RESEARCH

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  Electrochemical Processes for CO2 Capture (2018-Present)

  Developing Various Electrochemically-Driven Processes to Selectively Capture CO2

  

  The coronavirus pandemic in early 2020 cascaded a frightening threat, which upended familiar routines, disturbed the global economy, and endangered people’s lives around the world. Despite scientists long warned this might happen, a little was actually done before the pandemic to prevent, or at least ease, the destructive consequences. A similar warning is being repeatedly echoed through the voice of scientists regarding climate change and its multiscale devastating impacts on the planet and human’s life. Designing any action plan to mitigate climate change must include a detailed strategy to lower greenhouse gas emissions especially carbon dioxide (CO₂) as repeatedly cited to have the most significant contribution to the observed increase in global average temperature since the mid-20^th century.

  Electrochemistry, a key part of the 2019 Nobel Prize in Chemistry, is believed to be a powerful tool for designing diverse CO₂ mitigation approaches, offering a unique advantage in the future, when the electrical energy is mostly generated by renewable; the carbon footprint and the cost of the electrochemical processes would be minimized. In this context, electrochemically driven processes for carbon capture and storage (CCS), as a new frontier within the electrochemistry and climate change framework that has drawn significant attention in the last few years, could be an attractive approach to either avoid further release of CO₂ by capturing it at the source point or to reduce the atmospheric CO₂ level through a direct air capture process.

  During my postdoctoral training at MIT, I developed various electrochemical based processes for CCS, namely proton concentration process (PCP) and electrochemically mediated amine regeneration (EMAR). In short, in a PCP, the pH sensitivity of CO₂ hydration is leveraged such that CO₂ is absorbed as bicarbonate and carbonate ions at high pH values and desorbed as gas at low pH values in an electrochemical cell with proton intercalating electrodes (Figure 1A). The EMAR process scheme is similar to that of the state-of-the-art amine-based thermal scrubbing processes, but the high-temperature desorber (normally operating at 120 ^oC) is replaced by an electrochemical cell that operates at moderate temperatures (e.g., 50 ^oC) in which copper ions are electrochemically generated from a copper plate anode to drive the dissociation of amine and CO₂ toward CO₂ desorption. Once the gas is flashed off, the CO₂ lean stream is regenerated via the electrochemical plating of copper on the cathode from the copper-amine complex (Figure 1B). For both PCP and EMAR, the process scheme consists of three chemical or electrochemical transitions that take place in an absorber, an anode, and a cathode. The electrochemical work requirement for the PCP and EMAR to desorb CO₂ captured from a flue gas stream are estimated to be 33.2 and 31.3 kJe/mol_CO2, respectively, suggesting the competitiveness of these approaches. These electrochemical based technologies offer several advantages over thermally driven amine-based processes, including operation at low temperature and the ability to desorb CO₂ at moderate pressures, which minimizes the downstream compression costs for CO₂ storage. Overall, the developed PCP and EMAR could be impactful electrochemical-based technologies that could effectively mitigate CO₂ emission and climate change.

   

  Related publications:

  1- Rahimi, K. M. Diederichsen, N. Ozbek, M. Wang, W. Choi, T. A. Hatton, An electrochemically mediated amine regeneration process with a mixed absorbent for post-combustion CO₂ capture, Environmental Science & Technology 54, 8999-9007, 2020.

  2- Rahimi, G. Catalini, S. Hariharan, M. Wang, M. Puccini, T. A. Hatton, Carbon dioxide capture using an electrochemically driven proton concentration process, Cell Reports Physical Science 1, 100033, 2020.

  3- Rahimi, G. Catalini, M. Puccini, T. A. Hatton, Bench-scale demonstration of CO₂ capture with an electrochemically driven proton concentration process, RSC Advances 10, 16832–16843, 2020.

  4- Rahimi, Public Awareness: What Climate Change Scientists Should Consider, Sustainability 12, 8369, 2020 (an Opinion article).

  5- Wang, M. Rahimi, A. Kumar, S. Hariharan, W. Choi, T. A. Hatton, Flue Gas CO₂ Capture via Electrochemically Mediated Amine Regeneration: System Design and Performance, Applied Energy 255, 113879, 2019.

  Figure 1. Schematics of (A) a proton concentration process (PCP) and (B) an electrochemically mediated amine regeneration (EMAR) developed for carbon capture from a flue gas stream. For both PCP and EMAR, the process scheme consists of three chemical or electrochemical transitions that take place in an absorber, an anode, and a cathode.

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  Thermally Regenerative Battery (2014-2017)

  Harvesting of Low-grade Thermal Energy as Electrical Power Using Thermally Regenerative Batteries

  Thermally Regenerative Ammonia-based Battery (TRAB)

  Considering the depletion of fossil fuels and global climate change, the need for clean and sustainable energy sources is quite evident. A significant potential to obtain clean energy exists from harvesting low-grade thermal energy as electrical power. Low-grade heat (<100 ͦC) use has drawn increasing attention due to its potential for electricity production without the need for additional fuels. A vast amount of low-grade heat is generated from industrial processes and can be collected from solar geothermal sources (Fig. 1). There have been many different methods examined to transform thermal energy into electricity, including solid state devices based on semiconductor materials, organic Rankine cycles, thermoelectrochemical systems (TES), and systems based on salinity gradient energy (SGE).

  
  

  Figure 1. Various sources of industrial waste heat

  Recently, an efficient, inexpensive, and scalable approach was developed at Penn State to generate electrical power from waste heat sources by combining different aspects of the TES and SGE techniques, called a thermally regenerative ammonia-based battery (TRAB). A maximum power density of 115 W m^–2 (normalized by the electrode projected area) was produced in a single (first) cycle, with 60 W m^–2 produced over multiple successive cycles with electrolyte regeneration (Zhang et al. 2015)

  

   

  In a TRAB, power is derived from the formation of metal ammine complexes, which are produced by adding ammonia to the anolyte, but not to the catholyte. Ammonia concentration differences between anolyte and catholyte generate a chemical potential, which can be released as electrical current. Only inexpensive materials are used in this process, and the electrodes can be regenerated in successive cycles. In a copper-based TRAB, two copper electrodes are immersed in solutions containing dissolved Cu(II) (copper nitrate), and they are alternately operated as anodes or cathodes in successive cycles (Fig. 2). Copper reduction occurs at the cathode, with copper corrosion at the anode in the presence of ammonia. Low-grade waste heat is used to volatilize the ammonia from the anode, which can be subsequently distilled and added to the other electrode chamber to form a cycle. Currently, we are focusing on improve the heat-to-electricity efficiency by altering the solution chemistry, reactor design, and membrane.

  

  Figure 2. Schematic of the TRAB to convert waste heat into electricity

   

  Related Publications:

  1- Rahimi, A. P. Straub, F. Zhang, X. Zhu, M. Elimelech, C. A. Gorski, B. E. Logan, Emerging electrochemical and membrane-based systems to convert low-grade heat to electricity, Energy & Environmental Science 11, 276–285, 2018.

  2- Rahimi, T. Kim, C. A. Gorski, B. E. Logan, A thermally regenerative ammonia battery with carbon-silver electrodes for converting low-grade waste heat to electricity, Journal of Power Sources 373, 95–102, 2018.

  3- Rahimi, A. D’Angelo, C. A. Gorski, O. Scialdone, B. E. Logan, Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery, Journal of Power Sources 351, 45–50, 2017.

  4- Rahimi, L. Zhu, K. L. Kowalski, X. Zhu, C. A. Gorski, M. A. Hickner, B. E. Logan, Improved electrical power production of thermally regenerative batteries using a poly(phenylene oxide) based anion exchange membrane, Journal of Power Sources 342, 956–963, 2017.

  5- Rahimi, Z. Schoener, X. Zhu, F. Zhang, C. A. Gorski, B. E. Logan, Removal of copper from water using a thermally regenerative electrodeposition battery, Journal of Hazardous Materials 322, 551–556, 2017.

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  Photocatalysis (2011-2014)

  Synthesis and Application of Modified TiO2-based Photocatalysis for Water Treatment

  

  PhotoSun Science and Research Group:

  The PhotoSun Science and Research Group at the Sharif University of Technology was established in 2011. The Research Group is led by Prof. Manouchehr Vosoughi and covers various aspects of photocatalysis, from the synthesis of efficient photocatalysts to their applications in water treatment. The main focus of the group is the development of novel, green, and cost-effective systems for the removal of contaminants from the environment.

  Currently, the research group is synthesizing highly efficient TiO₂ photocatalyst by doping with various metals and nonmetals, in order to reach the visible-light-driven photocatalyst. PhotoSun Research Group aims to develop highly efficient photocatalytic systems by understanding and optimizing the main parameters that control the performance of the process. Additionally, environmental applications of synthesized photocatalysts such as organic pollution degradation and water disinfection are being investigated.

  As one of the few undergraduate student members of the group, I have been involved in various projects of the group as listed below:

  • Effect of synthesis parameters on the photocatalytic degradation of organic contaminants, September 2011-December 2011.

  • Design of laboratory-scale photoreactor for the photocatalytic reaction using Osram 400W as a light source, February 2011.

  • Comparative study of the photocatalytic performance of various transition-metal-doped TiO₂ (transition metals: Fe, Co, Ni, Cu, Zn, Ag), February 2011-March 2012.

  • Design of photoreactor systems by providing a unique blade mixer and using a low voltage LED lamp as a visible light source, July 2012.

  • Photocatalytic degradation of paraquat agricultural contaminant from aqueous solution using lanthanum-sulfur co-doped TiO₂ under visible light irradiation, July 2012-September 2012.

  • Photocatalytic degradation of azo dyes (Acid Orange 7, Methylene Orange, and Methylene Blue) under visible light using Ag-S/PEG/TiO₂ photocatalysis: Optimization by response surface methodology (RSM), July 2012-September 2012.
  • Photocatalytic degradation of environmental pollutants under solar radiation, October 2013-January 2014.

   

  Related Publications:

  1- Feilizadeh, M. Rahimi, S. M. E. Zakeri, N. Mahinpey, M. Vossoughi, M. Qanbarzadeh, Individual and interaction effects of operating parameters on the photocatalytic degradation under visible light illumination: Response surface methodological approach, The Canadian Journal of Chemical Engineering 95, 1228–1235, 2017.

  2- Feilizadeh, M. Vossoughi, M.E. Zakeri, M. Rahimi, Enhancement of efficient Ag-S/TiO₂ nanophotocatalyst for the photocatalytic degradation under visible light, Industrial & Engineering Chemistry Research 53, 9578–9586, 2014.

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  Hollow Fiber Membrane Contactors (2012-2014)

  Removal of CO2 and H2S from Natural Gas Using Hollow Fiber Membrane Contactor

  

  Pure-Chemical Science and Research Group:

  I attended a training/research program at UAE University, Al-Ain, UAE, during summer 2012, which focused on the use of COMSOL software to model membrane contactors. At first, I expected that it will be a temporary period to learn a new field of research in chemical engineering; however, as time passed, the beauty of modeling and simulation attracted me and as a consequence, after coming back to Iran, I established the Pure-Chemical Science and Research Group (PChSRG) in order to advance in this field of research.

  As the president of PChSR Group, I am privileged to have the opportunity to interact with other members of the group who are excellent students from various universities in Iran. This group of around twelve undergraduate students aims to model various aspects of hollow fiber membrane contactors under real conditions. Since our founding, we have presented two national conference papers from the activities of this research group.

Research Advisors

Prof. Manouchehr Vossoughi

Professor of Chemical Engineering

ResearchGate

Prof. T. Alan Hatton

Professor of Chemical Engineering

Website

Prof. Bruce Logan

Professor of Chemical & Environmental Engineering

Google Scholar

Prof. Christopher Gorski

Associate Professor of Environmental Engineering

Website

Prof. Mohamed Al Marzooqi

Professor of Chemical Engineering

Website