The term “dual function material” (DFM)
was coined
by our research group for codispersed catalysts (e.g., Ru) and alkaline
sorbents on the same high-surface-area carrier. These materials allow
for combined CO2 capture and catalytic conversion, thus
their dual functional nature. Herein, we report an additional, unexpected
function; combining Ru with specific adsorbents and carriers substantially
enhances CO2 capture capacity. Investigation of several
Ru + sorbent/carrier formulations shows that the enhancement effect
is not inherent with Ru but requires a specific combination of DFM
components. Most surprisingly, significant enhancement of CO2 adsorption is retained during multiple cycles of adsorption in O2 and methanation, where RuO
x
species
are present. Ru0 is known to adsorb CO2, as
required for methanation, but the significant enhancement in the presence
of RuO
x
indicates that Ru does not directly
contribute to the adsorption mechanism. Instead, Ru allows for more
efficient activation of adsorption sites on the alkaline sorbent via
catalytic reduction during pretreatment. This is verified by greater
adsorption capacity in materials with higher catalytic activity. These
findings open up new pathways for designing materials with higher
capture capacity than conventionally thought. Such materials can play
a key role in mitigating the negative effects of climate change.
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