Xin, Kun (PhD)
In order to control and reduce the emission of greenhouse gas especially CO2 into the atmosphere, CO2 capture from fossil fuel power plants is getting great attention. The main strategies with corresponding research status are:
(1) Post-combustion capture is applicable to most of the existing coal-fired plants. Amine adsorption technology is widely used and amine scrubbing is well established for natural gas. But solvent degradation, equipment corrosion and high energy consumption for regeneration of the absorbents make the process complicated and costly. Improved solvents or adopting other promising processes such as membrane technology may reduce energy consumption.
(2) Oxy-fuel combustion would be feasible when the oxygen production is well established.
(3) Pre-combustion capture transforms carbon fuel in the gasification process to carbonless fuel hydrogen which has great profits and needs more research.
As for the technology, the use of dense membranes or porous membranes with an embedded liquid inside (i.e. supported liquid membranes) is the most common way of creating a selective membrane that allows preferential transport of one of the components present in the feed gas, with advantages including integration of extraction and stripping processes, small scale of the equipment, relative environmental safety, low energy consumption and operating cost. This technology can be used in both pre- and post-combustion capture. In supported liquid membranes, the liquid inside the pores play key role in the separation. At the beginning of this century, a new generation of solvent named Deep Eutectic Solvents (DES), an alternative of ILs, with the advantage of low cost, non-toxic and being biodegradable, has emerged. DESs consist predominantly of ionic species, also have interesting solvent properties for high CO2 dissolution. Thus the combination of green DES systems with membranes result in a breakthrough technology in the field of CO2 capture.
The objective of the project is to develop completely new CO2 task specific DES supported membranes (DESSM) for both low temperature (pre- and post-combustion capture and bio-gas purification) and higher temperature (pre-combustion capture integrated with water-gas shift reaction) combining an experimental effort and a thermodynamic modelling to achieve a fast screening of the various DES combinations. Summarizing, the project will address the following issues:
Development of models (including H-bonding characteristics) to predict the properties of DESs including density, heat capacity and CO2 solubility.
The implement of process simulation to compare the absorption method using conventional amine or different types of DESs as solvents with membrane technology as well as with the novel DESSM for post-combustion capture.
The characterization and assessment of CO2 task specific DES properties for low temperature or for both low and high temperature applications.
The study of the effect of support properties (porosity, tortuosity, pore sizes etc.) on the permeation characteristics of the supported liquid membranes and their stability.
The integration of the new DESSM in lab scale modules for post and pre-combustion capture, for bio-gas/bio-methane purification as well as the integration of separation and reaction in a single unit for water-gas shift reaction.
Technical validation of the DES Supported Membrane Modules at lab scale.