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Direct CO 2 Capture and Reduction to High‐End Chemicals with Tetraalkylammonium Borohydrides
Author(s) -
Lombardo Loris,
Ko Youngdon,
Zhao Kun,
Yang Heena,
Züttel Andreas
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202100447
Subject(s) - chemistry , formate , inorganic chemistry , alkyl , formic acid , kinetics , borohydride , mesitylene , chloride , dimethylamine , organic chemistry , catalysis , physics , quantum mechanics
We demonstrate the ability of tetraalkylammonium borohydrides to capture large amounts of CO 2 , even at low CO 2 concentrations, and reduce it to formate under ambient conditions. These materials show CO 2 absorption capacities up to 30 mmolCO2 g −1 at room temperature and 1 bar CO 2 . Every BH 4 − anion can react with three CO 2 molecules to form triformatoborohydride ([HB(OCHO) 3 ] − ). The thermodynamics and kinetics of the reaction were monitored by a magnetic suspension balance (MSB). Direct CO 2 capture and reduction from air was achieved with tetraethyl, ‐propyl, and ‐butylammonium borohydride. The alkyl chain length played an important role in the kinetics and thermodynamics of the reaction, especially in CO 2 diffusivity (crystallinity and free‐volume), activation energy (charge‐transfer dependent on the alkyl chain), and hydrophobicity. Adding HCl gave formic acid and the corresponding chloride ammonium salt, which can be recycled. In addition, transfer of formate was achieved for the N‐formylation of an amine.