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At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Simultaneously upgrading CO 2 and light alkanes into value-added products

We will discuss recent results from our group in reacting CO 2 and light alkanes to produce syngas, olefins, aromatics, and oxygenates. We will mainly use the simultaneous upgrading of CO 2 and ethane (SU-CO 2 Et) as examples to demonstrate the feasibility and reaction pathways of these processes. We will briefly discuss synthesis methods and essential structural characterization techniques that can be applied to SU-CO 2 Et catalysts. We will then illustrate how to identify and apply distinct active sites for different upgrading processes, using a combination of kinetic studies, in situ characterization, and density functional theory (DFT) calculations. We will conclude the Perspective by pointing out challenges and potential directions in catalyst design and synthesis, as well as structural characterization and mechanistic investigations, to further advance the simultaneous upgrading of CO 2 and light alkanes.

03 NATURAL GAS↗
DOE OSTI2019

Supply and value chain analysis of mixed biomass feedstock supply system for lignocellulosic sugar production

Here the sustainable supply of high-quality, low-cost biomass feedstock to cellulosic biorefineries is still a challenge. Utilizing corn stover as the single feedstock to a biorefinery also poses a source of risk to seasonal feedstock availability, affordability, and sustainability. Implementing a year-round feedstock switching strategy or utilizing an optimal mixture of corn stover, miscanthus, and switchgrass is demonstrated to diminish these concerns while reducing the cost of sugar production by as much as 3.8% and 13.6%, respectively, when compared to a baseline sugar price of 441.9 $ metric ton-1 (t) attributed to a fixed corn stover feedstock basis. This study determines that a mixing ratio of corn stover, miscanthus, and switchgrass of 36%, 50%, and 14%, respectively, minimizes the selling price of sugar. If miscanthus is sufficiently available in the future, its fraction could be further increased to 70% by reducing the fraction of corn stover. We find that the mixed feedstock considered in this study reduces the nutrient replacement and feedstock transportation costs and improves the quality of feedstock (determined by total carbohydrates and ash) relative to corn stover alone. Results suggest that a high-quality feedstock with a high carbohydrate content is an important metric for consideration, beyond strictly the feedstock cost, to reduce the selling price of sugar and its uncertainties. In the future this may be supported by the increased availability of higher carbohydrate feedstocks such as miscanthus.

09 BIOMASS FUELS↗
DOE OSTI2018

Bioconversion of Methane for Value-Added Products

This chapter will briefly summarize the background of methane production from natural gas and biogas together with an introduction to the biomolecular basis of methanotrophy and the actual and potential commercial applications. This chapter also discusses the safety considerations for using methane in laboratory and safe development of methane-based bioprocesses. In the end, this chapter will focus on the process development for biological conversion of methane into desired products with attention to the enhancement of mass transfer efficiency and the development of bioreactor designs.

09 BIOMASS FUELS↗