Enthalpy Of Absorption Research Articles

Harvesting CO2 reaction enthalpy from amine scrubbing

Amine-based CO2 capture technology suffers high energy consumption, of which the exergy loss of CO2 absorption enthalpy is a significant contributor to the process irreversibility. Recovery and utilisation of CO2 absorption enthalpy is therefore of paramount significance to advance amine technology towards low capture cost. The present study proposed a reaction enthalpy harvesting amine process (REHA) with the purpose to directly utilise the CO2 absorption enthalpy for building heating. In the REHA process, we redefine the operational conditions of CO2 capture process with dual targets of high capture performance as well as high enthalpy recovery. It is revealed that using the benchmark mono-ethanolamine (MEA) absorbent 1.62 GJ/tonne CO2 could be harvested though process modification and multiple heat extraction, enabling a high energy recovery efficiency of 82%, whilst maintaining 90% absorption efficiency and low heat requirement of 2.6 GJ/tonne CO2. Integration of REHA with CO2 capture process enables an appreciable cost of CO2 avoided decreased from $63.5/tonne to $54/tonne CO2 (16% reduction) at a heat price of $7/GJ and 5-months heat supply. The economic viability of REHA process is anticipated to be further promoted with the rise of heating price and increasing demand of space heating.

Thermodynamic improvement of lithium hydrides for hydrogen absorption and desorption by incorporation of porous silicon

Lithium is a popular lightweight material in the field of energy storage because of its hydrogen-binding properties and electrochemical advantages. The high hydrogen uptake capacity (∼12.6 wt%) of lithium hydride (LiH) is limited by the major thermodynamic constraint of requiring a higher temperature (∼700 °C) for desorption at 0.1 MPa. Incorporating a third element that creates Li phases during LiH dehydrogenation can help overcome thermodynamic constraints. This study involves modifying the hydrogen storage properties and thermodynamic characteristics of LiH through mechanical alloying with porous silicon (PS). Pressure composition isotherms measure the reversible hydrogen storage capacity (∼3.39 wt%) of LiH-PS alloy at different temperatures. The energy of hydrogen interaction is quantified by isosteric heat of absorption, which provides the enthalpy change in the reaction system. Hydrogen absorption and desorption enthalpies of 94.5 kJ (mol H2)−1 and 114.9 kJ (mol H2)−1 demonstrate the lowest energy demand among previously reported LiH alloys. The energy of hydrogen interaction is quantified by isosteric heat of absorption, which provides the enthalpy change in the reaction system. The hydride decomposition of the alloy indicates the possible range of hydrogen desorption.

Zwitterionic "Solutions" for Reversible CO2 Capture.

The zwitterions resulting from the covalent attachment of 3- or 4-hydroxy benzene to the 1,3-dimethylimidazolium cation represent basic compounds (pKa of 8.68 and 8.99 in aqueous solutions, respectively) that chemisorb in aqueous solutions 0.58 mol/mol of carbon dioxide at 1.3 bar (absolute) and 40 °C. Equimolar amounts of chemisorbed CO2 in these solutions are obtained at 10 bar and 40 °C. Chemisorption takes place through the formation of bicarbonate in the aqueous solution using imidazolium-containing phenolate. CO2 is liberated by simple pressure relief and heating, regenerating the base. The enthalpy of absorption was estimated to be -38 kJ/mol, which is about 30 % lower than the enthalpy of industrially employed aqueous solutions of MDEA (estimated at -53 kJ/mol using the same experimental apparatus). The physisorption of CO2 becomes relevant at higher pressures (>10 bar) in these aqueous solutions. Combined physio- and chemisorption of up to 1.3 mol/mol at 40 bar and 40 °C can be attained with these aqueous zwitterionic solutions that are thermally stable and can be recycled at least 20 times.

The Effect of Different Milling Methods on the Physicochemical and In Vitro Digestibility of Rice Flour.

Preparation methods have been found to affect the physical and chemical properties of rice. This study prepared Guichao rice flour with wet, dry, semi-dry, and jet milling techniques. Differences in the particle size distribution of rice flour were investigated in order to assess their impact on pasting, thermal, gel, starch digestibility, and crystalline structure using an X-ray diffractometer (XRD) and a Rapid Visco Analyzer (RVA) across in vitro digestibility experiments. The results showed that semi-dry-milled rice flour (SRF) and wet-milled rice flour (WRF) were similar in damaged starch content, crystalline structure, and gelatinization temperature. However, compared with dry-milled rice flour (DRF) and jet-milled rice flour (JRF), SRF had less damaged starch, a higher absorption enthalpy value, and a higher gelatinization temperature. For starch digestibility, the extended glycemic index (eGI) values of WRF (85.30) and SRF (89.97) were significantly lower than those of DRF (94.47) and JRF (99.27). In general, the physicochemical properties and starch digestibility of WRF and SRF were better than those of DRF and JRF. SRF retained the advantages of WRF while avoiding the high energy consumption, high water consumption, and microbial contamination disadvantages of WRF and was able to produce better rice flour-associated products.

Equilibrium absorption of CO2 in aqueous solution of N-dimethylamino ethanol and 2-(ethylamino)ethanol, measuring and thermodynamic modeling

The equilibrium carbon dioxide solubility in aqueous solutions of N-dimethylaminoethanol (DMAE) 40 wt% + 2-(ethylamino) ethanol (EAE) 5 wt% and DMAE 30 wt% + EAE 5 wt% was measured at various temperatures (313.15, 328.15, 343.15, 358.15 K) in the range of pressures from 6.5 to 236 kPa. The enthalpy of absorption of carbon dioxide was measured for the mixture of DMAE (40 wt%) + EAE (5 wt%), at 328.15 K. The Deshmukh-Mather model was used to correlate the equilibrium solubility of carbon dioxide data, and the model parameters were optimized. The optimized model could correlate the vapor-liquid equilibrium with the 9.4 average absolute percentage deviation (AAD%), and the obtained AAD% for enthalpy of absorption in aqueous solution of DMAE (40 wt%) + EAE (5 wt%) was 24.0.

A promising artificial intelligence-based tool to simulate the efficient and sustainable hydrogen sulfide elimination using deep eutectic solvents

This work applies artificial intelligence (AI) methodologies and relevance tests to investigate the hydrogen sulfide (H2S) elimination capacity of a wide range of DESs (deep eutectic solvents). A great deal of effort is made to deploy a practical model to predict the H2S removal ability of eighteen different DESs as a function of DES chemistry, equilibrium conditions, and H2S-DES interaction. Multiple linear regression and Pearson’s correlation methods are employed to measure the direction and relative influence of hydrogen bond acceptor (HBA), hydrogen-bond donor (HBD), the HBA and HBD concentration, water dose, pressure, temperature, and absorption enthalpy on the DES capacity to absorb H2S molecules. Both tests approve that absorption enthalpy (ΔH) of H2S by DESs, hydrogen bond acceptor (HBA), pressure, and temperature mainly control the considered separation process. The relevance tests also identify that the H2S solubility in DESs improves by either a decrease in ΔH, HBA molecular weight, and temperature or an increase in pressure. Then, five diverse AI types are applied to estimate H2S molality in DESs as a function of the involved explanatory variables, and their accuracy is compared. The sensitivity analysis clarifies that the cascade neural network (CNN) with only 20 hidden nodes is the most reliable AI tool to simulate the considered problem. Further investigations approve that the CNN tool provides more accurate predictions for H2S solubility in DESs when it is equipped with the logarithm and tangent sigmoid transfer functions in the hidden and output neuronic layers. Also, amongst eleven checked training algorithms, the Levenberg-Marquardt presented the best performance. This structure-regulated CNN tool can predict 512 actual H2S solubility records in DESs with the MSE = 0.0031, MAE = 0.02, RAE = 2.03%, AARE = 3.03%, and multiple-R = 0.99943.

Acidic protic ionic liquid‐based deep eutectic solvents capturing SO2 with low enthalpy changes

AbstractWith the aim of lowering energy consumption for gas regeneration, rational design of absorbents with low absorption enthalpy changes while retaining good gas solubility is of both scientific and practical significance. Herein, we demonstrated that acidic protic ionic liquid (APIL)‐based deep eutectic solvents (DESs), which comprise N‐ethylimidazole hydrochloride ([EimH]Cl) and ethylene glycol (EG), were able to reversibly absorb SO2 with high solubility (11.60 mol kg−1) and SO2/CO2 selectivity (655) at 293.2 K and 101.3 kPa. Meanwhile, [EimH]Cl/EG DESs exhibit very low enthalpy changes (ΔrHm) ranging from −27.1 to −25.6 kJ mol−1, and thus ease of desorption at very mild temperature conditions (303.2 K) with desorption ratios up to 99.6%. Recycling experiments showed that no obvious loss in capacity was found after six absorption–desorption cycles, suggesting good regeneration performance of [EimH]Cl/EG DESs. Moreover, spectroscopic analysis revealed the charge‐transfer interaction between [EimH]Cl/EG and SO2.

COSMO-RS predictive screening of type 5 hydrophobic deep eutectic solvents for selective platform chemicals absorption

Platform chemicals are crucial to the development of designer chemicals in industry; however, the utilization of these chemicals is limited from requiring separation from an aqueous phase. Type 5 hydrophobic deep eutectic solvents (HDES) have recently proven their ability to extract various low concentration solutes from aqueous solution. However, identifying a suitable HDES experimentally is a daunting task due to the large number of hydrogen bond donors (HBD), hydrogen bond acceptors (HBA), and their mixing ratio, with the HDES being ever increasing. In this study, Conductor-like Screening MOdel for Real Solvents (COSMO-RS) was utilized for over one hundred HDES and their relative solubilization ability for sorbitol, 5-hydroxymethyl furfural, and levulinic acid. Moreover, energetic mechanisms of solubilization were analyzed through the prediction of sigma profiles, sigma potentials, activity coefficients, and excess enthalpy of absorption. COSMO-RS results show that HBAs with tetra alkyl chains and amino acid-based HBDs are suitable HDES components for absorbing sorbitol, 5-hydroxymethyl furfural, and levulinic acid through a combination of van der Waals and hydrogen bonding interactions. These interactions are quantitatively examined through calculated excess enthalpy predictions, for example tetrabutylammonium bromide and arginine with a compositional ratio of 8:1, respectively, had an excess enthalpy of mixing with HMF of −7.9 kcal/mol despite the steric hindrance factor valuing ∼ 4.0 kcal/mol.

Efficient and Reversible Capture of CO2 in CO2-Binding Organic Liquids Formed by 1,1,3,3-Tetramethylguanidine and Glycerol Derivatives

A class of CO2-binding organic liquids (CO2-BOLs) composed of 1,1,3,3-Tetramethylguanidine (TMG) and Glycerol (Gly) and Gly’s amino derivatives were developed for highly efficient and reversible CO2 capture. These CO2-BOLs exhibited high gravimetric CO2 solubility up to 0.196 g CO2·g–1 at 313.2 K and 1.0 atm, superior to most functionalized ILs and other absorbents. The influential factors of CO2 absorption, such as components of CO2-BOLs, absorption temperature, and CO2 partial pressure together with water contents were investigated, and the recyclability of CO2-BOLs was verified to be excellent. The absorption mechanism of CO2-BOLs was explored with the help of spectral analysis, quantum chemical calculation, and thermodynamic analysis. All the results revealed that chemisorption took place once these CO2-BOLs were exposed to CO2, and alkyl guanidine carbonates were produced. Besides, it is illustrated that introducing the amino group to Gly could reduce the nucleophilic reactivity of CO2-BOLs, along with the absorption enthalpy simultaneously.

Thermodynamic model for CO2 absorption in imidazolium-based ionic liquids using cubic plus association equation of state

In order to achieve efficient capture of carbon dioxide (CO2) by ionic liquids (ILs), IL with good performance of high CO2 absorption capacity and low energy consumption need to be explored. Density, heat capacity, CO2 solubility and absorption enthalpy are key properties for the performance evaluation of IL solvents. In this work, the cubic plus association equation of state (CPA EoS) was applied for the integrated modelling of above properties in CO2 physical and chemical absorption by 22 imidazolium-based ILs. The results show that the density, heat capacity of pure ILs and CO2 solubility in a broad range of temperature (281–403 K) and pressure (0.1–23 MPa) were accurately calculated with deviations less than 1.27%, 0.54% and 3.73%, respectively. CO2 chemisorption was satisfactorily described by CPA EoS with an error of 0.12% considering interactions for the reactive sites between CO2 and amino groups in IL. Furthermore, the prediction capabilities of CPA EoS were verified with results showing good quantitative agreement with density and solubility data in literature. The effects of structures of ILs studied in this work on the CO2 solubility and absorption enthalpy were analyzed. [NH2emim][BF4], [Omim][Tf2N] and [Emim][eFAP] were found to have better performance of CO2 absorption. This model provides a feasible approach to determine synthetically the key properties of CO2-IL systems for the selection of proper ILs, design and simulation of the CO2 capture process.

A systematic approach based on artificial intelligence techniques for simulating the ammonia removal by eighteen deep eutectic solvents

The current research attempts to model the ammonia removal capacity of deep eutectic solvents (DES) employing artificial intelligence (AI) techniques. Four well-known AI classes apply to estimate the ammonia dissolution amount in eighteen DESs. The DES chemistry (type, molar concentration of components, and water dose), equilibrium temperature/pressure, and DES-ammonia absorption enthalpy help AI models estimate the ammonia solubility in DESs. The combination of trial-and-error and statistical analysis determines the best structure of AI models first. Then, several well-established model selection strategies apply to find the highest-accurate AI class. It was found that the adaptive neuro-fuzzy inference system (ANFIS) is more reliable than the other tested AI models. The designed ANFIS model precisely estimates 1356 experimental samples of ammonia removal by DESs with the mean absolute relative deviation percent of 3.51, mean absolute deviation percent of 0.121, root mean squared error of 0.216, and correlation of determination of 0.9980. The selected AI model monitors the influence of DES components, molar dose, equilibrium pressure, and equilibrium pressure on ammonia elimination by these green solvents. Both trend and relevancy investigations approved that the ammonia absorption tendency of DESs intensifies by increasing the equilibrium pressure, absorption enthalpy, the number of moles of hydrogen bond acceptor (HBA), and molecular weight of hydrogen bound donor (HBD). In addition, increasing the equilibrium temperature, water dosage in DES structure, HBA molecular weight, and the number of HBD moles decreases ammonia removal by DESs.

Diamine based hybrid-slurry system for carbon capture

Hybrid adsorption-absorption slurry systems are very attractive for CO2 capture, given their ability to simultaneously lower regeneration energy and increase absorption rate and uptake, because of enhanced mass and heat transfer mechanisms. In this work, novel hybrid slurries were formulated from the dispersion of 1 wt.% of solid adsorbents in a water-lean solvent of 30 wt.% of Tetramethyl-1,3-diaminopropane (TMPDA) + 10 wt.% Ethanol (EtOH) for CO2 capture. Different solid particles were suspended in the water-lean solvent such as activated carbon, ion-exchanged zeolite Y (Mg-Y), and polyethyleneimine doped silicas (PEI-SG and PEI-MCM-41). The CO2 uptake of the solid and fluid components of the slurries was confirmed by pH, density, and Fourier transform infrared analysis. The neat water lean solvent reduced the absorption energy by 16 % and slightly increased the CO2 uptake by 0.6 % compared to the aqueous TMPDA solvent. Additionally, the hybrid slurries exhibited further reductions in absorption energy of 10 – 30 % compared to the benchmark TMPDA-based solvents. The PEI-MCM-41-based slurry presented the highest CO2 uptake of 0.33 g CO2.g−1 and lowest regeneration energy of 2261.30 kJ.kg−1 among the studied systems. Additionally, the hybrid slurry exhibited a 21 % reduction in CO2 uptake compared to the benchmark 30 wt.% aqueous monoethanolamine (MEA) and similar capacity to aqueous methyl diethanolamine (MDEA), however, resulting in a far higher reduction in absorption enthalpy of 56 %, and 29 % compared to aqueous MEA and MDEA, respectively. The results obtained here encourage further development and optimization of hybrid slurry systems as potential efficient systems for CO2 capture.

Energy, exergy, economic, environment, exergo-environment based assessment of amine-based hybrid solvents for natural gas sweetening

Natural gas is the cleanest form of fossil fuel that needs to be purified from CO2 and H2S to diminish harmful emissions and provide feasible processing. The conventional chemical and physical solvents used for this purpose have many drawbacks, including corrosion, solvent loss, high energy requirement, and the formation of toxic compounds, which ultimately disrupt the process and affect the environment. Hybrid solvents have lately been researched to cater to these liabilities and enhance process economics. This study screened eight solvents based on CO2 selectivity viscosity, absorption enthalpy, corrosivity, working capacity, specific heat, and vapor pressure. From the screened solvents, ten cases of hybrid solvents are simulated and optimized on Aspen HYSYS®. Furthermore, 5Es (Energy, Exergy, Economic, Environmental, and Exergy-environmental) analyses were performed on optimized cases, and results were compared with the base case, MEA (30 wt%). The hybrid blend of Sulfolane and MDEA with weight percentages of 6% and 24%, respectively, showed the highest energy savings of 20% concerning the base case. In addition, it offered 93% savings in exergy destruction and 17.26% in the total operating cost of the process. It is also promising to the environment due to reduced entropy sent to the ecosystem and controlled CO2 emissions. Therefore, the blend of Sulfolane and MDEA is proposed to Supersede the conventional solvent MEA for the natural gas sweetening process.

CFD modeling of MEA-based CO2 spray scrubbing with computational-effective interphase mass transfer description

Great concerns for global warming and stringent regulations have spurred the development of feasible technologies to reduce CO2 emissions from the power generation sector. In thermal power plants, spray scrubbing is one of the most used methods for separating gaseous pollutants, which inspires the idea of applying spray scrubbing in CO2 capture. However, this new idea still necessitates investigation, particularly in developing a novel modeling tool. This motivates us to present the CFD modeling of CO2 spray scrubbing using MEA solution in this work. CO2 spray scrubbing is a complex process. Herein, the established model combines the multiphase flow with interphase transfer and chemical reactions in the Euler-Lagrange framework. To efficiently describe the interphase mass transfer, we proposed a new method based on the thermodynamic consistency between the CO2 equilibrium pressure and the enthalpy of CO2 absorption. Validated by the experimental data, this method can achieve an acceptable balance between accuracy and computational cost. The zwitterion mechanism was employed to describe the chemical reactions. Kinetic analysis shows that E = (1 +Ha2)0.5 can reasonably evaluate the enhancement factor value in a wide range of MEA concentrations. Additionally, the effects of operating parameters on CO2 removal were numerically studied, focusing on mass transfer characteristics. Therefore, the proposed numerical model will be beneficial for facilitating the deployment of CO2 spray scrubbing in the power sector, and the numerical results provide helpful information for design and optimization.

Comprehensive exploration of the adsorption capacity of innovative betaine-based deep eutectic solvents for carbon dioxide capture

Compared with traditional organic solvents and ionic liquids, deep eutectic solvents (DESs) as innovative emerging solvents has attracted widespread attentions in the field of CO2 absorption due to its remarkable advantages, such as low melting point, cheapness, easy preparation, regeneration and biodegradation. Herein the halogen-free DESs constituting of betaine as hydrogen bond acceptor, 1,2-propanediol and diethylene glycol as hydrogen bond donor were employed to absorb CO2. The CO2 absorption capacity of DESs with different molar ratios was measured at a certain temperature (303.15–348.15 K) and pressure (180–770 kPa). The results show that the solubility of CO2 in DESs can be improved by decreasing the temperature and increasing the pressure. The solubility of CO2 in DESs increases with increasing mole ratio of 1,2-propanediol, but decreases with increasing mole ratio of diethylene glycol. The Jou and Mather model was used to calculate the CO2 solubility data, which was compared with the experimental results. Through the estimated Henry's constant, the gibbs free energy, enthalpy and entropy of absorption were calculated and the results indicate that the CO2 dissolution in DESs is a non-spontaneous exothermic process. Regeneration can be achieved by depressurizing and heating the DES-CO2 system. By comparing with the Henry's constant Hm of the reported solvents, this work provides the possibility and space for further optimizing the use of new materials DESs to capture CO2.

Ionic Liquid Mixtures for Direct Air Capture: High CO2 Permeation Driven by Superior CO2 Absorption with Lower Absolute Enthalpy.

This paper reports a series of liquid materials suitable for use as high-performance separation membranes in direct air capture. Upon mixing two ionic liquids (ILs), namely N-(2-aminoethyl)ethanolamine-based IL ([AEEA][X]) and 1-ethyl-3-methylimidazolium acetate ([emim][AcO]), the resulting mixtures with a specific range of their composition showed higher CO2 absorption rates, larger CO2 solubilities, and lower absolute enthalpies of CO2 absorption compared to those of single ILs. NMR spectroscopy of the IL mixture after exposure to 13CO2 allowed elucidation of the chemisorbed species, wherein [AEEA][X] reacts with CO2 to form CO2-[AEEA]+ complexes stabilized by hydrogen bonding with acetate anions. Supported IL membranes composed of [AEEA][X]/[emim][AcO] mixtures were then fabricated, and the membrane with a suitable mixing ratio showed a CO2 permeability of 25,983 Barrer and a CO2/N2 selectivity of 10,059 at 313.2 K and an applied CO2 partial pressure of 40 Pa without water vapor. These values are higher than those reported for known facilitated transport membranes.

Three-component 1,1,3,3-tetramethylguanidine based CO2-binding organic liquids: Statistical solvent design and thermodynamic modeling of CO2 solubility by LJ-Global TPT2 EoS

In this study, three-component CO2-binding organic liquids (CO2BOLs) are introduced for high pressure CO2 absorption. The non-aqueous, green solvents consist of a superbase (1,1,3,3-tetramethylguanidine (TMG)), a tertiary alkanolamine (Dimethylethanolamine (DMEA), Diethylethanolamine (DEEA) and N-methyldiethanolamine (MDEA)) and an alcohol (MeOH, n-BuOH, sec‑BuOH, tert‑BuOH and 1-HexOH). The best combination of solvent components was determined to be the TMG/DMEA/n-BuOH BOL (molar ration:1/1/1) based on both CO2 loading (αeq= 0.431 mol CO2/mol solvent) and absorption rate (αR= 0.225 mol CO2/mol solvent within 20 min) by implementing screening experiments. The mixture design approach was applied for the design of experiments, modeling and investigating the effect of components’ proportion on αeq and αR at the constant temperature of 35.0 °C and initial CO2 pressure of 25.0 bar. The highest αeq (0.573 mol CO2/mol BOL) and αR (0.362 mol CO2/mol solvent) were obtained using TMG/n-butanol (1/1) and DMEA BOLs, respectively. The CO2 solubility data in the two-component BOLs: TMG/n-BuOH, TMG/DMEA and DMEA/n-BuOH as well as the three-component TMG/DMEA/n-BuOH BOL were gathered at 25.0, 35.0 and 45.0 °C and the pressures up to 35.0 bar using equimolar solvent mixtures. The LJ-Global TPT2 EoS was used in the simultaneous VLE and chemical equilibrium calculation algorithm for the thermodynamic modeling of CO2 solubility in the BOLs. The AAD% in the modeling of TMG/n-BuOH, TMG/DMEA, DMEA/n-BuOH and TMG/DMEA/n-BuOH BOLs were calculated to be 11.5%, 12.4%, 10.5 and 12.9%, respectively. The enthalpies of CO2 absorption in BOLs and the speciation of the system components were predicted from reaction equilibrium constants and using LJ-Global TPT2 EoS.

High-pressure CO2 solubility measurement in aqueous mixtures of (2-amino-2-methyl-1-propanol (AMP) and deep eutectic solvent (tetra butyl ammonium bromide 1: 3 ethylene glycol)) at various temperatures

In this work, we measured the CO2 solubility in a mixture of aqueous 2-amino-2-methyl-1-propanol (AMP) and deep eutectic solvent (DES) made by tetra butyl ammonium bromide (TBAB) and ethylene glycol (EG) statically at high-pressure. Measurements were performed isothermally at 313.15, 328.15, and 343.15 K and in the pressure range of 100–5100 kPa. The solvent compositions used for the DES (TBAB 1: 3 EG) + AMP + H2O systems were (7.5–30–62.5) (15–30–55) (22.5–30–47.5) and (30–30–40) wt.%. The solubility results showed that decreasing temperature and increasing pressure enhanced the solubility of CO2 in the solvent mixtures. Also, increasing the mass concentration of deep eutectic solvent in the system at a constant temperature reduces the gas's solubility. Besides, in this study, a correlation of gas partial pressure against CO2 loading and temperature was obtained to calculate the gas solubility in the studied system, which agrees with the experiment. Finally, the heat absorption enthalpy of CO2 was calculated using the Clausius-Clapeyron equation. The enthalpy of dissolution changed with a smoother slope as the mass percentage of DES increased.

Intensification of hydrogen sulfide absorption by diethanolamine in industrial scale via combined simulation and data-based optimization strategies

A novel combinatorial approach including computer-aided simulation and robust statistical data-based methods was introduced to intensify the chemical absorption process of H2S by diethanolamine (DEA) from sour industrial off-gas. Effects of three parameters (lean amine H2S impurity (LAHI), lean amine temperature (LAT) and column pressure (CP) on the alteration trends and sensitivity of H2S removal were studied using response surface methodology (RSM) and Sobol’s sensitivity analysis (SA). Then, the optimal conditions for maximizing the H2S removal were determined. Results depicted that H2S removal will be decreased at higher LAHI and LAT. SA showed that LAHI (83%) was the most impactful factor on H2S removal. LAT (15%) and CP (2%) showed a relatively-low and negligible effects on the removal efficiency, respectively. It was shown that low impact of LAT and CP on H2S removal arised from weak variations of thermodynamic parameters of H2S absorption (H2S solubility, equilibrium constant, and enthalpy of absorption) with those factors. Maximum H2S removal of 99.995% was resulted at the optimal values of LAHI = 0.01 molH2S/molDEA, LAT = 53.7 °C, and CP = 1500 kPa.

Analysis of hydrogen embrittlement in palladium–copper alloys membrane from first principal method using density functional theory

Hydrogen embrittlement has significant effects on membrane properties, and it is vital to develop countermeasures to avoid this problem from the start. The impact of hydrogen on pure palladium and palladium-copper alloys used for hydrogen purification/separation was investigated in this study. It was discovered that the lattice parameter and crystalline structure of pure Pd change from 3.92 Å to 5.55 Å and from cubic structure to triclinic structure, respectively. The presence of hydrogen atoms in the crystalline structure is responsible for this alteration. The absorption enthalpy of Pure Pd and PdCu of −4.38eV and −4.86eV, respectively, showed that a PdCu membrane with a lower enthalpy value increased anti-hydrogen brittleness. Due to hydrogen exposure, the mechanical characteristics of pure palladium were considerably affected. This study demonstrates that the mean peak on EF of Pd–Cu (0.259eV) is lower than that of pure Pd (0.955eV) when exposed to hydrogen, indicating more stability and lower hydrogen embrittlement in Pd–Cu alloy than pure Pd. Density functional theory-based simulation is used to analyse what happened at the grain boundary, the causes of hydrogen embrittlement, and possible ways to prevent it.