Effect Of Catalyst Concentration Research Articles

Solar-Induced Removal of Benzophenones Using TiO2 Heterogeneous Photocatalysis at Lab and Pilot Scale

This work presents the main results regarding the use of solar heterogeneous photocatalysis with TiO2 on the removal of Benzophenone-1 and Benzophenone-2 (BP1 and BP2) in aqueous samples at lab and pilot scale. BP1 and BP2 are two UV-filters that have been classified as potential endocrine disruptors, and their presence in water has been reported by different researches. Experiments were conducted at lab scale using simulated sunlight radiation, while at pilot scale a solar compound cylinder-parabolic (CCP) collector and direct sunlight were employed. Effects of catalyst concentration and solution pH on contaminants elimination were assessed. Pollutants were completely removed at lab conditions in just 60 min of reaction, while under pilot scale tests elimination was around 90.0% in 360 min. Mineralization of treated samples was around 60%. In general, it was found that the photo-generation of hydroxyl (HO·) radicals contributes to BP1 and BP2 removal, and that higher doses of TiO2 could have an inhibitory effect. Additionally, presence of some inorganic ions on the aqueous matrix (drinking water) used in the pilot-scale tests would be associated to a reduction on the extent of pollutants degradation, which together with aspects such as the type of reactor and the atmospheric and climate conditions would limit the process efficiency in comparison with results at lab-scale experiments.

Nb2O5 supported in mixed oxides catalyzed mineralization process of methylene blue

Heterogeneous photocatalysis has become a significant green technology for water treatment. The application of Nb2O5 catalyst for the photodegradation of contaminants has merged as an important tool to this process. Furthermore, it is known that catalytic phases supported on metal oxides are an alternative method for enhancing its activity. In this work, supported Nb2O5 on mixed oxides as catalyst was applied to degrade methylene blue dye, leading to almost 100% of dye degradation without the need of any additives, after only three hours of sunlight exposure. The effect of catalyst concentration, exposure time and light source were investigated. The best catalyst activity was found at 1.5 g L−1 and for higher catalyst concentrations the degradation was kept constant. Plausible intermediates of this degradation process were observed and characterized by NMR, LC/MS and CZE techniques. After degradation, the catalyst was recovered and could be further re-applied in other three reaction cycles without significant loss of catalytic activity.

Esterification of Glycerol with Acetic Acid in Bioadditive Triacetin with Fe<sub>2</sub>O<sub>3</sub>/Activated Carbon Catalyst

Esterification and transesterification processes for biodiesel production generate glycerol which is possible to be converted into triacetin. It is an actractive bioadditive for increasing octane number of fuel. The production of this bioadditive in a biodiesel plant also increases the revenue as raw material comes from biodiesel process production as by-product.This study examines the effects of catalyst concentration and temperature on triacetin production using glycerol from esterification process and acetic acid at volume ratio of 1:3 as raw materials. An activated charcoal as catalyst is activated with sulfuric acid at concentration of 2% and 3% (w/w). The esterification temperatures are varied at 90 and 100°C and the reaction time is set for 3 hours. The samples are taken frequently at certain interval times of 15, 30, and 60 minutes for chemical analysis using Gas Chromatography Mass Spectometry. It is observed that using 2% and 3% (w/w) of catalysts at 90°C and 60 minutes reaction time converts 41.037% and 57.441% of glycerol respectively.

Surface graft polymerization of lactic acid from the surface of cellulose nanocrystals and applications in chloroprene rubber film composites

Cellulose nanocrystals (CNCs) have been modified through surface graft polymerization of (l)-lactide for the purpose of improving dispersion and reducing aggregation of CNCs into chloroprene rubber (CR). Statistically designed experiments have been carried out to study the effects of polymerization conditions (temperature, and catalyst and monomer concentrations) on water contact angle, solvent dispersibility, and particle size distribution of the produced mCNCs. The effects of catalyst concentration and interaction of monomer-catalyst concentrations were found to be significant. Dry films produced from mCNCs exhibited surface hydrophobicity as evidenced by very high water contact angles (> 90°). In addition, mCNCs in powder form exhibited very good water/latex dispersibility. Blending of mCNCs with CR latex resulted in well-dispersed modified CNC/CR composites based on microscopy observations. The tensile properties of cast films produced from CNC/CR and mCNC/CR composites have been evaluated and it has been found that increasing the CNC and mCNC content increases tensile strength and modulus while maintaining elongation at break close to that of the unfilled CR. Composites containing 3 wt% of mCNCs exhibited the best properties with tensile strength and modulus improving by about 200% and 450%, respectively. These results are very promising and suggest that these mCNC/CR composites could find applications in the manufacturing of cut/fat resistant medical gloves, balloons, catheters, and other biomedical devices.

Novel preparation of MoO3/γ-Al2O3 nanocatalyst: application in extra-heavy oil visbreaking at atmospheric pressure

In this study, the effect of gamma alumina-based molybdenum oxide nanoparticles, on the viscosity reduction of extra-heavy crude oil in a catalytic cracking process in atmospheric pressure and at 250–350 °C investigated for the first time. Molybdenum oxide nanoparticles synthesized using the polyol method and heating by microwave radiation. According to the dynamic light scattering (DLS) analysis, obtained nanoparticles have an average size of 6 nm. These nanoparticles coated on gamma-alumina powder using the novel method of per-vaporation, and through this method, 0.011 g of molybdenum oxide nanoparticles coated over per 1 g of catalyst, during 14 days. The performance of the synthesized catalysts in the cracking process of extra-heavy crude oil investigated. Statistical design of the experiment (DOE) used to study the effect of catalyst concentration and process temperature on product viscosity and to obtain optimal value of these factors. Based on the central composite design (CCD) method, the cubic model developed to correlate the catalyst wt% and temperature for upgraded oil viscosity. By applying the synthesized nanocatalyst in the range of 0.59–4 wt%, the viscosity reduction from 32 to 86% was observed. The highest viscosity reduction happened at 350 °C and 2% weight percent of nanocatalysts, in which the viscosity reduced from 20,000 cp to 2800 cp.

Mn(III) Catalyzed Electrochemical Reduction of CO2 on Carbon Electrodes

Though challenging, conversion of carbon dioxide (CO2) to valuable products is an emerging area of research. Electrochemical reduction (ECR) has emerged as an efficient and rapid technique to achieve this goal. Herein, 5,10,15,20-tetraphenyl-21H, 23H-porphine manganese(III) chloride [(Mn(TPP)Cl)] catalyzed CO2 reduction at vitreous carbon electrode in acetonitrile electrolyte is reported. The effect of catalyst concentration, addition of Brönsted acid (CF3CH2OH) to CO2-saturated solution have been studied and reported. Based on the results, possible mechanistic pathways have also been suggested and discussed.

Experimental Study on the Esterification of Fat Trap Grease in a Continuous Reactor

In this work, the esterification reaction of fat trap grease (FTG) with high free fatty acid (FFA) content (166 mgKOH/g) was studied using methanol as a reagent and sulfuric acid as catalyst, in a continuous chaotic mixer-reactor. Esterification reached its chemical equilibrium in 1 h compared to 5 h in a mechanically stirred batch reactor. The effects of catalyst concentration, feeding flow rate and temperature on FFA conversion were examined. And the results show that at 5.4% w/w of H2SO4 and a mass flow rate of 8 g/s, a maximum conversion rate of 97% was achieved. It was observed that the water produced during the esterification reaction can slow the reaction progress. Therefore, water removal effect on reaction progress, using different techniques, was examined. It was proven that the water removal highly improved the reaction rate. The total removal of water reduced the reaction time from 1 h to 35 min in continuous reactor.

Catalyst concentration, ethanol content and initial pH effects on hydrogen production by photocatalytic water splitting

Operational variables effects on hydrogen production in photocatalytic water splitting system were evaluated using Pd-TiO2/ZSM-5. This material was synthetized and had its physicochemical properties properly characterized. Using experimental design techniques allowed the simultaneous evaluation of the effects of catalyst concentration, ethanol (sacrificial reagent) content and initial solution pH on hydrogen production rate. It was verified that an increase in catalyst concentration or ethanol content has a positive influence on system productivity until a maximum point is reached, from which a decrease on gas evolution rate occurs. In contrast, an increase in the initial solution pH presented a linear negative effect on hydrogen production in all analyzed experimental region. Among evaluated conditions, the highest total hydrogen production rate, 712 μmol h−1 (791 μmol gcat−1 h−1), was obtained using a catalyst concentration of 1.5 g L−1, a 16% ethanol content and initial solution pH equal to 4.

Efficient hydrogen generation over a novel Ni phyllosilicate photocatalyst

Nickel phyllosilicate (NiPS) materials (made from 5, 10 Ni wt.% on SiO2; 5NiPS and 10NiPS) were prepared by a hydrothermal method. The obtained materials were characterized by XRD, TEM, SEM/EDX, FTIR, DRS, DSC/TGA, AAS and nitrogen adsorption procedures that provided information about the new synthesized spherical materials which exhibited a phyllosilicate structure shell covering a silica core. A diffuse reflectance spectroscopy study illustrated that the NiPS materials have indirect band gap energies (5NiPS =2.05 eV; 10NiPS =2.11 eV). The photo-catalytic properties of the new materials were evaluated for hydrogen production through the water photo-reduction reaction. The effects of catalyst concentration, electrolyte concentration, nickel concentration, and hole scavenger type on the hydrogen evolution were studied. After 60 min of irradiation under visible light, the photo-catalysts exhibited a good photo-catalytic activity with hydrogen efficiencies of 148 and 41 μmol/g.min for 5NiPS and 10NiPS, respectively. A decrease in the (e−/h+) recombination in the NiPS materials was shown to be related to an increase in the photo-catalytic performance.

Insights into a CQD-SnNb2O6/BiOCl Z-scheme system for the degradation of benzocaine: Influence factors, intermediate toxicity and photocatalytic mechanism

The development of a novel Z-scheme system with a high separation efficiency of the charge carriers for remarkably enhanced photocatalytic activity is highly desirable. Herein, a carbon quantum dot-modified SnNb2O6/BiOCl (CQD-SNO/BOC) Z-scheme system, in which the CQDs acted as a bridge for the charge carriers, was successfully synthesized. As expected, the CQDs acted as a bridge for the charge carriers that could separate and accumulate electrons from SnNb2O6 and holes from BiOCl by promoting the transfer of the photoinduced charge carriers, which enabled the BiOCl holes to maintain their high oxidation capability. Additionally, the CQDs not only endowed the SNO/BOC Z-scheme system with a large specific surface area that provided a greater number of active sites but also noticeably improved its visible light absorption capacity. Therefore, the CQD-SNO/BOC Z-scheme system showed an improved photocatalytic performance for the degradation of benzocaine (BC), which was over 20 times, 10 times and 2 times greater than those of BiOCl, SnNb2O6 and SNO/BOC Z-scheme systems, respectively. In addition, the effects of catalyst concentration, pH value, different anions, and humic acid (HA) concentration on the photodegradation of BC were investigated in depth. Simultaneously, a four-stage pathway for the degradation of BC was proposed based on the degradation products that were identified, and the accuracy of this pathway was further verified based on biotoxicity assessments and toxicity predictions of the products. According to the ESR spectra and active species trapping experiments, a mechanism for the CQD-SNO/BOC Z-scheme system was proposed, in which the CQD bridge accelerated charge transfer. Based on these results, the CQD-modified Z-scheme system could be an efficient and promising photocatalyst for the degradation of PPCPs in water.

Metal (II) complexes with derived from 3-hydroxy-2-(3-nitrophenyl)-4H-chromen-4-one; synthesis and photocatalytic activity

The synthesized novel flavonol was studied by 1H NMR spectroscopy, 13C NMR spectroscopy, FTIR, GC–mass spectrometry. And moreover, the metal complexes (M = Fe, Ni, Cu) with TiO2 nanocomposites are synthesized and studied by UV–Vis–NIR spectroscopy, GC–mass spectrometry, UV–Vis–DRS, XRD profile, SEM and TEM techniques. The performance of photocatalytic degradation of malachite green (MG) under visible light irradiation by Metal (M = Fe, Ni, Cu,) complex of 3-hydroxy-2-(3-nitrophenyl)-4H-chromen-4-one of nanocomposite was studied. In photocatalytic degradation of MG, the detail investigations are made by the effect of catalyst concentration; initial MG concentration and addition of inorganic salts. The MG photo degradation result of different ML–TiO2 is as follows Cu(II) > Fe(II) > Ni(II). Interestingly, the CuL–TiO2 has better photocatalytic efficiency of 97% as compared to the other ML–TiO2 in visible light at 80 min. The adsorption malachite green on ML–TiO2 was found to boost by the Langmuir and Freundlich approach.

The Effect Catalyst Natural Zeolite of Lampung On The Synthesis Of α-Terpineol From Turpentine

The major component of turpentine is α-pinene. Alpha pinene can be hydrated using an acid catalyst to produce α-terpineol. It can be used as a perfume, anti -insect, and disinfectants. The using of heterogeneous catalysts as natural zeolite can be a new alternative to replacehomogeneous catalysts. The purpose of this study was to determine the effect of zeolite catalysts and the reaction time which resulting the highest conversion on hydration reactions of turpentine to α-terpineol. Parameters were the effect of catalyst concentration of (5%, 10% and 15%) and the reaction time (60 minutes, 120 minutes and 180 minutes). The turpentine, aquadest and isopropyl alcohol were reacted in the three neck flask at the temperature of 70°C. The result of this study showed that the best condition the hydration of turpentine α-terpineol was achieced at 15% catalyst concentration and the reaction time of 180 minutes. The convertion was obtained to be 4.875%.Keywords— Turpentine, Hydration, Alpha terpineol, Catalys,Natural Zeolite.

The Formation of Glycerol Oligomers with Two New Types of End Groups in the Presence of a Homogeneous Alkaline Catalyst.

The purpose of this work was to synthesize and characterize oligoglycerols with the chains of more than four repeating units. Those oligoglycerols may have some interesting applications, among others, as polyoxyalkylation starters. The glycerol oligomerization process was carried out during 12 h, at 230 °C, under the pressure of 0.4 bar, with the use of sodium carbonate as a homogeneous basic catalyst; various concentrations of the catalyst in the reaction medium were used. The reaction products were analyzed with the use of direct infusion electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (13C NMR) and Fourier transform infrared spectroscopy (FTIR) techniques. Based on the analytical findings, the compositions of the obtained product mixtures and the structures of oligoglycerols present in individual fractions were determined. The effect of catalyst concentration on the composition of the post-reaction mixture was observed. Moreover, in addition to the conventional linear oligomers (α,α-oligoglycerols), two new types of the oligomers were for the first time detected in the post-reaction mixture: one with two hydroxyl groups and the other with a carboxylate group at the α-carbon atom.

Optimization of ethylene trimerization using catalysts based on TiCl3/half‐sandwich ligands

Catalytic trimerization of ethylene using three titanium‐based complexes [η5‐C9H6C(R)thienyl]TiCl3 with various types of bridges (R = cyclo‐C5H10 (C1), cyclo‐C4H8 (C2) and (CH3)2 (C3)) has been successfully optimized and compared. First of all, three benzofulvene precursors, C9H6C(R), were synthesized. Then the corresponding indenyl‐based ligands were obtained via the reaction of the precursors with thienyllithium. The final titanium‐based catalysts display a distorted tetrahedral geometry, as expected for Ti(IV), with the ligand coordinated with a hemilabile behaviour. The structures of the compounds were confirmed on the basis of various analyses. The effect of catalyst concentration, ethylene pressure, reaction temperature and nature of the bridge as the significant factor affecting coordination and orientation of thienyl group relative to the metal centre on 1‐hexene (1‐C6) productivity and selectivity was investigated. Results revealed that the bulky bridge groups such as cyclo‐C5H10 and cyclo‐C4H8 are appropriate for ethylene trimerization due to the closer coordination of sulfur atom with Ti, especially in cationic state, and catalyst C2 with cyclo‐C4H8 bridge exhibits moderate productivity equal to 785 kg 1‐C6 (mol Ti)−1 h−1. According to the results, ethylene at a pressure of 10 bar, 50°C and 1.5 μmol of catalyst were selected as the best conditions for obtaining 1‐C6 with high productivity and selectivity. The presence of indenyl enhances the thermal stability of the catalysts and preserves their activity in higher temperatures such as 50 and 80°C.

Copper phosphide and persulfate salt: A novel catalytic system for the degradation of aqueous phase micro-contaminants

The heterogeneous activation of sodium persulfate (SPS) using copper (I) phosphide (Cu3P) nanoparticles was tested in this work. The catalyst was synthesized via a two-step method involving preparation of Cu(OH)2 and subsequent low temperature phosphidation and characterized with BET, XRD, TEM/HRTEM, SEM and XPS techniques. The XRD pattern showed the existence of hexagonal Cu3P phase with mean primary crystallite size of ca. 28 nm. The XP spectra indicated the presence of residual Cu(OH)2 and Cu3(PO4)2 species on the catalyst surface, originating from the synthesis methods employed, which disappeared after exposure to reaction conditions.The activity of Cu3P was evaluated for the degradation of antibiotic sulfamethoxazole (SMX), which occurred in short reaction times. The effect of catalyst concentration (20–80 mg/L), SPS dosage (0.05–1 g/L) and SMX concentration (0.5–4.1 mg/L) on degradation was studied. Results obtained in ultrapure water (UPW) showed that SMX degradation increases with increasing catalyst content in the range 20–80 mg/L and SPS concentration in the range 0.05–0.5 g/L. In contrast, increasing SPS concentration at 1 g/L leads to lower reaction rates. Experiments were also conducted in bottled water, secondary treated wastewater, UPW spiked with bicarbonate or chloride ions, as well as UPW containing humic acid. With the use of t-butanol and methanol as radical quenching agents, SO4•- was found to be the primary radical species responsible for SMX degradation. The simultaneous use of Cu3P and solar irradiation as persulfate activators resulted in a synergistic effect in experiments performed in UPW and wastewater.From a mechanistic point of view, Cu3P acts as an electron mediator or bridge to facilitate the electron-transfer processes and this is accompanied by the intermediate formation of radicals. The catalyst remains intact, thus implying the catalytic nature of the process.

Turbo thin film continuous flow production of biodiesel from fungal biomass

Direct biodiesel production from wet fungal biomass may significantly reduce production costs, but there is a lack of fast and cost-effective processing technology. A novel thin film continuous flow process has been applied to study the effects of its operational parameters on fatty acid (FA) extraction and FA to fatty acid methyl ester (FAME) conversion efficiencies. Single factor experiments evaluated the effects of catalyst concentration and water content of biomass, while factorial experimental designs determined the interactions between catalyst concentration and biomass to methanol ratio, flow rate, and rotational speed. Direct transesterification (DT) of wet Mucor plumbeus biomass at ambient temperature and pressure achieved a FA to FAME conversion efficiency of >90% using 3 wt/v % NaOH concentration, if the water content was ≤50% (w/w). In comparison to existing DT methods, this continuous flow processing technology has an estimated 90–94% reduction in energy consumption, showing promise for up-scaling.

Heterogeneous Fenton oxidation using Fe-ZSM5 catalyst for removal of ibuprofen in wastewater

Heterogeneous Fenton oxidation using Fe-zeolite catalyst (of ZSM5 type) was investigated for the removal of ibuprofen (20 mg/L) in water. In particular, the effects of catalyst concentration, oxidant dosage, temperature, solution pH, and water matrix on pollutant conversion and mineralization were evaluated. The activity of leached iron species in solution was also measured to determine the contribution of the homogeneous reaction.Oxidation rate of ibuprofen obeyed a pseudo-first-order kinetics with respect to the pollutant concentration, and the apparent rate constant increased with catalyst and hydrogen peroxide concentrations in the investigated ranges (1-5 g/L of Fe-zeolite and 0.5-7 times the stoichiometric amount of oxidant). Energy activation of 53 kJ/mol was obtained from Arrhenius plot. However, the mineralization yield was not significantly improved by a too large excess of H2O2 or increase of temperature. In the selected conditions (25 °C, 4.8 g/L of catalyst, 2 times the stoichiometric amount of H2O2), 88% of ibuprofen and 27% of TOC were removed after 3 hours of reaction under “natural” pH conditions.Very low leaching (up to 0.2 mg/L) and negligible activity of leached iron in solution indicated that Fenton reaction was mainly induced by iron species on the catalyst surface.Degradation rate of ibuprofen was slower in wastewater effluent as compared to distilled water, mainly due to alkaline buffering and radical scavenging effects of organic and inorganic compounds present in the matrix.Mono- and multi-hydroxylated ibuprofen adducts were found as main oxidation intermediates -in line with free-radical mechanism- as well as 4-isobutylacetophenone from decarboxylation route.

PEMBUATAN BIODIESEL METIL ESTER DARI MINYAK JELANTAH DAN METANOL DENGAN KATALIS ABU GOSOK

Biodisel methyl ester research has been used waste cooking oil and methanol with ash replenishment as a catalyst.This research was doing to saw the effect of catalyst concentration on biodiesel from used cooking oil. The research used a Completely Randomized Design with five treatments is M1 (catalyst 2 g), M2 (catalyst 4 g), M3 (catalyst 6 g), M4 (catalyst 8 g) and M5 (catalyst 10 g) withing three replications. The data were analyzed using Analysis of Variance (ANOVA) and continued with DNMRT at 5% level. The research results has showed that the addition of a catalyst concentration of ash significantly (P 0,05) on the water content. The best treatment is M5 with acid number 0,71 mg KOH/g, total glycerol content of 0,01%, density 0,88 g/cm3, viscosity of 47,94 cSt, iodin number 66,83 gI2/100, water content of 0,06%, flash point 249,33°C, saponification number154,84 mg KOH/ g and levels of methyl ester 99,5%.

Indigestible pyrodextrins prepared from corn starch in the presence of glacial acetic acid

This study was conducted to evaluate the feasibility of using acetic acid (0–2.5%) as the catalyst in the production of pyrodextrins from corn starch at 140–180 °C, and to elucidate the effects of catalyst concentration and pyrolytic temperature on the characteristics of indigestible pyrodextrins. In the absence of acetic acid, noticeable changes to the loss of birefringence, increased solubility, plateau of molecular weight reduction, decreased reducing sugar content and digestibility were observed at 180 °C. By using catalyst, the alterations in the aforementioned characteristics of pyrodextrins were intensified. Moreover, by using 0.5–1.0% catalyst, the substantial alterations in birefringence, solubility and molecular weight were observed concurrently for pyrodextrins formed at 170 °C. Further increasing the concentration of acetic acid to 1.0–2.5% decreased the intervening temperature to 160 °C. The findings suggest that indigestible pyrodextrins with desired characteristics could be tailored via using various combinations of catalyst concentration and pyrolytic temperature.

Process intensification using a spiral capillary microreactor for continuous flow synthesis of performic acid and it’s kinetic study

The continuous production of performic acid is getting significant importance due to it’s versatile oxidizing properties in various applications such as in the food, oil and chemical industries. In this work, an attempt has been made for synthesis of performic acid in a continuous flow microreator in polytetrafluoroethylene spiral capillary microreactor (PSCMR) with and without homogeneous catalyst. The effect of catalyst concentration, hydrogen peroxide concentration, temperature and radius of curvature on formation of perfomic acid was studied. The maximum conversion of FA was obtained within 6 min at 30 °C and 4 mol% catalyst. The maximum PFA was obtained (5.175 mol/L) when the reaction was performed in spiral capillary microreactor having 13.25 mm radius of curvature (Number of turns = 21). However, in the radius of curvature of 18.25 mm (Number of turns = 15) and 23.25 mm (Number of turns = 12) of the PSCMR gave 3.393 mol/L and 3.105 mol/L of PFA respectively at residence time of 9 min. Based on the kinetic equations and experimental data, the kinetic constants were determined. Thus, the average rate constants for forward and backward reaction are 0.0097 and 0.04354 L/(mol min) respectively. Based on the kinetic data, it was found that the activation energies of PFA synthesis and hydrolysis were 31.716 and 13.701 kJ/mol respectively.