화학공학소재연구정보센터
Catalysis Today, Vol.242, 184-192, 2015
Chemical energy storage in gaseous hydrocarbons via iron Fischer-Tropsch synthesis from H-2/CO2-Kinetics, selectivity and process considerations
The potential of a new practical application of Fischer-Tropsch synthesis is investigated, the production of C2-4 components to increase the heating value of substitute natural gas (SNG), starting from CO2 and H-2, produced from renewable electricity. This process route offers the possibility to convert electrical energy into chemical energy. The resulting chemical energy carrier can be stored in the natural gas grid, easy to distribute. An iron-based catalyst promoted with potassium (100 g Fe/2 g K) is studied over a wide range of operation conditions to investigate its suitability to produce C-2-C-4 components from H-2/CO2 mixtures. The achieved hydrocarbon distribution (alpha = 0.2-0.3) allows for the production of Substitute Natural Gas components (68 C% C-1, 30 C% C-2-C-4, C5+ approx. 2 C%). The catalyst stability is good, at least for 50 days. The hydrocarbon selectivity remains almost constant during the experiment, methane becoming slightly more predominant over time. Catalyst activity seems to be strongly influenced by the (H2O/H-2)(out) ratio (possibly due to oxidation), which correlates with CO2 conversion. At high values of (H2O/H-2)(out), the activity of the catalyst seems to change and cannot be described using the same reaction rate kinetics determined for lower (H2O/H-2)(out) values. The maximal CO2 conversion achieved is 44% (p = 2 Mpa, (H-2/CO2)(in) = 8). Experimental results show that higher conversions could not be achieved neither with an increase in temperature nor in modified residence time. The H-2/CO2 inlet ratio is the most promising parameter to reach high CO2 conversions without a high oxidation potential in the product gas. Interesting catalytic effects have been identified, however experimental results will be supported by additional work in order to get a better understanding of the CO2 hydrogenation under Fischer-Tropsch conditions with iron catalysts. (C) 2014 Elsevier By. All rights reserved.