Chemical recycling of CO2 through hydrothermal conversion in a continuous flow reactor
The development of methods for the abatement of CO2 emissions is an urging task. As a complement for capture and storage technologies, that consider CO2 as a residue, utilisation technologies that consider CO2 as a resource have the advantage of generating an added value, but their development still is in an early stage. Among the different carbon dioxide conversion technologies proposed, hydrothermal reforming has shown the potential to selectively convert carbon dioxide into valuable products such as formic acid, methane and methanol, favoured by the increased reactivity of CO2 in hydrothermal conditions. However, current research on this technology is limited to discontinuous or semicontinuous process layouts that show limitations for practical applications in terms of productivity, equipment durability and energy efficiency. For a scalable, cost-effective deployment of this technology, a fully continuous reactor design is required, but to accomplish this goal several challenging scientific and technical questions must be solved, including: controlling reaction conditions for the selective generation of the desired products; incorporating the catalyst regeneration cycle in the process; and integrating the hydrothermal reduction reaction with CO2-production.
The objective of this research project is the development of a continuous process for the hydrothermal reduction of CO2. For this purpose, a pilot facility will be built. The facility will be based on a tubular reactor with cooling by sudden expansion of the effluent. This design will enable a precise control of reaction conditions with favourable prospects for energy integration and without diluting the products stream. Moreover, with respect to previous studies, the temperature operation ranges will be extended until 500ºC, conditions that can improve the performance of the process due to the acceleration of reaction kinetics and the possibility of operating in a single fluid phase without solubility limitations. Using this facility, the kinetics of key reaction steps will be measured.
Innovative catalyst designs based on zinc aerogel-supported metal nanoparticles of reductants (Fe, Zn) and catalysts (Cu, Ni) will be tested, with the objective of achieving a high catalytic efficiency as a well as a high stability of the catalyst. Integration with CO2 production processes will be assessed considering two scenarios of CO2 supply: a pressurized gas stream delivered by an oxy-fuel combustion process, and an aqueous sodium bicarbonate solution coming from an absorption process.
Finally, the possibilities for the integration of the hydrothermal reduction of CO2 with the hydrothermal conversion of biomass will be assessed, testing if key products of biomass conversion such as aldehydes and reducing sugars can be used to regenerate the reducing metal or as co-reagents for the conversion of CO2 into valuable products.
Project Title: Reciclado químico de CO2 mediante conversión hidrotermal en un reactor en continuo.
Project Code: ENE2014-53459-R.
Funding Organization: Ministerio de Economía Y Competitividad (MINECO)
Period of realization: 2015- 2018
Principal Investigators: Ángel Martín Martínez and Mª Dolores Bermejo– High Pressure Processes Group, University of Valladolid.
From the High Pressure Processes Group, University of Valladolid:
- Dr. Rafael Mato Chaín
- Miriam Rueda Noriega
- Luis Miguel Sanz Moral
From other institutions:
- Dr. Antonio Nieto-Márquez Ballesteros (UNIVERSIDAD POLITÉCNICA DE MADRID)
- Dr. James McGregor (SHEFFIELD UNIVERSITY)
- Laura Quintana Gómez (SHEFFIELD UNIVERSITY)
- Dr. Ana Nunes (UNIVERSIDADE NOVA DE LISBOA)
- Ana Inês Brandão Paninho (UNIVERSIDADE NOVA DE LISBOA)
- Dr. Eduardo Pérez Velilla (UNIVERSITY OF ADÍS-ABEBA)