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Title: Novel Electro-Deoxygenation Process for Bio-oil Upgrading

Abstract

Biomass is a potential source of renewable fuel. Bio-oil produced by fast pyrolysis is a prospective option to replace fossil fuels for transportation. However, bio-oil needs to be upgraded to remove its high oxygen and water content, and acidity to produce useful fuels. The upgrading of bio-oil is generally accomplished by hydrodeoxygenation (HDO) using hydrogen. The instability of bio-oil poses a major challenge in transportation to central upgrading facility. An electro-deoxygenation (EDOx) process was evaluated to fully or partially deoxygenate bio-oil using solid oxide electrolysis process. This device uses an oxygen ion conducting membrane which under an applied electric potential removes oxygen in the form of an ion and transports it to the opposite side of the membrane where it is released as oxygen molecule. When water is present in the bio-oil vapor, the process generates in situ hydrogen to facilitate deoxygenation over the electrode that functions as catalyst. The significant features of the EDOx process are: Minimal or No external hydrogen needed, The electricity can be obtained locally from co-gen facilities that use renewable sources and/or from existing infrastructure; Additionally, partial or complete removal of the oxygen from the pyrolyzed material stabilizes the hydrocarbon product for transport; Deoxygenation willmore » also result in a product with none of the acidity problems typical of pyrolysis oil; As oxygen is removed as O2(g) and not as oxides of carbon, EDOx can theoretically be very high in carbon and hydrogen efficiency; If the production of char is minimized in the pyrolysis step, the entire system can achieve high atom efficiencies; EDOx has the potential to be integrated directly with a pyrolysis reactor and thus, the overall system will operate at atmospheric pressure thereby obviating the need for expensive pressure vessels. Modularity of both the fast pyrolysis and EDOx units allows a smaller integrated facility to be economically attractive, increasing both the flexibility for deployment and broadening the potential customer base. Oxygen can be recovered as a co-product which will aid in overall process economics. A series of tests conducted using model compounds and aqueous fraction of bio-oil demonstrated the potential of the process. The project culminated in an integrated test wherein a slip stream of bio-oil from a fast pyrolysis unit was introduced to a solid oxide stack. integrated testing of stack-cell EDOx reactor with the fast pyrolysis system successfully demonstrated conversion of pyrolysis oil vapor to an upgraded liquid product and displayed a significant level of deoxygenation. As a result, correlation of pyrolysis oil deoxygenation with the stack current (Amperes) was made. Liquid and gas yields were also estimated, and product analysis was done to provide a clear baseline performance for future development of the EDOx process. In addition to the experimental work and results, computational chemistry work at PNNL demonstrated the feasibility of deoxygenation via dehydroxylation of the oxygenates (Guaiacol - Phenol) present in the pyrolysis vapor by using DFT (Density Functional Theory). This was also confirmed by 13C NMR analysis of the liquid product with the decrease of carbon-hydroxyl (C-OH) group in the product. Additional work is required to evaluate new catalytic materials and process optimization schemes for improvement of the deoxygenation process to produce hydrocarbon fuels and chemicals. Techno-economic analysis (TEA) and life cycle analysis were also conducted. Results show that the EDOx configurations have lower life cycle GHG emissions of 5 – 8.4 g CO2 eq. and 7.4 – 11 g CO2 eq. per MJ of a vehicle operated with diesel and gasoline, respectively compared to HDO (39 gCO2 eq. per MJ). Furthermore, the EDOx process offers potentially10 times more small-scale pyrolysis upgrading facilities in the U.S. compared to HDO, suggesting that small-scale on-site EDOx processes can reach more inaccessible forest biomass resources. The plant is designed to use 300 metric tons/day of forest residue to produce 1.1 M gallons per year of gasoline and diesel which is an overall yield of 47 L of fuel produced per dry metric ton of feedstock. The processing steps include: Feedstock collection Fast pyrolysis conversion of feedstock to bio-oil Electrochemical deoxygenation of bio-vapor to produce stable deoxygenated oil Further hydrotreating of electrochemical deoxygenated oil Product separation of deoxygenated oil The capital cost for the plant is estimated to be $53 million (2015 basis). At an ROI of 10%, the minimum fuels (gasoline and diesel) selling price is $1.89/gal which is competitive with the estimated MFSP of the state of the art HDO technology reported to be between the range of $1.74- $2.04/gal. In addition we project that the revenue from sales of the biofuel product at the estimated MFSP will be $210 million. Although the MFSP of the EDOx process is relatively competitive with the HDO technology, the EDOx process has the potential to have a lower MFSP if the EDOx reactor can reach its full deoxygenation potential, thereby reducing the hydrogen demand required for further deoxygenation and reduce cost. Therefore, further research can possibly lead to additional cost improvements.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]
  1. (Elango) [OxEon Energy, LLC
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Drexel Univ., Philadelphia, PA (United States)
  4. Technology Holding, LLC
Publication Date:
Research Org.:
OxEon Energy, LLC
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Contributing Org.:
OxEon Energy, LLC Pacific Northwest National Laboratory Drexel University
OSTI Identifier:
1458768
Report Number(s):
DOE-OxEon-6288
DOE Contract Number:
EE0006288
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; Bio-oil, pyrolysis oil, deoxygenation, electrodeoxygenation, bio-oil stabilization, bio-oil upgrading

Citation Formats

Elangovan, S, Santosa, Daniel, Elliott, Douglas C, Spatari, Sabrina, and Karanjikar, Mukund. Novel Electro-Deoxygenation Process for Bio-oil Upgrading. United States: N. p., 2018. Web. doi:10.2172/1458768.
Elangovan, S, Santosa, Daniel, Elliott, Douglas C, Spatari, Sabrina, & Karanjikar, Mukund. Novel Electro-Deoxygenation Process for Bio-oil Upgrading. United States. doi:10.2172/1458768.
Elangovan, S, Santosa, Daniel, Elliott, Douglas C, Spatari, Sabrina, and Karanjikar, Mukund. Fri . "Novel Electro-Deoxygenation Process for Bio-oil Upgrading". United States. doi:10.2172/1458768. https://www.osti.gov/servlets/purl/1458768.
@article{osti_1458768,
title = {Novel Electro-Deoxygenation Process for Bio-oil Upgrading},
author = {Elangovan, S and Santosa, Daniel and Elliott, Douglas C and Spatari, Sabrina and Karanjikar, Mukund},
abstractNote = {Biomass is a potential source of renewable fuel. Bio-oil produced by fast pyrolysis is a prospective option to replace fossil fuels for transportation. However, bio-oil needs to be upgraded to remove its high oxygen and water content, and acidity to produce useful fuels. The upgrading of bio-oil is generally accomplished by hydrodeoxygenation (HDO) using hydrogen. The instability of bio-oil poses a major challenge in transportation to central upgrading facility. An electro-deoxygenation (EDOx) process was evaluated to fully or partially deoxygenate bio-oil using solid oxide electrolysis process. This device uses an oxygen ion conducting membrane which under an applied electric potential removes oxygen in the form of an ion and transports it to the opposite side of the membrane where it is released as oxygen molecule. When water is present in the bio-oil vapor, the process generates in situ hydrogen to facilitate deoxygenation over the electrode that functions as catalyst. The significant features of the EDOx process are: Minimal or No external hydrogen needed, The electricity can be obtained locally from co-gen facilities that use renewable sources and/or from existing infrastructure; Additionally, partial or complete removal of the oxygen from the pyrolyzed material stabilizes the hydrocarbon product for transport; Deoxygenation will also result in a product with none of the acidity problems typical of pyrolysis oil; As oxygen is removed as O2(g) and not as oxides of carbon, EDOx can theoretically be very high in carbon and hydrogen efficiency; If the production of char is minimized in the pyrolysis step, the entire system can achieve high atom efficiencies; EDOx has the potential to be integrated directly with a pyrolysis reactor and thus, the overall system will operate at atmospheric pressure thereby obviating the need for expensive pressure vessels. Modularity of both the fast pyrolysis and EDOx units allows a smaller integrated facility to be economically attractive, increasing both the flexibility for deployment and broadening the potential customer base. Oxygen can be recovered as a co-product which will aid in overall process economics. A series of tests conducted using model compounds and aqueous fraction of bio-oil demonstrated the potential of the process. The project culminated in an integrated test wherein a slip stream of bio-oil from a fast pyrolysis unit was introduced to a solid oxide stack. integrated testing of stack-cell EDOx reactor with the fast pyrolysis system successfully demonstrated conversion of pyrolysis oil vapor to an upgraded liquid product and displayed a significant level of deoxygenation. As a result, correlation of pyrolysis oil deoxygenation with the stack current (Amperes) was made. Liquid and gas yields were also estimated, and product analysis was done to provide a clear baseline performance for future development of the EDOx process. In addition to the experimental work and results, computational chemistry work at PNNL demonstrated the feasibility of deoxygenation via dehydroxylation of the oxygenates (Guaiacol - Phenol) present in the pyrolysis vapor by using DFT (Density Functional Theory). This was also confirmed by 13C NMR analysis of the liquid product with the decrease of carbon-hydroxyl (C-OH) group in the product. Additional work is required to evaluate new catalytic materials and process optimization schemes for improvement of the deoxygenation process to produce hydrocarbon fuels and chemicals. Techno-economic analysis (TEA) and life cycle analysis were also conducted. Results show that the EDOx configurations have lower life cycle GHG emissions of 5 – 8.4 g CO2 eq. and 7.4 – 11 g CO2 eq. per MJ of a vehicle operated with diesel and gasoline, respectively compared to HDO (39 gCO2 eq. per MJ). Furthermore, the EDOx process offers potentially10 times more small-scale pyrolysis upgrading facilities in the U.S. compared to HDO, suggesting that small-scale on-site EDOx processes can reach more inaccessible forest biomass resources. The plant is designed to use 300 metric tons/day of forest residue to produce 1.1 M gallons per year of gasoline and diesel which is an overall yield of 47 L of fuel produced per dry metric ton of feedstock. The processing steps include: Feedstock collection Fast pyrolysis conversion of feedstock to bio-oil Electrochemical deoxygenation of bio-vapor to produce stable deoxygenated oil Further hydrotreating of electrochemical deoxygenated oil Product separation of deoxygenated oil The capital cost for the plant is estimated to be $53 million (2015 basis). At an ROI of 10%, the minimum fuels (gasoline and diesel) selling price is $1.89/gal which is competitive with the estimated MFSP of the state of the art HDO technology reported to be between the range of $1.74- $2.04/gal. In addition we project that the revenue from sales of the biofuel product at the estimated MFSP will be $210 million. Although the MFSP of the EDOx process is relatively competitive with the HDO technology, the EDOx process has the potential to have a lower MFSP if the EDOx reactor can reach its full deoxygenation potential, thereby reducing the hydrogen demand required for further deoxygenation and reduce cost. Therefore, further research can possibly lead to additional cost improvements.},
doi = {10.2172/1458768},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jun 29 00:00:00 EDT 2018},
month = {Fri Jun 29 00:00:00 EDT 2018}
}

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