Absorption Of NH3 Research Articles

Efficient and selective absorption of NH3 by supramolecular OHP[5]-based ternary deep eutectic solvents

Developing an efficient absorbent for selective ammonia capture is of significant importance in the recovery and utilization of ammonia resources. Herein, a series of supramolecular-based ternary deep eutectic solvents (DESs) was designed and prepared using per-hydroxy pillar[5]arene (OHP[5]) and ethylamine hydrochloride as the key components. It is found that the supramolecular-based ternary DES EaCl-Gly (1:2)-6% OHP[5] could be employed as an efficient absorbent for reversible absorption of NH3. The NH3 uptake capacity reached 2.39 mmol/g and 10.84 mmol/g at 298.2 K under the pressure of 10 kPa and 100 kPa, respectively. Meanwhile, a higher NH3/CO2 selectivity (84) was obtained at 298.2 K and 100 kPa owing to the low solubility of CO2 in EaCl-Gly (1:2)-6% OHP[5]. The results of 1H NMR and FTIR spectra further clarified the absorption mechanism of NH3 by EaCl-Gly (1:2)-6% OHP[5]. Accordingly, the chemical absorption and physical dissolution capacity of NH3 in EaCl-Gly (1:2)-6% OHP[5] were calculated on the basis of isotherm data and thermodynamic equations. This study offers a promising application of pillar[5]arene to form supramolecular-based DESs for efficient NH3 absorption.

Developing a novel technology for slurry management by project-based learning

Farming is responsible for 30% of global anthropogenic emissions. A novel technology, aligning with current regulations of covering slurry stores, has been developed for processing anaerobic digestate liquor, which is obtained from the screw press stage. Instead of using hazardous chemicals, such as sulfuric acid, to capture ammonia and greenhouse gases, the artifact contains calcium chloride as deliquescent salt. Preliminary simulations in Aspen Plus® v12 showed that the absorption of NH3 and carbon dioxide during the solid–liquid separation was feasible and the resulting clean brine could be used as chemical amendment of untreated slurry. The characterization of the performance of the artifact was organized following a project-based learning active teaching method, for a group of 3 students (17-year-olds) of secondary education, as part of the In2ScienceUK program. The collection of empirical data allowed the contents of the curriculum to be contextualized, enhancing environmental awareness of participants. A titrimetric method was employed to determine the content of NH3 and CO2 in the brine, and the granulation of the dewatered liquor with the fibers of anaerobic digestate was investigated by determining the compression strength required to break the pellets. The operation capacity of the prototype was found to be 250 m3 of liquor per year, at a cost of £1/m3. The use of the filtered brine as chemical amendment also represented an additional 5.60 grams of ammoniacal nitrogen and 0.96 grams of inorganic carbon per cubic meter of unprocessed slurry. The concentrated liquor was a good binding agent that provided the pellets with a compressive strength of 207.00 ± 26.36 N, which was above the threshold value for commercialization purposes (50 N). The advances in the development of the prototype enhanced the suitability of the technology for industrial scale applications but hindered the adoption of subsequent editions of this pedagogic tool.

Pressure-swing absorption and desorption behaviours of ammonia in bis(trifluoromethylsulfonyl)amide salts

The absorption and desorption behaviours of NH3 in bis(trifluoromethylsulfonyl)amide (TFSA) salts were investigated using the pressure-swing method.

Efficient and reversible separation of NH3 by deep eutectic solvents with multiple active sites and low viscosities

The efficient separation and collection of ammonia (NH3) during NH3 synthesis process is essential to improve the economic efficiency and protect the environment. In this work, ethanolammonium hydrochloride (EtOHACl) and phenol (PhOH) were used to prepare a novel class of deep eutectic solvents (DESs) with multiple active sites and low viscosities. The NH3 separation performance of EtOHACl + PhOH DESs was analyzed completely. It is figured out that the NH3 absorption rates in EtOHACl + PhOH DESs are very fast. The NH3 absorption capacities are very high and reach up to 5.52 and 10.74 mol·kg−1 at 11.2 and 100.4 kPa under 298.2 K, respectively. In addition, the EtOHACl + PhOH DESs present highly selective absorption of NH3 over N2 and H2 and good regenerative properties after seven cycles of absorption/desorption. The intrinsic separation mechanism of NH3 by EtOHACl + PhOH DESs was further revealed by spectroscopic analysis and quantum chemistry calculations.

Ethanolammonium chloride-glycerol deep eutectic solvents for efficient and reversible absorption of NH3 through multiple hydrogen-bond interaction

Efficiently separating NH3 from the exit gas of NH3 synthesis tower has significant economic and environmental benefits, such as improving the NH3 conversion rate and reducing pollution emission. In this study, a series of EtOHACl + Gly deep eutectic solvents (DESs) with numerous hydrogen-bond sites were synthesized. The findings suggest that the use of EtOHACl + Gly DESs can result in both exceptional NH3 absorption capacities and superior selectivities. EtOHACl + Gly (1:2) has the NH3 capacities of up to 12.39 mol/kg at 298.2 K and 105.5 kPa, while its N2 and H2 capacities are negligible. Additionally, the absorbed NH3 can be easily released by heating and reducing pressure, and the NH3 capacities remain stable after undergoing six cycles. The study also examined the interaction mechanism of EtOHACl + Gly DESs for the NH3 separation, utilizing spectral characterizations, quantum chemistry calculations and molecular dynamics simulations.

Mathematical model and experiment investigation on electrodialysis separation process of LiBr from NH3-H2O-LiBr ternary solution in ammonia absorption refrigeration system

The utilization of NH3-H2O-LiBr ternary working fluid is effective to improve the COP of the ammonia absorption refrigeration system (AARS). However, LiBr impairs the absorption of NH3 in the absorber and consequently limits the COP promotion. To address this limitation, electrodialysis (ED) is introduced into AARS to reduce the LiBr concentration in the absorber because it has been widely applied in ion separation from industrial waste solutions. In this study, a simulation model for the NH3-H2O-LiBr ternary solution ED separation process was developed based on the overall mass transfer equation. Experiments were conducted to measure and verify the coefficients in the model. The results showed that the NH3 transport was hard to be separated by ED. For the LiBr, the overall transport number and the overall electro-osmotic permeability were −3.49 × 10−3 kg min−1 A−1 and -1.33 × 10−4 L min−1 A−1. The overall diffusion permeability, overall osmosis permeability, and average resistance were dependent on the LiBr concentrations in the solutions. Moreover, the influences of ED parameters on the LiBr separation were studied using the model and the energy efficiency was applied to evaluate the separation performance. The energy efficiencies were 0.0325 and 0.323 when the membrane pair exceeded 10 and the membrane effective area (Aeff) surpassed 0.0325 m2. The energy efficiency increased with the decrease of current density and the increase of LiBr concentration difference between the two solutions. Moreover, an effective method was built to obtain a set of suitable ED parameters that meet high ED energy efficiency and the LiBr separation requirements in AARS.

Intensification of absorption rate of carbon dioxide and ammonia in a simulated packed (Stephens–Morris) column using pulsed gas phase under optimized parametric conditions

BackgroundReducing gas emissions is a significant challenge in our ecosystem. Gas-liquid absorption is used in chemical industry to remove components from gas streams. Stephens–Morris tube, known for liquid-liquid and gas-liquid systems, has gained attention for gas absorption columns utilizing disc-shaped packing elements to improve mass transfer by creating tortuous flow path. MethodsThis investigation focuses on physical absorption of CO2 and NH3 in gas-liquid systems based on various process parameters vis. liquid flow rate (0.24–0.60 L/min), gas flow rate (6–60 L/min), pulsation frequency (0–9.06 Hz), pulsation amplitude (0–26 mm), effect of solute gas concentration (0–100 %), and effect of varying the number of discs in the disc column (15, 20, 25, 33). Response Surface Methodology (RSM) was used to predict maximum absorption efficiency under optimized conditions. Significant FindingsPulsation frequency and amplitude proportionally increased absorption coefficient, while liquid flow rate affected it differently in pulsed and unpulsed absorption. In gas film-controlled system, mass transfer coefficient was proportional to the gas flow rate. RSM yielded R2 of 0.975 while relative error and dwill was 0.097 and 0.96, respectively. Understanding system characteristics and operations at optimal pulsation frequencies and amplitudes can maximize absorption effectiveness, particularly for low-solubility gases dominated by liquid phase resistance.

Efficient absorption of low pressure NH3 by non-ionic phenol-based deep eutectic solvents with multiple acidic sites

In chemical industry, efficient absorption of ammonia (NH3) from industrial exhaust remains a challenge and significant issue for resource utilization and pollution control. Present study proposed a new strategy to design non-ionic deep eutectic solvents (DESs) using phenolic analogues. Several phenol-based DESs with multiple acidic sites were constructed by paring catechol (Cat) or resorcinol (Res) with phenol (PhOH) and investigated as feasible NH3 absorbents from physical property, NH3 absorption performance, and mechanism analysis. Among the as-obtained DESs, Res/PhOH (1:3) demonstrated attractive NH3 absorption capacity at 303.15 K (11.862 mol/kg at 101.3 kPa, and 6.391 mol/kg at 5.0 kPa), surpassing most DESs and ionic liquids (ILs) reported in the literatures. Meanwhile, it displayed good reversibility, satisfactory thermal stability, and high NH3/CO2 selectivity. The mechanism of NH3 absorption was further elucidated using FTIR and NMR spectra, and Quantum chemistry calculation, and inferred as the strong and multiple interaction between NH3 and weakly acidic sites of DESs.

Protic amino-2-propanol hydrochloride-based deep eutectic solvents with multiple hydrogen bond sites for efficient capture of NH3

The ammonia (NH3) emitting into the atmosphere during the industrial process of synthesizing ammonia not only constitutes serious air pollution, but also causes a waste of ammonia resources. Therefore, there is an urgent need to develop efficient ammonia capture technology. In this work, we report an efficient capture of NH3 by protic amino-2-propanol hydrochloride-based deep eutectic solvents (DESs). These DESs with multiple hydrogen bond sites exhibit remarkable NH3 uptake with up to 0.244 g NH3 per g DES at 293 K and 1 bar and good recyclability. Further mechanism study suggested that the introduction of hydrogen bond donors with rich hydroxyl groups provides a large number of hydrogen bond sites to achieve efficient absorption of NH3 through the intermolecular hydrogen bonds interaction. This research has obtained an alternative absorber for the capture of NH3, and it also provides ideas for the design of high-efficiency NH3 deep eutectic solvents absorbent.

IMPREGNATED FIBROUS CHEMISORBENTS FOR THE COLORIMETRIC DETECTION OF AMMONIA

The paper presents research results on the colorimetric behavior of impregnated fibrous chemisorbents (IFCS) of basic gases with visual identification of the dynamic absorption capacity “response” moment (IFCS-I) during the absorption of ammonia. Chemisorbents were obtained by impregnation of fibrous carriers with polybasic hydroxyl acid aqueous solutions with adding acid-base indicators (Ind). IFCS-I based on oxyethylenediphosphonic (IFCS-OEDPA-I), citric (IFCS-CA-I), and malic (IFCS-MA-I) acids were used. Azolithine (Az), lakmoid (LA), methyl orange (MO), methyl red (MR), Tropeolin OOO (TrOOO), Congo red (CoR), bromocresol green (BCG), broxylenol blue (BXB), bromophenol blue (BPB), bromophenol red (BPR), thymol blue (TB), xylenol orange (XO), and phenol red (PR) were used as acid-base indicators. The specificity of the changes in the colorimetric functions of IFCS-I during the absorption of NH3 by them was revealed. It was found that the color of the initial IFCS-I samples significantly depended not only on the structure of Ind, but also on the nature of the polybasic hydroxy acid being part of them. The colors of the samples based only on OEDPA (Ind = CoR, BCG, BPB), CA (Ind = CoR, TrOOO, BCG, BPB, BPR, XO) and some MA (TrOOO, BCG) are similar to the colors of aqueous solutions of Brönsted acids. The difference in the colors of the other samples from the colors of strong acid aqueous solutions with the same Ind is apparently due to specific interactions between hydroxy acid anions and neutral dye forms. During “response” to NH3 only some IFCS-I samples based on OEDPA (Ind: MO, TrOOO, Az and BPR), CA (Ind: CoR, MR, MO, TrOOO, BXB, BPR, TB, PR) and MA (Ind: LA, MR, MO, Az, BXB, XO, TB, PR) are discolored in contrast to the behavior of SO2 indicator chemisorbents.

Ultra-high NH3 absorption by triazole cation-functionalized ionic liquids through multiple hydrogen bonding

Ionic liquids (ILs) are considered as prospective absorbents for NH3 separation and purification owing to extremely low vapor pressure, great affinity and structural tunability. Up to date, versatile ILs for NH3 absorption have been developed, but NH3 mass capacity of all the reported ILs or IL-based absorbents are still not comparable to that of traditional water absorbent. How to simultaneously improve NH3 mass capacity, selectivity and keep stable reversibility using IL absorbents is still a great challenge. In this work, the triazole cation-functionalized ionic liquids (TCFILs) by introducing multiple protic H sites into N-heterocyclic cations were firstly designed and synthesized for enhancing NH3 absorption. These TCFILs showed superhigh NH3 mass capacity up to 0.365 g NH3/g IL at 30 °C and 1 bar, which is the maximum among the reported absorbents, and is even comparable to that of traditional water absorbent used in industrial. Moreover, the TCFILs also exhibited excellent selectivity of NH3/CO2 up to 182 and recycling stability. Such great comprehensive performances of NH3 absorption and separation were proved to originate from multiple hydrogen bonding between NH3 and protic hydrogens of the TCFIL cations. Therefore, this work will provide useful guidance to design competitive functionalized ILs for efficient and reversible absorption of NH3.

Polyol-Mediated Synthesis of V2O5-WO3/TiO2 Catalysts for Low-Temperature Selective Catalytic Reduction with Ammonia.

We demonstrated highly efficient selective catalytic reduction catalysts by adopting the polyol process, and the prepared catalysts exhibited a high nitrogen oxide (NOX) removal efficiency of 96% at 250 °C. The V2O5 and WO3 catalyst nanoparticles prepared using the polyol process were smaller (~10 nm) than those prepared using the impregnation method (~20 nm), and the small catalyst size enabled an increase in surface area and catalytic acid sites. The NOX removal efficiencies at temperatures between 200 and 250 °C were enhanced by approximately 30% compared to those of the catalysts prepared using the conventional impregnation method. The NH3-temperature-programmed desorption and H2-temperature-programmed reduction results confirmed that the polyol process produced more surface acid sites at low temperatures and enhanced the redox ability. The in situ Fourier-transform infrared spectra further elucidated the fast absorption of NH3 and its reduction with NO and O2 on the prepared catalyst surfaces. This study provides an effective approach to synthesizing efficient low-temperature SCR catalysts and may contribute to further studies related to other catalytic systems.

A shock-tube study of NH3 and NH3/H2 oxidation using laser absorption of NH3 and H2O

Ammonia (NH3) is an attractive carbon-free fuel, yet its low reactivity presents many challenges for direct use in combustion applications. These combustion challenges could be resolved by mixing NH3 with more reactive fuels such as hydrogen (H2). To further contribute to NH3 and NH3/H2 kinetics—which arguably still requires much improvement—new experiments were conducted over a wide range of temperatures (1474–2307 K), near-atmospheric pressure, several NH3/O2 mixtures (equivalence ratios varying from 0.56 to 2.07), and near-stoichiometric NH3/H2/O2 mixtures with NH3:H2 ratios of 80:20 and 50:50. During these experiments, laser absorption diagnostics near 10.4 µm and 7.4 µm were simultaneously employed to measure NH3 and H2O time histories, respectively. Characteristic parameters, such as NH3 half-life time and H2O induction delay time, were extracted from the time-history profiles, and these parameters present stringent speciation targets for mechanism validation. After an assessment of most modern kinetics models, three, most accurate, mechanisms were compared against the experimental results. Only one model was able to partially reproduce the pure NH3 experiments, yet none of the models were capable of predicting the NH3/H2 experiments. Reaction pathway analysis showed that NH3 oxidation proceeds via forming NH2 then followed three different routes to form N2. Importantly, the models considered showed different levels of importance for each route. Sensitivity analysis showed that the NH3/H2 experiment is mostly sensitive to NH3+OH⇄NH2+H2O. Interestingly, this reaction showed no sensitivity for the NH3/O2 experiments. Overall, the models exhibited significantly slower reactivity than the NH3/H2 experiments, and the kinetics analysis showed that the start of this reactivity is governed by the levels of H-atoms in the early stages of the experiments. At these early stages of the experiments, propagation and branching reactions in the H2/O2 system are the main contributors to generating H radicals, along with the reaction NH3+H⇄NH2+H2 which proceeds in its reverse direction.

Molecular insight into the effect of ion structure and interface behavior on the ammonia absorption by ionic liquids

AbstractMolecular dynamics simulations were performed to elucidate the roles of ion structure and interface behavior in absorption of gases (NH3, N2, H2) by ILs (protic IL [Bim][Tf2N] and conventional IL [Bmim][Tf2N]). The results indicated that NH3 compete with [Tf2N]− to interact with N3‐H site of [Bim]+ cation, forming a strong N3H∙∙∙N(NH3) hydrogen bond with the energy of −79 kJ/mol, which is twice as much as the energy of the hydrogen bond between C2H of [Bmim]+ and NH3 (−33.2 kJ/mol). Moreover, there is a dramatic increase in the number density of cations near the IL‐gas interface, resulting in the NH3 molecules permeate into the bulk rapidly and effectively and achieving the high selective absorption of NH3 to H2 and N2. Considering the inevitable trace water in the raw gases, the influence of water was studied and it was shown that trace water can enhance the absorption of NH3 by [Bim][Tf2N].

Chelation‐activated multiple‐site reversible chemical absorption of ammonia in ionic liquids

AbstractDeveloping new and facile strategies for multiple‐site reversible chemical absorption of pollutant gases is of wide interests in chemical engineering research. Herein, a series of lithium (Li)‐triethylene glycol (TEG)–chelated ionic liquids (ILs) with crown‐ether‐like cation and different anions were designed. The Li‐TEG–chelated ILs were prepared in quantitative yields by simply mixing equimolar TEG and Li salts. It is found that the chelation of TEG with Li+ activates the hydroxyl sites in TEG for strong interaction with ammonia (NH3). Thus, the hydroxyl sites chelated with Li+, as well as the chelation‐unsaturated Li+, provide the multiple sites for chemical absorption of NH3 in Li‐TEG–chelated ILs. Moreover, the absorption of NH3 in Li‐TEG–chelated ILs is totally reversible, with the NH3 solubilities remaining unchanged after eight times of recycling. The results obtained herein can provide useful guidance for the construction of gas absorbents with high capacity and excellent reversibility.

Highly efficient absorption and separation of NH3 by simple lithium deep eutectic solvents

• Serials of metallic DES with multiple binding sites for NH 3 were prepared. • The as-obtained DESs demonstrates efficient and reversible absorption for NH 3 . • LiCl/EG (1:3) DES possesses absorption high up to 0.219 g NH 3 per g DES. • The absorption behavior was systematically investigated. • The ideal selectivity of NH 3 /CO 2 was as high as 389.7. It remains a challenge in chemical industry to achieve highly efficient and reversible capture of ammonia (NH 3 ) for improving environment and ecology. In this work, new lithium deep eutectic solvents (DESs) by pairing simple lithium salt with various hydrogen bond donors of ethylene glycol (EG), formamid (FM), glycerol (Gly), 1,3-dimethyl-2-imidazolidinone (DMI), and N, N'-dimethylpropyleneurea (DMPU) were conducted. Their physical properties were characterized and NH 3 absorption performance were investigated from the parameters of temperature, gas flow rate, molar ratio, different HBAs and HBDs. Results demonstrated that LiCl/EG (1:3) DES possessed fast absorption rate, exceptional NH 3 absorption mass ratio of 0.219 g g −1 and high NH 3 /CO 2 selectivity of 389.7 at 303.15 K, exceeding all the reported metallic ILs and IL-based DESs. 1 H NMR and FT-IR spectra analysis implied that the excellent performance was originated from the comprehensive interaction of lithium and hydroxyl groups with NH 3 . Present work will provide useful idea for designing metallic DESs for NH 3 separation applications.

Joint Method for the Experimental and Computational Characterization of Ammonia Absorption Columns

AbstractWell‐designed absorption columns are indispensable to industry. A prototypical system is the absorption of gaseous NH3. This experiment employed the method of transfer units where collection of vapor (V) and liquid (L) flow rates and concentrations enabled the characterization of the number of transfer units (NTU), height of transfer unit (HTU), and overall gas phase mass transfer coefficient (Ky). A nonmonotonic relationship between V, L, NTU, and HTU values was found; Ky showed a monotonic relationship with V and L. Computer‐simulated, correlation‐based, and experimental NTU, HTU, and Ky values demonstrated close numerical similarities. This experiment highlighted the importance of a combined empirical, theoretical, and simulation approach in achieving more reliable results from absorption column analysis.

Designing Low-Viscosity Deep Eutectic Solvents with Multiple Weak-Acidic Groups for Ammonia Separation

Developing NH₃ separation technology with high efficiency is very meaningful for the advancement of the NH₃ synthesis process. In this work, a new class of deep eutectic solvents (DESs) were designed by pairing N,N,N′,N′-tetramethyl-1,3-propanediamine dihydrochloride ([TMPDA]Cl₂) with phenol (PhOH) at the molar ratios of 1:3∼7. [TMPDA]Cl₂ + PhOH DESs have multiple weak-acidic groups and viscosities of as low as 48.1 cP at 298.2 K. They also exhibit excellent performance for the separation of NH₃, showing not only efficient and selective but also reversible absorption of NH₃. Especially, the solubilities of NH₃ in [TMPDA]Cl₂ + PhOH DESs at low pressures can reach 4.49 mol/kg of NH₃ at 298.2 K and 13.3 kPa, being superior to those of most of the DESs and ILs reported in the literature. The mechanism of NH₃ absorption was further elucidated by quantum chemistry calculations and ¹H NMR spectra. It is validated that the efficient absorption of NH₃ in DESs origins from the strong interaction of multiple weak-acidic groups of DESs with NH₃.

Highly efficient and selective separation of ammonia by deep eutectic solvents through cooperative acid-base and strong hydrogen-bond interaction

Exploring absorbents showing low volatility, high efficiency and good reversibility for NH3 absorption is of great significance. In this work, a novel class of DESs with both weak acid site and strong hydrogen-bond donating site were designed by using imidazolium hydrogen chloride ([ImH]Cl) and glycerol (Gly) as the motifs. The densities, viscosities and thermal stabilities of DESs were measured first. Then, the solubility, reversibility and selectivity of DESs for NH3 absorption were investigated systematically. It is found that the absorption of NH3 in DESs is chemical type, and there is strong interaction existing between DESs and NH3. As a result, the NH3 solubilities of DESs are very attractive especially at low pressures, with the values of 12.934 mol/kg at 298.2 K and 101.3 kPa, and 4.450 mol/kg at 298.2 K and 10.0 kPa. The NH3 absorbed by DESs can be easily desorbed by heating and evacuating. Moreover, the absorption of N2 and H2 in DESs is negligible, and has little effect on the absorption of NH3. Finally, the underlying mechanism of NH3 absorption was examined by theoretical and spectroscopic technique.

Canopy uptake of volatilized 15NH3 derived from urea applications by tomato (Lycopersicum esculentum Mill.) in plastic-shed vegetable production systems

The absorption of NH3 by the tomato canopy and the dynamics of this process in the plastic-shed vegetable production systems have not been reported. To quantify the contribution of the leaf absorption of 15NH3, two field experiments were established to measure the amount of NH3 translocated and recovered cumulatively (Experiment Ⅰ) and instantaneously (Experiment Ⅱ) by tomato canopy. Four applications of 15N-labeled urea as side dressing using a plastic tray method to simulate field management conditions. This experimental procedure prevented the uptake of N from the labeled urea by the roots. The results showed that total NH3 loss accounted for 17.9 % of the N applied using the tray method, with average losses of 21.5 % and 14.3 % during the summer and winter growing seasons, respectively. The average canopy absorption of volatilized 15NH3 was 12.2 % of the total N applied and the average canopy absorption rate of 15NH3 reached to 2.81 % of the total 15N-urea applied. Additionally, an average of 44.13 % of the absorbed 15NH3-N was transferred into the tomato fruit. Across four growth stages, whole-plant 15N accumulation increased gradually over the first three stages, with peak absorption occurring during the topping and pruning stage. Then, absorption rates decreased significantly during harvesting. NH3 uptake by the tomato canopy was significantly more dynamic in summer than in winter. Our findings shed significant light on how NH3 is taken up by the greenhouse tomato canopy and can contribute to improving the sustainability of agricultural systems.