Liquid Phase Conditions Research Articles

New Class of Ionic Liquid Crystal Proposed by Using Quantum Chemical Calculation

AbstractThe current investigation conducts a thorough analysis of the nonlinear optical properties, binding characteristics, and electronic features of 1‐proplene‐3‐methylimidazolium (PMIM)‐X ionic liquid (IL) crystal. These findings reveal that the dissociation energy of PMIM‐X indicates a preference for ionic dissociation over neutral dissociation. Notably, the ionic dissociation energy shows an increasing trend with both the electron affinity (EA) and the size of X. In the process of forming the IL crystal PMIM‐X, this study observes a charge transfer from PMIM to X species. It is noteworthy that the extent of charge transfer intensifies with the increasing size of X. Additionally, the calculated energy gap exhibits a positive correlation with both EA and the size of X. Although these results suggest promising nonlinear optical behavior for PMIM‐X, it is crucial to acknowledge the limitations of the study. All calculations are conducted on single atoms in the gas phase, overlooking potential effects that may arise in the liquid phase or bulk conditions. Therefore, future investigations should consider these factors for a more comprehensive understanding of the behavior of PMIM‐X in practical applications.

Uncertainty Evaluation for Determination of Sibutramine in Health Food by HPLC-MS/MS

High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to determine the content of sibutramine in health foods according to the BJS 201701 standard Determination of Compounds such as Sibutramine in Food. By evaluating each uncertainty component, the influencing factors of the uncertainty were identified and the expanded uncertainty of sibutramine detection in health foods was provided. Using the example of illegal addition of sibutramine to health products, the HPLC-MS/MS method was used for qualitative screening and quantitative analysis of samples. The sources of uncertainty in the quantitative results were analysed, including sample weighing, sample volume determination, standard solution preparation, standard curve fitting and determination of sample repeatability. The synthetic relative standard uncertainty of the measurement results was calculated and the expanded uncertainty was reported. By optimizing the liquid phase conditions, the sample can be detected within 5 min with a linear correlation coefficient of 0.998. When the content of sibutramine in health products was 42.2 mg/kg, the extended uncertainty of the results was 4.56 mg/kg (k = 2) with a 95% confidence interval. Among the various components affecting the results of detection, the uncertainty introduced during the process of preparing the standard solution has the greatest impact on the results. A proper evaluation of the uncertainty, detailed analysis and quantification of the various sources of uncertainty can help to improve the reliability of test results.

Simultaneous determination of 102 synthetic cannabinoids in electronic cigarette oil by liquid chromatography-tandem mass spectrometry

Synthetic cannabinoids (SCs), which are among the most widely abused new psychoactive substances, are much more potent and have greater efficacy than natural cannabis. SCs can be disguised in various ways and are commonly sold in the form of electronic cigarette oil. SCs belong to a large family with structures consisting of a core with substituents, linker, ring with substituents, and tail. New SCs can be developed by adding substituents, such as halogen, alkyl, and alkoxy groups, to the aromatic ring system or by changing the alkyl chain length. Since the emergence of so-called first-generation SCs, subsequent developments have led to eighth-generation indole/indazole amide-based SCs. As of July 1, 2021, the entire category of SCs was added to the list of controlled substances, but implementation requires urgent improvements in detection technologies. Typically, each method is limited to a few SCs. Owing to the vast number of chemically diverse SCs and their fast update speed, the determination and identification of various types of SCs using a single method is challenging. Therefore, rapid, sensitive, and accurate quantitative methods that includes various types of SCs must be developed to meet the demand for the qualitative and quantitative analysis of new SCs in seized electronic cigarette oil. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of 102 SCs in electronic cigarette oil. The mass spectrometry and liquid-phase conditions influencing SC separation and determination were optimized. Using the external standard method, 102 SCs were successfully identified in electronic cigarette oil. The samples were extracted using methanol. Target analytes were separated on a Shimadzu Shim-pack GIST-HP C18 AQ column (100 mm×2.1 mm, 1.9 μm) at a column temperature of 40 ℃. The mobile phases consisted of (A) 0.1% formic acid aqueous solution and (B) methanol-acetonitrile (1∶1, v/v). The gradient elution conditions were as follows: 0-8 min, 55%A-15%A; 8-15 min, 15%A; 15-16 min, 15%A-55%A; 16-18 min, 55%A. The flow rate was 0.4 mL/min and the injection volume was 1 μL. Operating in the multiple reaction monitoring mode, the 102 SCs were identified within 18 min. Each SC exhibited a good linear relationship in the range of 1-100.0 μg/L with a correlation coefficient (r)≥0.9915. The limits of detection were 0.01-0.30 μg/L and the limits of quantification were 0.04-0.99 μg/L, which meet the requirements for analyzing SCs in actual samples. Precision was determined using standard solutions with 2, 10, and 50 μg/L of the SCs. The precisions (n=6) were 0.3%-6.0%. The recoveries of the 102 SCs, as evaluated by spiking electronic cigarette oil at low (2 μg/mL), medium (10 μg/mL), and high (50 μg/mL) levels, were 80.1%-119.8%. Good performance was observed for the analysis of real samples. The developed method is accurate, rapid, sensitive, and effective for the determination of the 102 SCs in electronic cigarette oil, satisfying the requirements for practical qualitative and quantitative analysis.

Quantitative analysis of the impurities in Etimicin using hydrophilic interaction liquid chromatography coupled with charged aerosol detector

Etimicin is a typical aminoglycoside antibiotic (AG). High performance liquid chromatography-evaporation light scattering detector (HPLC-ELSD) method is a commonly used method for determining impurities in Etimicin. However, due to the poor reproducibility, low sensitivity and narrow linear range of the ELSD, high-throughput quantitative analysis of impurities in Etimicin currently poses a challenge. In this study, a sensitive method using hydrophilic interaction liquid chromatography coupled with charged aerosol detector (HILIC-CAD) was developed for the analysis of the impurities in Etimicin. The liquid phase conditions for determination impurities in Etimicin were optimized using Box Behnken design (BBD) and response surface methodology (RSM), resulting in satisfactory separation and optimal CAD output signal. We also studied the influence of CAD parameters on the signal-to-noise ratio and linearity of Etimicin and its impurities. This method has also been proven to be effective in separating impurities from two other typical AGs, Isepamicin and Amikacin. In the method validation, the coefficient of determination (R2) of Etimicin, Isepamicin and Amikacin and their impurities were all greater than 0.999, within the range of 0.5–50 μg/mL. The average recoveries of the impurities of three typical AGs were 99.03 %-101.22 %, RSDs all were less than 2.5 % for intra-day and inter-day precision, with good precision and accuracy. The developed HILIC-CAD quantification method was sensitive, accurate and highly selective for quantitative analysis of impurities in the AGs without need ion-pairing reagents, which is ensure the public medication safety. The method is first reported application of HILIC-CAD method for quantitative analysis of the impurities in AGs.

CTAB-induced synthesis of two-dimensional copper oxalate particles: using l-ascorbic acid as the source of oxalate ligand.

Copper oxalate is typically synthesized through a precipitation reaction involving copper salts mixed with oxalic acid or oxalate solutions. However, in this study, we were successful in synthesizing well-formed square-like copper oxalate particles under liquid-phase conditions at ambient temperature and pressure using ascorbic acid as the source of the oxalic acid ligand. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) caused the morphology of copper oxalate particles to undergo a transition from three-dimensional to two-dimensional. And the inhibition of the assembly of primary copper oxalate nanocrystals along the [001] direction became stronger with the increase of CTAB concentration. The impact of CTAB on the crystallization, growth, and self-assembly processes of primary copper oxalate nanocrystals was analysed using various testing methods. Based on these analyses, the possible mechanism of CTAB-induced synthesis of two-dimensional copper oxalate particles was finally proposed.

Biohydrogen Production under Aerial Conditions by a Nitrogen-Fixing Bacterium Isolated from a Steel Signboard

Hydrogen gas is attractive as a clean fuel source if it can be produced efficiently without relying on fossil fuels. Biohydrogen production using photosynthetic bacteria may enable environmentally friendly hydrogen production but is currently limited by factors such as low oxygen tolerance. In this study, we isolate a new strain of bacteria that can produce hydrogen under aerial-phase conditions compared with those under liquid-phase conditions in a nitrogen gas or an argon gas atmosphere. Bacterial strains were cultured from scrapings taken from a steel signboard. Investigation of the hydrogen production of the strains under aerial- and liquid-phase conditions and subsequent DNA sequencing led to identification of the bacterium Cereibacter sp. KGU-NF001. Aerial-phase conditions were achieved by filter membranes with the bacterial strains and placing the membranes on medium-soaked cotton wool. The gas atmosphere affected the behavior of the isolated bacterial strains under both aerial- and liquid-phase conditions. Cereibacter sp. KGU-NF001 showed promising oxygen tolerance and was able to maintain hydrogen production of 1.33 mL/mg/d even when the atmosphere contained 12% oxygen. Our findings illustrate that biohydrogen production may be achieved by photosynthetic bacteria under oxygen-containing aerial-phase conditions, indicating a possible pathway to help lower our reliance on fossil fuels.

Unveiling the role of transition metal catalysts in low-temperature, liquid-phase isopropanol oxidation

Driven by the increasing need to optimize industrial chemical reactions through effective catalysts, this study reports the comprehensive oxidation process of isopropanol under liquid phase conditions at subambient temperatures, investigating the catalytic potential of transition metal oxides. The complete oxidation of isopropanol within the liquid phase at reduced temperatures was investigated, employing transition metal oxides as catalysts (Cr2O3, Fe2O3, NiO, and ZnO). These solids were prepared using the sol–gel method and the precipitation method. The results from structural (FTIR, XRD) and textural (BET) analyses were consistent with those reported in the literature. The employed solid substances exhibited favorable catalytic activity for the full oxidation of isopropanol, maintaining a consistent selectivity of 100 %, regardless of the temperature conditions under examination (40, 60, and 80 °C). These catalytic tests reveal that chromium oxide is a typical catalyst for this type of reaction. Furthermore, a kinetic analysis of the reaction was conducted, revealing that the reaction proceeds according to a sequential A-B-C mechanistic pathway. The low values of apparent activation energy for all the solids align with the high initial reaction rates in the studied temperature range. This study revealed the effective role of transition metal oxides, particularly chromium oxide, as catalysts for the total oxidation of isopropanol under liquid phase conditions at subambient temperatures, offering vital insights to enhance efficiency in chemical industrial processes.

Micro-flow size-exclusion chromatography for enhanced native mass spectrometry of proteins and protein complexes

Size-exclusion chromatography (SEC) employing aqueous mobile phases with volatile salts at neutral pH combined with native mass spectrometry (nMS) is a valuable tool to characterize proteins and protein aggregates in their native state. However, the liquid-phase conditions (high salt concentrations) frequently used in SEC-nMS hinder the analysis of labile protein complexes in the gas phase, necessitating higher desolvation-gas flow and source temperature, leading to protein fragmentation/dissociation. To overcome this issue, we investigated narrow SEC columns (1.0 mm internal diameter, I.D.) operated at 15-μL/min flow rates and their coupling to nMS for the characterization of proteins, protein complexes and higher-order structures (HOS). The reduced flow rate resulted in a significant increase in the protein-ionization efficiency, facilitating the detection of low-abundant impurities and HOS up to 230 kDa (i.e., the upper limit of the Orbitrap-MS instrument used). More-efficient solvent evaporation and lower desolvation energies allowed for softer ionization conditions (e.g., lower gas temperatures), ensuring little or no structural alterations of proteins and their HOS during transfer into the gas phase. Furthermore, ionization suppression by eluent salts was decreased, permitting the use of volatile-salt concentrations up to 400 mM. Band broadening and loss of resolution resulting from the introduction of injection volumes exceeding 3% of the column volume could be circumvented by incorporating an online trap-column containing a mixed-bed ion-exchange (IEX) material. The online IEX-based solid-phase extraction (SPE) or “trap-and-elute” set-up provided on-column focusing (sample preconcentration). This allowed the injection of large sample volumes on the 1-mm I.D. SEC column without compromising the separation. The enhanced sensitivity attained by the micro-flow SEC-MS, along with the on-column focusing achieved by the IEX precolumn, provided picogram detection limits for proteins.

Selective Styrene Oxidation Catalyzed by Phosphate Modified Mesoporous Titanium Silicate

Selective oxidation of organics over an efficient heterogeneous catalyst under mild liquid phase conditions is a very demanding chemical reaction. Herein, we first report the modification of the surface of mesoporous silica MCM-41 material by phosphate for the efficient incorporation of Ti(IV) in the silica framework to obtain highly ordered 2D hexagonal mesoporous material STP-1. STP-1 has been synthesized by using tetraethyl orthosilicate, triethyl phosphate, and titanium isopropoxide as Si, P, and Ti precursors, respectively, in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) under hydrothermal conditions. The observed specific surface area and pore volume of STP-1 were 878 m2g−1 and 0.75 ccg−1, respectively. Mesoporous STP-1 has been thoroughly characterized by XRD, FT-IR, Raman spectroscopy, SEM, and TEM analyses. Titanium incorporation (Ti/Si = 0.006) was confirmed from the EDX analysis. This mesoporous STP-1 was used as a heterogeneous catalyst for the selective oxidation of styrene into benzaldehye in the presence of dilute aqueous H2O2 as an oxidizing agent. Various reaction parameters such as the reaction time, the reaction temperature, and the styrene/H2O2 molar ratio were systematically studied in this article. Under optimized reaction conditions, the selectivity of benzaldehyde could reach up to 93.8% from styrene over STP-1. Further, the importance of both titanium and phosphate in the synthesis of STP-1 for selective styrene oxidation was examined by comparing the catalytic result with only a phosphate-modified mesoporous silica material, and it suggests that both titanium and phosphate synergistically play an important role in the high selectivity of benzaldehyde in the liquid phase oxidation of styrene.

CoRu/CNTs@Ti3C2 Nanocomposite for Highly Efficient and Stable Hydrogen Evolution Reaction

Cheap, stable, and efficient catalysts were a prerequisite for the large-scale application of hydrogen energy. Herein, carbon nanotubes (CNTs) were utilized as the carbon source and compounded with Ti3C2 MXene sheets under liquid-phase conditions to fabricate the CNTs@Ti3C2 skeleton. Then, ruthenium (Ru) chloride and cobalt (Co) nitrate were introduced as the metal source and carbonized the mixture at high temperature to obtain carbon/MXene composites loaded with cobalt-ruthenium metal nanoparticles (CoRu/CNTs@Ti3C2). Thanks to the uniform dispersion of CoRu nanoparticles on the surface of the CNTs@Ti3C2 skeleton, more catalytic active sites were exposed and that endowed the composite with excellent hydrogen evolution reaction (HER) performance. Therefore, the obtained CoRu/CNTs@Ti3C2 composite exhibited a relatively low HER overpotential (η10) of 74 mV and a Tafel slope of 80 mV·dec–1 under acidic electrolyte (0.5 M H2SO4) with stable electrochemical activity (only increased by ∼10 mV after 3000 cycles testing). This work provided a feasible opportunity for the large-scale and low-cost production of stable and efficient catalysts for practical applications.

Photoacoustic Infrared Analysis of the Reactivity of Electrons Accumulated in Titanium(IV) Oxide Particles Under a Liquid-phase Photocatalytic Condition

Infrared absorption of accumulated electrons in titanium(IV) oxide under a liquid-phase condition was investigated by using photoacoustic spectroscopy. By analyzing electron accumulation during ultraviolet (UV) irradiation and the reaction of accumulated electrons with an acceptor after UV turnoff, we suggested that the reaction rate of accumulated electrons depends on the energy difference between electron energy levels and a redox potential of the acceptor.

Feasible Detoxification Coating Material for Chemical Warfare Agents Using Poly(methyl methacrylate)-Branched Poly(ethyleneimine) Copolymer and Metal-Organic Framework Composites.

Defense against chemical warfare agents (CWAs) is regarded as a top priority for the protection of humanity, but it still depends on physical protection with severe limitations such as residual toxicity and post-treatment requirement. In this study, a strategically designed functional polymeric substrate was composited with a metal-organic framework catalyst to remove toxicity immediately. A series of PMMA-BPEI copolymers exhibited high processability as a coating and accelerated the catalytic activity of Zr(IV)-based metal-organic framework catalysts (UiO-66). Among them, PMB12_40 composite coating on a cotton fabric, containing a PMMA-BPEI copolymer (PMMA/BPEI = 1/2) and 40% of UiO-66 catalyst, can efficiently decompose nerve agent simulants (methyl-paraoxon) under both liquid phase (t1/2 = 0.14 h) and humidified (t1/2 = 4.8 h) conditions. Moreover, a real agent, GD, was decomposed 100% by PMB12_40 in 4 h at 25 °C and 65% relative humidity. On the basis of superior catalytic activity, the PMB composites are anticipated to be a potential material for active chemical protection coating.

The Influence of Rotating Speed on the Sealing Characteristics of a Liquid-Sealing Impeller for a Liquid Oxygen Turbopump

In order to explore the influence of rotating speed on the internal flow and sealing characteristics of the liquid-sealing impeller for a liquid oxygen turbopump of a rocket engine, unsteady numerical simulations of the flow characteristics and sealing performance of the first-stage liquid-sealing impeller for a liquid oxygen turbopump under liquid phase conditions were performed. The results show that the pressurization value increases with the increase in the rotating speed. The first-stage liquid-sealing impeller, whose structure is symmetrically distributed along the center of the rotation axis, tends to be an isobaric seal at a rotating speed of 12,000 rpm, and when the rotating speed is decreased or increased, it enters the leakage state or negative pressure sealing state, respectively. The matching relationship between the rotating speed and inlet pressure has a significant effect on the pressurization value, pressurization coefficient and leakage flow rate. Under the working condition with a good match between the rotating speed and inlet pressure, the pressurization value increases significantly and the leakage flow rate decreases significantly, and the pressurization coefficient is stable between 0.88 and 0.89. The empirical formulas proposed by Wood and the Shanghai Research Institute of Chemical Industry (1979) have high reference values for the design of the liquid-sealing impeller with a flow channel (groove) and retainer.

Effects of Different Lengths of a Nucleic Acid Binding Region and Bound Nucleic Acids on the Phase Behavior and Purification Process of HBcAg Virus-Like Particles.

Virus-like particles (VLPs) are macromolecular structures with great potential as vehicles for the targeted administration of functional molecules. Loaded with nucleic acids, VLPs are a promising approach for nanocarriers needed for gene therapy. There is broad knowledge of the manufacturing of the truncated wild-type lacking a nucleic acid binding region, which is mainly being investigated for vaccine applications. Whereas for their potential application as a nanocarrier for gene therapy, hepatitis B core antigen (HBcAg) VLPs with a nucleic acid binding region for efficient cargo-loading are being investigated. VLP structure, loading, and phase behavior are of central importance to their therapeutic efficacy and thereby considerably affecting the production process. Therefore, HBcAg VLPs with different lengths of the nucleic acid binding region were produced in E. coli. VLP attributes such as size, zeta potential, and loading with host cell-derived nucleic acids were evaluated. Capsid’s size and zeta potential of the VLP constructs did not differ remarkably, whereas the analysis of the loading with host cell-derived nucleic acids revealed strong differences in the binding of host cell-derived nucleic acids dependent on the length of the binding region of the constructs, with a non-linear correlation but a two-zone behavior. Moreover, the phase behavior and purification process of the HBcAg VLPs as a function of the liquid phase conditions and the presence of host cell-derived nucleic acids were investigated. Selective VLP precipitation using ammonium sulfate was scarcely affected by the encapsulated nucleic acids. However, the disassembly reaction, which is crucial for structure homogeneity, separation of encapsulated impurities, and effective loading of the VLPs with therapeutic nucleic acids, was affected both by the studied liquid phase conditions, varying pH and concentration of reducing agents, and the different VLP constructs and amount of bound nucleic acids, respectively. Thereby, capsid-stabilizing effects of the bound nucleic acids and capsid-destabilizing effects of the nucleic acid binding region were observed, following the two-zone behavior of the construct’s loading, and a resulting correlation between the capsid stability and disassembly yields could be derived.

Chiral Determination of Naringenin by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry and Application in Citrus Peel and Pulp.

A chiral separation method of naringenin in citrus pulp and peel was established using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) in this study. The liquid-phase conditions for separation were Chiralpak IG-3 column at 40°C, mobile phase of methanol, and 0.1% formic acid solution (85/15; v/v). Isovolumetric elution can complete the detection within 5 min. Considering the matrix effect, the matrix standard calibration curve was used for sample quantification. Quantitation was achieved by fitting a calibration curve using a standard matrix. The mean overall recoveries of the two enantiomers from orange pulp were 91.0–110.0% and orange peel were 85.3–110.3%, with relative standard deviations of 1.5–3.8 and 0.9–3.6% at the 0.5, 2.5, 50, and 250 μg/kg levels, respectively. The limit of quantification for all enantiomers in the citrus matrix did not exceed 0.5 μg/kg. Furthermore, the absolute configuration of the naringenin enantiomer was determined by combining experimental and predicted electron circular dichroism spectroscopy, and it was confirmed on a Chiralpak IG-3 column that the first eluting enantiomer was (S)-naringenin. The determination of chiral naringenin content in actual citrus samples showed that the naringenin content in hybrid citrus and citrus pulp was significantly higher than that in pomelo. The method established in this study can be used for the determination of naringenin enantiomers in citrus, which is beneficial to variety selection.

A durable Ni/La-Y catalyst for efficient hydrogenation of γ-valerolactone into pentanoic biofuels

Zeolite-supported metal catalysts containing hydrogenation centers and acid sites are promising in the chemoselective hydrogenation of biomass platform molecules into value-added chemicals and fuels. The primary challenge of employing such bifunctional catalysts for biomass conversion lies in catalyst stability in the liquid phase under harsh conditions. Herein, we have prepared a Ni/La-Y nanocatalyst via an improved wet impregnation method. Compared with Ni nanoparticles on H-Y, La addition shows a significantly enhanced stability and performance in the continuous liquid-phase hydrogenation of γ-valerolactone (GVL) into ethyl pentanoate (EP) at 200 °C for 1000 h. Complementary characterization studies reveal that La addition in the metal/zeolite catalyst not only efficiently modulates the acid property of the zeolite to alleviate coke formation, but also suppresses zeolite dealumination and metal agglomeration and leaching upon catalysis over a 1000 h period. These findings provide an efficient approach for improving the stability of zeolite-supported bifunctional catalysts, leading to potential application in hydrogen-assisted biomass valorization under the liquid-phase conditions.

Oxidative carbonylation of methane to acetic acid over micro-mesoporous rhodium-modified zeolites

It was first demonstrated that under liquid-phase conditions, an increase in the mesoporosity of ZSM-5 zeolite boosts a rhodium-containing catalyst activity in the oxidative carbonylation of methane to acetic acid (the acetic acid yield is 570 μmol g cat −1 ). To increase the mesoporosity of zeolite, two approaches were used: ultrasonic treatment and desilication of zeolite. The ultrasonic pretreatment leads to an increase in the acetic acid yield with a decrease in the total yield of oxygenates (methanol/acetic acid molar ratio is 0.2). On the contrary, preliminary desilication contributes to an increase in the total yield of oxygenates, mainly due to methanol (methanol/acetic acid molar ratio is 1.8). The combination of ultrasonic pretreatment and desilication of zeolite improves the total yield of oxygenates with an increase in the acetic acid yield. Such a change in the catalytic properties is attributed both to the acidity of the parent zeolite and the local atomic environment of rhodium. XAS spectroscopy showed that rhodium can be present on the zeolite surface either as nanoclusters giving rise to methanol or as isolated rhodium atoms, which promote the acetic acid formation. • Oxidative conversion of methane to acetic acid with the assistance of СО was studied. • Rhodium-modified microporous and micro-mesoporous zeolite catalysts were used. • Ultrasonic treatment of the zeolite leads to an increase in the yield of acetic acid. • Desilication of the zeolite leads to an increase in the yield of methanol. • The formation of acetic acid is facilitated by the monoatomic distribution of rhodium.

Modernization of the Catalyst Composition for the Synthesis of Acrylic Acid Nitrile in Aqueous and Non-Aqueous Media

The effect of the components of the catalyst solution for the hydrocyanation of acetylene on the activity and selectivity of the process under liquid-phase conditions has been studied. The introduction of ZnSO 4 and ZnO additives into the shop catalyst did not give a positive effect under these conditions. Studies of catalysts in non-aqueous media lead to an increase in their activity and selectivity in comparison with aqueous media. It has been shown that the composition of the CuCl - NMP - DMF catalyst is characterized by high activity (up to 32 g / l.h.) and selectivity (83-90%), i.e. the activity of this composition is almost twice as high as compared to the water-based ones (12-18 g l.h.).

Membranes for the Gas/Liquid Phase Separation at Elevated Temperatures: Characterization of the Liquid Entry Pressure.

Hydrophobic membranes were characterized at elevated temperatures. Pressure was applied at the feed and permeate side to ensure liquid phase conditions. Within this scope, the applicability of different polymeric and ceramic membranes in terms of liquid entry pressure was studied using water. The Visual Method and the Pressure Step Method were applied for the experimental investigation. The results show the Pressure Step Method to be an early detection method. The tests at higher pressure and temperature conditions using the Pressure Step Method revealed the temperature as being the main factor affecting the liquid entry pressure. Novel LEP data up to 120 °C and 2.5 bar were obtained, which broadens the application range of hydrophobic membranes.

Kinetics on 1,3-butadiene dimerization by the cycloaddition reactions in high pressure and high temperature micro-reactor

The kinetics of 1,3-butadiene dimerization based on the cycloaddition reactions including Diels-Alder reaction under high temperature and high pressure were investigated in a microchannel reactor. Our findings suggest that the butadiene dimerization produced 4-vinyl-cyclohexene (VCH) and 1,5-cyclooctadiene (COD). The results indicate that COD can only be formed under high temperature conditions. The apparent kinetic parameters of butadiene dimerization under high pressure were obtained by fitting experimental data. As the reaction pressure increased, the reaction rate in the solution was found to increase slightly. Compared with the gas phase dimerization of butadiene in the literature, it can be concluded that the reaction rate constants in the liquid phase are greater than that in the gas phase. To our best knowledge, this is the first work reporting the kinetic parameters of butadiene dimerization with the radical polymerization excluded under high pressure liquid phase condition.