Feed Molar Ratio Research Articles

Tuning the peroxidase-mimic activity of CuX-trithiocyanuric acid complexes for colorimetric detection of gastric cancer-associated D-amino acids

A cascade colorimetric detection of salivary D-amino acids (DAAs) holds promise for the preliminary screening diagnosis of gastric cancer. Pursuing metal-organic complexes with high peroxidase-mimic (POD-mimic) activity is crucial to enhance diagnosis efficiency. In this work, we developed a straightforward strategy in a “one-pot” process to modulate the POD-mimic activity of CuX-trithiocyanuric acid (CuX-TTCA) complexes. By adjusting the molar ratios of CuX (Cl, Br, and I) and TTCA during synthesis to modify the coordination configuration of Cu(I) in CuX-TTCA, we easily tuned their POD-mimic activities. Among them, CuCl-TTCA-2 with a feeding molar ratio of 2:1 for CuCl:TTCA exhibited remarkable POD-mimic activity attributed to its exposed catalytic active sites and efficient mass transfer ability during catalysis. Long-lived 1O2 was identified as the primary reactive oxygen intermediate. A highly sensitive and selective cascade colorimetric detection platform was developed for two typical DAAs associated with gastric cancer, namely D-proline and D-alanine, achieving limit of detection values of 1.1 and 0.8 μM, respectively. As a proof-of-concept application, our cascade detection platform demonstrated excellent specificity in distinguishing saliva samples between gastric cancer patients and healthy individuals. The outstanding selectivity and reliable outcomes from DAAs assay make our detection platform highly promising for preliminary screening diagnosis of gastric cancer and patient self-detection applications. Our straightforward strategy for tuning POD-mimic activity provides an in-depth understanding on structure-activity relationship in nanozymes, offering valuable opportunities to advance enzyme-mimic optimization for other potential applications.

Histidine phosphatase-ferroptosis crosstalk modulation for efficient hepatocellular carcinoma treatment

Altering the mechanisms of tumor cell death and overcoming the limitations of traditional chemotherapy is pivotal to contemporary tumor treatment. Inducing ferroptosis, while circumventing safety concerns associated with ferrous vectors, through nonferrous ferroptosis is a promising but underexplored frontier in cancer therapy. Histidine phosphatase (LHPP) has emerged as a novel therapeutic target in treating hepatocellular carcinoma (HCC), but the precise mechanism of LHPP against HCC remains unclear. Herein, we explore the effects of upregulating LHPP expression on ferroptosis and tumor immunogenicity induction by simply delivering a miRNA-363-5p inhibitor (miR-363-5pi) via a previously optimized gemcitabine-oleic acid (GOA) prodrug. Efficient miRNA encapsulation was achieved through hydrogen bonding at an optimized GOA/miRNA molar feed ratio of 250:1, affording spherical nanoparticles with a uniform hydrodynamic size of 147.1 nm and a negative potential of -21.5 mV. The mechanism of this LHPP-ferroptosis crosstalk is disclosed to be an inhibited phosphorylation of the PI3K/Akt pathway, leading to a remarkable tumor inhibition rate of 88.2% in nude mice bearing Bel-7402 tumor xenografts via a combination of LHPP-triggered nonferrous ferroptosis and GOA-induced chemotherapy. The biocompatibility of GOA/miR-363-5pi is strongly supported by their non-hematologic toxicity and insignificant organ damage. In addition, the tumor immunogenic activation potential of GOA/miR-363-5pi was finally explored. Overall, this study is the first work that elucidates the precise mechanism of LHPP for treating HCC via ferroptosis induction and achieves the transformation of chemotherapy and gene therapy into ferroptosis activation with tumor cell immunogenicity, which lays a new therapeutic foundation for the clinical treatment of HCC.Graphical

COMPARISON OF BIODIESEL PRODUCTION FROM OLEIC ACID IN BATCH REACTOR AND MEMBRANE REACTOR

This study examines the production of biodiesel by the esterification reaction between oleic acid and ethanol. Conversions between reactions carried out with batch reactors and membrane reactors are compared and the advantages of membrane reactors are stated. The parameters examined in the study are catalyst concentration (2%, 4%, 6%), ethanol/oleic acid molar ratio (3,6,9) and temperature (between 45-65°C). The effect of these parameters on oleic acid conversion was evaluated and the reactions were carried out under the conditions determined because of the optimization. The highest conversion value in the batch reactor was obtained as 85.5% at 65°C, with an alcohol: acid molar feed ratio of 6:1 and a catalyst concentration of 4%. In addition, 50% conversion was achieved in the batch reactor with an ethanol/oleic acid molar ratio of 3, temperature 55°C and 4% catalyst ratio, while 75% conversion was achieved in the membrane reactor. These results show that the acid conversion achieved in the membrane reactor is 26% higher compared to batch reactors under the same operating conditions.

Synthesis of Ultrahigh Molecular Weight Poly (Trifluoroethyl Methacrylate) Initiated by the Combination of Palladium Nanoparticles with Organic Halides

Ultrahigh molecular weight polymers display outstanding properties and have great application potential. However, the traditional polymerization methods have inevitable disadvantages that challenge the green synthesis of ultrahigh molecular weight polymers. The paper achieved an ultrahigh molecular weight poly (trifluoroethyl methacrylate) via a novel polymerization and discussed the mechanistic, kinetic, and experimental aspects. The combination of palladium nanoparticles with ethyl 2-bromopropionate has been identified as an exceedingly efficient system for initiating the polymerization of trifluoroethyl methacrylate. An ultrahigh molecular weight poly (trifluoroethyl methacrylate) with a number-average molecular weight up to 3.03 × 106 Da has been synthesized at a feeding molar ratio of [poly (trifluoroethyl methacrylate)]/[ethyl 2-bromopropionate]/[palladium nanoparticles] = 3.95 × 104:756:1 at 70 °C. The reaction orders concerning palladium nanoparticles, ethyl 2-bromopropionate, and poly (trifluoroethyl methacrylate) were determined to be 0.59, 0.34, and 1.38, respectively. By analyzing a series of characterizations, we verified that the polymerization of poly (trifluoroethyl methacrylate) was initiated by the ethyl 2-bromopropionate residue radicals, which were generated from the interaction between palladium nanoparticles and ethyl 2-bromopropionate. The comparatively large size of the palladium nanoparticles provided a barrier to chain-growing radicals, promoting the synthesis of ultrahigh molecular weight polymers.

Enhanced antifouling and anti-swarming properties poly (sulfobetaine methacrylate-co-2-hydroxy-3-phenoxypropyl acrylate) hydrogel coatings for urinary catheters

Catheter-associated urinary tract infection (CAUTI) remains an unsolved challenge to date, particularly with the emergence and rapid spread of antimicrobial-resistant bacterial pathogens. Despite extensive research, a catheter coating that can offer intrinsic resistance to host protein deposition, bacterial biofilm formation, and swarming is still urgently required. Zwitterionic hydrogel coatings due to their superior lubricity and antifouling properties represent a promising candidate, but their weak mechanical stability in water and poor resistance to bacterial swarming migration limit their application in urinary catheters for infection control. In this research, we describe the fabrication of a multifunctional catheter coating by copolymerizing zwitterionic sulfobetaine methacrylate (SBMA) polymers and a swarming inhibitor material, 2-hydroxy-3-phenoxypropyl acrylate (HPA). The introduction of polyHPA (PHPA) effectively impeded the uncontrolled swelling behavior of the zwitterionic PSBMA hydrogel, resulting in enhanced mechanical stability. Moreover, the copolymer coating retains the antifouling and anti-swarming properties of the homopolymers when challenged with fibrinogen, Escherichia coli, and Proteus mirabilis. The HPA content significantly correlated with its anti-adhesion activity against fibrinogen and biofilm, and the coating with an SBMA: HPA monomer feed molar ratio of 4:1 showed the best antifouling activity, reducing fibrinogen deposition by about 40 % and biofilm coverage by around fourfold compared to the uncoated polydimethylsiloxane (PDMS) surface. Furthermore, the copolymer coating also exhibited no cytotoxicity, suggesting it as a promising catheter coating for preventing CAUTI.

Synthesis and characterization of Zn-In-S composites for photocatalytic benzyl alcohol oxidation and nitrobenzene reduction

Photocatalytic transformation of organics is a promising alternative to conventional synthetic methodologies. ZnIn2S4 is active in photocatalytic redox reactions, but its performance is hindered by fast charge carrier recombination, and optimizing its properties through synthesis or modification is complicated. Herein, Zn-In-S based composites were prepared via a facile solvothermal method by varying the ratio of sulfide precursor (TAA) with a fixed Zn/ In molar ratio of 1: 2. The phase composition of the obtained materials depends on the amount of TAA. At lower ratios, composites consisting of crystalline In(OH)3 and unknown ZnxInySz phase were formed. Pure-phase ZnIn2S4 was obtained when the feed molar ratio of zinc and TAA was 1: 6 or higher. The photocatalytic oxidation of benzyl alcohol (BA) and reduction of nitrobenzene (NB) in a coupled system were applied to evaluate the activity of Zn-In-S-based composites. Under visible light irradiation, the ZnxInySz/ In(OH)3 composite (ZIS14) synthesized with a molar ratio of Zn to TAA of 1: 4 exhibited boosted and optimal performance compared to the bare ZnIn2S4 and other samples. After 5 hours of irradiation, the BA conversion and benzaldehyde (BAD) yield were 57 % and 55 %, respectively, and the NB conversion and aniline (AN) yield were 70 % and 35 %, individually, outperforming previous studies under similar experimental conditions. This work not only elucidates the photoredox process of BA and NB in one system, but also has significant implications for understanding the complex hydro/solvothermal processes involved in the fabrication of multicomponent sulfides.

(Invited) Development of Ag- and Sn-Based Colloidal Quantum Dots for Near Infrared Photodetection

Low-cost photodetectors with sensitivity in the second near-infrared window (NIR-II, 1000–1700 nm) are highly demanded. Recently, we made the first demonstration of an Ag2Se colloidal quantum dots (QDs) photodiode with sensitivity up to 1200 nm. By employing secondary phosphine to elevate the precursor reactivity, the Ag2Se QDs with a distinct excitonic absorption peak was achieved. These nanocrystals were deposited from solution into a mesoporous TiO2 scaffold to increase the light absorption and charge separation and reduce the exciton diffusion length. By incorporating a suitable hole-transporting layer between the active layer and Ag anode, the resulting devices showed a responsivity of 4.17 mA/W at 1200 nm.1 Also, Ag2Te QDs are excellent for advancing the detection wavelength. Their synthesis with desired particle sizes, narrow size distribution and high photoluminescence quantum yield (PL QY) is challenging. We systematically investigate critical parameters affecting the synthesis in an organic phase. It shows that high Ag/Te feed ratio leads to smaller size and higher PL QY; under 4:1 Ag/Te feed molar ratio, addition of secondary phosphine leads to narrower size distribution and excellent colloidal stability; under 6:1 Ag/Te feed molar ratio, excess 1-dodecanethiol as a strong ligand slows the nucleation and results in fewer nuclei, leading to a broad size distribution and poor optical properties; additional n-trioctyl phosphine as a weak ligand provides better colloidal stability; and another weak ligand n-tributylphosphine improves Ag2Te QD colloidal stability, focuses size distribution, and enhances PL QY. After optimization relatively large Ag2Te QDs with distinct excitonic absorption peaks (~1050 – 1450 nm) and PL emission peak 1.3 – 1.7 µm (QY up to 6.2%) were obtained. NIR-II photodetection has been demonstrated with a responsivity of ~1.5 mA/W at 1400 nm.2 More recently, we have been developing Sn-based chalcogenide QDs and obtained preliminary photodetection results. These results demonstrate that Ag and Sn chalcogenide QDs offer a low-toxicity route for low-cost fabrication of NIR-II photodetection. Reference: [1] Graddage N, Ouyang J, Lu J, Chu TY, Zhang Y, Li Z, Wu X, Malenfant PRL, Tao Y. Near-Infrared-II Photodetectors Based on Silver Selenide Quantum Dots on Mesoporous TiO2 Scaffolds. ACS Applied Nano Materials 2020, 3: 12209–12217.[2] Ouyang J, Graddage N, Lu J, Zhong Y, Chu TY, Zhang Y, Wu X, Kodra O, Li Z, Tao Y, Ding J. Ag2Te Colloidal Quantum Dots for Near-Infrared-II Photodetectors. ACS Applied Nano Materials 2021, 4: 13587–13601. Keywords: Environmentally Friendly; Near Infrared; Quantum Dots; Photodetection.

Light-Triggered Reversible Swelling of Azobenzene-Containing Block Copolymer Worms via Confined Deformation Prepared by Polymerization-Induced Self-Assembly.

Stimuli-responsive block copolymer nanoparticles (NPs) have received close attention in recent years owing to their tremendous application potential in smart materials. Azobenzene-containing NPs are widely studied due to the advantages of light as a stimulus and fast reversible trans-cis isomerization of azobenzene chromophores. However, the inefficient preparation process and difficult reversible transformation of morphologies limit their development. Herein it is demonstrated that the light-triggered reversible swelling behavior of wormlike NPs with high azobenzene content could be realized via confined deformation. These worms are prepared in large quantities via polymerization-induced self-assembly based on the copolymerization of 11-(4-(4-butylphenylazo)phenoxy)undecyl methacrylate (MAAz) and N-(methacryloxy)succinimide (NMAS) monomers. Upon UV/visible light irradiation, the reversible deformation of worms is achieved when the feed molar ratio of NMAS/MAAz is relatively high or via crosslinking using diamines, which leads to the reduction of the photoisomerization efficiency. The diameter variation of the worms is influenced by the amount and types of crosslinkers. Moreover, the scalability of this strategy is further proved by the fabrication of photo- and reductant-responsive crosslinked worms. It is expected that this study not only provides a new route to affording reversible photoresponsive NPs but also offers a unique insight into the reversible photodeformation mechanism of azobenzene-containing NPs.

A Mini Review on Liquid Phase Catalytic Exchange for Hydrogen Isotope Separation: Current Status and Future Potential

Liquid phase catalytic exchange (LPCE) appears a highly promising technology for separating hydrogen isotopes due to being less energy-intensive and having a high separation factor. This paper provides an overview of the current development of the hydrophobic catalysts used in the LPCE process, including the LPCE fundamentals, factors influencing its effectiveness, and proposals for future research areas. This paper specifically reviews the active metal catalysts, catalyst supports, operating temperatures, and molar feed ratio(gas-to-liquid,G/L). The addition of a second metal such as Ir, Fe, Ru, Ni, or Cr and modified catalyst supports showed enhancement of LPCE performance. Additionally, the validated optimized temperature of 60–80 °C and G/L of 1.5–2.5 provide an important basis for designing LPCE systems to improve separation efficiency. This paper concludes by highlighting potential research areas and challenges for future advancements in the sustainability of LPCE for hydrogen isotope separation, which include the optimization, scalability, techno-economic analysis, and life-cycle analysis of modified catalyst materials.

Structural and viscosity studies of dendritic hyper branched polymer as viscosity index improvers

Star-like structural compounds were synthesized from different moles % of either dodecyl acrylate or triethylenetetramine using a one-pot commercial synthesis technique. The polymers that were created had various terminations. Fourier Transform Infrared (FTIR) spectroscopy and 1HNMR were used to verify the produced polymers' chemical composition with different terminations. Furthermore, by analysis of Dynamic Light Scattering (DLS), the size and distribution of the synthesised branched polymers were evaluated. Using a Gel-permeation chromatograph, the modified hyperbranched polymer's molecular weight, synthesized with various end points, were assessed. The unorganized structured prepared compounds with various molar feed ratios dodecyl acrylate: triethylenetetramine (DDA: TETA) was designed as A, B, C, D and E. Moreover, the synthesized additives function as viscosity index improvers (VII). As the concentration of polymeric additives increases, it leads to higher VI values. Similarly, with the increase in percentage of triethylenetetramine in the prepared hyperbranched polymers, the VI also increases. Notably, the most effective VI achieved is (E) = 212. It is noteworthy that all the synthesized hyperbranched polymers exhibited Newtonian behavior in the rheological study.

Thermadapt shape memory vitrimeric polymyrcene elastomer

Earlier studies of β-Myrcene (Myr)/ β-ketoester functional (acetoacetoxy)ethyl methacrylate (AAEMA) copolymers exhibited compositional drift, leading to ambiguity in microstructure/thermomechanical property correlations while shape memory recovery times were excessively long ~1 h. The terpene-based 1,3-diene Myr and AAEMA were copolymerized via nitroxide-mediated polymerization (NMP) with an initial Myr molar feed ratio ranging from 0.1 to 0.9. Reactivity ratios estimated by the Meyer-Lowry method were rMyr = 0.20 and rAAEMA = 0.22 with respective 95% confidence intervals of [0.13, 0.37] and [0.15, 0.23], suggesting alternating copolymerization. Bulk terpolymerization with styrene (Sty) afforded linear poly(Myr-stat-Sty-stat-AAEMA) prepolymers designed to modulate glass transition temperature Tg and stiffness. Subsequent cross-linking with isophorone diamine (IPDA) formed catalyst-free vinylogous urethane dynamic linkages. ATR-FTIR, dynamic mechanical analysis (DMA), and tensile measurements confirmed the recyclability of vitrimers through hot pressing at 110 °C, demonstrating minimal changes in rheological and mechanical properties even after four cycles. By heating the vitrimers to above their Tg (to ~45 °C), they exhibited a shape memory effect with high shape fixity and fast shape recovery (< 1 min). The vitrimers could undergo permanent shape reprogramming through reconfiguration of dynamic bonds at ~110 °C. This work shows the adaptability of Myr-based rubbers by vitrification and appropriate copolymerization for the synthesis of more sustainable elastomers with stimuli responsive properties.

Hydrogen sulfide methane reforming: A kinetic modeling and techno-economic analysis study

Hydrogen sulfide (H2S) methane (CH4) reforming (H2SMR) is a promising process for sustainable energy production from conventional fuels, offering triple benefits for generating clean hydrogen (H2), consuming toxic H2S, and producing an economically valuable by-product carbon disulfide (CS2). In this work, we studied the optimal operating conditions and assessed the economic feasibility of the non-catalytic H2SMR process, employing a combination of kinetic modeling, process modeling, and techno-economic analysis. Plug flow reactor simulations were performed with our newly developed mechanism to shed light on the optimal operating conditions. It was concluded that a H2S/CH4 molar feed ratio of 2 results in the highest hydrogen production rate, and a feed ratio of 1–2 and a temperature of 1100–1300 °C are needed to maximize the CS2 production rate. However, feed ratios higher than 2 increase the conversion rate of CH4 and therefore benefit the purity of the H2 product. Comparing the cases for a feed ratio of 2 at 1300 °C and a feed ratio of 9 at 1200 °C, the cost is significantly higher for the feed ratio of 9, mainly attributed to the higher electricity cost for higher inlet flow rate and H2S recycling, as well as the cost for the additional steam required during the preheating process. The cost of hydrogen production by H2SMR process could be as low as $1.47/kgH2 for a feed ratio of 2 and solar PV as an energy source, which is more competitive than a cost of $1.97/kgH2 for the steam methane reforming process. Furthermore, since CS2 is a valuable by-product, the higher amount of CS2 formed at a feed ratio of 2 becomes the main source of revenue, which completely covers the cost of hydrogen production. This study demonstrates the huge potential of H2SMR process as a clean and economic-competitive way to produce hydrogen.

Development of a bifunctional material incorporating carbon microspheres for the intensified hydrogen production by sorption-enhanced glycerol steam reforming

Glycerol steam reforming is a green and sustainable alternative to hydrocarbon steam reforming for hydrogen production. Reaction intensification by in-situ CO2 removal using Ni/CaO-based bifunctional sorbent-catalyst materials was investigated in this paper to improve the hydrogen yield and purity significantly. Employing carbon microspheres as the foundation for sorbent synthesis resulted in the development of a hollow CaO sphere sorbent with higher and more stable sorption capacity over multiple adsorption/regeneration cycles compared to sorbents synthesized with conventional methods. The incorporation of different stabilizers improved further the capacity and stability of sorbents. The sorbent materials were tested under different sorption and regeneration temperatures in a dry and wet atmosphere. The intensified sorption-enhanced steam reforming process was evaluated under various reaction temperatures, weight hourly space velocities, and steam-to-carbon molar feed ratios. The bifunctional materials synthesized with carbon microspheres led to improved reaction performances, including a more extended pre-breakthrough period and a more stable behavior during reaction/regeneration cycles.

A novel and clean technique for the one-pot production of green chemical γ-valerolactone from furfural using bifunctional H3PW12O4/UiO-66 catalyst: Pervaporation membrane reactor

This study focuses on the synthesis of gamma-valerolactone (GVL) from furfural using a bifunctional H3PW12O4-UiO-66 catalyst. The membrane was prepared using PBI polymer. H3PW12O4-UiO-66 catalysts with different amounts of H3PW12O4 were synthesized. The catalytic activity of these synthesized catalysts was investigated in pervaporation membrane reactor to obtain GVL from furfural and the catalyst containing 2 g of H3PW12O4 was identified as the optimum catalyst. After determining the optimum catalyst, the effect of temperature, molar feed ratio, and catalyst concentration on the reaction and separation performance was investigated. The optimum values were determined as 90 °C, molar feed ratio 10 and 6 g/L catalyst concentration by evaluating both reaction and separation performance. The performance of the pervaporation membrane reactor (PVMR) was compared with a batch reactor operated under the same conditions. In the batch reactor operating at 90°C, molar feed ratio of 10, and 6 g/L catalyst concentration, a 65% furfural conversion and 51% GVL yield were obtained, whereas the PVMR achieved 100% furfural conversion and 94.21% GVL yield. This comparison demonstrates the improved efficiency of the PVMR in increasing conversion and yield compared to the traditional batch reactor. The obtained conversion and yield values under the investigated operating conditions highlight the proposed process as a promising alternative for the production of GVL from furfural.

Optimizing single-atom cerium nanozyme activity to function in a sequential catalytic system for colorimetric biosensing

Ever-increasing attention is being drawn towards single-atom nanozymes (SAzymes) for colorimetric biosensing applications. A series of atomically dispersed cerium (Ce) nanozymes are synthesized with different feeding molar ratios of Ce/Zn or under various pyrolysis temperatures, and their enzymatic performance, including peroxidase-, oxidase-, and catalase-activities, is explored. Both theoretical and experimental results demonstrate that Ce species symmetrically coordinate with nitrogen atoms to form CeN4 moieties which exhibit peroxidase-like activity. The best Ce-based SAzyme achieves remarkable peroxidase-like specificity and enables the colorimetric sensing of H2O2. This sensitivity provides a versatile reporter platform for detecting the activities of natural enzymes involved in H2O2 generation and further monitoring their substrates as well as inhibitors, for example, organophosphorus pesticides (OPs) when integrating with the acetylcholine esterase-choline oxidase biocatalyzed cascade. More importantly, this proposed sequential catalytic biosensor exhibits the capability to monitor trace OPs in the real samples with high sensitivity yet insignificant interference. This work sheds new light on further design of highly active lanthanide-based SAzymes to boost enzyme-mimicking reactions for the applications in rapid on-site colorimetric analysis of emerging contaminants in environmental and food samples.

Parametric and sensitive analysis of Pd-Ag membrane reactor performance in biogas reforming to generate decarbonized hydrogen by Computational Fluid Dynamic-Response Surface Methodology

The efficient production of hydrogen from renewable sources is pivotal for the development of sustainable energy systems. Biogas steam reforming (BSR) conducted in palladium-based membrane reactors (MRs) offers a pathway for high-purity H2 generation at lower temperatures compared to traditional processes. In this study, a computational fluid dynamics (CFD) model was developed to simulate the BSR process within a Pd-Ag MR. The CFD model has integrated comprehensive kinetics, mass transport, and hydrodynamics, and its accuracy was confirmed through validation against experimental data, demonstrating substantial agreement. As a novel approach, to optimize the BSR reaction conditions to get the best MR performance, the CFD model was coupled with response surface methodology (RSM), which has been employed to enable the identification of optimal values for key parameters such as reaction temperature, pressure, gas hour space velocity, feed molar ratio, and sweep gas ratio, where the temperature was found to have the most significant impact on the MR’s performance within the examined intervals of input parameters. The objective of RSM method applied to CFD modeling was to maximize with high accuracy CH4 conversion, H2 recovery, and reduce CO2 emissions. RSM models effectively established correlations between input parameters and responses. The determined optimal conditions for the BSR process were a temperature of 683 K, a reaction pressure of 6 bar, a GHSV of 3000 h−1, a H2O/CH4 ratio of 1.34, and a sweep ratio of 9. Under these conditions, the system achieved remarkable results with 100 % CH4 conversion, 43 % H2 recovery, and an 81 % reduction in CO2 emissions. This study underscores the effectiveness of integrating CFD with RSM for the precise modeling and optimization of MRs in BSR reactions. The synergy between these approaches provides a robust framework for advancing the efficiency and sustainability of hydrogen production processes from renewable sources.

One-step conversion of ethane to ethylene oxide in AC parallel plate dielectric barrier discharge

This work studied the one-step conversion of ethane (C2H6) to ethylene oxide (EO) in an AC parallel plate dielectric barrier discharge (DBD) system with two frosted glass plates under ambient temperature and atmospheric pressure. EO is directly produced from C2H6 in a single step without the requirement to separate and recycle ethylene. The effects of the applied voltage, input frequency, and O2/C2H6 feed molar ratio on the EO synthesis performance were examined. The results showed that a higher applied voltage and lower input frequency generated more highly energetic electrons, resulting in a higher current. More electrons collided with reactant gas molecules to initiate plasma reactions, increasing C2H6 and O2 conversions. The increased O2/C2H6 feed molar ratio enhanced C2H6 and O2 conversions. The optimum conditions were found to be an applied voltage of 7 kV, input frequency of 550 Hz, and O2/C2H6 feed molar ratio of 1:1, which demonstrated the highest EO selectivity (42.6%), EO yield (19.4%), and lowest power consumption per EO molecule produced (6.7 x 10-18 Ws/molecule).

Simulation study of reactive distillation process for synthesis of dimethyl maleate

Abstract Conventional dimethyl maleate (DMM) synthesis relies on the use of sulfuric acid as a catalyst which requires water washing and produces a large amount of wastewater that harms the environment. The use of this method is expensive since it involves numerous processes such as neutralization of sulfuric acid, washing with water, distillation etc. and the yield of dimethyl maleate is not very high. Reactive distillation integrates the two important industrial processes such as reaction and distillation into a single unit which shortens the overall process, reduces capital and operating costs, and maintains the reaction in a forward direction to enhance the conversion of maleic anhydride by continuously removing of the products. In this work, simulation study based on experimental investigation of reactive distillation process for the synthesis of dimethyl maleate was carried out using Aspen Plus V11. DZH strong cation exchange resin was used as catalyst for esterification reaction of maleic anhydride with methanol. A reactive section of column was packed with Katapak SP type packing loaded with DZH catalyst while non-reactive sections consist of wire gauze packing. In order to describe a reactive distillation process for synthesis of dimethyl maleate, RAD-FRAC equilibrium stage model was employed. The NRTL activity model and RK equation of state model were selected to describe vapor-liquid equilibrium of the system. The reliability of the developed simulated model was verified by validating the simulation results with the experimental ones. The effect of various design and operating parameters on the conversion of maleic anhydride and purity of dimethyl maleate has been studied. It was found that the optimal condition for RD, were as follow: total number of theoretical stages 17, rectifying stages 3, reactive stages 7, stripping stages 5, reflux ratio 0.25, operating pressure 0.1 MPa, reboiler duty 250 Cal/Sec, feed mole ratio 1:5. Under optimized condition the water formed as a results of esterification reaction was constantly removed from the reactive section of the column to maintain reaction balance, the conversion of maleic anhydride was 99.95 %, purity of dimethyl maleate achieved was 0.997 and the reactive distillation process was feasible to produce dimethyl maleate without any wastewater.

Reduction of SO2 to Elemental Sulfur in Flue Gas Using Copper-Alumina Catalysts

This study aims to propose an advanced catalyst for the selective catalytic reduction of SO2, as a sustainable process to mitigate the emission of this toxic gas, which is a significant environmental concern. The conversion of SO2 through catalytic reduction with CH4 to elemental sulfur was investigated using Al2O3-Cu catalysts. The reaction was conducted under atmospheric pressure and at a temperature range of 550–800°C. A remarkable 99.9% SO2 conversion rate and 99.5% sulfur selectivity were achieved using the Al2O3-Cu (10%) catalyst at 750°C. The highest conversion rates of SO2 to elemental sulfur, with minimal production of undesirable by-products such as H2S and COS, were obtained when the SO2/CH4 molar feed ratio was set at 2, which is the stoichiometric ratio. Furthermore, the optimal catalyst exhibited excellent long-term stability for SO2 reduction with methane.

TO ISSUE INCREASING THE EFFICIENCY OF THE MASS TRANSFER PROCESS IN AGITATORS

This study investigates the impact of impeller design on the rate of esterification reaction in a batch reactor. Different impeller designs were tested and compared, including Backswept impeller, C-shaped, Double Blade impeller, and Pitched impeller. The results showed that the choice of impeller design has a significant effect on the rate of esterification reaction, with the Backswept impeller proving to be the most effective. In this work, it is aimed to investigate the esterification of acetic acid and methanol in a batch stirred reactor for the synthesis of methyl acetate. The temperature range of 303.15 K is examined, with sulphuric acid used as the homogeneous catalyst in varying concentrations of 0.0633 mol·L1 to 0.3268 mol·L-1. The feed molar ratio of acetic acid to methanol also varied from 1:1 to 1:4 to observe its influence on the reaction rate. The research delves into the effects of temperature, catalyst concentration, and reactant concentration on the reaction rate. The experimental data is correlated using a second-order kinetic rate equation, and the forward and backward reaction rate constants and activation energies are determined from the Arrhenius plot. The developed kinetic model is compared with previous models in literature. In order to find the most effective impeller for esterification reaction, diameter of impellers was accepted same in the constant volume and dimension of batch reactor. The obtained kinetic equation proves useful for the simulation of a reactive distillation column for the synthesis of methyl acetate. Keywords: the batch reactor, impeller, esterification, effectivity, mass transfer, mixing, mechanical mixers, Logarithmic Shear Rate, Eddy Diffusivity.