Experimental determination of thermophysical properties and phase equilibria of mixtures CO2 + Iolic Liquid to develop new clean technologies for biomass processing with energy purposes
Ionic liquids (ILs) are substances composed entirely of ions that generally are liquid around or below 100°C. The unique physicochemical properties of ILs such as low vapor pressure, and high solvation ability to dissolve various organic and inorganic substances allows their use as green solvents in several applications. Furthermore, ionic liquids can be easily modified by changing the structure of the cations or anions and, thus also their properties.
One of the most promising application of ionic liquids is cellulose processing. Some ILs have been demonstrated to be highly effective solvents for the dissolution of cellulose in amounts as high as 25% in mass, sometimes even at room temperature. Nevertheless the high viscosity of ILs which is greatly increased when they dissolve cellulose is the main limitation for their use in those processes.
It is known that mixing an IL with molecular solvents allows decreasing its viscosity and its melting point can be decreased. This is also possible when using carbon dioxide (CO2) as a co-solvent, which has the advantages of being non-toxic, cheap, and can be easily separated of the IL by depressurization. ILs and CO2 are considered to be a promising media for the development of “green” technology. In biphasic mixtures IL-CO2 at high pressure, CO2 can dissolve significantly into the IL-rich liquid phase as well at moderate pressures as high as 75% in mol, but no ionic liquid dissolves in the gas phase.
One of the main limitations for the use of CO2 as a processing media in combination with ILs is that the dissolution kinetics of CO2 in the ILs is very slow. To overcome this limitation in this project it is proposed to develop a continuous mixing system CO2+IL that also can facilitate mixing process with biomass.
The specific objectives of this project are the following:
- Knowledge of the thermodynamic behavior of the mixtures CO2 + ILs (solubility of CO2 in the ILs, melting points of the ionic liquids in the system CO2 + IL)
- Knowledge of the density and viscosity of the mixtures CO2 + ILs.
- Development of a continuous mixing system of CO2 + IL and characterization of the mixture stability through the variation of the physical properties such as dielectric constant or density.
- Experimental evaluation of improving in cellulose processing in IL media by applying different pressures of CO2 in process of cellulose dissolution. Hydrolysis and acylation.
- Techno-economical study of the process
Project Title: Determinación de Propiedades Termofísicas y Equilibrio de Mezclas CO2 + Líquido Iónico para el Desarrollo de Nuevas Tecnologías Limpias de Procesado de Biomasa con Fines Energéticos
Project Code: VA295U14
Funding Organization: Junta de Castilla y León
Period of realization: 2015- 2017
Principal Investigators: Prof. Dr. José Juan Segovia Puras and Prof. Dr. Mª Carmen Martín González, TERMOCAL University of Valladolid.
From the High Pressure Processes Group, University of Valladolid:
- Dr. Mª Dolores Bermejo Roda
- Dr. Fidel Mato Chaín
- Joana Maria Cristovao Lopes
From TERMOCAL, University of Valladolid:
- Prof. Dr. Miguel Ángel Villamañán Olfos
- Dr. Cesar Rubén Chamorro Camazón
- Dr. Rosa María Villamañán Olfos
- Manuel Sobrino García
From the company IS-Proyectos de Energías Renovables S.L.
- Dr. Pablo Jimeno Largo