| 1 | Please provide a short description of the state-of-the-art and/or current trends in the field? How does the result fit into it? |
| Currently, hydrogen is referred to as a potential pollution-free energy carrier, but its advantages are unlikely to be realized, unless efficient means are found to produce hydrogen with reduced CO2 emissions. Biomass,which is considered a CO2 neutral energy source, can be used to produce hydrogen via different thermochemical routes (gasification, fast pyrolysis followed by steam reforming of the bio-oil produced, etc.). However, high costs, along with the several technical problems that need to be solved, currently prohibit the industrial application of such biomass-based routes. It is very likely that the production of H2 via steam reforming (SR) of natural gas will continue to be the dominant technology for the next few decades, despite the appreciable amount of CO2 released during the operation of such units. High-temperature operation of the SR reactor, catalyst deactivation due to coking, use of high-temperature metallurgy for the reactor construction, and complex design of the multicolumn pressure swing absorption (PSA) system raise significantly the cost of H2 production. Carbon dioxide capture and storage has emerged as a critical technology pathway to control the heat-trapping capability of the atmosphere (greenhouse effect). Currently, the only commercially available technology to separate CO2 is based on amine scrubbing systems which introduce severe technology penalties and high utility costs. Therefore, the development of new concepts for H2 production via SR, with reduced capital cost and CO2 emissions, is extremely desirable. The continuous but complex multistep SR process can be replaced by a much simpler, energy efficient single-step process which employs a bed packed with an admixture of catalyst and sorbent for the selective removal of CO2. The latter is known as sorption enhanced reforming (SER) process. The R&D result constitutes one of the most promising sorbents, which combines high CO2 sorption capacity, long life-time for high temperature applications and induces high hydrogen production via SER. | |
| 2 | What is the problem/need/knowledge gap that the research result is responding to? How was it addressed before? |
| The sorbent properties (heat tolerance, sorption capacity and stability in multicycle operation, fast kinetics) are very important for the economic viability of the SER process. Materials which are of interest for high temperature (>600 °C) applications are mostly calcium oxide and lithium oxides. Studies on lithium oxides proved that the reactivity of lithium orthosilicate (Li4SiO4) is better than that of lithium zirconate (Li2ZrO3), sorbing up to 8 mol CO2/kg of sorbent under 100 % CO2 at 650 °C. However, subsequent studies proved that both materials overcome the diffusion limitations and show accepted capacities when the size of the particle approximates the unrealistic for industrial applications value of 1 μm. Calcium oxide has been thoroughly studied because of its high sorption ability, about 13-14 mol/kg of CaO under 100%CO2 flow at 650 °C . Even though there are studies on sorption ability of different materials, scarce publications are concerned with the lifetime of the sorbents. However, once the material loses its CO2 fixing ability, regeneration of the sorbent, in higher temperatures, is required. Therefore, development of a sorbent material which keeps its regeneration ability constant is of high importance for the economical and waste management efficiency of the process. Natural Ca-based sorbents, such as limestone and dolomite, are potentially ideal sorbents because of their wide availability and low cost. However, fast reactivity loss affects the cost of the CO2 separation system. It was also reported that the CO2 absorption capacity of the Ca-based sorbents decays as a function of the number of calcination carbonation cycles. The highest carbonation capacity of CaO is 14mol/kg and it decreases to 3.78 mol/kg after 20 cycles and keeps decreasing. Replacing limestone and dolomite with a synthetic sorbent of higher lifetime in a carbonation-calcination cycle is economically feasible, provided its uptake is higher than that of limestone and dolomite for a large number of cycles.
The present CaO-based CO2 sorbent, CaO-Ca12Al14O33 (85-15 wt%), exhibits high sorption capacity and long life-time for high temperature applications, such as SER. The active component of the material is CaO while Ca12Al14O33 provides a stable framework inhibiting sintering and deactivation of CaO. The new material shows a low tortuosity in its pore system resulting in a decreased resistance in CO2 access to the active sites. The weight increase achieved approaches 50% (12 mol CO2/kg of material), with a slight loss in capacity (12%) after 60h time on stream. The methane conversion attained at 650 0C is 95 % and CO2 is reduced by 67% compared to conventional steam reforming. |
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| 3 | What is the potential for further research? |
| The potential for further developments in future research is high. There is still margin for innovation and research. Further research could be carried out regarding sorbent regeneration in pure CO2 flow, in order to attain a pure CO2 stream in the reactor exit, which will be thereupon stored permanently in underground tanks. However, regeneration in CO2 flow usually takes place at high temperatures ( > 800 0C), fact which could induce the agglomeration of CaO particles and consequently the reduction of the sorption ability of the material. | |
| 4 | What is the proposed method of IPR-protection? (patent, license, trademark etc.) |
| The product does not need IPR protection. The whole procedure for the synthesis of CaO-Ca12Al14O33 has been already published in prestigious scientific journals and is IPR protected as a service produced at Aristotle University. | |
| 5 | What are the steps that need to be taken in order to secure the IPR-protection? What is the cost of IPR-protection? |
| No steps need to be taken for IPR protection. | |
| 6 | What is you overall assessment of the scientific maturity of the research result? |
| The Laboratory of Petrochemical Technology at Aristotle University provides a complete technical and scientific background for the synthesis of efficient materials to be used in chemical engineering. Although further studies are required for scale up, the strengths of the product are clearly visible: high CO2 sorption capacity, long lifetime, high natural gas conversion, high hydrogen concentration in the reactor exit. All in all, this material is a winning product that combines technological innovation, simple construction and above all value for money. | |
Vaios Alexiadis
