Tandem Conversion of CO₂ to Valuable Hydrocarbons in Highly Concentrated Potassium Iron Catalysts

Abstract

The alarming atmospheric concentration and continuous emissions of carbon dioxide (CO2) require immediate action. As a result of advances in CO2 capture and sequestration technologies (generally involving point sources such as energy generation plants), large amounts of pure CO2 will soon be available. In addition to geological storage and other applications of the captured CO2, the development of technologies able to convert this carbon feedstock into commodity chemicals may pave the way towards a more sustainable economy. Here, we present a novel multifunctional catalyst consisting of Fe2O3 encapsulated in K2CO3 that can transform CO2 into olefins via a tandem mechanism. In contrast to traditional systems in Fischer‐Tropsch reactions, we demonstrate that when dealing with CO2 conversion (in contrast to CO), very high K loadings are key to activate CO2 via the well‐known ‘potassium carbonate mechanism’. The proposed catalytic process is demonstrated to be as productive as existing commercial processes based on synthesis gas while relying on economically and environmentally advantageous CO2 feedstock.

Turning Waste into Value: Potassium‐Promoted Red Mud as an Effective Catalyst for the Hydrogenation of CO2

“…Lastly, if we compare the data reported herein with the state‐of‐the‐art iron‐based catalysts reported for this application (Table S4), we find that red mud outperforms most of them and only our recent Fe‐MOF‐mediated catalyst displays a higher space–time yield into olefins (31.8 vs. 16.6 mmol g cat −1 h −1 ). Furthermore, we compared the red mud sample with commercially available iron(III) oxide (see Experimental Section and Table S5).…”

“…This reduction is accompanied with a decrease in peak intensities related to hematite and an increase in those related to magnetite. If we look in detail at the 30°–50° 2 θ region, we can see that iron carbide is formed during the reaction (Figure b). Finally, no significant differences were found in the phase distribution by comparing spectra of samples with and without K promotion.…”

Coated sulfated zirconia/SAPO-34 for the direct conversion of CO2to light olefins

“…The Fe 2 O 3 @KO 2 catalyst was prepared following the procedure described elsewhere 31 via mortar mixing of Fe 2 O 3 and KO 2 at a molar ratio of Fe/K = 2. The resultant mixture was heated up to 100°C for 12 h prior to the catalytic measurements.…”

“…The synthesis of the standalone Fe based catalyst was done according to our recent work. 31 Note that due to the high content of K in the Fe based catalyst, mixed bed configurations result in the loss of acidity of the zeolite component. 14 The catalytic performance of the multifunctional systems is summarized in Fig.…”

“…In our approach, we combine the excellent pre-cracking ability of sulfated zirconia with the remarkable shape selectivity of SAPO-34 by designing SAPO-34 core ZrS shell particles. This coated material combined with a potassium doped Fe catalyst and under reaction conditions favorable for the FTS like transformation of CO 2 , including high concentrations of water vapor, 31 results in the selective formation of C 2 -C 4 olefins with unrivaled productivities.…”