Table 1.

Measured absorption capacity C_A at 40 °C for an amine concentration of 1.5 mol L⁻¹ and initial absorption rate R_IA at 40 °C and an amine concentration of 1.5 mol L⁻¹ for aqueous solutions of PZ, 2,6-DMPZ, 2,5-DMPZ and synthesised amines HHPY, MHHPY, DMHHY and HHPZ. For comparison, the reactivity of conventional absorbents such as MEA, DEA and AMP (1.5 mol L⁻¹, unless otherwise stated) are included.

Amine	CA[a]	RIA[b]
PZ	0.92	0.045
2,6-DMPZ	0.86[c]	0.025[d]
2,5-DMPZ	0.88	0.018[e]
HHPY	0.85	0.032
MHHPY	0.86	0.018
DMHHPY	1.33	0.032
HHPZ	0	0
MEA	0.56[12], [f]	0.027
DEA	0.60[12], [f]	0.015
AMP	0.84[12], [f]	0.006

^[a]Mol CO₂/mol amine; data used to calculate C_A were measured in the absorption reactor/FTIR system.

^[b]Mol CO₂/mol amine, min⁻¹; data used to calculate R_IA were measured by microscale TGA. Initial absorption rates were calculated by using linear regression to determine the slope of the absorption capacity curve. R²≥0.995.

^[c]A precipitate formed during CO₂ absorption/FTIR.

^[d]A precipitate formed during the CO₂ and N₂ runs of the TGA experiment.

^[e]A precipitate formed during the CO₂ run of the TGA experiment. This could be mainly due to the evaporation of water.

^[f]3 mol L⁻¹ concentration analysed.