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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Effect of Mo precursors in Microwave-assisted Methane Dehydroaromatization over Mo/HZSM5 catalysts

Natural gas flaring occurs in remote shale regions due to limited pipeline takeaway capacity. The conversion of the associated natural gas into aromatics in modular microwave reactors is a viable alternative to monetize the wasted gas. Microwaves offer rapid, selective heating in compact reactor systems that can enable on-demand chemical production at the well-site. Mo-HZSM-5 catalysts are widely used for aromatic production, but the location and nature of the active sites are still under debate. This study focuses on the use of 6 different Mo precursors to elucidate insights into the Mo properties that are desirable for BTX production. The catalysts were characterized by different methods (XPS, TPR, Raman, etc) to determine differences in Mo catalytic properties that may affect performance and understand these differences through performance testing under microwave at 700C for methane dehydroaromatization. Metal precursors that enable a better distribution of Mo into the pores and over the surface lead to improved benzene yield, whereas those that limited Mo to primarily the surface suffer rapid deactivation and low benzene yields. Additionally, strong Lewis acidity that arises from the sodium containing precursor drastically shifts the product selectivity towards dehydrogenation, which produces more ethylene and carbon. This catalyst had the highest deactivation constant of all catalysts tested.

gas flaring reduction↗
DOE OSTI2025

Catalysis: Volume 36 (Preface)

This volume reviews the extensive literature published in the area of microwave-assisted catalytic approaches for waste conversion, non-reductive CO2 conversion, CO₂ utilization, heterogeneous catalysis and its integration with solid oxide electrolysis cell (SOEC) systems for chemical production, mechanistic pathways in ethylene epoxidation.

CO2 utilization↗
DOE OSTI2023

Oxidative ethane dehydrogenation under thermal vs. microwave heating over Ga/ZSM-5 and GaPt/ZSM-5

Conventional thermal heating versus microwave heating for the oxidative dehydrogenation of ethane with CO 2 as the oxidative co-reactant over 2%Ga/ZSM-5 and 1.5%Ga0.5%Pt/ZSM-5. The Ga/ZSM-5 and GaPt/ZSM-5 had a similar ethane conversion under microwave heating at 450 °C, compared to the thermally heated catalyst at 650 °C. The bimetallic GaPt/ZSM-5 performed better than the Ga/ZSM-5. Both the GaPtMWFB-450 °C and GaMWFB-450 °C resulted in a lower production rate to carbon monoxide and water than the TFB-650 °C, suggesting that the microwave heating is less favorable to the water gas shift reaction. In this study, microwave heating increased the catalytic conversion of ethane and selectivity to ethylene.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Recent advances in chemical recycling and upcycling of plastic waste into valuable materials, chemicals, and energy: a comprehensive review

The global plastic waste crisis has increased in severity in recent years: annual plastic production is projected to reach 500 million metric tons by 2025, and plastic waste accumulation is expected to surpass 12 billion metric tons. Despite these growing volumes, only ∼9% of plastic waste is currently recycled; the majority is either landfilled, incinerated, or mismanaged, contributing to escalating greenhouse gas emissions—from 1.7 Gt carbon dioxide equivalent (CO 2 -eq.) in 2015 to an estimated 6.5 Gt CO 2 -eq. by 2050—and physical environmental pollution. This review provides a comprehensive overview of advanced plastic upcycling strategies to address this issue and recover value from diverse plastic waste streams. Recent developments in solvent-based dissolution, chemical depolymerization, and thermochemical conversions are examined for major plastic types, including polyolefins, polycondensation polymers, and PVC. Underlying reaction pathways, catalyst designs, and processing parameters that govern product selectivity, efficiency, and conversion yields are discussed in depth. Emerging techniques such as microwave-assisted depolymerization, tandem catalysis, and co-processing approaches are highlighted for their potential to enhance efficiency under milder conditions. Emphasis is also placed on the production of high-value products such as monomers, naphtha-range hydrocarbons, and syngas, and discussion is provided on catalyst stability, contaminant removal, scalability, life cycle effects on the environment, and technoeconomic viability. Finally, the review outlines future research directions focused on catalyst innovation, integrated process design, supportive policy frameworks, and interdisciplinary collaboration. All recommendations are aimed at accelerating large-scale implementation of plastic upcycling technologies and advancing the global circular plastics economy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Insights into Designing an Efficient and Reliable Microwave-Assisted Methane Dehydroaromatization Process: Effect of Microwave Absorber on Catalyst Performance

Microwave-assisted methane dehydroaromatization has the potential to address challenges of traditional dehydroaromatization reactions. However, catalysts for microwave-enhanced reaction systems require effective coupling of fields with the catalyst to produce heat and reach reaction temperatures. Here, this work presents an in-depth understanding of the effect of the addition of silicon carbide as a microwave absorber on catalyst performance among other variables, the viability of the microwave reactor configuration, and insights into designing an effective and reliable microwave-based methane dehydroaromatization process. The effect of other parameters including temperature, weight hourly space velocity, role of microwave absorber, and methane concentration during microwave-assisted methane dehydroaromatization reaction are studied. Mo/ZSM-5 was found to suffer from low permittivity and nonuniform heating under microwave conditions. Mixing silicon carbide powder as a microwave absorber with the catalyst was found to provide more uniform heating. When assessing the catalytic performance of the mixture, it was found that higher methane partial pressures at 2000 cc/g cat .h and a temperature range of 500-600°C produced the highest amount of benzene. The formation of graphitic carbon on the spent catalyst increased with temperature, gas-solid contact period, and methane concentration, which resulted in higher methane conversion and benzene selectivity. The study indicates that under microwave heating the presence of localized carbon enhanced catalyst life by coupling with microwave energy, leading to localized heating, and improving benzene selectivity.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Advancing Porous Carbons: Understanding the Importance of Surface Chemistry for the Energy–Environment Nexus

This review intends, in a critical way, the comprehensive view of the importance of porous carbons surface chemistry for their applications in an energy− environment nexus. Surface chemistry is presented as a combination of functional heteroatom-containing groups, dopants, and structural defects. First, we briefly address carbon surface chemical environment and the methods of its modification and characterization, indicating their practical limitations. Then, the effects of surface chemistry on separation, catalysis, energy storage, sensing and microwave absorption are introduced. Besides a critical analysis of published findings on these topics, we also include our views on the advancement in the processes which rely on porous carbons surface chemistry, and identify strategic areas and directions that should deserve further attention. We focus on new findings and important original contributions to the field. Since the community of carbon researchers grows following the strategic application of these materials, the role of functional groups, dopants and structural defects in various cutting-edge applications is emphasized, showing the progress in the field and the evolution of findings. A clear determination of the effects of carbon surface is often a challenge since carbons porosity and the locations of specific bonds/sites/ defects in the carbon texture provide nanoconfinement effects.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Microwave catalytic conversion of acetylene for co-production of hydrogen and carbon nanotubes

Natural gas conversion to hydrogen and solid carbon can drastically reduce the carbon footprint. Microwave plasma pyrolysis is an emerging process for chemical industries to directly convert methane (CH 4 ), the major component of natural gas, to hydrogen and carbon, which offers benefits such as fast process dynamics, flexibility, and high product yield. However, the formation of unwanted by-products, like acetylene (C 2 H 2 ), will require extra cost for gas separation. Plasma pyrolysis of CH 4 produces large amount of acetylene at downstream, which is currently used mainly for welding. Here, to avoid gas separation and upgrade acetylene from the downstream of methane plasma reactor, a novel approach toward its transformation to carbon nanotubes (CNT) and pure hydrogen (H 2 ) over Ni-based bimetallic catalyst driven by microwave irradiation has been reported in this work. The dominant gas product was hydrogen. Low concentrations of methane, ethane, and ethylene were observed in the product stream. Catalytic acetylene decomposition was carried out at 400 °C over Al 2 O 3 supported Ni catalyst. The results showed that, at 400 °C, acetylene was dehydrogenated to CNT and hydrogen was the dominant gas in product stream over 10Ni-1Pd-Al 2 O 3 catalyst. Characterizations of spent catalysts was conducted using Raman spectroscopy and transmission electron microscopy (TEM) to investigate the properties of carbon deposited over the catalyst during the catalytic acetylene decomposition. The results highlight that methane can be efficiently converted to hydrogen and CNT through 2-step process, microwave plasma and microwave catalytic conversion of intermediate acetylene, operated in a single reactor system driven by microwave.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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 OSTI2026

Dielectric Resonator Design for Low Power and Low Temperature Microwave Plasma

Waveguide-based microwave plasmas generally operate at high temperatures (2000 - 6000K)[1], making it difficult to directly interface solid materials with the plasma without significant thermal damage. Dielectric microwave resonators (DMRs), long studied for wave-based manipulation of electromagnetic radiation for telecom and optics, can focus radiation to extremely small mode volumes, creating intense localized fields with low-power input.[2] This phenomenon can be used for applications ranging from efficient plasma electronics to near-ambient plasma-materials interactions. Such DMR-based plasmas have been demonstrated a handful of times in the literature, but the majority of research towards this utilize the lowest frequency resonance mode.[3], [4], [5] By carefully controlling the geometry of cylindrical resonators, a variety of electromagnetic modes can be excited. In this work, COMSOL Multiphysics simulations are used to study the electric field enhancement and absorption properties of CaTiO3 DMRs as a function of geometry and excitation frequency. Whereas previous studies have utilized the HEM111 resonance frequency to drive low power plasma excitation, we find that higher order resonance frequencies are more effective at field enhancement and result in less power loss within the dielectric material, hence less wasted heating. The effectiveness of these modes is also geometry dependent and can be computationally optimized for plasma generation. Complementing these computational efforts, we demonstrate a new closed-system reactor design built in a WR-650 waveguide and experimentally demonstrate the formation of atmospheric argon microwave plasma using < 30 W input power on DMR dimers. We observe a shifting resonance frequency as the DMRs heat in response to microwave excitation and develop a Python-based lock-in mechanism to effectively track the DMR resonance over time, leading to stable plasma operation. We use infrared thermal imaging to monitor the temperature of the DMR dimers and surrounding quartz chamber, demonstrating thermal temperatures < 60 degreesC. Finally, we utilize optical emission spectroscopy (OES) to probe the plasma properties as a function of the resonance mode.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

A Review of Microwave-Assisted Synthesis-Based Approaches to Reduce Pd-Content in Catalysts

This review article focuses on the latest advances in the synthesis of inorganic nano-catalysts using microwave heating, which has progressed significantly since its initial implementation in the mid-1980s. Over the years, nanoparticles (NPs), which inherently offer better surface accessibility for heterogeneous catalysis, have been synthesized using a wide array of heating methods. Microwave heating is one such method and employs a unique heating mechanism that can have several benefits for catalysis. When compared to conventional form of heating which relies on inter-layer mixing via convection, microwave heating operates through the chemical polarity in the target chemicals leading to an “inside-out” mode of heating. This heating mechanism is more targeted and therefore results in rapid synthesis of catalytically active NPs. Platinum group metals (PGM) have classically been the focus of nano-catalysis; however, recent efforts have also applied non-PGM group metals with the goals of lower costs, and ideally, improved catalytic reactivity and durability. This is especially of interest with respect to Pd because of its current historically high cost. Investigations into these new materials have primarily focused on new/improved synthetic methods and catalytic compositions, but it is important to note that these approaches must also be economic and scalable to attain practical relevance. With this overarching goal in mind, this review summarizes notable recent findings with a focus on Pd-dilution and microwave heating in a chronological fashion.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Microwave-Assisted Reforming of Tar Model Compound Using the Ni/La-CeO2 Catalyst

Gasification of solid feedstocks like coal, biomass and waste plastic produces syngas as a desired product. However, this process also produces an unwanted byproduct known as tar, which is a sticky compound consisting of a mixture of complex aromatic and polyaromatic hydrocarbons. The tar formed during the gasification process lowers the syngas yields and reduces the gasification efficiency by damaging the reactor. Therefore, it is essential to reduce the amount of tar formed during the gasification process. Catalytic reforming of tars is one way to mitigate tars. The goal of this research is to explore the possibility of microwave-assisted catalytic tar conversion to syngas. However, due to the complexity of the tar, toluene has been used as a model tar compound as it is stable and easy to handle. Ni-La/CeO2 was used as a catalyst for this study, which was synthesized by wet impregnation method. Fresh and spent catalysts were analyzed using various techniques to understand the reaction mechanism. The reaction was performed both under microwave (MW) and conventional (CV) reactor for comparison.

catalysis↗
DOE OSTI2025

Microwave-Assisted Catalytic Gasification of Various Biomass with Mixed Plastic Wastes for H2-Rich Syngas Production

Co-gasification of plastics mixture with biomass has shown synergistic effects in Microwave (MW) reactor resulting in higher H2-rich syngas yield and reduced char/tar. This study investigates a microwave-assisted catalytic gasification of variable feedstock such as various biomass blended with mixed plastics waste using Fe-based catalyst to produce H2 rich syngas as a primary product.

catalysis, biomass gasification↗
DOE OSTI2023

Plasma assisted distributed chemical production

The present development is a process to produce commodity chemicals such as methanol and syngas using an integrated plasma catalysis technology. The method comprises providing a fixed or fluidized bed reactor having a microwave plasma flame and a catalyst bed with a catalyst, wherein the catalyst is an alloyed bimetallic nanowire. In the process, the plasma flame fluidizes the catalyst thereby producing a more effective catalyst than the non-fluidized catalyst. It is anticipated that the reactor can have a throughput capacity of up to 30 Lpm/kW and can be effective for the conversion of CO 2 , CH 4 , air, water, and combinations thereof, through reactions such as pure CO 2 splitting, reverse water gas shift (RWGS) for CO production, methanol synthesis, and plasma reforming of methane, thereby making a system that would be attractive for small GTL units.

Sunkara, Mahendra↗