Amine-based
CO2 capture technology requires high-energy
consumption because the desorption temperature required for carbamate
breakdown during absorbent regeneration is higher than 110 °C.
In this study, we report a stable solid acid catalyst, namely, SO4
2–/ZrO2-HZSM-5 (SZ@H), which
has improved Lewis acid sites (LASs) and Bronsted acid sites (BASs).
The improved LASs and BASs enabled the CO2 desorption temperature
to be decreased to less than 98 °C. The BASs and LASs of SZ@H
preferred to donate or accept protons; thus, the amount and rate of
CO2 desorption from spent monoethanolamine were more than
40 and 37% higher, respectively, when using SZ@H than when not using
any catalyst. Consequently, the energy consumption was reduced by
approximately 31%. A catalyzed proton-transfer mechanism is proposed
for SZ@H-catalyzed CO2 regeneration through experimental
characterization and theoretical calculations. The results reveal
the role of proton transfer during CO2 desorption, which
enables the feasibility of catalysts for CO2 capture in
industrial applications.
High energy duty restricts the application of amine-based absorption
in CO2 capture and limits the achievement of carbon neutrality.
Although regenerating the amine solvent with solid acid catalysts
can increase energy efficiency, inactivation of the catalyst must
be addressed. Here, we report a robust metal–organic framework
(MOF)-derived hybrid solid acid catalyst (SO4
2–/ZIF-67-C@TiO2) with improved acidity for promoting amine
regeneration. The TiO2 coating effectively prevented the
active components stripping from the surface of the catalyst, thus
prolonging its lifespan. The well-protected Co–N
x
sites and protonated groups introduced onto the
TiO2 surface increased the amount and rate of CO2 desorption by more than 64.5 and 153%, respectively. Consequently,
the energy consumption decreased by approximately 36%. The catalyzed
N–C bond rupture and proton transfer mechanisms are proposed.
This work provides an effective protection strategy for robust acid
catalysts, thus advancing the CO2 capture with less energy
duty.
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