Gerard D. Elzinga

The crucial role of the K+-aluminium oxide interaction in K+-promoted alumina- and hydrotalcite-based materials for CO2 sorption at high temperatures.

CO(2)-free hydrogen can be produced from coal gasification power plants by pre-combustion decarbonisation and carbon dioxide capture. Potassium carbonate promoted hydrotalcite-based and alumina-based materials are cheap and excellent materials for high-temperature (300-500 degrees C) adsorption of CO(2), and particularly promising in the sorption-enhanced water gas shift (SEWGS) reaction. Alkaline promotion significantly improves CO(2) reversible sorption capacity at 300-500 degrees C for both materials. Hydrotalcites and promoted hydrotalcites, promoted magnesium oxide and promoted gamma-alumina were investigated by in situ analytical methods (IR spectroscopy, sorption experiments, X-ray diffraction) to identify structural and surface rearrangements. All experimental results show that potassium ions actually strongly interact with aluminium oxide centres in the aluminium-containing materials. This study unambiguously shows that potassium promotion of aluminium oxide centres in hydrotalcite generates basic sites which reversibly adsorb CO(2) at 400 degrees C.

Sorption-enhanced hydrogen production for pre-combustion CO2 capture: Thermodynamic analysis and experimental results

Hydrotalcite-based materials have been identified as suitable materials for high temperature (400 8C) adsorption of CO2. In pre-combustion decarbonisation processes for natural gas based power cycles, it should be possible to use this material to improve conversions in the water-gas shift (WGS) and steam-reforming (SMR) reaction. The efficiencies for electricity production from natural gas have been calculated for some different system configurations, in which hydrotalcite-based material could be used. The calculated efficiency penalties ranged from 5.5 to 8.6 percentage points. The assumptions made in the system study have been tested on the laboratory scale. Hydrotalcite-based materials are found to be an excellent choice for use in the sorption-enhanced WGS reactor. The requirements for very low residual concentrations of CO2 at 400 8C and large amounts of catalyst in the sorptionenhanced SMR reactor make its application less likely. Suggestions are made to how the SESMR could be improved.