Pentaerythritol-Based Molecular Sorbent for CO2 Capturing: A Highly Efficient Wet Scrubbing Agent Showing Proton Shuttling Phenomenon

5 years ago

Pentaerythritol-Based Molecular Sorbent for CO2 Capturing: A Highly Efficient Wet Scrubbing Agent Showing Proton Shuttling Phenomenon

Ala’a F. Eftaiha, Ala’a Al-Khateeb, Enas Nabih, Khaleel I. Assaf, Bernhard Rieger, Fatima Alsoubani, Carsten Troll, Abdussalam K. Qaroush

Pentaerythritol (PE) is considered a biodegradable material that combines the ease of synthesis, nonvolatility, and extra stability under basic conditions (acidic gas sequestration, e.g., CO₂), which makes it a useful candidate for postcombustion capture (PCC) application. To overcome corrosion problems associated with CO₂ binding organic liquids, a binary mixture comprised of PE/1,8-diazabicyclo-[5,4,0]-undec-7-ene (DBU) (1:4 molar ratio) dissolved in dimethyl sulfoxide (DMSO) was exploited for CO₂ capturing. The formation of ionic alkyl organic carbonate (RCO₃^– DBUH⁺) was confirmed using ¹³C NMR (157.4 ppm) and ex situ attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) (two peaks were identified, viz., 1670 and 1630 cm^–1, which were ascribed to the symmetric and asymmetric stretching of both C═O and O^···C^···O⁻ within RCO₃H and RCO₃^–, respectively). The charged adduct was measured using a thermostated beaker coupled with conductivity and pH meter probes. The sorption capacity of a 5.0% PE (w/v) solution was measured volumetrically with high efficiencies as, ca. 16 and 18.5 wt %, for wet and dry conditions, respectively. In addition, density functional theory (DFT) was performed to understand the mechanism of action in the case of H₂O, and simple alcohols, e.g., methanol and ethanol. Moreover, we reported on the newly discovered medium-dependent proton shuttling phenomenon that was verified experimentally and theoretically.

Publisher URL: http://dx.doi.org/10.1021/acs.energyfuels.7b01125

DOI: 10.1021/acs.energyfuels.7b01125