ja8b09325_si_001.pdf (1.63 MB)
A Carbon-Neutral CO2 Capture, Conversion, and Utilization Cycle with Low-Temperature Regeneration of Sodium Hydroxide
Version 2 2018-10-23, 16:04
Version 1 2018-10-19, 16:48
journal contribution
posted on 2018-10-19, 00:00 authored by Sayan Kar, Alain Goeppert, Vicente Galvan, Ryan Chowdhury, Justin Olah, G. K. Surya PrakashA highly efficient recyclable system
for capture and subsequent
conversion of CO2 to formate salts is reported that utilizes
aqueous inorganic hydroxide solutions for CO2 capture along
with homogeneous pincer catalysts for hydrogenation. The produced
aqueous solutions of formate salts are directly utilized, without
any purification, in a direct formate fuel cell to produce electricity
and regenerate the hydroxide base, achieving an overall carbon-neutral
cycle. The catalysts and organic solvent are recycled by employing
a biphasic solvent system (2-MTHF/H2O) with no significant
decrease in turnover frequency (TOF) over five cycles. Among different
hydroxides, NaOH and KOH performed best in tandem CO2 capture
and conversion due to their rapid rate of capture, high formate conversion
yield, and high catalytic TOF to their corresponding formate salts.
Among various catalysts, Ru- and Fe-based PNP complexes were the most
active for hydrogenation. The extremely low vapor pressure, nontoxic
nature, easy regenerability, and high reactivity of NaOH/KOH toward
CO2 make them ideal for scrubbing CO2 even from
low-concentration sourcessuch as ambient airand converting
it to value-added products.