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[Display omitted] • Flexible improvement on PSA O 2 production at wide product flow rate range is studied. • Individual effects of process parameters on O 2 production performance are obtained. • Adjusted/unadjusted PSA experiments using appropriate valve settings are conducted. • Process improvement strategies for different product flow rate ranges are proposed. • Higher O 2 purity, recovery and productivity with lower energy consumption are gained. Improvement on oxygen (O 2) concentrator using pressure swing adsorption (PSA) technology according to variable product demands is of great significance, which, for instance, provides the key step for success in practical O 2 therapy for COVID-19 patients who need to be delivered with a wide product flow rate range (1–15 standard liter per minute (SLPM)) of medical O 2 (purity > 82%). This work studied the individual effects of major PSA process parameters on O 2 production performance at the product flow rate of 3.46–19.88 SLPM (0.64–3.68 SLPM per kilogram of adsorbent (SLPM/kg)), based on a self-designed two-bed PSA unit with a modified Skarstom cycle using Li-LSX zeolite adsorbents. The improvement strategies were accordingly proposed based upon influential mechanisms of each parameter: 1) at lower product flow rates (≤2.00 SLPM/kg), increasing the purge flow rate and decreasing the adsorption pressure to suppress excess O 2 adsorption, and decreasing the feed flow rate to ensure low energy consumption; 2) at higher product flow rates (≥2.00 SLPM/kg), decreasing the purge flow rate and increasing the adsorption pressure to eliminate N 2 breakthrough and O 2 -rich product waste, and appropriately increasing the feed flow rate to enhance cost-effectiveness. An improved set of parameters rendered O 2 purity (95.67–74.86%), recovery (11.28–49.05%), productivity (0.47–2.04 mmol/kg/s) increased by up to 3.52–20.08%, 0.36–20.47%, 6.82–19.61%, and energy consumption (4.07–0.95 kWh/kgO 2) decreased by up to 10.56–18.10%, in comparison to two conventional sets, respectively. The results are beneficial for developing intellectualized and flexibly-controlled O 2 concentrators for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distillation separation process is proposed to recover NO 2 and SO 2 from flue gases. • The feasibility of NO 2 /SO 2 distillation separation is theoretically verified. • A distillation process with advantageous dual-column liquid-phase feeding is designed. • Process optimization based on robust sensitivity analysis are demonstrated. • Significant economic benefits from the recovered NO 2 and SO 2 products are estimated. High-purity NO 2 and SO 2 have significant economic values and are widely used in many fields. The large amounts of NO 2 and SO 2 in industrial flue gases are worthy of recovery for environmental protection and economic benefits. In this work, a dual-column distillation separation process was proposed to further separate and upgrade NO 2 and SO 2 following a flue gas adsorption capture process. The feasibility of distillation separation of NO 2 /SO 2 from the desorbed gas, and the advantage of liquid-phase feeding way over gas-phase counterpart in terms of lower energy consumption (1286.39 kW) were demonstrated. Key process parameters such as the number of total stages, the feed stage number, the mole flow rate at bottom of column, the reflux ratio and operating pressure for the two columns (15, 6, 16.66 kmol/h, 0.16, 4 bar; 21, 10, 4.43 kmol/h, 0.50, 1 bar) were determined. Heat and mass transfers along the column height as well as the process robustness against feed composition fluctuation indicate its applicability for practical operation and adaptation to industrial needs. An economic analysis shows a significant annual revenue of 14,333.52 thousand USD based on high-purity (>99.5%) SO 2 and NO 2 products recovered from a typical scale (~1000,000 m3/h) of iron-ore sintering flue gas, not only offsetting the total operating cost of the entire adsorption capture-distillation recovery process but also generating net profit. [ABSTRACT FROM AUTHOR]

• Binary adsorption of N 2 and O 2 on FAU zeolites at plateau conditions is obtained. • Water interacting with zeolites via hydrogen bond competes with N 2 and O 2 adsorption. • Effect of water content is greater than that of temperature change on air separation. • Trade-off between N 2 /O 2 selectivity and performance stability is addressed. • X zeolite with Si/Al close to 1.5 is recommended for PSA O 2 production in plateau. Adsorption thermodynamics of N 2 and O 2 on faujasite (FAU) zeolites with different Si/Al molar ratios under plateau conditions of wide ranges of temperature and humidity for pressure swing adsorption (PSA) oxygen production were studied based on validated molecular simulations. Binary adsorption isotherms and N 2 /O 2 selectivity on each adsorbent were obtained. The results suggest that dehydrated feed air with very low dew point of 213 K could still lead to ~10 wt% water adsorption capacity in FAU zeolites. The effect of water content was larger than that of temperature change on N 2 /O 2 separation performance, causing reductions in N 2 /O 2 selectivity of 50.9% and affinities of 15.6% and 10.6% for N 2 and O 2 at 238 K, and those of 45.7%, 13.7% and 11.1% at 298 K on FAU-1.1, respectively. The strong interaction of water with zeolites via hydrogen bond was shown to decrease the pore volume by 25.61%, occupy the cationic sites, and thermodynamically form competitive adsorption over N 2 and O 2. The increase in Si/Al molar ratio suppressed the negative impact of water and temperature change but sacrificed the N 2 /O 2 selectivity. To reach an optimal balance between the air separation performance and the adsorbent robustness, X zeolites with Si/Al molar ratio close to 1.5 would be recommended for PSA O 2 production under the plateau special condition. [ABSTRACT FROM AUTHOR]

• The properties of ECSCs are controllable by adjusting the fuel in SCS process. • The superb S bet , V P, and V meso of ECSCs are beneficial to improve the naphthalene adsorption capacity. • ECSCs exhibit unprecedented high capacity, fast kinetics, and low desorption energy. Sorptive capture and recycling of gaseous naphthalene from industrial emissions are of both environmental significance and economic benefit. Constructing carbonaceous sorbents with matchable pore size and adequate active sites is significant towards the trade-off between adsorption and desorption for naphthalene. In this study, we developed a series of porous carbonaceous sorbents (ECSCs) using facile, inexpensive, and effective solution combustion synthesis (SCS) with subsequent calcination and pickling. The MgO@C precursors were fabricated via a fast and self-exothermic combustion reaction, and after calcination and MgO removal by pickling, the tailored pore structure was created. The morphology, porous structure, and surface chemical properties of ECSCs are precisely controlled by adjusting the type and content of fuel in combustion. For the optimized ECSC-G14 prepared on fuel-balanced condition, its layer-by-layer network facilitates adsorption mass transfer, and its high specific surface area (1987 m2·g−1) and abundant 3–6 nm mesoporosity promotes the accessibility of active sites. Consequently, an unprecedented high naphthalene uptake (3.075 mmol·g−1 at 398 K) and fast kinetics (∼1.43 × 10−2 s−1 at 2.82 × 10−3 mol·m−3 feed concentration) were achieved. Combined characterization and molecular calculation revealed the synergistic contribution of O and N to reversible adsorption with superb regenerability (E a of 42.71 kJ·mol−1) and cyclic properties. This study provides an effective strategy and theoretical support to customize the properties of porous carbons, overcoming the adsorption–desorption dilemma for gas purification. [ABSTRACT FROM AUTHOR]