José Antonio Medrano Jiménez (PhD)
CLingCO2 Chemical looping reforming for pure hydrogen production with integrated CO2 capture
Brief description of the project
It is well accepted that nowadays the increase in greenhouse effects as a result of the anthropogenic emissions is the main cause of the climate change. CO2 is the major responsible gas, coming mostly from fossil fuels combustion. One of the most interesting strategies to stabilize the atmospheric CO2 concentration is the Carbon Capture and Storage (CCS) technology, which involves CO2 capture from emission sources followed by storage of pure CO2 underground. Besides, H2 is considered a promising energy carrier in future energy systems. On an industrial scale H2 is mainly produced by steam reforming of natural gas/methane. In the present project, a novel integrated reactor is proposed to provide hydrogen production with integrated pure CO2 capture.
Chemical looping has demonstrated that is a cheap and interesting technology for CCS. It consists of two interconnected reactors where there is not direct mixing of air and fuel. With this technology oxygen is supplied by a metal solid with high reactivity for being oxidized and reduced as well as high oxygen capacity. This solid is named “oxygen carrier”. In the Fuel Reactor, oxygen carrier (fully oxidized) is reduced by the reaction with the fuel. This reduced solid is transferred to the second reactor (Air Reactor) where is re-oxidized. By optimization of the operation conditions, an exit stream from the fuel reactor consisting of CO2 and H2O, which can be easily separated, could be achieved.
In the novel proposed multifunctional reactor, steam reforming is going to be carried out under the chemical looping technology. Hydrogen produced during the process will be selectively separated from the fuel reactor through perm-selective membranes resulting in an ultra-pure hydrogen stream. This fact improves the steam reforming and Water Gas Shift reactions by a displacement of the equilibrium towards products. Thus the outlet flow of the fuel reactor would only consist of a CO2/H2O mixture that can be easily separated, providing a pure stream of CO2 suitable for CCS. The main drawback of the reaction in the fuel reactor is that needs heat supply at high temperatures because of the process is highly endothermic. However, due to the chemical looping technology, the returning oxygen carrier from the Air Reactor, where a highly exothermic reaction occurs, would carry and provide the heat for the process in the Fuel Reactor reaching an auto-thermal regime. As it has been described in the present paragraph, this novel reactor achieves a high degree of process intensification, where auto-thermal process and different valuable pure streams could be achieved.
Development and Objectives
The development of the proposed project requires the combination of different key points that must be studied. An extensive review of the literature, studies of different oxygen carriers, membranes or hydrodynamics of the proposed reactor will provide good information for the process. Besides, by developing a phenomenological model, the best reaction conditions could be predicted for the experimental evaluation. By combining the key studies of the reactor and the developed phenomenological model, the design of the novel reactor and the experimental evaluation will be carried out to achieve the expected results. A list of objectives is represented below.
1. Thermodynamic studies for the new reactor concept.
2. Development of a new phenomenological model which would predict experimental results.
3. Reactivity investigation for different oxygen carriers. Pd-based membranes characterization and evaluation.
4. Hydrodynamic and back-mixing studies on fluidized bed membrane reactors.
5. Scale-down and scale-up of the novel reactor proposed.
6. Experimentation at lab scale and in the pilot plant.