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Supporting information

Functionalized Polysilsesquioxane – Based Hybrid Silica Solid Amine Sorbents for the

Regenerative Removal of CO2 from air

Kochukunju Adisser Saraladevi Abhilash,* Thomas Deepthi, Retnakumari Amma Sadhana, and

K. George Benny

Analytical and Spectroscopy Division, Analytical Spectroscopy and Ceramics Group,

Propellants, Polymers, Chemicals and Materials Entity, Vikram Sarabhai Space Centre,

Trivandrum 695022, Kerala, India.

e-mail: abhilashkadisser@gmail.com

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Scheme S1. General scheme for the formation of polysilsesquioxane.

Figure S1. FT-IR spectrum of MAHSM.

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(a) (b)

Figure S2. a) 13C CP-MAS and b) 29Si CP-MAS NMR of MAHSM.

Figure S3. Raman spectrum of MAHSM

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Figure S4. XRD of MAHSM.

Figure S5. Thermogram of MAHSM.

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Figure S6. Heat of adsorption of MAHSM using isothermal DSC.

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(a)

(b)

Figure S7. (a) Thermogram and Total ion current (TIC) of the sample

(b) MS of the evolved species.

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Figure S8. CO2 adsorption from air by MAHSM at different temperatures.

Figure S9. Effect of temperature on desorption of CO2 shown by MAHSM.

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Figure S10. IR spectrum of MAHSM after (a) CO2 adsorption (b) CO2 desorption.

Figure S11. Structures of (a) Ionic carbamate (propyl ammonium carbamate)

(b) bound carbamate (silyl propyl carbamate) with corresponding IR peak positions.

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Figure S12. 13C CP-MAS NMR of MAHSM (a) after 1 cycle (b) after 50 cycles of adsorption at

30 °C in air and desorption at 80 °C under He flow (c) after 40 cycles of adsorption at 30 °C in

100% CO2 and desorption at 120 °C under He flow.

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Table S1. Effect of molar concentration of silane on the CO2 adsorption of the product.

Ratio

(x:y)a)

CO2 adsorption (120 min in 100% CO2)

(mmol/g)

Material prepared as

such from aged silane

mixture

Material prepared after

diluting aged silane mixture

in absolute ethanol

1:0 0 0.05

2:1 0.3 1.25

1:1 0.86 2.28

1:2 1.4 1.72

a)x = 3-Amino propyl triethoxy silane, y = Vinyl triethoxy siloxane

Table S2. Effect of aging period of ASVS (1:1) mixture on thermal stability and CO2 adsorption

properties of final product.

Aging

period

Td (5%)

(°C)

CO2 adsorption

(120 min in 100% CO2)

(mmol/g)

1 day 395 1.92

2 days 410 2.11

5 days 458 2.28

7 days 460 2.26

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Table S3. Comparison with the best solid amine sorbents reported for direct air capture.

Sorbent Adsorption

half time

(Thalf)

(min)

Av.rate of

adsorption to

reach Thalf

(μmol/g/min)

Maximum

Adsorption

(mmol/g)

Amine

efficiency

(%)

HAS644

(400 ppm CO2, 25°C,

Humid air)

167 5.1 1.72 17.3

AEAPDMS-NFC-FD65

(506 ppm CO2, 25°C

RH 40%)

92 7.6 1.39 28.0

MAHSM

(400 ppm CO2, 30°C, RH

60%) (This work)

50 17.9 1.68 37.3