Reaction Kinetics and Catalysis Letters

Current research reports and chronological list of recent articles..

Reaction Kinetics and Catalysis Letters is a medium for the rapid publication of original contributions in such fields as kinetics of homogeneous reactions in gas, liquid and solid phase; homogeneous and heterogeneous catalysis; adsorption in heterogeneous catalysis; transport processes related to reaction kinetics and catalysis; preparation and study of catalysts; reactors and apparatus.

The publisher is Springer. The copyright and publishing rights of specialized products listed below are in this publishing house. This is also responsible for the content shown.

To search this web page for specific words type "Ctrl" + "F" on your keyboard (Command + "F" on a Mac). Then: type the word you are searching for in the window that pops up!

Additional research articles see Current Chemistry Research Articles. Magazines with similar content (reaction kinetics and catalysis):

Reaction Kinetics and Catalysis Letters - Abstracts

High catalytic activity of gold nanoparticle-templated, tyrosine-rich peptide self-assemblies for 3,3′,5,5′-tetramethylbenzidine oxidation in the absence of hydrogen peroxide

Abstract

In this study, gold nanoparticle-templated, tyrosine-rich peptide (YC7@AuNPs) self-assemblies were examined as peroxidase enzyme–mimic catalysts for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and its activity was monitored by changing the reaction conditions such as pH, temperature, initial TMB concentration, and catalyst (Au) loading amount. The YC7@AuNPs catalysts were active for TMB oxidation even in the absence of hydrogen peroxide. Michaelis–Menten kinetic analysis showed that the YC7@AuNPs catalysts without hydrogen peroxide have activities comparable to other peroxidase–mimic catalysts using hydrogen peroxide in terms of the Michaelis constant.

Datum: 25.06.2019

Nanodisperse gold catalysts in oxidation of benzyl alcohol: comparison of various supports under different conditions

Abstract

Monodisperse gold particles (ca. 2 nm) were prepared and deposited on various supports (SiO2, Al2O3, HAP, MgAl2O4 and MgO). The acid/base properties of supports were characterized by NH3 and CO2 sorption. The size of the gold nanoparticles spans in the 1.7–6.5 nm mean diameter range after calcination as determined from TEM measurements. The amounts of accessible surface sites were estimated by binary concentration pulse chromatography of CO with Kr adsorption. The data are in agreement with the results of CO adsorption obtained by DRIFT spectroscopy. The activities of the catalysts were compared in the oxidation of benzyl alcohol in stirred batch reactors under two different conditions: in xylene solvent with atmospheric oxygen at 60 °C (in presence and in absence of K2CO3), and in a solvent-free mixture at elevated pressure and temperature (5 bar O2, 150 °C, 5 h). The activities of catalysts in benzyl alcohol conversion are described in two variants, namely related to (i) active catalytic sites (ASNA), and (ii) number of Au atoms on the geometric surface of particles (GSNA). The activities of catalysts in xylene solvent at 60 °C were excellent, with 0.28–1.11 s−1 characteristic GSNAini values (initial reaction rates related to surface Au atoms, Ausurf) in presence of K2CO3. The observed order of activities under these conditions is Au/SiO2 < Au/Al2O3 < Au/HAP < Au/MgAl2O4 < Au/MgO. In the experiments performed at 150 °C under solvent-free conditions, the reaction partners are depleted in greater extents (with the exception of Au/Al2O3), thus the obtained average GSNAave (average reaction rate during 5 h reaction related to Ausurf) values are less reliable, however selectivity data provide useful information as well. These estimated average GSNAave values (0.14–0.83 s−1) attest still good activities. For the interpretation of the obtained data, the roles of active sites on gold nanoparticles of various dispersion and the accessibility of their surfaces as well as the acid–base properties and surface hydroxyl concentration of supports, water ad- and desorption phenomena are considered simultaneously.

Datum: 21.06.2019

Sulfonic acid-functionalized hierarchical SAPO-34 for fructose dehydration to 5-hydroxymethylfurfural

Abstract

Sulfonic acid-functionalized hierarchical SAPO-34 (S1-SAPO-34-SO3H) was prepared by post-grafting 3-mercaptopropyltriethoxysilane, and the sulfonic acid group was then oxidized by H2O2. The obtained catalysts were characterized by XRD, SEM, FTIR, TG, nitrogen adsorption, XRF, and acid–base titration. The acidity of the modified SAPO-34 increased, which confirmed the success of grafting. The catalytic properties during the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) were investigated. The yield of 5-HMF was up to 72%, and a 34% increase was found compared with the case of SAPO-34. The findings were discussed and attributed to the synergistic effects caused by both the acid groups and the mesopores. More basic investigations with regard to the conditions, including the reaction time, temperature, solvent, load and regeneration, are needed.

Datum: 17.06.2019

Oxy-steam reforming of methanol on copper catalysts

Abstract

The influence of copper content in the monometallic catalysts supported on the CeO2·Al2O3 binary oxide system on their catalytic activity and physicochemical properties in oxy-steam reforming of methanol was investigated. It was shown that activity and selectivity depends on the content of copper, its dispersion on the catalysts surface. It was confirmed that optimal copper content was 20 wt% of Cu. Copper catalysts with 20 wt% of Cu exhibited the highest methanol conversion and reaction rate value compared to the rest of the investigated catalysts systems. The kinetic measurements performed in oxy-steam reforming of methanol on 20%Cu/CeO2·Al2O3 catalysts, showed an activation energy for this system equal Ea (OSRM) = 66.56 kJ/mol.

Datum: 14.06.2019

Cerium modification for improving the performance of Cu-SSZ-13 in selective catalytic reduction of NO by NH 3

Abstract

A series of Ce-Cu-SSZ-13 catalysts were synthesized by the ion exchange method based on the Cu-SSZ-13 prepared via a one-pot method and investigated for the selective catalytic reduction by NH3. Compared with Cu-SSZ-13, the catalytic activity and sulfur resistance of Ce-Cu-SSZ-13 were enhanced by modifying with cerium. XRD, N2-BET, MP-AES, XPS, H2-TPR and in situ DRIFTS were carried out to characterize the catalysts. XPS results suggested that more active sites on the surface of Ce-Cu-SSZ-13 catalysts. H2-TPR showed that the redox capacity of the Cu-SSZ-13 catalyst was enhanced after doping with Ce. In situ DRIFTS results demonstrated that the synergistic effect existing between copper and cerium species enhanced the adsorption performance of NH3 and NO + O2 on the catalyst surface. All of the above factors played important roles for achieving the high NH3-SCR performance.

Datum: 14.06.2019

1,3-Butadiene production from ethanol–water mixtures over Zn–La–Zr–Si oxide catalyst

Abstract

Zn–La–Zr–Si oxide composition has been investigated in the ethanol-to-butadiene process using ethanol–water mixtures with different water content. An increase of H2O content in the initial reaction mixture decreases ethanol conversion, 1,3-butadiene selectivity, yield and productivity. The results of in situ FTIR spectroscopy (with ethanol and acetone as probe molecules) have shown the main reason for a decrease in activity of the catalyst to be H2O adsorption on active sites of aldol condensation of acetaldehyde and, to a lesser extent, ethanol dehydrogenation. Zn–La–Zr–Si oxide composition is a highly active and selective catalyst for the ethanol-to-butadiene process when ethanol–water mixture of 80 vol% ethanol and 20 vol% H2O is used, 60% 1,3-butadiene yield is achieved.

Datum: 13.06.2019

Enhancement of catalytic performance over different transition metals modified CeO 2 for toluene abatement

Abstract

Pure CeO2 and CeO2–MOx (M: Mn, Zr and Ni) catalysts were synthesized by the co-precipitation method and evaluated for the oxidation of toluene. The characterization showed that the specific surface area and the porous texture of catalysts were improved due to the doping of transition metal. Besides, the doping of MOx into ceria contributed to the generation of structural defects, which could contribute to the easier storage and release of surface oxygen. Furthermore, the CeO2–MOx (M: Mn, Zr and Ni) catalysts exhibited higher concentration of Ce3+ and surface adsorbed oxygen than pure CeO2, which could correlate with the generation of oxygen vacancies, resulting in the enhancement of redox properties. Hence, CeO2–MnOx exhibited the best apparent catalytic activity of toluene due to its more Ce3+, structural defects and active oxygen species.

Datum: 12.06.2019

Pt–Ir/Al 2 O 3 catalysts for the ring opening of naphthenes. Performance as a function of time

Abstract

The catalytic performance of a Pt–Ir/Al2O3 catalyst for the selective ring opening of decalin was studied as a function of time. Fresh and used catalysts were evaluated with the reaction tests of cyclohexane dehydrogenation and cyclopentane hydrogenolysis to assess the metal function properties. The transformation of decalin was used as a test reaction for the ring opening of naphthenes. For this test the yield to ring contraction products passed through a maximum at intermediate values of conversion while yields to dehydrogenation, ring opening, and cracking products increased with conversion. Coke deposition also increased with reaction time but its distribution on the metal and acid sites did not change. Coke was more toxic for hydrogenolysis than for de/hydrogenation and therefore the products ratio of (ring opening)/(dehydrogenation) decreased at end of the reaction. Higher yields to dehydrogenated products produced a higher coke deposition while high activity in both hydrogenolysis and dehydrogenation favored the ring opening reaction.

Datum: 12.06.2019

Activity and selectivity of Co(Ni)Mo sulfides supported on MgO, Al 2 O 3 , ZrO 2 , TiO 2 , MCM-41 and activated carbon in parallel hydrodeoxygenation of octanoic acid and hydrodesulfurization of 1-benzothiophene

Abstract

Mo, CoMo and NiMo sulfide catalysts were prepared using MgO, Al2O3, ZrO2, TiO2, MCM-41 and activated carbon supports. The catalysts were tested in parallel hydrodeoxygenation (HDO) of octanoic acid and hydrodesulfurization (HDS) of 1-benzothiophene. For all supports, NiMo catalysts were more active in both HDO and HDS than Mo and CoMo catalysts. HDO activity of NiMo catalysts decreased with type of support in the following order TiO2 > C > ZrO2 > Al2O3 > MCM-41 > MgO. The products of HDO were linear C7 and C8 hydrocarbons. Some isomerization and cracking activity was observed only with MCM-41 support. HDS activity of NiMo catalysts decreased in the following order C > ZrO2 > TiO2 > Al2O3 > MgO > MCM-41. HDO/HDS selectivity was influenced by the active phase and the support type and it was the highest over the NiMo/TiO2 catalyst.

Datum: 12.06.2019

Facile solvo-hydrothermal synthesis of Bi 2 MoO 6 for the photocatalytic reduction of CO 2 into ethanol in water under visible light

Abstract

Bi2MoO6 photocatalysts were synthesized by the hydro- and solvothermal methods. Using different solvents, pH values of the precursor suspensions and temperature during synthesis were tested, by and experimental design, to investigate the effect of these variables on the catalysts’ photocatalytic activity. To evaluate and compare the physical properties of the samples, X-ray diffraction analysis, SEM, BET measurements, UV–vis spectroscopy and zeta potential were applied. The results revealed that the pH is the statistically significant variable more important for both solvents and differences in catalysts characterizations, like morphology and crystallinity, were found with the solvents change. The as-synthesized samples exhibited good performance for the photoreduction of CO2 into ethanol in liquid phase. The yields of ethanol obtained over Bi2MoO6–H2O and Bi2MoO6–EG/Et catalysts, under the optimal conditions, were 34.44 and 24.43 µmol g−1 h−1, respectively.

Datum: 10.06.2019

K 2 WO 4 /Al 2 O 3 catalysts for methanethiol synthesis from methanol and H 2 S: effect of catalyst preparation procedure

Abstract

A series of the K2WO4/γ–Al2O3 catalysts was prepared with different introducing strategy of the K2WO4 to alumina and characterized by means of N2 adsorption–desorption, XRD, XPS, CO2/NH3-TPD, H2-TPR. It was found that the different introduction strategy of K2WO4 did not change the valence state of surface species of the catalysts but markedly influenced the structures, dispersion of tungsten and potassium species and acid-basic properties. The catalysts prepared by the sol–gel precipitation method exhibit larger surface area, better dispersion of the W species and more favorable acid-basic properties, thus possess higher activity for the reaction, particularly, at the lower reaction temperature of 320 °C, the methanethiol yield was about 8.3% higher than that over the catalyst prepared by traditional impregnation method. As a model catalyst, the catalysts prepared by sol–gel precipitation method show a higher and more stable reactivity with small dosage of water and CS2, and worth in industrial application.

Datum: 07.06.2019

Kinetic modeling of transesterification of gmelina seed oil catalyzed by alkaline activated clay (NaOH/clay) catalyst

Abstract

The kinetic modeling of transesterification of gmelina seed oil, GSO catalyzed by alkaline activated clay catalyst was investigated. The catalyst synthesized by activating clay with sodium hydroxide was used to examine the distribution of transesterification products. The reaction was conducted at 8:1 methanol/oil molar ratio, 6 wt% catalyst concentration and agitation speed of 300 rpm, temperatures of 45, 50 and 55 °C with different time interval. The kinetics was studied using elementary reaction mechanism of Eley–Rideal (ER). The results obtained showed that the clay belongs to kaolinite group and alkaline activated clay catalyst, was able to convert GSO to biodiesel with significant changes in concentrations of the transesterification products and reactants between 0 and 2.5 h. The kinetic investigation revealed that the data fitted the Eley–Rideal (ER) kinetic model with surface reaction between non-adsorbed methanol and adsorbed triglyceride as rate determining step, the rate determining step occurring at a temperature of below boiling point of methanol. The activation energy and frequency factor for the forward reaction were determined to be 2.90 kJ/mol and 0.025 h−1, respectively. The predictive power of the developed model for RDS was checked by fitting experimental data and it revealed good correlation.

Datum: 05.06.2019

Removal of methyl violet 2B by FePO 4 as photocatalyst

Abstract

FePO4 was successfully synthesized via a simple method as a heterogeneous catalyst for photo degradation of methyl violet 2B in aqueous solution. The FePO4 was identified by the X-ray diffraction, Fourier transform infrared spectroscopy analyses and the scanning electron microscopy image The analysis was completed by the pHPZC and the band gap energy. The photocatalytic performance of FePO4 was investigated using reduction of methyl violet 2B as a model reaction. The results showed that FePO4 had converted nearly 99% of methyl violet 2B under UV light with optimum operating conditions of 1 g L−1 of FePO4, natural pH (pH 6.75), and 10 mg L−1 of methyl violet 2B, a kinetic study was also realized. The recyclable character of the catalyst under the optimum conditions for three cycles was successfully investigated without any structural modification of the FePO4.

Datum: 05.06.2019

Thermodynamic and mechanism study of syngas production via integration of nitrous oxide decomposition and methane partial oxidation in the presence of 10%NiO–La 0.3 Sr 0.7 Co 0.7 Fe 0.3 O 3−δ

Abstract

10%NiO–La0.3Sr0.7Co0.7Fe0.3O3−δ (10%NiO-LSCF3773) was synthesized using the EDTAcitrate complexing method. Non-catalytic and catalytic nitrous oxide decomposition and methane partial oxidation using 10%NiO–LSCF3773 was experimentally studied, assuming that the reactions occurred separately in a membrane reactor at feed side and permeate side. The experimental results are in good agreement with the chemical equilibrium composition calculated using Aspen Plus, and the changes of standard Gibbs free energy of each relevant elementary reactions. The mechanism of the reactions was proposed to follow Eley–Rideal surface reaction. The optimal temperature was 800 °C, under atmospheric pressure, where (1) NO2 formation was not detected (2) no production of C2 + and C3 + (3) complete conversion of N2O, CH4 and O2 were achieved (4) high purity syngas was obtained with no significant amount of undesired products and (5) readily utilizable syngas at the ratio of two was achieved.

Datum: 04.06.2019

Oxidation of ethylene to acetaldehyde by N 2 O on Na-modified FeZSM-5 zeolite

Abstract

The oxidation of ethylene to acetaldehyde by N2O on Na-modified FeZSM-5 zeolite in a flow mode was studied at a temperature of 300 to 375 °C and with varying the feed mixture ratio N2O:ethylene:He from 5:5:90 to 5:95:0. It was found that in this range of conditions, acetaldehyde could be produced with selectivity up to 55%. Other reaction products were COx, coke and some amount of unidentified products, which were mostly the result of non-oxidative transformations of ethylene. To study the mechanism of the reaction, we used a quasi-catalytic mode in the temperature range 150–200 °C. The products accumulated on the surface during the reaction in the quasi-catalytic mode could be extracted from the surface and identified using various analytical methods. This approach allowed us to determine that the primary product of ethylene oxidation is ethylene oxide, which then isomerizes into acetaldehyde.

Datum: 04.06.2019

Quantum chemical evaluation of the role of $${{{\text{HO}}_{2}}^{ \cdot }}$$ HO 2 · radicals in the kinetics of the methyl linoleate oxidation in micelles

Abstract

The process of lipid peroxidation (LPO) plays an extremely important role in the human body due to the fact that its uncontrolled development can lead to oxidative stress and a number of serious diseases. The traditional approach to the analysis of the mechanism and kinetics of LPO is based on the well-known ideas that emerged from the study of radical-chain oxidation of hydrocarbons in a homogeneous medium. However, the distinctive feature of LPO is that this process is heterogeneous and the processes of diffusion of active intermediates between the aqueous and hydrocarbon phases should play a significant role in it. In the present work, an attempt has been made to theoretically estimate the contribution of these processes to the oxidation kinetics of model substances used in practice in the study of LPO. In the course of the calculations, a quantum chemical and kinetic analysis of the role of hydroperoxyl radical in the radical-chain mechanism of oxidation of methyl linoleate in micelles was carried out. The molecular dynamics method shows the important role of changing the dynamic rigidity of a hydrocarbon fragment of a chain during the formation of a peroxyl radical and hydroperoxyl group during the oxidation of a substrate in a heterogeneous medium. Quantum chemical calculations of the thermodynamics of reactions involving $${{{\text{HO}}_{2}}^{ \cdot }}$$ radicals and the effects of their solvation made it possible to estimate the kinetic constants of the reaction rates. Using kinetic modeling, their relative contribution to the oxidation kinetics was revealed. In this case, it is possible to explain a number of anomalies associated with the oxidation of polyunsaturated fatty acids and their esters in micelles compared with their oxidation in a homogeneous hydrocarbon medium.

Datum: 04.06.2019

Supported Co/activated carbon catalysts for the one-pot synthesis of isophorone diamine from hydroamination of isophorone nitrile

Abstract

Supported Co/activated carbon (Co/AC) catalysts were prepared by the incipient wetness impregnation method and applied to the one-pot hydroamination of isophorone nitrile (IPN) into isophorone diamine (IPDA). The 20 wt% Co/AC heat-treated in N2 exhibited superior catalytic performance to the 20 wt% Co/AC heat-treated in H2, by which a maximum 90.2% yield of IPDA was achieved and it could be recycled at least four times. XRD, XPS, TEM and BET has demonstrated that the existence of the fcc form of Co as well as the smaller and more uniformly dispersed Co particles in the Co/AC catalyst heat-treated in N2 may contribute to the excellent catalytic performance.

Datum: 04.06.2019

Characterization and competitive benzene hydrogenation activity of nickel supported on SBA-15/L x O y (L = Zn, Ti, W) composites in an aromatic mixture

Abstract

SBA-15/metal oxide composites were prepared by the mixing-calcination method and the nickel phase was impregnated by the wet impregnation method. The textural and structural properties of catalysts were characterized with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence, UV–visible diffuse reflectance spectra, and nitrogen adsorption–desorption analysis. Ni/composite materials were used for competitive hydrogenation of benzene in the range of 403–463 K and ambient pressure. It is found that the reaction kinetics follows the pseudo-first-order kinetic for hydrogen. Activity data demonstrated that the highest activity and the best selectivity were obtained for Ni/SBA-15/TiO2 (> 93%) at 403 K, and nickel supported over SBA-15/W2O (> 73%) at 403 K.

Datum: 03.06.2019

Catalytic N 2 O decomposition over La(Sr)FeO 3 perovskites

Abstract

In this study, La1−xSrxFeO3 perovskites with x = 0, 0.25, 0.50, 0.75 and 1.0 have been synthesized via a sol gel auto-combustion method using glycine as fuel. All materials were characterized with x-ray powder diffraction (XRD), N2 porosimetry, scanning electron microscopy (SEM) and O2 Temperature programmed adsorption- desorption (O2/TPA-D). The catalytic activity of perovskites was tested for the decomposition of N2O to N2 and O2 as a probe reaction in a bench scale plug flow reactor. The most active catalyst was La0.75Sr0.25FeO3 and the catalytic activity is strongly correlated to the amount of the reverse oxygen uptake from the perovskite structure. According to the N2O decomposition mechanism the slow and rate determining step was found to be the dissociation of N2O adsorbed on the surface of catalyst as $${\text{N}}_{ 2} {\text{O}}^{ - }_{{({\text{ads}})}}$$ .

Datum: 03.06.2019

The Boreskov Institute of Catalysis and the 14th International Conference on Fundamental and Applied Aspects of Physical Chemistry

Datum: 01.06.2019

Category: Current Chemistry Research

Last update: 03.04.2018.