In the current study, a new type of composite adsorbent was synthesized by amine modification of binder-containing zeolite 4A bodies and its potential application in the post-combustion CO2 capture was evaluated. A wide range of aliphatic straight chain amines such as propylamine (PA), butylamine (BA), pentylamine (PEA), and their respective branched chain amines, iso-propylamine (IPA), iso-butylamine (IBA), and iso-pentylamine (IPEA), were used in a smaller fraction to modify binder-containing zeolite 4A bodies. The synthesized materials were characterized by various spectro-analytical techniques to elucidate the effect of amine modification on physicochemical properties of binder-containing zeolite 4A bodies and its reactivity for CO2 capture. Among all of the studied hybrid adsorbents, the iso-butylamine-modified binder-containing zeolite 4A bodies (IBA-Z4A) exhibited excellent CO2 adsorption performance with a maximum adsorption capacity of 2.56 mmol g–1 at 25 °C and 1 bar of pressure. Notably, IBA-Z4A also demonstrated excellent purity (98%) and remarkably high CO2/N2 selectivity (335) as compared to the pristine binder-containing zeolite 4A bodies (24). Such enhanced CO2 adsorption capacity and high CO2/N2 selectivity values for IBA-Z4A can be attributed to the symbiotic interactions between CO2 and amines governed by the basicity, electron density at the N atom of amines, and the steric effect of adsorbing molecules (CO2 and N2) at the adsorbent surface. Notably, IBA-Z4A also displayed a marginal isosteric heat of adsorption for CO2 (51 kJ mol–1) along with the encouraging thermochemical cyclic stability over five consecutive CO2 adsorption–desorption cycles at 25 °C and 1 bar, believed to be the best suited for post-combustion CO2 capture.

The current study reports the utilization of tetraethylenepentamine (TEPA)-modified hierarchical silica particles having bimodal meso/macroporosity for CO2 capture under simulated direct air capture (DAC) conditions (400 ppm CO2 in He). Results infer a typical relation between TEPA loading and CO2 capture, where TEPA-impregnated HS (HS-TEPA-70) exhibits exceptionally high CO2 uptake (5.20 mmol/g), shorter adsorption half time (110 min), and excellent amine efficiency (0.32 mmol of CO2/mmol of N) with moderate CO2/N2 selectivity at 30 °C under DAC conditions. HS-TEPA-70 also showed appreciable CO2 adsorption performance (5.88 mmol/g) under humid conditions (50 ± 3% RH) with 400 ppm CO2 in He at 30 °C. TEPA-impregnated HS even displays better thermal stability up to 10 consecutive adsorption–desorption cycles with minimal amine leaching and moderate CO2 regeneration energy. Moreover, the pelletized form of HS-TEPA-70 also demonstrates better CO2 adsorption performance (3.34 mmol/g), which makes it a promising candidate for CO2 capture from ambient air by temperature swing adsorption.

To understand critical problems associated with solid waste and its consequences for the environment, a laboratory experiment is presented on the synthesis of aluminum-based metal−organic framework (MOF) MIL-53(Al) from household waste (PET bottles and aluminum foil/can), for undergraduate students of chemistry. This work is designed to teach students the research methodology and basic understanding of MOFs and their application in carbon capture and storage (CCS). Students also learnt several instrumentation techniques such as UV−vis spectroscopy, powder X-ray diffraction (P-XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and gas sorption to characterize the physicochemical properties of . The facile production of MIL-53(Al) enabled the students to investigate its applicability in CO 2 sorption. The calculations of essential parameters such as CO 2 over N 2 selectivity and the use of statistical tools in data processing are also explained to the students. In the end, the instructor presented his/her feedback by evaluating the answer sheets (pre-and postlab work) and by demonstrating the overall lab work through a model presentation.

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Direct Air Capture (DAC) emerges as a new technology that can contribute to “negative carbon emission.” Recent progress in surface chemistry and material synthesis has allowed a new generation of...

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Incorporation of rice-husk-ash (RHA), an agricultural waste, in situ during the synthesis of MIL-101(Cr) resulted in a significant improvement in the CO2 adsorption properties over the synthesized RHA-MIL-101(Cr). The newly synthesized RHA-MIL-101(Cr) composite exhibited an enhancement of 14–27% in CO2 adsorption capacity as compared to MIL-101(Cr) at 25 °C and 1 bar. The content of RHA incorporated in RHA-MIL-101(Cr) fine tuned the CO2 capture performance to achieve high working capacity (0.54 mmol g−1), high purity (78%), superior CO2/N2 selectivity (18) and low isosteric heat of adsorption (20–30 kJ mol−1). The observed superior CO2 adsorption performance of RHA-MIL-101(Cr) is attributed to the fine tuning of textural characteristics—enhancement of 12–27% in BET surface area, 12–33% in total pore volume and 18–30% in micropore volume—upon incorporation of RHA in MIL-101(Cr).

In this study, the effects of AlN/GaN superlattice (SL) thickness on performances of AlGaN/GaN high electron mobility transistor (HEMT) heterostructure grown by metal-organic chemical vapor deposition (MOCVD) on silicon is investigated. Stress in GaN is controlled by varying the total thickness of the AlN/GaN SL. Improved crystal quality and surface roughness accomplished with 2200 nm-thick AlN/GaN SL, leads to an increase in high electron mobility (1760 cm2/V·s) as well as two-dimensional electron gas (2DEG) concentration (1.04×1013 cm-2). AlGaN/GaN metal-insulator-semiconductor HEMT (MIS-HEMT) fabricated on the heterostructure with SL buffer layer exhibits a significant improvement in maximum saturation current of 1100±29 mA/mm at VGS = 0 V and a low on-resistance (RON) of 4.3±0.15 Ω·mm for the optimized AlN/GaN SL. The 2200 nm-thick AlN/GaN SL supports the growth of stress-free GaN heterostructure, which can reduce the insertion loss for sub-6 GHz RF applications. This GaN HEMT structure based on superlattice buffer layer is suitable for low-frequency RF power applications.