Surface Bespoke Mesoporous Silica for Carbon Dioxide Adsorption

Amine functionalized mesoporous adsorbents were synthesized and evaluated for adsorption of CO2. In the present study the mesoporous silica surface was treated with a surfactant tetra-n-propyl ammonium hydroxide (TPAOH) with an aim to tailor the characteristics of mesoporous silica walls. The as synthesized adsorbents were tested for determining equilibrium adsorption capacity using 100% CO2 and diluted 15% CO2 stream at different temperatures (30, 55, and 75°C). Equilibrium CO2 adsorption capacity of TEPA modified surface-treated silica was 2.51 and 2.54 mmol=g at 75°C under 15 and 100% CO2 concentration respectively. The as-synthesized adsorbents were also tested for determining dynamic adsorption capacity using 100% CO2 and diluted (15, 50, and 75%) CO2 stream at different temperatures (30, 55, and 75°C). Dynamic CO2 adsorption capacity of TEPA modified silica was 1.67 and 4.29 mmol=g at 75°C under 15 and 100% CO2 concentration respectively. This signifies the role of surfactant treatment affecting the pore characteristics with consequent increase in adsorption capacity of TEPA modified silica over unaltered matrices, increasing the equilibrium CO2 adsorption capacity by a factor of 32. Consistent cyclic regeneration indicates excellent practical usability of the adsorbent. Low and wide angle X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy have been performed to study the morphological properties of the present adsorbent support