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The industrial application of emerging water‐lean solvents to CO2 capture from flue gas is challenged by their high viscosity. In this work, we report a novel water‐lean CO2 solvent which possesses lower viscosity and higher CO2 cyclic capacity than other water‐lean solvents reported in the literature. The new solvent consists of N, N‐dimethyl‐1, 2‐ethanediamine (DMEDA), physical cosolvent N‐methyl‐2‐pyrrolidone (NMP) and up to 15% water (named ENH). We evaluated the effect of the solvent composition on the viscosity, CO2 cyclic capacity and regeneration energy of ENH and compared it with the reference monoethanolamine (MEA) based solvents. It was found that ENH containing 5% H2O (ENH‐5%H2O) with a CO2 loading of 0.767 mol CO2·mol amine–1 had a viscosity of 7.603 mPa·S at 40 ˚C, which was comparable with that of traditional blended amines. Excellent cyclic capacity performance was also observed, with ENH‐5% H2O showing a 140% improvement compared to aqueous MEA. Regeneration energy of ENH‐5% H2O was estimated to be 2.418 GJ·tCO2–1 which is 36% lower than the 30 wt. % aqueous MEA solvent. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Aiming to solve the problem of high ammonia loss during ammonia-based CO2 chemical absorption process, an ammonia wash system was recommended to be added after the absorber column. Hence, we need to deal with a lot of wash water. Recently, we proposed a vacuum membrane distillation (VMD) system to regenerate ammonia from ammonia wash water. The stripping gaseous ammonia can be used for producing a high-concentration ammonia solution for solvent make-up in the CO2 capture system, and the wash water after distillation can be reused. In this work, we investigated 0.3 M ammonia solutions on different operation factors such as feed flow rate, feed temperature, pressure in the permeate side, and CO2 loading. The experimental results show that both temperature and pressure in the permeate side have significant influences on the ammonia stripping process. Increasing feed temperature and reducing pressure in the permeate side will not only improve ammonia removal efficiency, but also enhance total transmembrane flux and overall mass transfer coefficient. The increase of feed flow rate can improve the total transmembrane flux, but will lower the ammonia removal efficiency. The increase of CO2 loading in the feed ammonia solution will decrease the ammonia removal rate. Furthermore, we investigated a continuous circulation experiment and found that the ammonia removal efficiency largely depended on the removal time. The removal efficiency can be up to 95.6% with a 120 min continuous circulation time. We think this VMD system has the potential to recover ammonia and solve the solvent loss problem. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

The low CO2 absorption rate and high ammonia volatile loss rate are two major issues for the ammonia-based CO2 capture technology. In this work, we investigated the effect of total pressure on CO2 absorption and ammonia vaporization in ammonia solutions on a wetted-wall column. We found that the elevated pressure absorption process was an effective way to increase CO2 absorption rate and suppress ammonia vaporization at the same time. We also studied the mass transfer mechanism at elevated pressure and found the overall mass transfer coefficients of CO2 absorption in both ammonia and MEA solutions at elevated pressures were lower than that under atmospheric pressure. The overall mass transfer coefficients of CO2 absorption in 3 M NH3 (298 K) at 1, 1.5, 2, 2.5 bar were 0.723 × 10−6, 0.652 × 10−6, 0.591 × 10−6, 0.555 × 10−6 mol/(s m2 Pa) and the corresponding gas side mass transfer coefficients were 13.8 × 10−6, 4.52 × 10−6, 2.61 × 10−6, 2.03 × 10−6 mol/(s m2 Pa), respectively. We also found the gas side mass transfer coefficient in the wetted-wall column was not only dependent on the hydrodynamic conditions of the column but also influenced by the total pressure. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWCNT)-based thermoelectric materials have been extensively studied in the field of flexible wearable devices due to their high flexibility and excellent electrical conductivity (σ). However, poor Seebeck coefficient ( S ) and high thermal conductivity limit their thermoelectric application. In this work, free-standing MoS 2 /SWCNT composite films with improved thermoelectric performance were fabricated by doping SWCNTs with MoS 2 nanosheets. The results demonstrated that the energy filtering effect at the MoS 2 /SWCNT interface increased the S of composites. In addition, the σ of composites was also improved due to the reason that S -π interaction between MoS 2 and SWCNTs made good contact between MoS 2 and SWCNTs and improved carrier transport. Finally, the obtained MoS 2 /SWCNT showed a maximum power factor of 131.9 ± 4.5 μW m -1 K -2 at room temperature with a σ of 680 ± 6.7 S cm -1 and an S of 44.0 ± 1.7 μV K -1 at a MoS 2 /SWCNT mass ratio of 15:100. As a demonstration, a thermoelectric device composed of three pairs of p-n junctions was prepared, which exhibited a maximum output power of 0.43 μW at a temperature gradient of 50 K. Therefore, this work offers a simple method of enhancing the thermoelectric properties of SWCNT-based materials.

Amine emissions from a post-combustion CO 2 capture process can lead to solvent loss and serious environmental issues. The emission characteristics of amine mixtures and influencing factors are seldom reported. This work comprehensively investigated emissions of AMP (2-amino-2-methyl-1-propanol)/MEA (monoethanolamine) from a 3.6 Nm 3 /h flue gas CO 2 capture platform. The condensation nuclei in flue gas dominated the generation of amine aerosols and resulted in a heavy total amine loss of over 1400 mg/Nm 3 , which is equivalent to 5.88 kg/t CO 2 captured under the high nuclei concentration scenario. Inside the absorber, a higher CO 2 concentration and lower lean solvent CO 2 loading can significantly promote the growth of aerosols due to the intensive reaction of CO 2 absorption. The maximum amine emissions were observed at 8-12 vol % CO 2 . The flue gas temperature and liquid/gas ratio had insignificant effects on aerosol emissions, while amine emissions after the absorber increased 340-500% as the lean solvent temperature increased from 30 to 50 °C. A synergistic control strategy of nuclei pretreatment, operating optimization, and water scrubbing can effectively reduce amine emissions to 4.0 mg/Nm 3 MEA and 8.3 mg/Nm 3 AMP.