Different Amounts Of Catalyst Research Articles

Synthesis of Co-Cr(0) and Co-Cr-B catalysts from bean pods extract by the green synthesis method and their application in sodium borohydride hydrolysis

AbstractIn this study, the effect of Co-Cr(0) and Co-Cr-B nanocatalysts on sodium borohydride hydrolysis was investigated. The extract obtained from the pods of the bean plant was produced using the environmentally friendly green synthesis method, along with the chemical reduction method as the production procedure for the catalysts. The analyses used to study the structure and surface morphology of catalysts are SEM, TEM, EDX, XRD, FTIR, and XPS. From the SEM and TEM pictures, the shape of the catalysts comprises of tiny spheres and has a porous nanostructure, and the particle size is 35–40 nm. The XRD investigation revealed that the catalysts had an amorphous structure. The catalysts’ structure has been confirmed to include the components Co, Cr, and B using EDX and XPS analyses. It was examined how different amounts of catalyst, different NaBH4/NaOH concentrations, and different solution temperatures affected the hydrolysis of sodium borohydride. The n-th order kinetic model was utilized to determine the activation energies of Co-Cr(0) and Co-Cr-B nanocatalysts, which were found to be 24.39 kJ/mol and 43.09 kJ/mol, respectively. Also, the turnover frequency (TOF) values of synthesized nanocatalysts Co-Cr(0) and Co-Cr-B at 60 °C were calculated as 19,210 mLmin− 1g− 1 and 12,410 mLmin− 1g− 1, respectively. The repeatability of catalysts in NaBH4 hydrolysis showed high activity even after the fifth use. Graphical Abstract

Facile “Green” synthesis of a novel Co–W–B catalyst from Rheum ribes shell extract and its effect on sodium borohydride hydrolysis: Kinetic mechanism

The present investigation aimed to assess the influence of the Co–W–B NPs catalyst on the process of sodium borohydride hydrolysis. The study involved the synthesis of Co–W–B NPs through the utilization of an eco-friendly green synthesis extract derived from the Rheum ribes shell in conjunction with the chemical reduction technique for catalyst production. The investigation of catalysts' structure and surface morphology was conducted through the utilization of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques. The average particle size was determined to be 35 nm in TEM analysis. The presence of Co–W–B nanoparticles and their elemental composition % were determined through EDX analysis, revealing values of 63.9% (Co), 31.89% (C), 1.75% (B), and 2.46% (W) within the nanoparticle. The manufactured Co–W–B catalyst's use for hydrolysis of sodium borohydride was studied under various conditions, including different concentrations of NaOH and NaBH4, different amounts of catalyst, and different temperature parameters. The hydrogen production rate for the Co–W–B NPs catalyst in NaBH4 hydrolysis was determined to be 5367 mLg−1min−1 at 30 °C. The study involved the determination of TOF values for a catalyst composed of Co–W–B NPs, which were subjected to varying temperatures. The activation energies were determined through the utilization of the n-th order and Langmuir-Hinshelwood kinetic models and subsequently calculated using the Arrhenius equation, resulting in values of 35.36 and 31.70 kJ/mol, respectively. The values of enthalpy and entropy, ΔH and ΔS, were determined through the utilization of Eyring's equation, 18.49 kJ/mol and −80.7 J/mol.K, respectively.

Direct Furfural Production from Deciduous Wood Pentosans Using Different Phosphorus-Containing Catalysts in the Context of Biorefining.

This study seeks to improve the effectiveness of the pretreatment stage when direct furfural production is integrated into the concept of a lignocellulosic biomass biorefinery. First of all, the catalytic effects of different phosphorus-containing salts (AlPO₄, Ca₃(PO₄)₂, FePO₄, H₃PO₄, NaH₂PO₄) were analysed in hydrolysis for their ability to convert birch wood C-5 carbohydrates into furfural. The hydrolysis process was performed with three different amounts of catalyst (2, 3 and 4 wt.%) at a constant temperature (175 °C) and treatment time (90 min). It was found that the highest amount of furfural (63-72%, calculated based on the theoretically possible yield (% t.p.y.)) was obtained when H₃PO₄ was used as a catalyst. The best furfural yield among the used phosphorus-containing salts was obtained with NaH₂PO₄: 40 ± 2%. The greatest impact on cellulose degradation during the hydrolysis process was observed using H₃PO₄ at 12-20% of the initial amount, while the lowest degradation was observed using NaH₂PO₄ as a catalyst. The yield of furfural was 60.5-62.7% t.p.y. when H₃PO₄ and NaH₂PO₄ were combined (1:2, 1:1, or 2:1 at a catalyst amount of 3 wt.%); however, the amount of cellulose that was degraded did not exceed 5.2-0.3% of the starting amount. Enzymatic hydrolysis showed that such pretreated biomass could be directly used as a substrate to produce glucose. The highest conversion ratio of cellulose into glucose (83.1%) was obtained at an enzyme load of 1000 and treatment time of 48 h.

Synthesis of Donor–Acceptor Copolymers Derived from Diketopyrrolopyrrole and Fluorene via Eco-Friendly Direct Arylation: Nonlinear Optical Properties, Transient Absorption Spectroscopy, and Theoretical Modeling

A series of PFDPP copolymers based on fluorene (F) and diketopyrrolopyrrole (DPP) monomers were synthesized via direct arylation polycondensation using Fagnou conditions which involved palladium acetate as catalyst (a gradual catalyst addition of three different percentages were used), potassium carbonate as the base, and neodecanoic acid in N, N-dimethylacetamide. This synthesis provides a low cost compared with traditional methods of transition-metal-catalyzed polymerization. Among the different amounts of catalyst used in the present work, 12% was optimal because it gave the highest reaction yield (81.5%) and one of the highest molecular weights (Mn = 13.8 KDa). Copolymers’ chemical structures, molecular weight distributions, and optical and thermal properties were analyzed. The linear optical properties of PFDPP copolymers resulted very similarly independently to the catalyst amounts used in the synthesis of the PFDPP copolymers: two absorptions bands distinctive of donor–acceptor copolymers, Stokes shifts of 41 nm, a good quantum yield of fluorescence around 47%, and an optical bandgap of 1.7 eV were determined. Electronic nonlinearities were observed in these copolymers with a relatively high two-photon absorption cross-section of 621 GM at 950 nm. The dynamics of excited states and aggregation effects were studied in solutions, nanoparticles, and films of PFDPP. Theoretical calculations modeled the ground-state structures of the (PFDPP)n copolymers with n = 1 to 4 units, determining the charge distribution by the electrostatic potential and modeling the absorption spectra determining the orbital transitions responsible for the experimentally observed leading bands. Experimental and theoretical structure–properties analysis of these donor–acceptor copolymers allowed finding their best synthesis conditions to use them in optoelectronic applications.

Pengaruh Perbedaan Jumlah Katalis terhadap Angka Yield pada Proses Pembuatan Biodiesel dari Minyak Goreng Sisa Menggunakan Pemanas Double Jacket

Biodiesel is biodegradable and non-toxic and has a low carbon content, high lubricity, and <p>Biodiesel is biodegradable and non-toxic and has a low carbon content, high lubricity, and higher ash point than diesel. The purpose of this study was to obtain data on the physicochemical properties of biodiesel from waste cooking oil (WCO) produced with different amounts of catalyst in the transesterification process. Methods This research carried out a two-step process: (1) esterification with an acid catalyst (H<sub>2</sub>SO<sub>4</sub>) and (2) transesterification with an alkali catalyst (KOH). The remaining frying oil is degummed by adding 2% H<sub>3</sub>PO<sub>4</sub>. Furthermore, the esterification process was carried out by adding 2% (v/v) H<sub>2</sub>SO<sub>4</sub> at 800 rpm for 90 minutes. The transesterification process using an alkaline catalyst (KOH) was varied from 0.7-1.5% at a temperature of 60 <sup>o</sup>C with a rotation of 800 rpm and a time of 90 minutes. In the ester/transesterification process, the ratio of methanol: oil is 1:2 (v/v). The biofuels are then tested for cetane number, flash point, density, viscosity, calorific value, and others. The results showed that the amount of wet catalyst (KOH) in the transesterification process gave a difference in the yield of WCO oil. The optimum value was obtained at the amount of 1% KOH catalyst, which was 85%.</p>

Hot Firing Tests of a Novel Green Hypergolic Propellant in a Thruster

This study investigates the ignition and combustion behavior of the recently developed green hypergolic combination named HIP_11 in a small thruster. The combination HIP_11 consists of highly concentrated hydrogen peroxide as oxidizer and a fuel based on the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate (EMIM SCN) with addition of copper thiocyanate (Cu SCN) to facilitate the hypergolic ignition. A dedicated thruster, featuring a 2-on-1 unlike impinging jet injector, was designed and manufactured. The initial tests were conducted with the injector only, without the combustion chamber mounted. These tests were conducted with two different amounts of catalyst: 1% and 5% Cu SCN. Subsequently, three hot firing series (around 35 tests) were conducted with the complete thruster, using the propellant combination 97% high-test peroxide and EMIM Cu SCN. The propellant mass flow rates were varied between 7 and and the oxidizer-to-fuel ratio from 3 to 7.

Chitosan/MCM-41-SO3H composites as catalyst of the etherification of limonene

Etherification of limonene with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol to ethers were performed using a mesostructured silica with sulfonic groups, like MCM-41-SO3H, immobilized in chitosan (CHT), as composite catalyst (MCM-41-SO3H/CHT). The main product of limonene etherification in the present of MCM-41-SO3H/CHT composites was the α-terpinyl ether, which can be used in pharmaceutical and fine industry.Composite materials with different amounts of catalyst were prepared. These materials were used in methoxylation of limonene. It was observed that the catalytic activity of composite materials increased with the loading of MCM-41-SO3H dispersed in chitosan. The composite catalyst with highest activity was [MCM-41-SO3H]3/CHT.Composite material, [MCM-41-SO3H]3/CHT, can be recovered and reused in reaction of limonene with methanol.As [MCM-41-SO3H]3/CHT composite showed the highest catalytic activity in methoxylation of limonene, this material was applied in etherification of limonene with ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol. An increased of activity with a decrease of the carbon number of alcohols was observed. A possible explanation is the presence of some internal limitations in channelling of composite catalyst.Selectivity of [MCM-41-SO3H]3/CHT to ethers was studied. When the carbon number of alcohol chain increase, a decrease of selectivity of composites is verified.

Equilibrium Analyses and Kinetics of Carbon Dioxide Methanation Using an Alumina‐Supported Ruthenium Catalyst

AbstractWith CO2 being accepted as the main cause of the climate change, considerable efforts currently focus on capturing CO2 from major point sources and to store it. Another, better way is to utilize the captured CO2 to produce useful fuels like methane. The Sabatier reaction was studied in this work, using 0.5 % ruthenium on alumina as catalyst. A quartz reactor packed with catalyst particles and placed in a vertical furnace was employed. A stoichiometric ratio of CO2/H2 was used and the temperature was changed between 150 and 400 °C, while the flow rate of the feed gas mixture was varied between 250 and 625 mL min−1, with different amounts of catalyst. The temperature was identified as the major parameter affecting the conversion. Carbon dioxide conversions greater than 85 % were obtained at temperatures higher than 350 °C.

Application of Photocatalytic Process Using UV/TiO2 for Degradation of Cefepime: A Comparison between Photocatalytic and Photolytic

Cephalosporin is a group of β-lactam antibiotics that has a wide antibacterial ability, so its therapeutic use is high. Although much research has been conducted about the fate of antibiotics in an aquatic environment, little investigation has been done about the removal of cephalosporin. In this study, Cefepime, a fourth-generation cephalosporin antibiotic was selected and different tests such as UV/TiO2, UV, TiO2 under darkness, and TiO2 under sunlight were applied to determine whether these methods are effective ways to remove Cefepime from aqueous solutions or not. Different amounts of catalyst and different pHs were used as effective parameters on degradation efficiency and were optimized. The Cefepime removal was measured by HPLC. The mobile phase was comprised of 10:90 Acetonitrile: water with a flow rate of 1 mL/min. The detected wavelength was 212 nm. Maximum removal efficiency (92.9%) for 20 mg/L Cefepime in neutral pH and catalyst dose of 70 mg/L after 120 min irradiation was observed. At the same conditions, the degradation efficiencies for UV, TiO2 under sunlight, and TiO2 under darkness were determined 77.65%, 53.24%, and 15.12% respectively. Also, the reaction rate constant was increased from 0.0054 to 0.0279 (1/min) for photolysis and photocatalysis, respectively. This work was economically compared with photolysis and the result showed that the EEO for the UV/TiO2 process was five times lower than UV processes.UV/TiO2 process could be an efficient method to successfully remove the Cefepime antibiotic from aqueous solutions.

Effect of Potassium Carbonate Catalyst on Pyrolysis of Milicia excelsa in a Fixed Bed Reactor

The effect of potassium carbonate catalyst on the products distribution from pyrolysis of Milicia excelsa (Iroko) at various temperatures (400, 500 and 600 oC) was investigated. Milicia excelsa sawdust was obtained from a sawmill in Ogbomoso, South-Western Nigeria and was sundried for five days in order to reduce its moisture content. Catalytic pyrolysis of the sawdust was performed with different amounts of catalyst (10, 20, 30 and 40 wt.%). Non-catalytic pyrolysis was also performed for the same temperatures and the products distributions from both batches were compared. Char yield generally increased with increase in catalyst amount for all the temperatures considered. Tar yield did not follow any definite pattern with increasing amount of catalyst as different trends were obtained for different temperatures. Gas yield generally decreased with increase in catalyst amount in the feed. Char yields from non-catalytic experiments were higher than those obtained from catalytic runs, with the highest value of 68% at 400 oC. Tar yields from catalytic pyrolysis were higher than those from non-catalytic process at 400 oC (biomass/catalyst ratio of 90/10) and at 500 oC (biomass/catalyst ratios of 70/70 and 60/40), the highest yield being 29.47% at 500 oC and biomass/catalyst ratio of 60/40. Gas yields from catalytic pyrolysis were higher than those from non-catalytic runs except at 500 oC (biomass/catalyst ratio of 60/40), the highest being 51.3% at 600 oC (biomass/catalyst ratio of 90/10). By making use of appropriate biomass/catalyst ratio and temperature, the yield of liquid fuel from catalytic pyrolysis of Milicia excelsa can be increased.Keywords— Catalyst, potassium carbonate, pyrolysis, biomass, product distribution

Comparative study of synthesis of cellulose propionate from different sources using NIS as a new catalyst

Propylation of cellulose from different sources with propionic anhydride using N-iodosuccinimide (NIS) under solvent-free condition was tested. It was done in the presence of NIS as a new catalyst for propylation using three different amounts of catalyst under mild reaction conditions. The degree of substitution by propionate was experimentally calculated and confirmed by FTIR and 1H NMR analyses. The propylation yields varied from 71.54 to 88.37% with the degree of substitution (DS) ranged from 1.32 to 2.80 for commercial cotton cellulose, 1.76–3.00 for rice husk cellulose, and 1.60–3.0 for wheat straw cellulose. The DS were easily controlled by changing the reaction duration (2–6 h) and the amount of the NIS catalyst (50, 75, and 100 mg for each 1.0 g of cellulose) in 25 mL of propionic anhydride. Prolonging the reaction’s duration has no favorable effect on the propylation process and led to decrease in the cellulose propionate (CP). Also, increasing the amount of NIS catalyst results in decrease the DS and CP yield. NIS was recognized as a novel and more successful catalyst for propylation of the hydroxyl groups of cellulose from different sources in high degree of substitution.

Rapid synthesis of cellulose propionate and its conversion to cellulose nitrate propionate

A highly rapid synthesis of cellulose propionate (CP) with high yield from commercial cotton cellulose using FeCl3·6H2O and ZnCl2 as catalysts and less amount of propionic anhydride in solvent free synthesis was investigated. It was done using different amounts of catalyst under microwave irradiation for maximum of 8 min reaction time. The degree of substitution by propionate (DSCP) was experimentally calculated and confirmed by FTIR and 1H-NMR. The yields of CP using ZnCl2 and FeCl3·6H2O as catalysts varied from 82.20 to 98.60% with the degree of substitution (DSCP) ranging from 2.47 to 2.96, and from 55.51 to 96.34% with DSCP ranging from 0.38 to 2.84, respectively. The DSCP was controlled by changing the reaction duration (2–8 min), and the amount of catalyst using fixed amount of propionic anhydride (25 mL/5.0 g cellulose). The degree of polymerization of CP is highly affected by the catalyst amount and reaction time, while the thermal stability of CP is slightly affected by the type of catalyst and reaction time. Novel cellulose nitrate-propionate mixed esters (CNP) were also synthesized by nitration of the obtained cellulose propionate with different degrees of nitration using (HNO3 + H2SO4) and (HNO3 + P2O5) as nitrating agents. The degree of nitration (DSCN) ranged between 0.10 and 2.53 for the HNO3/H2SO4 mixture and between 0.22 and 1.24 for the HNO3/P2O5 mixture. The effect of nitrating agent and reaction time on the degree of polymerization and thermal stability of CNP were also investigated using GPC, TGA, DTA and DSC analysis.

Photocatalytic Degradation of High Density Polyethylene using CaO Nanocatalyst

The photodegradation of high density polyethylene (HDPE) using CaO nanoparticles as a catalyst was carried out using 500 W lamp. After exposure, morphology as well as thermal properties of the HDPE was investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). SEM results showed that the HDPE is more prone to crack into small fragments, which indicated a rise in crystallinity with different amounts of catalyst i.e. CaO nanoparticles. The DSC results confirmed the remarkable influence of photodegradation on degree of crystallinity (XC%), fusion enthalpy (ΔH J g-1) and melting temperature (Tm) of HDPE. Infrared spectrometry (FTIR) demonstrated all functional groups of HDPE, present before and after photodegradation. Overall results showed that HDPE was photodegraded into small fragments successfully by using CaO nanopartilces, where different functional groups such as carbonyl, esters and vinyl were obtained during chain scission.

Catalytic supercritical water gasification of eucalyptus wood chips in a batch reactor

Eucalyptus wood chips were reacted under supercritical water conditions to evaluate the effect of a NiFe2O4 catalyst, residence time and temperature parameters. Experiments were performed in a batch reactor at 400 °C , 450 °C and 500 °C using three different amounts of catalyst (0, 1.0, 2.0 g) and three different residence times (30, 45, 60 min). Results showed that eucalyptus wood chips reacted and produced CO2 as the dominant gas in all cases, followed by H2 and CH4. However, the presence of NiFe2O4 catalyst led to a 60% increase in H2 produced, while significantly reducing the solid residue and enhancing the percentage of methyl derivatives in the organic liquid products. The highest H2 mol% was at 450 °C, 2 g of catalyst and 60 min of residence time. Analysis of the derived oils showed that they were mostly composed of ketones, aldehydes, methylbenzenes and alkylated phenols. Increasing the reaction temperature to 500 °C increased the molar composition of methane by 62% compared to its yield at 450 °C. In generally, this work showed that NiFe2O4 acted as an effective heterogeneous catalyst for improved production of H2 and CH4 via supercritical water gasification process.

Synthesis, characterization and catalytic activity of dioxidouranium(VI) complexes of ONNO tetradentate Mannich bases

The reaction of dibasic tetradentate ONNO donor Mannich bases, derived from ethylenediamine and 2,4–di–tert–butylphenol (H2L1) (I), 2,4–di–methylphenol (H2L2) (II), 2–tert–butyl–4–methylphenol (H2L3) (III) and 2,4–di–chlorophenol (H2L4) (IV), with UVIO2(MeCOO)2·2H2O in a 1:1 M ratio in refluxing MeOH gave the corresponding mononuclear trans-dioxidouranium(VI) complexes of the type trans-[UVIO2L(MeOH)] (H2L = H2L1 to H2L4) (1–4). The synthesized complexes are stable in air, reddish-brown in color and soluble in most solvents. These complexes are characterized by elemental analysis, various spectroscopic (FT-IR, UV/Vis, 1H and 13C NMR) techniques and single-crystal X-ray analysis of 3 and 4. The complexes adopt distorted pentagonal bipyramidal geometry around the metal centre. The ligand acts as tetradentate, coordinating through two phenolato oxygen and two imino nitrogen atoms; two oxido groups are trans to each other. These complexes are used as catalysts to study the oxidative bromination of thymol and styrene. The catalytic oxidative bromination of thymol resulted in the formation of three products namely, 2-bromothymol, 4-bromothymol and 2,4-dibromothymol while oxidative bromination of styrene gave two products, 2-bromo-1-phenylethane-1-ol and 1-phenylethane-1,2-diol. In order to find out the optimized reaction conditions for the fixed concentration (10 mmol) of substrate, effects of different amounts of catalyst, KBr, HClO4, and oxidant (H2O2) have been investigated. Under the optimized reaction conditions, all the complexes have shown good catalytic potentials for the oxidative bromination of substrates, establishing the functional similarity to vanadium dependent haloperoxidases. Changes in the UV–visible absorption spectra of dioxidouranium(VI) complexes upon addition of H2O2 suggest the formation of the corresponding oxidoperoxidouranium(VI) complexes.

Catalytic gasification of refuse-derived fuel in a two-stage laboratory scale pyrolysis/gasification unit with catalyst based on clay minerals

Municipal solid waste (MSW) disposal is a serious environmental issue requiring immediate solution and good waste management strategy. Mechanical-biological treatment (MBT) plants offer the opportunity to reduce the amount of MSW that is, otherwise, disposed of in landfills. Up to 40% of MSW is converted to waste fuel, also called refuse-derived fuel (RDF). Gasification is a promising alternative of RDF processing. It can be defined as high temperature treatment of the feedstock with lower than stoichiometric amount of oxygen resulting mainly in a gaseous product (syngas). High hydrogen content, specific ratio of H2/CO, and low tar content are important parameters of syngas for its application in both energy production and chemical synthesis. Reduction of tar content in syngas can be achieved by catalytic tar cracking. In this work, a catalyst prepared from natural clay was characterised by thermogravimetric, specific surface area, X-ray diffraction, X-ray fluorescence and scanning electron microscopy (SEM) analyses. Catalyst activity was tested in two reactions, namely in decomposition of model tar constituent, p-xylene, and in cracking of tar produced in RDF gasification experiments. Influence of the reaction temperature and the amount of catalyst on the p-xylene conversion and products’ distribution was studied. The results proved high catalytic activity of the prepared catalyst in the decomposition of p-xylene. Coupled RDF pyrolysis and the produced volatiles gasification experiments were carried out in a two-stage laboratory scale reactor using a bed of tar cracking catalyst in the second stage. Tar decomposition experiments were carried out at the reactor temperatures of 700–850 °C applying different amounts of catalyst (0.75 g, 1 g, 1.25 g, 1.5 g, 2 g and 4 g) per 1 g of pyrolised RDF. Results indicate that the presence of catalyst had significant effect on both tar cracking efficiency and gas composition. Loss of the catalyst specific surface area was observed when the experiments were carried out at temperatures exceeding 800 °C.

Pd-catalysts for DFAFC prepared by magnetron sputtering

Samples of a palladium catalyst for direct formic acid fuel cell (DFAFC) applications were prepared on the Elat® carbon cloth by magnetron sputtering. The quantity of Pd was equal to 3.6, 120 and 720μg/cm2. The samples were tested in a fuel cell for electro-oxidation of formic acid, and were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).The XPS measurements revealed a high contribution of PdCx phase formed at the Pd/Elat® surface interface, with carbon concentration in PdCx from x=9.9–14.6at.%, resulting from the C substrate and CO residual gases. Oxygen groups, e.g. hydroxyl (–OH), carbonyl (CO) and carboxyl (COOH), resulted from the synthesis conditions due to the presence of residual gases, electro-oxidation during the reaction and oxidation in the atmosphere. Because of the formation of CO and CO2 on the catalysts during the reaction, or because of poisoning by impurities containing the –CH3 group, together with the risk of Pd losses due to dissolution in formic acid, there was a negative effect of catalyst degradation on the active area surface. The effect of different loadings of Pd layers led to increasing catalyst efficiency. Current–voltage curves showed that different amounts of catalyst did not increase the DFAFC power to a great extent. One reason for this was the catalyst structure formed on the carbon cloth. AFM and SEM measurements showed a layer-by-layer growth with no significant variations in morphology.The results for electric power recalculated for the Pd loading per 1mg of catalyst layers in comparison to carbon substrates decorated by Pd nanoparticles showed that there is potential for applying anodes for formic acid fuel cells prepared by magnetron sputtering.

Catalytic activity of mono and bimetallic Zn/Cu/MWCNTs catalysts for the thermocatalyzed conversion of methane to hydrogen

Mono and bimetallic multiwalled carbon nanotubes (MWCNTs) fortified with Cu and Zn metal particles were studied to improve the efficiency of the thermocatalytic conversion of methane to hydrogen. The surface of the catalyst and the dispersion of the metal particles were studied by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and with energy-dispersive X-ray spectroscopy (EDS). It was confirmed that the metal particles were successfully dispersed on the MWCNT surface and XPS analysis showed that the Zn was oxidised to ZnO at high temperatures. The conversion of methane to hydrogen during the catalytic pyrolysis was studied by pyrolysis gas chromatography using different amounts of catalyst. The best yields of hydrogen were obtained using pyrolysis conditions of 900°C and 1.2mg of Zn/Cu/MWCNT catalyst for 1.5mL of methane.The initial conversion of methane to hydrogen obtained with Zn/Cu/MWCNTs was 49%, which represent a good conversion rate of methane to hydrogen for a non-noble metal catalyst.

An exponential chemorheological model for viscosity dependence on degree-of-cure of a polyfurfuryl alcohol resin during the post-gel curing stage

In the present study, the chemorheological behavior of a bio-based polyfurfuryl alcohol (PFA) resin has been determined by rheological isothermal tests at different curing temperatures for the post-gel curing stage of the resin, using three different amounts of catalyst (2, 4 and 6 wt %). Instead of modeling the evolution of the complex viscosity using a widely used chemorheological model such as the Arrhenius model for each tested temperature, the change of the complex viscosity as a function of the degree-of-cure was predicted using a new exponential type model. In this model, the logarithm of the normalized degree-of-cure is used to predict the behavior of the logarithm of the normalized complex viscosity. The model shows good quality of fitting with the experimental data for 4 and 6 wt % amounts of catalyst. For the 2 wt % amount of catalyst, scattered data leads to a slightly lower quality of fitting. Altogether, it is demonstrated that the new exponential model is a good alternative to conventional chemorheological models due to its simplicity and suitability.

Kinetics Modeling of the Heterogeneously Catalyzed Esterification of 2,3-Butanediol with Acetic Acid

Esterification of 2,3-butanediol using a homogeneous catalyst was studied in 1945 under the Synthetic Rubber Program. The aim of this paper is to show that this reaction can be carried out with a heterogeneous catalyst, which presents many advantages such as the possibility of separation and recycling. The kinetic behavior of heterogeneous esterification of 2,3-butanediol with acetic acid over an ion-exchange resin Amberlyst 36 was investigated in a batch reactor. The experiments were conducted with different amounts of catalyst (from 1.1% to 4.4%, relatively to the initial molar quantity of 2,3-butanediol), with molar ratios of reactants (acetic acid to 2,3-butanediol) varying from 2 to 12, and at temperatures from 50 to 110 °C. Our experimental system was able to acquire kinetic data, even during the first minutes of the reaction. A simple model based on reliable hypotheses was built and the experimental data were used to determine all the kinetic and thermodynamic constants of the reaction. A single set of parameters is able to represent correctly the evolution of all different species present during the esterification reaction in function of time.