Carbon dioxide (CO2) decomposition was performed at a normal atmosphere and room temperature in dielectric barrier discharge microplasma reactors to reduce CO2 emissions and convert CO2 into valuable chemical materials. The outlet gases, including CO2, CO, and O2, were analyzed with gas chromatography. The results indicated that the conversions of CO2 in dielectric material‐packed reactors were all higher than that in nonpacked reactors. Particle size, dielectric constant, particle morphology, and acid‐base properties of the dielectric materials (including quartz wool, quartz sand, γ‐Al2O3, MgO, and CaO) all affected the CO2 decomposition process. The conversion of CO2 and energy efficiency achieved the highest values of 41.9 and 7.1% in a CaO‐packed reactor for the higher dielectric constant and basicity of CaO. Quartz wool was also an excellent dielectric packing material because its fiber structure provided rigid sharp edges. © 2014 American Institute of Chemical Engineers AIChE J, 61: 898–903, 2015

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Ionic liquids (ILs) provide a new way for efficient separation and recovery of NH3 because of low vapor pressure and adjustable properties. However, high viscosity or solid state of functionalized ILs at ambient temperature makes them impossible to use in traditional scrubbing processes. Therefore, combining ILs with porous solid materials to form novel IL-supported materials for NH3 adsorption is an effective method to solve the above problem. In this work, three protic ILs (PILs) including imidazolium bis­(trifluoromethylsulfonyl)­imide ([Im]­[NTf2]), 1-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([1-Mim]­[NTf2]), and 2-methylimidazolium bis­(trifluoromethylsulfonyl)­imide ([2-Mim]­[NTf2]) were supported onto activated carbon (AC) to prepare PIL-supported materials. The effects of PILs and AC types, PIL loadings, temperatures, and partial pressures on NH3 adsorption, as well as the recyclability of the PIL-supported materials, were investigated in detail. Among the investigated PIL-supported materials, 20 wt % [2-Mim]­[NTf2]-supported AC-980 exhibits the higher capacity of 68.61 mg of NH3/g of adsorbent at 303.15 K and 0.10 MPa with good NH3 selectivity and fast adsorption rate because of the synergistic interaction of hydrogen bonding between the PIL and NH3 and hierarchical pores, which is 30% higher than that of pure AC. Meanwhile, the PIL-supported material shows good recyclability after five cycles, implying great potentials for NH3 separation industrial processes.

Ammonia (NH3) is an important chemical in several fields, such as agriculture, pharmaceutical, material, and chemicals manufacturing. However, NH3 is a toxic gaseous pollutant and NH3 release results in environment pollution. Minimizing NH3 emission is of great significance for solving NH3-related environmental issues and promoting the reuse of NH3 resources. Ionic liquids (ILs) are energy-saving gas absorbents, because of their low vapor pressure, good chemical stability, and high NH3 solubility. The recent research progress of conventional, functionalized ILs and novel IL-based materials and solvents for NH3 separation was summarized. The effects of anions and cations on NH3 absorption capacity, as well as the absorption mechanism of ILs, were discussed in detail in this Review. The simulated dynamic parameters of NH3–IL systems including mass diffusivity, heat- and mass-transfer coefficient were also discussed. In addition, this Review summarized the industrial application achievement of ILs in NH3 separation and recovery from NH3-containing tail gas, which spans from simulation, pilot plant to industrial applications. Finally, the research trends in NH3 separation by IL-based systems were proposed based on existing research.

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