewed literature with 2 additional currently under review. Finally, the project also led to training of several doctoral students who were placed in research jobs in industry and academia. Specifically, Mugdha Ambast (UH) has joined Cummins, Kevin Gu (UVa) has joined GM, and Abhay Gupta (UH) is to join Caterpillar.
02 PETROLEUM↗
Life-cycle Analysis of Conversion of Post-Use Plastic via Pyrolysis with the GREET Model
In this report, we present an updated LCA of the PTF pathway developed at Argonne. Benavides et al. (2017) analyzed the environmental impact of producing ultra-low sulfur (ULS) diesel fuel from PUP via pyrolysis (the most common PTF technology). We used the Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET®) model and collected data from eight PTF companies to assess the potential energy and environmental benefits associated with this technology (Argonne, 2020). We conducted a survey and aggregated the dataset based on the different responses, which included plant capacity, process yields, feedstock composition, material and energy inputs, and outputs, and other parameters. We calculated the energy, greenhouse gas (GHG) emissions, and water consumption of its intermediate product pyrolysis oil and final product PUP-derived ULS diesel and compared the results to those metrics for their conventional counterparts (crude naphtha and petroleum ULS diesel fuel).
10 SYNTHETIC FUELS↗
Manufacturing Supply Chain Development for Modular Solar-Thermochemical Conversion Platform - CRADA 387 (Final Report)
Modular chemical process intensification (MCPI) is an emerging field where chemical processing is performed using small-scale modular equipment instead of conventional large centralized chemical plants. Conventional chemical plants benefit from economies of scale that encourage scale-up to ever larger plants. A goal of MCPI is to develop technology that intensifies processing so that equipment can be dramatically smaller and integrated into modular systems. Scale-up occurs by adding more modules in parallel rather than making the equipment larger. A key concept is that equipment and modules can ultimately be cheaper by leveraging economies of mass production, analogous to the automotive industry, in manufacturing the equipment. This project made significant progress toward this outcome by meeting the RAPID institute metric to reduce equipment cost by 20% for each doubling in manufacturing volume. The MCPI application was thermochemical technology that is being commercialized by STARS Technology Corporation, one of the CRADA partners. The technology converts solar and renewable power to chemical energy to produce renewable hydrogen, fuels, and chemicals. The benefit to the public is reduction in greenhouse gases that are contributing to climate change. The project transitioned the steam methane reforming (SMR) reactor from conventional fabrication methods to additive manufacturing (AM) direct metal laser sintering (DMLS) process. This is projected to reduce the cost of making a reactor by 58% when producing 100 reactors per year. Innovations in the DMLS process produced a patented design that reduces reactor weight by 60%. Reductions in material costs and processing time extend the DMLS advantage to higher production volumes. The new design promises to be 38% cheaper than the conventional processes at 1000 units per year. The resulting 87% reduction in the steam methane reforming (SMR) module cost in scaling from current costs meets the RAPID metric. The project was successful in producing and testing the first ever additively manufactured SMR reactors. A reactor achieved over 82% efficiency in converting electric power to chemical energy, which is a world record for an inductively heated SMR. The project has contributed to the design and assembly of a first demonstration plant that is headed to a hydrogen bus filling station in Thousand Palms, CA.
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