Catalyst Contact Time Research Articles

Boosting biodiesel production from waste vegetable oil water using Acid-Base Sequential Catalysis

<p>The use of active and recyclable catalysts is advantageous for catalytic biodiesel synthesis from waste vegetable oils which is in demand owing to frequent calls on environmental pollution and for clean renewable energy production. For this study, homogenous catalysts are effective at converting single-origin feedstocks low in free fatty acids (FFA) and water into biodiesel. Biodiesel production based on waste vegetable oil was carried out to establish an optimal catalyst régime. Acid-catalyzed transesterification and sequential base catalysis were used to convert waste vegetable oil to biodiesel at varying amounts of catalyst (0.46-0.58%) and different contact times (1-2 hr). Optimal yields were obtained at 2 hrs contact time and 0.50% amount of catalyst. Characterization tests conducted were specific gravity (0.8718-0.8935), flash point (117-1370C), viscosity (4.29-6.09mm2/s) and cetane index (40-43) values were within biodiesel specifications. The study, therefore, confirmed that acid-base sequential catalysis holds a lot of promise for the creation of affordable, environmentally friendly technologies. The biodiesel's characteristics were also in good agreement with American (ASTM D6571) fuel specifications. Therefore, the work recommends the utilization of acid (H2SO4) and base (NaOH) catalysis in the technologically enhanced conversion of waste vegetable oil into biodiesel.</p>

Abatement of microbes and organic pollutants using heterostructural nanocomposites of rice straw CQDs with substituted strontium ferrite

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr0·4Ti0·4Mg0·2Fe2O4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr0.4Ti0·4Mg0·2Fe2O4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV–2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr0·4Ti0·4Mg0·2Fe2O4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes.

Continuous Direct Mechanocatalytic Suzuki-Miyaura Coupling via Twin-Screw Extrusion.

This work establishes the first direct mechanocatalytic reaction protocol within an extruder, focusing on the Suzuki-Miyaura reaction. Through the coating of either the extruder screws or barrel with Pd, we executed the cross-coupling reaction without the reliance on molecular catalyst compounds or powders, and solvents continuously. We identified the influence and interplay of crucial reaction parameters such as temperature, mechanical energy input, residence time, rheology, and catalyst contact time and finally obtained 36 % and 75 % of the reaction product after one and four reactor passes respectively.

An investigation of Ca-doped MgO nanoparticles for the improved catalytic degradation of thiamethoxam pesticide subjected to visible light irradiation

The remediation of pesticides from the environment is one of the most important technology nowadays. Herein, magnesium oxide (MgO) nanoparticles and calcium-doped magnesium oxide (Ca-doped MgO) nanoparticles were synthesized by the co-precipitation method and were used for the degradation of thiamethoxam pesticide in aqueous media. Characterization of the MgO and Ca-doped MgO nanoparticles were performed by XRD, SEM, EDX, and FT-IR analysis to verify the synthesis and variations in chemical composition. The band gap energy and crystalline size of MgO and Ca-doped MgO nanoparticles were found to be 4.8 and 4.7 eV and 33 and 34 nm respectively. The degradation of thiamethoxam was accomplished regarding the impact of catalyst dosage, contact time, temperature, pH, and initial pesticide concentration. The pH study indicates that degradation of thiamethoxam depends on pH and maximum degradation (66%) was obtained at pH 5 using MgO nanoparticles. In contrast, maximum degradation (80%) of thiamethoxam was observed at pH 8 employing Ca-doped MgO nanoparticles. The percentage degradation of thiamethoxam was initially increasing but decreased at higher doses of the catalysts. The degradation of the pesticide was observed to be increased with an increase in contact time while high at room temperature but decreased with a temperature rise. The effect of the initial concertation of pesticide indicates that degradation of pesticide increases at low concentrations but declines at higher concentrations. This research study reveals that doping of MgO nanoparticles with calcium enhanced the degradation of thiamethoxam pesticide in aqueous media.

Adsorbed oxygen atoms for improving the oxidative dehydrogenation of ethane over B-site-doped layered perovskite La2Ti2O7

In this study, Nd, Ga, and Sm were used to partially replace Ti in layered perovskite La2Ti2O7 (A2B2O7 type) with the aim of developing a highly efficient low-temperature catalyst for the oxidative dehydrogenation of ethane (ODHE). Ethylene was successfully produced by the ODHE over the modified catalysts at temperatures of as low as 600 °C, and the Ga-doped catalyst exhibited the highest ethylene yield of 16.9 % at 625 °C with a high gas hourly space velocity of 35,273 h−1 and short reactant–catalyst contact time of 0.1 s. Thermal activation improved the ethylene yield to 33.6–39.4 % at 650–700 °C with a short contact time (<0.1 s) and productivity of approximately 10 gethylene·gcatalyst−1·h−1, which exceeds reported values. However, the pure catalytic activity could not be depicted at higher temperatures (>700 °C) because the reaction became more complex owing to thermally activated processes such as thermal dehydrogenation, thermal–oxidative dehydrogenation, and reforming reactions. The effects of B-site doping were explored through in situ characterization and density functional theory calculations, and a mechanism for the ODHE was proposed based on the results. Adsorbed oxygen atoms, which form by the dissociation of molecular oxygen at high temperatures, are responsible for the selective dehydrogenation of ethane to ethylene. Overall, the electronic modification of the B-site doped La2Ti2O7 catalysts improved the catalytic activity at 525–575 °C, and the experimental and calculation results confirmed that dissociatively adsorbed oxygen atoms were responsible for the improved ODHE.

Chemical recycling of plastic waste to monomers: Effect of catalyst contact time, acidity and pore size on olefin recovery in ex-situ catalytic pyrolysis of polyolefin waste

The catalytic upgrading of post-consumer mixed polyolefinic waste pyrolysis vapors has been studied over five different solid acid catalysts to understand the effect of vapor-catalyst contact time and catalyst properties on the recovery of light olefins (C2-C4). HZSM-5 with Si/Al ratio of 11 and 27 produced the highest light olefins yields (83.4 wt% and 72.1 wt%, respectively) at a very short contact time of ∼5 ms while extending the contact time (≥23 ms) decreased the olefin yields and resulted in higher yields of aromatics (∼30.0 wt% and ∼40.0 wt%, respectively). Short contact time (5 ms) was not sufficient for HZSM-22 to crack pyrolysis vapors to C2-C4 olefins (8.0 wt%) but increasing contact time improved C2-C4 yields to 53.5 wt% without increased production of aromatics, which may be attributed to its small pore size (shape selectivity). SAPO-34, SAPO-11, and Al-MCM-41 were not selective to light olefins at any studied contact time.

Designing of a magnetically recoverable (Ce+3, +4/Fe+2. Fe+3) oxide@ 2D g-C3N4 surface for enhanced photo-Fenton catalytic degradation of Bismarck-Brown R and Congo red dyes: kinetics, optical properties,and mechanistic pathway studies

ABSTRACT Co-precipitation-assisted hydrothermal synthesis was employed to synthesize Fe3O4/CeO2 nanohybrids over 2D g-C3N4 (CF@GCN) for photo-Fenton catalytic degradation of Bismarck brown R (BBR) and Congo Red (CR) dyes. Initially, Fe loading was deployed in CF@GCN with different sets of molar ratios of Fe against the 1 mole of Ce (Ce: Fe=1:0.2-1). Among different sets, the one with 0.8 moles of Fe against the 1 mole of Ce (C1F0.8@GCN) performed excellently for BBR and CR dye degradation via aiding in the photo-Fenton process. Morphological, structural, compositional, and electronic states of the final nanocomposite were evaluated using powder X-ray diffraction, transmission electron microscopy/high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. BET analysis of the final nanocomposite showed an excellent surface area of 56.76 m2g−1, allowing for effective degradation. UV–vis spectrophotometry, UV-DRS, and PL (photoluminescence) techniques were performed to monitor the optical properties of the final nanocomposite. Taulc’s plots estimated the band gaps of catalysts, and the final nanocomposite’s band gap was 2.2 eV, which was key for capturing photons from the light source and functioning the degradation process. Further, operating parameters such as catalyst dose, dye concertation, pH, H2O2 dose, and contact time studies were done with the final nanocomposite. C1F0.8@GCN degraded BBR up to 94.5 % within 30 minutes with a first-order rate constant of 0.09747 min−1 and CR dye up to 97.7 % within 45 minutes with a first-order rate constant of 0.07391 min−1. All results supported a nanocomposite of Fe3O4 nanoparticles and CeO2 nanorods grown over 2D g-C3N4 sheets. As predicted, composing Fe3O4 sped up catalyst recovery. Also, the final nanocomposite’s dye degradation rate was consistent till the 6th run. So, the study proposes a cost-effective plan for dealing with organic water contaminants like hazardous dyes.

Multipollutant Abatement through Visible Photocatalytic System

Water pollution damages the aquatic environment due to the presence of organic contaminants, which in turn is distressing to the ecosystem. Photocatalytic activity is a greener and promising method to degrade these organic contaminants. In this research, we present the degradation of diverse water pollutants through zinc/iron oxide nanoparticles serving as photocatalysts. The photocatalyst was studied for its efficiency to photodegrade congo red, brilliant green and para nitro phenol. Moreover, it also presented an antibacterial activity against the bacterium E. coli. Photocatalyst was characterized via X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, and fourier-transform infrared spectroscopy. Tauc plot was used to measure the optical band gap (1.84 eV). The effect of various parameters such as catalyst dose, contact time, dye dose/concentration and pH were also investigated to determine the optimum point of maximum degradation through response surface methodology. A face-centered composite design was used, and a quadratic model was followed by congo red, brilliant green dyes and para nitrophenol. The maximum photodegradation efficiencies were 99%, 94.3%, and 78.5% for congo red, brilliant green and phenol, respectively. Quantum yield for congo red, brilliant green and para-nitrophenol were 9.62 × 10−8, 1.17 × 10−7 and 4.11 × 10−7 molecules/photons, while the reaction rates were 27.1 µmolg−1h−1, 29.61 µmolg−1h−1 and 231 µmolg−1h−1, respectively.

Synthesis and characterization of nanostructured ternary composites of graphene oxide/Fe3O4/NiO for waste water treatment

Photocatalysis using solar energy and semiconductors is widely used in the purification of air and the processing of wastewater. Present study deal with cost-effective GO synthesis, supporting NiO/Fe3O4 ternary nanocomposites; for the rapid photocatalytic degradation of the Rhodamine B Dye. For this purpose, nickel oxide nanoparticles and iron oxide nanoparticles were synthesized by hydrothermal method. Synthesis of graphene oxide was done by using modified hummers method. These trimetallic nanoparticles were characterized by FTIR (Fourier Transform Infrared Spectroscopy), Scanning Electron Microscopy (SEM) and X-ray Diffraction Crystallography (XRD) for structure, shape and composition determination. The photocatalytic degradation of Rhodamine B dye was conducted and various parameters like catalyst amount, dye concentration, pH and contact time optimization were performed to evaluate dye degradation efficiency of Fe3O4/NiO/Graphene trimetallic nanoparticles. Kinetic models were studied to check degradation rate and Pseudo 1st order kinetic model was most suitable to the experimental data of dye degradation.

Photocatalytic Degradation of Malachite Green by NiAl-LDH Intercalated Polyoxometalate Compound

Composites based on layered double hydroxide with polyoxometalate K3[-PW12O40] and K4[-SiW12O40] were synthesized to form NiAl-[SiW12O40] and NiAl-[PW12O40]. The materials were characterized by XRD, FTIR, SEM, and UV-DRS and were then applied as a photocatalyst to degrade MG. The effects of catalyst loading, pH value, and contact times on photodegradation performance were carried out in this study. The results indicated that NiAl-LDH was successfully synthesized by showing the peak diffractions at angles 11.63°, 23.13°, and 35.16°. Both kinds of attained NiAl-[SiW12O40] and NiAl-[PW12O40] had typical structures of LDH that were proved by appearing diffraction at 2θ angles 10.76°, 26.59°, 30.8°, and 63.11° for NiAl-[PW12O40] and at 2θ angles 8.26°, 11.34°, 29°, and 35.1° for NiAl-[SiW12O40]. The materials used for the fifth regeneration were characterized by FTIR, which still presents characteristics of LDH structure. The photocatalyst was applied for the first time to degrade MG. The decrease of band gap on NiAl pristine than LDH composite from 4.76 eV to 3.22 eV for NiAl-[SiW12O40] and 3.78 eV for NiAl-[PW12O40] respectively, was presented by DR-UV analysis. LDH composite shows improved degradation photocatalytic performance in comparison with LDH pristine. It was present by the %degradation MG performances were 68.94% for NiAl LDH, 84.51% for NiAl-[PW12O40]), and 88.91% for NiAl-[SiW12O40]. The degradation percentage indicates that the LDH-polyoxometalate composite has succeeded in increasing the ability of photodegradation catalytic and the regeneration ability of LDH pristine. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Photocatalytic Performance Improvement by Doping Ag on ZnO/MWCNTs Nanocomposite Prepared with Pulsed Laser Ablation Method Based Photocatalysts Degrading Rhodamine B Organic Pollutant Dye.

ZnO/MWCNTs nanocomposite has significant potential in photocatalytic and environmental treatment. Unfortunately, its photocatalytic efficacy is not high enough due to its poor light absorbance and quick recombination of photo-generated carriers, which might be improved by incorporation with noble metal nanoparticles. Herein, Ag-doped ZnO/MWCNTs nanocomposite was prepared using a pulsed laser ablation approach in the liquid media and examined as a degradable catalyst for Rhodamine B. (RhB). Different techniques were used to confirm the formation of the nanostructured materials (ZnO and Ag) and the complete interaction between them and MWCNTs. X-ray diffraction pattern revealed the hexagonal wurtzite crystal structure of ZnO and Ag. Additionally, UV-visible absorption spectrum was used to study the change throughout the shift in the transition energies, which affected the photocatalytic degradation. Furthermore, the morphological investigation by a scanning electron microscope showed the successful embedding and decoration of ZnO and Ag on the outer surface of CNTs. Moreover, the oxidation state of the formed final nanocomposite was investigated via an X-ray photoelectron spectrometer. After that, the photocatalytic degradations of RhB were tested using the prepared catalysts. The results showed that utilizing Ag significantly impacted the photo degradation of RhB by lowering the charge carrier recombination, leading to 95% photocatalytic degradation after 12 min. The enhanced photocatalytic performance of the produced nanocomposite was attributed to the role of the Ag dopant in generating more active oxygen species. Moreover, the impacts of the catalyst amount, pH level, and contact time were discussed.

Photocatalytic Activity of Aluminium Oxide Nanoparticles on Degradation of Ciprofloxacin

In this research, Al2O3 nanoparticles were successfully synthesized using facile chemical precipitation method as a photocatalyst. The synthesized photo catalyst was characterized using scanning electron microscopy. The photocatalytic activity of the synthesized Al2O3was studied on the degradation of ciprofloxacin as a model pollutant in UV light irradiation by conductometry method. The experiments were carried out by varying contact time from 1- 5 hours and catalyst load from 0.5 – 2.5g. The optimum catalyst dose and contact time were found to be 1g and 1 hour respectively for the drug degradation. The result exhibited photocatalysis activity. The photocatalytic activity can be attributed to higher absorption of Ultra-Violet light by the synthesized Al2O3 that led to formation of a large number of reactive species. The Kinetics study of the photodegradation process was explained in terms of the modified Langmuir Hinshelwood model. The values of the kinetic rate constant (k) of the photodegradation were 8.0x10-3min-1 and 5.0x10-2min-1in the absence and presence of the synthesized photocatalyst respectively.

Synthesis of recyclable GO/Cu3(BTC)2/Fe3O4 hybrid nanocomposites with enhanced photocatalytic degradation of aflatoxin B1

This study evaluated the photocatalytic performance of the activated carbon assisted GO/Cu3(BTC)2/Fe3O4 photocatalyst for aflatoxin B1 (AFB1) degradation under ultraviolet light. The nanocomposite was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption. The numerous factors influencing the degradation efficiency of AFB1 including catalyst dose, pH importance, and contact time were also probed. The elevated degradation performance of AFB1 by 99% was due to a larger surface area and improved GO/Cu3(BTC)2/Fe3O4 photocatalyst. The degradation process followed a pseudo-first-order kinetic model. Moreover, it is possible to quickly isolate the catalyst from the solution and retain successful operation. In the degradation of AFB1, the hole(h+) and the hydroxyl radicals(OH) were found to play a significant role. These studies showed that GO/Cu3(BTC)2/Fe3O4 has high capturing capacity and photoactivity synergy, thereby offering a quick effect, and green solution to AFB1 degradation.

Facile fabrication of novel Fe3O4-SnO2-gC3N4 ternary nanocomposites and their photocatalytic properties towards the degradation of carbofuran

Herein, Fe3O4–SnO2 nanoheterojunction has been synthesized and successfully encapsulated in gC3N4 matrix using a novel hydrothermal technique. The synthesized material was characterized using sophisticated analytical methods like XRD, TEM, BET, UV–Vis, VSM and XPS to evaluate structural, morphological, optical, magnetic and surface chemical properties. The hybrid nanostructure Fe3O4-SnO2-gC3N4 has been utilized for the LED light-induced photocatalytic degradation of carbofuran. The catalyst exhibited notable photocatalytic performance under visible light with an efficiency of ~89% and pseudo first order rate constant of 0.015 min−1. The result of change in variables like catalyst dose, pollutant concentration, pH and contact time on the photodegradation efficiency and degradation kinetics was studied. The incorporation of Fe3O4 improved the magnetic separation of the catalyst after several cycles of operation, thereby improving the practical utility of the catalyst system to tackle organic pollutants.

Preparation and application of α-Fe2O3@TiO2@SO3H for photocatalytic degradation and COD reduction of woodchips industry wastewater.

In this study, we investigated the efficiency of photocatalytic degradation and chemical oxygen demand (COD) reduction from woodchips industry wastewater using α-Fe2O3@TiO2@SO3H. A magnetic α-Fe2O3@TiO2@SO3H was prepared as a heterogeneous photo-Fenton catalyst. The Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and elemental mapping (MAP) analyses were performed to determine the structure and morphology of synthesized photocatalysts. The response surface methodology (RSM) was used to optimize the photo-Fenton process based on a Box-Behnken design (BBD). The parameters such as catalyst dosage, H2O2 dosage, pH, and contact time on photocatalytic degradation and the reduction of COD were studied. The maximum photocatalytic degradation of 93.75% and COD reduction of 86.54% were achieved at a dosage of the catalyst of 1 g L-1, H2O2 dosage of 40 mg L-1, and a pH of 3.5 at 45 min. The kinetics of the photo-Fenton process was studied for the woodchips wastewater treatment under optimum conditions. The pseudo-second-order kinetic model for photocatalytic degradation and COD reduction was obtained. The results indicated that a α-Fe2O3@TiO2@SO3H could be used as an effective heterogeneous photocatalyst for the treatment of woodchips industry wastewater. Preparation and application of α-Fe2O3@TiO2@SO3H for photocatalytic degradation and COD reduction of woodchips industry wastewater.

Tunable HMF hydrogenation to furan diols in a flow reactor using Ru/C as catalyst

• The hydrogenation of HMF to furan diols was studied and optimized in flow reactor. • The commercial Ru/C was an efficient catalyst for the BHMF and BHMTHF synthesis. • The highest BHMF and BHMTHF yields were ascertained only tuning the contact time. • The catalyst was stable up to 6 h and easily reactivable through acetone washing. • Internal mass transfer limitations occurred and affected the overall reaction rate. 5-hydroxymethylfurfural (HMF), accessible from various feedstocks, represents an important renewable platform-chemical, precursor for valuable biofuels and bio-based chemicals. In this work, the continuous hydrogenation of an aqueous solution of HMF to give strategic monomers, 2,5-bis(hydroxymethyl)furan (BHMF) and 2,5-bis(hydroxymethyl)tetrahydrofuran (BHMTHF) was investigated in a continuous flow reactor adopting a commercial Ru/C (5 wt%) as catalyst. The influence of the main process variables on products yield and selectivity was studied and optimized. The highest BHMF and BHMTHF yields of 87.9 and 93.7 mol%, respectively, were achieved by tuning the catalyst contact time, keeping all other variables constant (temperature, pressure, hydrogen flow rate, initial HMF concentration). Intraparticle diffusion limitation for hydrogen and HMF was shown to occur at some of the tested conditions by performing the HMF hydrogenation with different catalyst particle sizes, confirmed by calculations. Constant catalyst activity was observed up to 6 h time-on-stream and then gradually reduced. Fresh and spent catalyst characterization showed no significant sintering and negligible leaching of ruthenium during time-on-stream. A decrease of the specific surface area was observed, mainly due to humin deposition which is likely the reason for catalyst deactivation. Catalyst performance could be restored to initial values by a thorough washing of the catalyst.

A novel ternary heterogeneous TiO2/BiVO4/NaY-Zeolite nanocomposite for photocatalytic degradation of microcystin-leucine arginine (MC-LR) under visible light

Microcystin-leucine arginine (MC-LR) is a carcinogenic toxin, produced by cyanobacteria. The release of this toxin into drinking water sources can threaten public health and environmental safety. Therefore, effective MC-LR removal from water resources is necessary. In the present study, the hydrothermal method was used to synthesize a novel ternary BiVO4/TiO2/NaY-Zeolite (B/T/N-Z) nanocomposite for MC-LR degradation under visible light. FESEM, FTIR, XRD, and DRS were performed for characterizing the nanocomposite structure. Also, the Response Surface Methodology (RSM) was applied to determine the impact of catalyst dosage, pH, and contact time on the MC-LR removal. High-performance liquid chromatography was performed to measure the MC-LR concentration. Based on the results, independent parameters, including contact time, catalyst dosage, and pH, significantly affected the MC-LR removal (P < 0.05). In other words, increasing the contact time, catalyst dosage, and acidic pH had positive effects on MC-LR removal. Among these variables, the catalyst dosage, with the mean square and F-value of 1041.37 and 162.84, respectively, had the greatest effect on the MC-LR removal efficiency. Apart from the interaction between the catalyst dosage and contact time, the interaction effects of other parameters were not significant. Also, the maximum MC-LR removal efficiency was 99.88% under optimal conditions (contact time = 120 min, catalyst dosage = 1 g/L, and pH = 5). According to the results, the B/T/N-Z nanocomposite, as a novel and effective photocatalyst could be used to degrade MC-LR from polluted water.

Effect of acidic MCM-41 mesoporous silica functionalized with sulfonic acid groups catalyst in conversion of methanol to dimethyl ether

The global issue of contamination and power reserves has given dimethyl ether (DME) considerable attention. It is an encouraging and clean green material for the future resulting from its clean combustion properties. In this paper, a novel MCM-41-propyl-SO3H catalyst was successfully prepared with tethering of the active sulfonic acid groups onto the support via covalent bonds. This material was investigated as catalyst for DME synthesis via methanol dehydration in a fixed bed flow reactor at different experimental settings. TGA, NH3-TPD, SEM, XRD and BET techniques​ were utilized to characterize the synthesized material. MCM-41 sulfonated catalyst showed great thermal stability, high surface area and significant acid loading. The catalytic tests also demonstrated that the maximum methanol conversion was observed at 350 °C and catalyst contact time of 8 s. In addition, the catalyst showed a total selectivity to DME; light hydrocarbons and higher oxygenated compounds were not formed at temperatures above 300° C.

Studying the Dependence of the Performance Efficiency of a Claus Reactor on Technological Factors with the Quality Evaluation of Sulfur on the Basis of Fuzzy Information

It has been determined that the principal parameters influencing the performance efficiency of a reactor at the thermal stage are as follows: the sour gas and its composition at the inlet into a Claus reactor, the air : sour gas ratio, the time the reaction mixture resides in a reactor, and the temperature and pressure in the reactor. At the same time, it has been established that the reactor temperature and pressure, the degree of catalyst activity, and the gases–catalyst contact time have an effect on the performance efficiency of a reactor at the catalytic stage. The effects produced by these process parameters on the performance efficiency of the Claus reactor of a sulfur production plant at the thermal and catalytic stages have been studied. The graphic dependences of the effect produced by the selected technological factors on the characteristics of sulfur production technology processes have been plotted. Some linguistic models of evaluating the quality of produced commercial sulfur have been developed, engaging the production model for the knowledge of expert specialists with the use of the initial fuzzy expert information. The resulting linguistic models make it possible to evaluate the quality of sulfur and its grade, depending on the mass fraction of sulfur, ash, organic compounds, and water. To describe the fuzzy term high quality of sulfur, corresponding membership functions have been constructed.

Photocatalytic Degradation of Congo Red Dye from Aqueous Environment Using Cobalt Ferrite Nanostructures: Development, Characterization, and Photocatalytic Performance

Highly efficient and effective treatments of hazardous dye-based color effluents are a major problem in the industrial sector. In this research, the cobalt ferrite (CoFe2O4) catalyst was produced and used for the degradation of Congo red (CR) as a model dye from aqueous solution. For a said purpose, cobalt ferrite (CoFe2O4) nanostructures with photocatalytic degradation potential were engineered via co-precipitation method using Fe2(SO4)3, CoO2, and triethylene glycol (as a stabilizing agent). As prepared, CoFe2O4 nanostructures were further surface-functionalized with 3-APTES and tested for CR degradation. The prepared CoFe2O4 nanostructures were characterized by X-ray diffraction, Fourier transform infra-red (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmitt-Teller (BET) analysis. UV-visible absorption was used to measure the optical band gap of prepared CoFe2O4 nanostructures through Tauc plots. The as-prepared CoFe2O4 nanostructure bandgap was found to be 2.71 EV while using an acidic medium. The degradation rates of CR dye for bs-CoFe2O4, as-CoFe2O4, and fs-CoFe2O4 nanostructures at pH 9 were 84, 87, and 92%, respectively. Furthermore, the influences of various process parameters, i.e., the effect of catalyst dose, contact time, dye dose/concentration, pH effect, and effect of different acids, were checked for the prepared three types of nanostructures, i.e., bs-CoFe2O4, as-CoFe2O4, and fs-CoFe2O4. The kinetics models properly explained that the reaction of degradation following pseudo-first-order kinetics.