Solvent Loading Research Articles

Greener Methodology: An Aldol Condensation of an Unprotected C-Glycoside with Solid Base Catalysts

The development of a new enamine-solid-base-catalyzed (ESBC) methodology for the aldol condensation reaction is reported. Solid base catalysts [nonactivated and activated magnesium oxide (MgO and MgOact) and calcium oxide (CaO and CaOact), a hydrotalcite (HT), and a porous metal oxide (PMO)] were investigated as safer and greener alternatives to previously reported catalytic systems. Multiple reaction parameters (temperature, solvent, time, and catalyst loading) were investigated todetermine optimal conditions for the practitioner to employ in the synthesis of C-glycosides. The optimized reaction conditions provided highly functionalized (E)α,β-unsaturated ketones from unprotected C-glycosides in good to excellent yields. Moreover, the ESBC methodology is applicable to a wide range of aromatic aldehydes that feature electron-rich and electron-poor moieties, as well as sterically bulky groups. Lastly, the recyclability of the MgO catalyst was demonstrated.

The effect of mesoporous silica impregnation on tribo-electrification characteristics of flurbiprofen

Tribo-electrification is a common occurrence within the pharmaceutical industry where solid dosage forms constitute majority of pharmaceutical formulations. Tribo-electrification of powders leads to a range of complications such as adhesion of particulate material to the processing equipment resulting in segregation, affecting the content uniformity. Flurbiprofen, a highly charging material, was used as a model drug to investigate the tribo-electrification and adhesion characteristics by impregnating the model drug inside a mesoporous silica matrix. The model drug was impregnated using i) solvent loading, and ii) physical mixing methods, at varying degree of silica to drug ratio (5–20% w/w). The resulting mixtures were tribo-charged using a custom built device based on a shaking concept inside a stainless steel capsule, consisting of a Faraday cup and connected to electrometer. The electrostatic charge and the percentage adhesion of Flurbiprofen were reduced in both drug loading methods. The solvent impregnation method using acetone was more successful at reducing the electrostatic charge build up on flurbiprofen than physical powder mixing. The percentage adhesion to the shaking capsule was reduced notably as a result of loading the drug in the SBA-15 porous network. The results illustrate that the incorporation of highly charged model drug inside a low-charging pharmaceutical carrier system to be an effective approach in control the induction of tribo-electrification phenomena during powder processing.

Flexible operation of post-combustion CO2 capture at pilot scale with demonstration of capture-efficiency control using online solvent measurements

Flexible post-combustion carbon capture and storage (CCS) has the potential to play a significant part in the affordable decarbonisation of electricity generation portfolios. PCC plant operators can modify capture plant process variables to adjust the CO2 capture level to a value which is optimal for current fuel cost, electricity selling price and CO2 emissions costs, increasing short-term profitability. Additionally, variation of the level of steam extraction from the generation plant can allow the capture facility to provide additional operating flexibility for coal-fired power stations which are comparatively slow to change output.A pilot-scale test campaign investigates the response of plant operating parameters to dynamic scenarios which are designed to be representative of pulverised coal plant operation. Online sensors continuously monitor changes in rich and lean solvent CO2 loading (30%wt monoethanolamine). Solvent loading is likely to be a critical control variable for the optimisation of flexible PCC operation, and since economic and operational boundaries can change on timescales 30 min or shorter, the development of methods for rapid, continuous online solvent analysis is key. Seven dynamic datasets are produced and insights about plant response times and hydrodynamics are provided. These include power output maximisation, frequency response, power output ramping and a comparison between two plant start-up strategies.In the final dynamic operating scenario, control of CO2 capture efficiency for a simple reboiler steam decoupling and reintroduction event is demonstrated using only knowledge of plant hydrodynamics and continuous measurement of solvent lean loading. Hot water flow to the reboiler is reduced to drop the capture efficiency. The “target” value for the minimum capture efficiency in the scenario was set at 30%, but a minimum CO2 capture efficiency of 26.4% was achieved. While there remains scope for improvement this represents a significant practical step towards the control of capture plant using online solvent concentration and CO2 measurements, and the next steps for its further development are discussed.

Preparation of cobalt substituted zinc aluminium chromite: photocatalytic properties and Suzuki cross coupling reaction

A series of cobalt substituted zinc aluminium chromite nanoparticles were synthesized by simple, cost effective sol–gel auto-combustion method. The synthesized samples were characterized by different sophisticated techniques. The thermal properties of chromite nanoparticles were evaluated using thermogravimetric analysis and differential thermal analysis. X-ray diffraction analysis reveals the formation of single cubic spinel phase with an average crystallite size 25 nm. Morphological studies were carried out by scanning electron microscopy and transmission electron microscopy. The chemical compositions of chromites have been examined by energy dispersive spectroscopy and X-ray photoelectron spectroscopy technique which reveals the purity of the prepared samples. The photocatalytic performance of the synthesized material was studied towards decomposition of aqueous Rhodamine B dye solution. We systematically investigated the effect of various parameters such as irradiation time of UV light, palladium doping and kinetic parameters of photocatalysis with chromites. The catalytic performance of the samples was studied for the two-component coupling reaction of aryl halide and phenyl boronic acid. The effects of solvent, temperature, and palladium loading on the material were also discussed.

Nghiên cứu tổng hợp zeolit Cr‐ZSM‐5 cho phản ứng cắt mạch nối đôi của axit béo

AbstractThis work showed the results from synthesis of Cr‐ZSM‐5 zeolite and their application as catalyst for oxidative cleavage of double bond in oleic acid. Cr‐ZSM‐5 catalyst was obtained by doping chromium into zeolite lattice of ZSM‐5 zeolite by imregnation. This catalyst showed the high catalytic efficiency for liquid phase oxidation of oleic acid with high conversion of 93 % after 3 hr reaction. Furthermore, the effects of conditions of oxidation such as solvent, tempreature and catalyst loading on efficiency of oleic oxidation were also estimated. The suitable conditions for oxidative cleavage of double bond of oleic acid were found to be temperature of 70°C, reaction time of 3 hrs with catalyst amount of 5 wt% in acetonitrile solvent.

Energy Savings in CO2 Capture System through Intercooling Mechanism

It has been globally recognized as necessary to reduce greenhouse gas (GHG) emissions for mitigating the adverse effects of global warming on earth. Carbon dioxide (CO2) capture and storage (CCS) technologies can play a critical role to achieve these reductions. Current CCS technologies use several different approaches including adsorption, membrane separation, physical and chemical absorption to separate CO2 from flue gases. This study aims to evaluate the performance and energy savings of CO2 capture system based on chemical absorption by installing an intercooler in the system. Monoethanolamine (MEA) was used as the absorption solvent and Aspen HYSYS (ver. 9) was used to simulate the CO2 capturing model. The positioning of the intercooler was studied in 10 different cases and compared with the base case 0 without intercooling. It was found that the installation of the intercooler improved the overall efficiency of CO2 recovery in the designed system for all 1-10 cases. Intercooler case 9 was found to be the best case in providing the highest recovery of CO2 (92.68%), together with MEA solvent savings of 2.51%. Furthermore, energy savings of 16 GJ/h was estimated from the absorber column alone, that would increase many folds for the entire CO2 capture plant. The intercooling system, thus showed improved CO2 recovery performance and potential of significant savings in MEA solvent loading and energy requirements, essential for the development of economical and optimized CO2 capturing technology.

Enzymatic Synthesis and Characterization of Sucrose Erucate

AbstractThe enzyme catalyzed synthesis is a environmentally friendly route compared to traditional syntheses. The lipase-catalyzed synthesis of sucrose erucate was achieved in a solvent mixture of t-butanol and dimethyl sulfoxide (4: 1) by esterification of sucrose with erucic acid using the immobilized Thermomyces lanuginosus lipase. Various process parameters like temperature, substrate molar ratio, solvent, time, and enzyme loading were studied. The optimal conditions for the esterification reaction obtained were 10 %(w/w) enzyme loading, a molar ratio sucrose/fatty acid 1: 1, mild reaction conditions (50 °C and atmospheric pressure) and reaction time (40 h with 55.6 % conversion). The sugar esters were characterized for surfactant properties at different concentration. Sucrose erucate showed a surface tension of (32.73 ± 0.01) mN m−1at a critical micellar concentration of 9.8 × 10−5 mol L−1 and good emulsification power.

Application of different drying techniques to fresh-cut salad waste to obtain food ingredients rich in antioxidants and with high solvent loading capacity

Wastes from iceberg salad fresh-cut processing were submitted to air-drying, freeze-drying, and supercritical-CO2-drying with or without ethanol as co-solvent. Drying was combined with grinding to obtain flours. Samples were analysed for macro- and micro-appearance, particle size, dietary fibre, polyphenol content, antioxidant activity, water vapour sorption, water and oil holding capacity. Air-drying produced a collapsed brown material allowing a flour rich in fibre (>260 g/kg) and polyphenols (3.05 mg GAE/gdw) with antioxidant activity (6.04 OD−3/min/gdw) to be obtained. Freeze-drying maintained vegetable structure and colour while partly retaining polyphenols (1.23 mg GAE/gdw). Supercritical-CO2-drying with ethanol as co-solvent, produced an expanded material able to entrap huge amounts of water and oil (43.2 and 35.2 g of water and oil for g of dry sample). Air-dried salad waste derivatives could be used as functional food ingredients, while supercritical-CO2-dried ones can be exploited as bulking agents and absorbers of oil spills or edible oils.

CO2 mass transfer model for carbonic anhydrase-enhanced aqueous MDEA solutions

In this study a CO2 mass transfer model was developed for carbonic anhydrase-enhanced MDEA solutions based on a mechanistic kinetic enzyme model. Four different enzyme models were compared in their ability to predict the liquid side mass transfer coefficient at temperatures in the range of 298–328 K, solvent concentrations in the range 15–50 wt%, CO2 partial pressures up to 50 kPa, solvent loading between 0 and 0.5 mol CO2 per mole MDEA and enzyme concentrations up to 8.5 g/L. The reversible Michaelis Menten model (MR) and the simplified model with product inhibition by the bicarbonate ion (SP) were able to predict the mass transfer with an absolute average relative deviation of less than 15%. The MR model could account for every influence (solvent concentration, temperature, solvent loading, CO2 partial pressure) of the different process conditions on the mass transfer, whereas the SP model is limited to applications with low CO2 partial pressure such as CCS from coal burning power plants. Two other models that were also investigated are not suitable for implementation into an absorber column simulation, as they cannot describe the influence of changing solvent loading on the mass transfer.

Photochemical Preparation of Anatase Titania Supported Gold Catalyst for Ethanol Synthesis from CO2 Hydrogenation

Hydrogenation of the greenhouse gas CO2 to higher alcohols through catalysis holds great promise for resource transformation in low-carbon energy supply system, but the efficient and selective synthesis of value-added ethanol by a robust heterogeneous catalyst under relatively mild conditions remains a major challenge. Based on our previous work on Au/TiO2 as an active and selective catalyst for ethanol synthesis, we report here that a facile photochemical route can be used for the preparation of anatase TiO2 supported gold catalyst (Au/a-TiO2) for efficient hydrogenation of CO2. Compared with the conventional deposition-precipitation method requiring strong bronsted base and flammable H2 gas in the complicated and time-consuming process, the photochemical way for the facile preparation of supported gold catalyst shows the advantages of green and energy-saving. Of significant importance is that an impressive space-time-yield of 869.3 mmol gAu −1 h−1, high selectivity, and excellent stability can be readily attained at 200 °C and total pressure of 6 MPa. The effects of irradiation time, solvent, and metal loading or Au particle size on ethanol synthesis are systematically investigated.

Catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone over zirconium (IV) Schiff base complexes on mesoporous silica with isopropanol as hydrogen source

Zr(IV)-salphen-MCM-41 was prepared by immobilizing a zirconium(IV) Schiff base complex onto the surface of MCM-41. The structural properties of the heterogeneous catalysts were characterized by FT-IR, UV, TG, XRD, SEM, TEM, BET, EDX, CO2-TPD, NH3-TPD and ICP-OES. Studies on the catalytic properties of the immobilized Zr(IV)-Schiff base complexes were performed using the reduction and cyclization of ethyl levulinate (EL) to γ-valerolactone (GVL) with isopropanol as the hydrogen source. Various reaction parameters, such as temperature, reaction time, solvent and catalyst loading were carefully investigated. The optimal conditions (GVL yield up to 90%) involved the utilization of Zr(Salphen)-MCM-41 as the catalyst in isopropanol. The key to heightened reaction performance was the incorporation of the phenolate and aniline groups in the ligands of bound to Zr. This increased the basicity of the catalyst, which subsequently enhances the efficiency of the transfer hydrogenation reported herein. Meanwhile, the immobilized catalyst can be easily separated and efficiently recycled at least five times without significant loss of activity. Finally, we proposed a plausible reaction mechanism based on experimental and characterization data.

A nickel(II) thiosemicarbazonato complex: synthesis, structure, electrochemistry, and application in catalytic coupling of terminal alkynes with arylboronic acids

A simple route for the synthesis of a new square-planar nickel(II) complex of 2-((3-methylthiophen-2-yl)methylene)hydrazinecarbothioamide is described. Elemental analysis, solution conductivity, and spectral measurements were used to authenticate the composition of the complex. In addition, the X-ray crystal structure of the complex was obtained. Each of the two ligands of the centrosymmetric structure is coordinated to the metal center via the azomethine N and the thioimidate S atoms, forming five-membered chelate rings. Infrared and NMR spectroscopic features of the complex are consistent with its molecular structure. The complex displays a quasi-reversible reduction with E 1/2 of −0.83 V (ΔE p 160 mV), indicating that the ligand system can stabilize the Ni(I) oxidation state. The complex acts as an active catalyst for the C–C coupling of aryl acetylenes with arylboronic acids containing a variety of substituents. The influence of solvent, base, reaction temperature, and catalyst loading on the C–C coupling reaction was evaluated. A new square-planar nickel(II) complex bearing 2-((3-methylthiophen-2-yl)methylene)-hydrazinecarbothioamide was synthesized and characterized by elemental analysis, FTIR, NMR, and single-crystal X-ray crystallographic technique. Cyclic voltammetric study indicates stabilization of Ni(I) oxidation state. The complex acts as an effective catalyst for the carbon–carbon cross-coupling reaction of substituted phenylacetylenes with various arylboronic acids under optimized conditions.

Comparison of the Kinetic Promoter Piperazine and Carbonic Anhydrase for CO2 Absorption

Kinetic promoter that enhance the reaction kinetics with CO2 are enabling the use of the low heat of reaction of slow absorbing solvents like MDEA. Mass transfer experiments with 30 wt% MDEA promoted by either by 1.7 and 8.5g/L enzyme carbonic anhydrase (CA) or 5 wt% piperazine (PZ) where conducted in a wetted wall column apparatus at 298, 313K and 328 for different solvent loadings. The mass transfer of PZ promoted solvents was strongly influenced by the solvent loading as it was steeply decreasing for all temperatures; the temperature was also influencing the mass transfer, but the extent was dependent on the solvent loading. CA promoted solvent mass transfer characteristics showed less dependency on the solvent loading and temperature. Lower enzyme concentrations were found to be much slower than MDEA/PZ solvents, whereas high enzyme concentrations might be as efficient in capturing CO2 as a 30 wt% MDEA/5 wt%PZ mixture in terms of overall mass transfer, considering change of mass transfer due to solvent loading over the height of a column.

Pilot Absorption Experiments with Carbonic Anhydrase Enhanced MDEA

Mass transfer experiments were carried out on DTU's pilot absorber unit, a 10 m high packed column filled with 250 Y Mellapak structured packing. The influence of temperature, solvent loading, column height and liquid flowrates on absorption performance were determined for a 30 wt% N-methyl-diethanolamine (MDEA) solvent, with and without the enzyme carbonic anhydrase (CA). The absorption experiments were performed at atmospheric pressure and a gas phase carbon dioxide mole fraction of 0.13. During experiments liquid samples were withdrawn at each meter of column height and the solvent loading was determined by both a density method and the BaCl2 method. After the solvent was loaded to equilibrium it was heated up and reintroduced into the column, where CO2 was stripped off using air as stripping gas. The addition of CA increased the mass transfer significantly in all experiments. Lower absorption temperatures resulted in higher mass transfer in absorption, when 28 and 40°C inlet temperature were chosen. The absorption performance decreased with lower solvent flow. The enzyme was also capable of enhancing the desorption process, where higher desorption rates were measured at 45 and 50°C with CA enhanced solvent compared to 55°C without CA.

Analysis on Regeneration Energy of NH3-based CO2 Capture with Equilibrium-based Simulation Method

In this paper, an equilibrium-based simulation method for CO2 capture using aqueous ammonia was investigated. Quantitative comparisons of the equilibrium- and rate-based methods were performed. Effects of the stage number on the equilibrium- and rate-based simulations were obtained. Analysis on regeneration energy of NH3-based CO2 capture with the equilibrium-based simulation method was carried out. As the stage number for the equilibrium-based simulations increases, the regeneration energy decreases gradually to a constant value. For the equilibrium-based simulations of the NH3-based CO2 regeneration process, with the increase of the reboiler heat duty, the regeneration energy decreases to a minimum value firstly, and then begins to increase. In addition, effects of the temperature, NH3 concentration and CO2 loading of the rich solvent flowing into the stripper on the regeneration energy were obtained using the equilibrium-based simulation method.

ProTreat® Simulation Accurately Represents Experimental Results for Post-combustion Carbon Dioxide Capture with Novel Mixed Amine Solvent in Real Process Environment

Comparison of ProTreat® simulations to data obtained from testing ION's advanced solvent at the NCCC facility demonstrated excellent agreement between process simulations and process telemetry. ProTreat® simulations created and executed to resemble test conditions during ION's testing campaign at NCCC converged with good accuracy. The models predicted temperature profiles for absorption and stripping columns the were directly compared with real data and served to evaluate the accuracy of the simulations. Lean and rich solvent loading predictions using ProTreat® were within 6% (mass/mass) of measured results. The software-generated temperature profiles in the absorber and stripper yielded variances of less than 5°F (2°C) at any height of the packing across all periods of evaluation with real data. Comparing ProTreat® simulations with actual process data has provided confidence in using ProTreat® as a viable method for predicting ION's proprietary solvent's gas treating capabilities.

Role of Solvent in Catalytic Conversion of Oleic Acid to Aviation Biofuels

The role of solvents in the conversion of oleic acid over Pt/C was studied. Three solvent systems (solvent-free, water, and dodecane systems) were employed for the conversion of oleic acid over Pt/C at 350 °C. Decarboxylation, hydrogen transfer, and aromatization were observed in these three reaction systems. In comparison to the non-solvent reaction system, much slower decarboxylation and aromatization rates and fewer heptadecane and aromatic products were observed in the hydrothermal and dodecane reaction systems. The decarboxylation and aromatization rates and yields of heptadecane and aromatics decreased with increased dodecane loading in the dodecane reaction system, and the decarboxylation and aromatization rates and yields of heptadecane and aromatics significantly decreased with the increase of water in the hydrothermal reaction system. The effects of solvent loading, catalyst loading, and reaction time on the reactions (decarboxylation, hydrogen transfer, and aromatization) were investigated. The...

Evaluation of the novel biphasic solvents for CO2 capture: Performance and mechanism

For its high potential in reducing energy penalty of power plant, the biphasic solvent for CO2 capture has recently attracted increasing attention. In this work, a novel blend of N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) and diethylenetriamine (DETA) was used to obtain a liquid-liquid phase separation solvent. The CO2 absorption loading of the PMDETA-DETA solvent (5M, 4:1) was 0.613mol CO2/mol of total amine, in which 99.7% of the capacity was contributed by the lower phase with 57% of the total volume. In addition, the PMDETA-DETA solvent maintained a high CO2 absorption capacity and good phase separation at 30–60°C. Based on the absorption results and the 13C NMR analysis, the reaction mechanism of CO2 absorption into PMDETA-DETA solvent was clarified. In the blend system, DETA played as a reactant to attack CO2 and PMDETA played as a proton acceptor to deprotonate the zwitterion. Therefore, the presence of PMDETA in the solution helped DETA to react with CO2 rather than participate in the deprotonation process of zwitterion, which ensured a high CO2 absorption capacity. The phase change mechanism indicated that, as more CO2 was absorbed into the system, the more products of carbamate and HCO3−/CO32− migrated to the lower phase while more PMDETA migrated to the upper phase, which led to the phase separation.

Dynamics of Postcombustion CO2 Capture Plants: Modeling, Validation, and Case Study.

The capture of CO2 from power plant flue gases provides an opportunity to mitigate emissions that are harmful to the global climate. While the process of CO2 capture using an aqueous amine solution is well-known from experience in other technical sectors (e.g., acid gas removal in the gas processing industry), its operation combined with a power plant still needs investigation because in this case, the interaction with power plants that are increasingly operated dynamically poses control challenges. This article presents the dynamic modeling of CO2 capture plants followed by a detailed validation using transient measurements recorded from the pilot plant operated at the Maasvlakte power station in the Netherlands. The model predictions are in good agreement with the experimental data related to the transient changes of the main process variables such as flow rate, CO2 concentrations, temperatures, and solvent loading. The validated model was used to study the effects of fast power plant transients on the capture plant operation. A relevant result of this work is that an integrated CO2 capture plant might enable more dynamic operation of retrofitted fossil fuel power plants because the large amount of steam needed by the capture process can be diverted rapidly to and from the power plant.

An alternative perspective of hollow fiber-mediated extraction: Bundled hollow fiber array-liquid-phase microextraction with sonication-assisted desorption and liquid chromatography–tandem mass spectrometry for determination of estrogens in aqueous matrices

A bundled hollow fiber array (BHF)-liquid-phase microextraction (LPME) approach has been developed for the ultra-high performance liquid chromatography tandem mass spectrometric determination of estrone, 17β-estradiol, estriol, and 17α-ethinylestradiol. The BHF was dipped in n-octanol to impregnate only the wall pores of the hollow fibers without deliberate loading of extractant solvent in the lumens, before placing it in the sample for extraction. Parameters influencing extraction efficiency, such as number of bundled hollow fibers, type of extraction and desorption solvent, agitation mode, extraction temperature and duration, and the salting out effect were examined. Under the most favourable experimental conditions, the enrichment factors were between 77 and 137-fold for the target compounds. The developed method offered high sensitivity and reproducibility. Low limits of detection and limits of quantification were achieved, i.e., between 0.251 and 0.440ng/L, and 0.995 and 1.82ng/L, respectively. Good intra and inter-day precision were obtained with relative standard deviations (RSDs) of less than 9%. BHF-LPME provided a new perspective on using membrane solvent-supported hollow fiber-mediated LPME. Raman spectroscopy was also introduced in this study to reaffirm that the polypropylene BHF did not play any role in the extraction; only the solvent was responsible.