Researchers at RTI International are conducting feasibility tests on using carbon as a reducing agent for CO2 utilization. A reducing agent (reductant) is an element or compound in a chemical reaction that reduces (adds electrons to) another species; the reducing agent then becomes oxidized (loses electrons) in the process. The chemistry for this proposed CO2 gasification process is based on the reverse Boudouard reaction, in which carbon (C) reduces CO2 to produce carbon monoxide (CO):
CO2 + C = 2CO
The reduced product (CO) can then be used to create other chemicals.
The scope-of-work has both laboratory and modeling components. The laboratory phase is focused on carbon reactions with multiple CO2 sources. This phase of the research utilizes thermogravimetric analysis (measuring small changes in weight as the temperature changes) and a bench-scale reactor system (Figure 1). The modeling effort is used to evaluate the overall process and demonstrate that it meets a net target cost of less than $10 per ton of CO2 stored with CO as the end product. Process simulation and modeling are being used to evaluate the economics and different configurations for optimizing CO2conversion. Process modeling is also being used to evaluate the addition of multiple supplemental processes for converting the CO into other chemicals.
The Department of Energy’s (DOE) Carbon Storage Program encompasses five Technology Areas: (1) Geologic Storage and Simulation and Risk Assessment (GSRA), (2) Monitoring, Verification, Accounting and Assessment (MVAA), (3) Carbon Dioxide (CO2) Use and Re-Use, (4) Regional Carbon Sequestration Partnerships (RCSP), and (5) Focus Areas for Sequestration Science. The first three Technology Areas comprise the Core Research and Development (R&D), which includes studies ranging from applied laboratory to pilot-scale research focused on developing new technologies and systems for greenhouse gas (GHG) mitigation through carbon storage. This project is part of the Core R&D CO2 Use and Re-use Technology Area and focuses on developing pathways and novel approaches for reducing CO2 emissions in areas where geologic storage may not be an optimal solution. Carbon dioxide use and re-use applications could generate significant benefits through the capture or conversion of CO2 to useful products such as fuels, chemicals, or plastics. Revenue generated from these applications could offset a portion of the CO2 capture cost. The program’s R&D strategy includes adapting and applying existing technologies that can be utilized in the next five years, while concurrently developing innovative and advanced technologies that will be deployed in the decade beyond.
The area of CO2 use and re-use for carbon storage is relatively new and less well-known compared to other storage approaches, such as geologic storage. Many challenges exist for achieving successful CO2 use and re-use, including the development of technologies capable of economically fixing CO2 in stable products for indirect storage. More exploratory technological investigations are needed to discover new applications and reactions. Each CO2 use and re-use technology approach has a specific application, advantages over others, and challenges that are the focus of existing and future research. Technologies being developed will work towards meeting carbon storage programmatic goals; and these technologies may provide coal-based electric power generating facilities and other industrial CO2 emitters additional tools to manage CO2 emissions. This project will demonstrate the feasibility of a CO2 utilization process for producing carbon monoxide as a commodity chemical, and will evaluate the economic feasibility of this process.
Development of the proposed technology supports the Program goal of reducing GHG emissions by utilizing waste CO2 to produce useful products. If successful, the technology would add to the suite of technologies becoming available to fossil fuel-based power plants and other large point sources for reducing CO2 emissions at reduced cost. This technology contributes to the Carbon Storage Program’s effort of developing cost-effective methods for CO2 use and re-use.
The overall objective of this project is to develop a process that utilizes carbon as a reducing agent for CO2 during the generation of a useful product with a net target cost of less than $10 per metric ton of stored CO2. A secondary objective is to evaluate whether additional processes can be added that would use the CO to produce other marketable chemicals and still achieve DOE/National Energy Technology Laboratory’s (NETL) Carbon Storage program goal of converting CO2 into useful products. Specific research goals of the project include:
Evaluate and identify the most reactive carbon sources for CO2 gasification,
Evaluate the potential to increase CO2 gasification reactivity with catalysts,
Demonstrate the economic feasibility of CO2 gasification for the production of CO,
Evaluate sensitivity of process economics to assist the experimental program; and,
Evaluate economic feasibility of producing commodity chemicals.
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