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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Model-Data for Joint Estimation of Biogeochemical Model Parameters from Multiple Experiments: A Bayesian Approach Applied to Mercury Methylation

This modeling archive supports the manuscript submitted for publication in the Environmental Modeling and Software. This study is supported by ORNL-SFA and IDEAS-Watershed. This study aims to improve calibration of complex biogeochemical models using datasets from multiple experiments targeting specific subprocesses. The proposed Bayesian joint-fitting scheme calibrates the entire biogeochemical model in one go using all the available datasets and estimate parameter uncertainties using Markov Chain Monte Carlo (MCMC). This allows for complete propagation of uncertainties and utilization of the information shared between different datasets. Mapping joint distribution of parameters guides model improvement by identifying null spaces in the parameter space. This archive contains files used to perform MCMC, post-process outputs and visualize results.

East Fork Poplar Creek↗
DOE OSTI2022

Ethanol to Para-xylene via Methyl Benzaldehyde

Para-xylene is an intermediate compound to several valuable commodity chemicals including polyethylene terephthalate (PET) and currently produced from fossil feedstock through a complex sequence of steps utilizing energy intensive process. Recent work from PNNL has demonstrated the conversion of ethanol produced from waste feedstocks such as municipal solid waste to para-xylene via simple three step process.

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

Terephthalic Acid Synthesis from Ethanol via p-Methyl Benzaldehyde

Terephthalic acid (TA) is a high volume and high market commodity chemical which is a monomer used in making polyethylene terephthalate (known as PET) for beverage bottles and packaging films. The global demand for TA in 2012 was 47 million ton and it is expected to grow at a 6 percent rate to reach around 65 million ton in 2018. TA is currently made from petroleum derived p-xylene produced as a co-product during ethylene production in the naphtha cracking process. At present, ethylene is mostly made by ethane cracking of cheap natural gas-shale gas, making naphtha cracking to produce p-xylene uneconomical. Combined with potential unavailability of the petroleum based p-xylene to meet market demand and the end user’s interest in sustainable PET products has created significant attention towards biomass based feed sources for the TA production. The goal of the proposed work is to develop a catalytic process from a biomass-sourced feedstock to a chemical intermediate that can serve as the basis for the economical and renewable TA production that meets market needs.

02 PETROLEUM↗
DOE OSTI2026

A Coupled Theoretical and Experimental Approach to Elucidating the Mechanisms of Methyl Esters

The goal of this project was to probe fundamental kinetics questions regarding the gas phase reactive behavior of oxygenates. In order to succeed, our program necessitated both the development of new experimental tools and the development of theory based kinetic models to explain the chemistry of oxygenate fuels. By using advanced hybrid additive manufacturing/ traditional manufacturing techniques to create specialized ceramic micro-reactors, the team was able to simulate extreme high-temperature environments with much greater precision and durability than was previously possible. These tiny, high-tech tubes allow researchers to capture and identify "fleeting" chemical species—molecules that exist for only a fraction of a millisecond—using sophisticated light sources and mass spectrometry. Additionally, the team supported the development of a tabletop VUV laser system for isomer detection without a synchrotron. Through this work, we have successfully mapped out the specific chemical pathways of various oxygen-rich fuels, solving long-standing mysteries about how these substances break down kinetically. Ultimately, this research provides the fundamental knowledge needed to design next-generation engines and fuels that are better for the environment.

09 BIOMASS FUELS↗