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BACKGROUND: Acidic hydrolysis of a birch (Betula pendula) xylan produced by a novel semi‐industrial‐scale aqueous‐based and highly sustainable method was studied in a batch reactor. Five commercial acidic heterogeneous catalysts were screened and significant differences in their performance were observed. Dowex 50WX2‐100 was selected for further studies and the influence of the reaction parameters, including stirring speed, pH (0.5–1.5), temperature (115–145 °C) and catalyst particle size (50–400 mesh) were studied. The goal was to maximize xylose yield by balancing between the kinetics of hydrolysis and the undesired degradation of monosaccharides. RESULTS: The results show that the maximum achieved yield of xylose was 76%, but higher yields were hindered by the consecutive dehydration of sugars. It was also observed that the hydrolysis and dehydration reactions do not follow the same dependence on the experimental parameters, which leaves room for optimization of the yield. A kinetic model was developed based on the data, which takes into account the consecutive reaction pathway and the influence of the experimental conditions, and a very good fit of the model to the experimental data was achieved. An activation energy of 119 and 88 kJ mol–1 was obtained for the hydrolysis and dehydration steps, respectively. CONCLUSION: Hydrolysis results of this novel, well‐characterized hemicellulose extract have not been published previously, and they contribute significantly to the understanding of the hydrolysis and dehydration of real feedstock, instead of highly purified and typically very deacetylated model compounds with different characteristics and behaviour in hydrolysis. © 2021 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The carbonation of epoxidized vegetable oils is a crucial step in the preparation of nonisocyanate polyurethane. Several research groups have screened homogeneous catalysts such as tetra‐n‐butylammonium bromide for this reaction, but the research devoted to the use of heterogeneous catalysts and on the application of kinetic modeling is rare. Hence, to develop this process on an industrial scale, an appropriate heterogeneous catalyst should be found and a kinetic model developed. A catalyst consisting of an ionic liquid supported on carboxymethyl cellulose has been proved to be a suitable heterogeneous catalyst for this carbonation reaction. A catalyst based on 1‐hydroxypropyl‐3‐n‐butylimidazolium chloride and niobium(V) chloride supported on protonated carboxymethyl cellulose (HBimCl‐NbCl5/HCMC) was synthesized and tested for the carbonation of epoxidized fatty acid methyl ester. Effects of the catalyst particle size, agitation speed, catalyst loading, and reaction temperature on the reaction kinetics were investigated. The carbonation reaction proceeded efficiently at a temperature of 443.15 K, agitation speed of 500 rpm, and using native catalyst particles with a median diameter of 652 μm. A kinetic model was developed to simulate the conversion of the epoxide group with time. [ABSTRACT FROM AUTHOR]

BACKGROUND: For many chemical systems, it is of great importance to find a durable, active and efficient catalyst that improves the process performance. Epoxidation of oleic acid with peracetic acid (Prilezhaev oxidation) was carried out in an isothermal loop reactor in the presence of heterogeneous catalysts. The kinetic experiments conducted under microwave heating (MW) were compared with identical experiments carried out under conventional (conductive/convective) heating. Extensive screening of heterogeneous catalysts was conducted and the influence of microwave irradiation on the reaction kinetics was studied. Several ion exchange resins were screened to explore their applicability and activity in the epoxidation of oleic acid. The perhydrolysis reaction (peracetic acid formed in situ from acetic acid and H2O2) was promoted with the use of various solid acid catalysts: Amberlite IR‐120, Amberlyst 15, Smopex®, Dowex 50x8‐100, Dowex 50x8‐50, Dowex 50x2‐100 and Nafion™. RESULTS: From the selected group of catalysts, Dowex 50‐x8100 and Dowex 50x8‐50 produced the highest yield of epoxidized oil. Only minor differences in the reactant conversion and the product yield were found in the experiments carried out under microwave exposure compared to the conventionally heated experiments in the presence of several ion exchange resins. CONCLUSIONS: The catalytic effect was much more prominent than the microwave effect, because the solid acid catalysts enhanced the slow step of the process, the perhydrolysis of acetic acid. The catalytic effect was very dominant and a considerable improvement of the oleic acid conversion and the epoxide yield was observed in the presence of the top‐performing catalysts. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Activity of heterogeneous catalysts for synthesis of Guerbet alcohols from hexanol was evaluated. Commercial synthetic hydrotalcite (HT) was used in the aldol condensation reaction, which is a part of the Guerbet reaction network. HTs were calcined at different temperatures in order to modify their basicity and additionally, NaOH was applied in some experiments as a homogeneous base. The homogeneous base proved to be more efficient in aldol condensation experiments, while HT also performed in an acceptable way. Bi-functional metal containing HTs were synthesized by wet impregnation and co-precipitation methods employing different active metals. The materials were characterized with a number of methods, including CO2-TPD, pyridine-FTIR, nitrogen physisorption, transmission electron microscopy, SEM-EDX and XRD. Copper containing catalysts produced hexyl-hexanoate with a very high selectivity, while Ni-containing counterparts exhibited the highest selectivity towards the Guerbet alcohol. The co-precipitated catalysts were more active in the current study than the ones produced by wet-impregnation. Nevertheless, synthesis of Guerbet alcohols from hexanol with a one-pot method proved to be challenging, with the best yield of the Guerbet product in 24 h being 5%. This is proposed to be largely due to thermodynamic limitations, which was confirmed by calculations of thermodynamics. [ABSTRACT FROM AUTHOR]

The ethyl ester of levulinic acid, ethyl levulinate is a completely bio-based chemical made from levulinic acid, which is a hydrolysis product of cellulose and bio-ethanol. The very precise kinetics of levulinic acid esterification with ethanol was studied in an isothermal batch reactor in the presence of homogeneous (H2SO4) and heterogeneous catalysts (cation exchange resin Smopex-101). The temperature interval of the experiments was 50-70 °C. A kinetic model was proposed for both kinds of catalysts, adopting equilibrium rate expressions in any case. The different role of the catalyst used was considered separately, while a unique equilibrium constant was assumed for each system. The kinetic parameters were successfully determined by non-linear regression analysis. The model gave a very good description to the experimental data. The heterogeneous catalyst was used to demonstrate the feasibility of continuous operation in isothermal fixed bed reactors. The catalyst showed a good stability and high conversions of levulinic acid were obtained in the laboratory-scale fixed bed reactor. The model was able to predict both dynamic and steady-state experimental data. [ABSTRACT FROM AUTHOR]

BACKGROUND Succinic acid is an important intermediate compound with high commercial significance in the chemical industry. It can be obtained from renewable resources such as furfural. This article describes the kinetic study of furfural oxidation with hydrogen peroxide over a fibrous polymer-supported sulphonic acid catalyst (Smopex-101). The influence of reaction temperature, initial concentration of hydrogen peroxide and furfural has been investigated in detail. Reaction kinetics has been studied both in batch and semi-batch modes. Self-decomposition of hydrogen peroxide and loss of carbon in the form of carbon dioxide has been thoroughly examined. Parameter estimation has been performed and comparison was made between catalytic and non-catalytic reactions. The catalyst stabilities have been discussed. RESULTS The results indicate that the reaction orders in hydrogen peroxide decomposition are different in catalytic and non-catalytic reactions. Furfural presence in the reaction mixture, its interactions with the catalyst and involvement in other reactions significantly suppressed the side reactions, improving hydrogen peroxide utilization. The desired product (succinic acid) has been obtained in good yields (80%) when furfural was added in a semi-batch mode. CONCLUSIONS The kinetic models predicted the consumption behavior of hydrogen peroxide and furfural in both catalytic and non-catalytic reactions and the kinetic parameters were statistically well identified. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Reaction mechanism and intrinsic kinetics of sugar hydrogenation to sugar alcohols on solid foam Ru/C catalysts – From arabinose and galactose to arabitol and galactitol. [Display omitted] • Selective hydrogenation of sugars to sugar alcohols was succesful. • Ru/C solid foams were used as heterogeneous catalysts. • Kinetic models based on reaction mechanisms were derived. • The models descibed well the individual sugar and mixture hydrogenation. Solid foam catalysts have two great benefits: thin catalyst layers guaranteeing a high effectiveness factor and a low pressure drop in continuous operation. The ability of ruthenium-based solid foam catalysts in the hydrogenation of monomeric sugars was illustrated with extensive experiments of L-arabinose and D-galactose hydrogenation at 90-120˚C and 20 bar hydrogen pressure. Kinetic experiments were carried out with individual sugars and binary sugar mixtures at different D-galactose-to-L-arabinose molar ratios to reveal the molecular interactions in the presence of the solid foam catalyst. High conversion of sugars and high selectivity to sugar alcohols were achieved in the isothermal and isobaric laboratory-scale reactor which operated under intrinsic kinetic control. The sugar hydrogenation process was considered from a viewpoint of elementary steps on the catalyst surface. By assuming plausible surface reaction mechanisms, it was possible to derive rate equations for the formation of sugar alcohols, both in case of individual sugars and binary sugar mixtures. The kinetic model based on the non-competitive adsorption of sugars and hydrogen on the ruthenium surface gave a very good description of the hydrogenation kinetics and product distribution on the solid foam catalysts. The work opens a perspective to the selective and very effective hydrogenation of several sugars to valuable sugar alcohols in the presence of open foam Ru/C catalysts, both in batch and continuous operation modes. [ABSTRACT FROM AUTHOR]

• Heterogenized catalyst were prepared and characterized for epoxide carbonation. • Epoxide groups in vegetable oils were successfully carbonated. • Hydrogen bond donors were important in the catalysis. • Kinetic analysis was done for the best catalyst. • A carbonation reaction mechanism was proposed. Cyclic carbonates are important platform molecules with relevant industrial applications such as polymers precursors, fuel additives and solvents. They can be obtained from epoxidized vegetable oils via a carbonation reaction with carbon dioxide. This process is typically performed using homogenous catalyst or co-catalyzed systems, requiring of a homogenous specie. At the present moment very little have been reported regarding fully heterogeneous catalysts applied to the carbonation of epoxidized vegetable oils. In this study, the carbonation of epoxidized methyl oleate was investigated with various heterogeneous catalysts. Diverse nucleophilic organic salts were supported on silica gel and SBA-15 and screened as single component heterogeneous catalysts for the carbonation of epoxidized methyl oleate as a model compound of vegetable oils. The effect of some textural features of the catalytic materials such as the average pore size and surface area were investigated. An improved catalytic performance was observed as the catalytic species were supported on a mesoporous material. The addition of weak Lewis acidity to the support was found to play an important role in the opening of the oxirane ring and its further conversion to a cyclic carbonate, by providing a source of hydrogen bond donor (HBD) to activate the oxirane ring. The methyl esters of oleic acid, tall oil and cottonseed oil were investigated as substrates. A plausible reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

Complete hydrogenation of d-galactose and l-arabinose mixtures on a Ru/C catalyst was achieved with excellent selectivities exceeding 95 %. No unexpected effects of temperature and pressure were observed. A detailed kinetic model was derived to describe the simultaneous hydrogenation of the monomeric sugars. [ABSTRACT FROM AUTHOR]

• Heterogeneous catalysts for ethene and diethyl ether formation from ethanol were screened. • The role of active sites in the product distribution was revealed. • Very precise kinetic data were produced in a microreactor device. • It was demonstrated that microreactors are strong tools in the study of gas-phase kinetics and catalyst stability. Dehydration and etherification of bio-ethanol was studied in a microreactor using γ-alumina, H-Beta-38 and Sn-Beta-38 as catalysts. An extensive series of kinetic experiments was carried out in the microreactor device operating at ambient pressure and temperatures 225–325 °C. The H-Beta-38 catalyst coated microplates exhibited the highest production rate of ethene. While the fresh H-Beta-38 catalyst allowed complete conversion of ethanol and 98% selectivity towards ethene, the catalyst deactivated significantly with time-on-stream. Diethyl ether was the dominating co-product, whereas trace amounts of acetaldehyde were detected in the experiments. Based on the kinetic studies, thermodynamic analysis and catalyst characterization results obtained with SEM-EDX, TEM, nitrogen physisorption, FTIR-Pyridine and white light confocal microscopy, a surface reaction mechanism was proposed. The fundamental hypothesis of the reaction mechanism was the co-existence of two kinds of active sites on the catalyst surface, namely the Brønsted sites promoting dehydration and the Lewis sites responsible for etherification. The Brønsted sites deactivate, whereas the Lewis sites are more stable, which leads to a shift of the product distribution during long-term experiments, from ethene to diethyl ether. The rate equations were implemented in the microreactor model. The kinetic and adsorption parameters included in the model were estimated by non-linear regression analysis. The experimental data were satisfactorily described by the proposed mechanism. The work demonstrated that microreactors are strong tools in the determination of catalytic kinetics and catalyst durability. [ABSTRACT FROM AUTHOR]

The degradation of the pharmaceutical compound diclofenac in an aqueous solution was studied with an advanced oxidation method, catalytic ozonation. Diclofenac was destroyed in a few minutes by ozonation but several long-lasting degradation by-products were formed. For this reason, the combination of heterogeneous catalysts and ozonation was applied to eliminate them completely. The kinetics of the diclofenac degradation and the formation of by-products were thoroughly investigated. Loading of Pt on the catalysts resulted in an improvement of the activity. The Mesoporous Molecular Sieves (MCM) were one of the promising catalysts for the degradation of organic pollutants. In this study, six heterogeneous catalysts were screened, primarily MCM-22-100 catalysts with different Pt concentrations loaded via the evaporation-impregnation (EIM) method, and they were applied on the degradation of diclofenac. It was found that the presence of Pt improved the degradation of diclofenac and gave lower concentrations of by-products. The 2 wt % Pt-H-MCM-22-100-EIM demonstrated the highest degradation rate compared to the proton form, 1% or 5 wt % Pt concentration, i.e., an optimum was found in between. Pt-H-Y-12-IE and Pt-γ-Al2O3 (UOP)-IMP catalysts were applied and compared with the MCM-22 structure. Upon use of both of these catalysts, an improvement in the degradation of diclofenac and by-products was observed, and the 2 wt % Pt-H-MCM-22-100-EIM illustrated the maximum activity. All important characterization methods were applied to understand the behavior of the catalysts (X-ray powder diffraction, transmission electron microscopy, nitrogen physisorption, scanning electron microscopy, energy dispersive X-ray micro-analyses, pyridine adsorption-desorption with FTIR spectroscopy, X-ray photoelectron spectroscopy). Finally, leaching of Pt and Al were analyzed by inductively coupled optical emission spectrometry. [ABSTRACT FROM AUTHOR]

Carbamazepine (CBZ), a widely used pharmaceutical compound, is one of the most detected drugs in surface waters. The purpose of this work was to identify an active and durable catalyst, which, in combination with an ozonation process, could be used to remove CBZ and its degradation products. It was found that the CBZ was completely transformed after ozonation within the first minutes of the treatment. However, the resulting degradation products, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD), were more resistant during the ozonation process. The formation and degradation of these products were studied in more detail and a thorough catalytic screening was conducted to reveal the reaction kinetics of both the CBZ and its degradation products. The work was performed by non-catalytic ozonation and with six different heterogeneous catalysts (Pt-MCM-41-IS, Ru-MCM-41-IS, Pd-H-Y-12-EIM, Pt-H-Y-12-EIM, Pd-H-Beta-300-EIM and Cu-MCM-41-A-EIM) operating at two temperatures 20 °C and 50 °C. The influence of temperature on degradation kinetics of CBZ, BQM and BQD was studied. The results exhibited a notable difference in the catalytic behavior by varying temperature. The higher reactor temperature (50 °C) showed a higher activity of the catalysts but a lower concentration of dissolved ozone. Most of the catalysts exhibited higher removal rate for BQM and BQD compared to non-catalytic experiments in both temperatures. The Pd-H-Y-12-EIM catalyst illustrated a higher degradation rate of by-products at 50 °C compared to other catalysts. [ABSTRACT FROM AUTHOR]

• Ethene, propene and 1-butene mixtures were selectively epoxidized with H 2 O 2 on TS-1 as heterogeneous catalyst. • The epoxidation of different olefins took place simultaneously. • Extensive transient and stationary experiments were conducted in a trickle bed reactor (TBR). • A trickle bed model was employed to describe the experimental data. Direct epoxidation of light olefin mixtures with hydrogen peroxide and titanium silicalite (TS-1) catalyst is interesting from a pure scientific viewpoint and it might have a considerable economic and environmental advantages. Direct epoxidation of olefin mixtures implies a significant process intensification as the separation steps of alkenes prior to the epoxidation process is avoided. Binary and ternary mixtures of ethene, propene and 1-butene were selectively epoxidized with hydrogen peroxide in the presence of TS-1 as the heterogeneous catalyst. Methanol was used as the solvent. Transient and stationary kinetic experiments were conducted in a laboratory-scale trickle bed reactor, which was operated under atmospheric pressure and isothermal conditions at 15–55 °C. The experiments were designed to investigate the kinetics of the epoxidation of light olefins at different temperatures, alkene-to-hydrogen peroxide molar ratios as well as gas and liquid residence times in the trickle bed reactor. The recorded transient responses of the reaction products confirmed that the components in the alkene mixtures are epoxidized simultaneously. The epoxide selectivity was 90 % or higher in most experiments; ring-opening products formed from the epoxides and methanol were observed as by-products. The concentration maxima of epoxides during the transient experiments were explained by accumulation of the epoxide products inside the catalyst, which resulted in partial blocking of active sites. After-treatment of the catalyst with methanol and nitrogen completely restored the initial activity. Kinetic modeling was applied, based on presumed elementary steps on the TS-1 surface to describe the behavior of the system at steady state conditions. The trickle bed reactor was described with a dynamic multiphase model, taking into account the kinetic and mass transfer effects. The numerical values of the activation energies, kinetic constants and mass transfer parameters were estimated by nonlinear regression analysis. The model gave a satisfactory description of the experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amberlyst-15 promotes DPE synthesis. • DPE density and viscosity were measured. • Intraparticle kinetic model was developed to describe all the experimental data. • Surface reaction kinetic laws were individuated to best fit the data. • The influence of internal diffusion was demonstrated to be influent. In the present work, a catalytic screening using the most common heterogeneous acid catalysts was conducted, using as a raw material ethyl levulinate. Extensive catalyst screening revealed that Amberlyst-15 can be considered a very suitable catalyst to promote the DPE synthesis from ethyl levulinate and phenol. The use of ethyl levulinate allowed to obtain 100% selectivity towards p,p -DPE isomer, a precursor for the NIPU synthesis. A kinetic investigation was conducted to determine the influence of different parameters on the reaction rate. Finally, a mathematical model with intraparticle diffusion limitations was employed to describe the experimental data and to retrieve the kinetic as well as adsorption parameters via non-linear regression analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prins cyclisation from isovaleraldehyde and isoprenol to tetrahydropyranol. • Zeolites with varying acidity and hierarchical materials as catalysts. • H-Beta-300 zeolite giving 72% selectivity to the desired product at 99% conversion. • The cis/trans ratio of tetrahydropyranols depends on porous structure. • Parallel formation of tetrahydropyranol and dihydropyran confirmed by DFT. In this work, several heterogeneous micro- and mesoporous, acidic catalysts were tested for the selective synthesis of Florol®, an industrial product formed via condensation and rehydration starting from isoprenol and isovaleraldehyde in dimethylcarbonate as a solvent. The results showed that a mildly acidic, microporous H-Beta-300 with SiO 2 /Al 2 O 3 ratio of 300 was the best catalyst, giving 72% selectivity with 99% conversion at 40 °C when using the molar ratio isoprenol to isovaleraldehyde of 1:5. More acidic zeolites gave slightly lower selectivity, while the lowest selectivity (up to 52%) was obtained with mesoporous catalysts exhibiting mild acidity and no strong Brønsted acid sites. Selectivity to pyranols was nearly constant when changing temperature, while a larger excess of isovaleraldehyde promoted formation of tetrahydropyranol. H-Beta-300 catalyst was successfully after calcination at 400 °C. DFT calculations pointed out on the parallel formation of tetrahydro pyranols and dihydropyrans, which are the corresponding dehydration products. [ABSTRACT FROM AUTHOR]

• A homogeneous catalyst was grafted on solid matrix. • The grafted catalyst was used to carbonize an epoxide. • Detailed kinetic and mass transfer models were derived for semibatch reactor. • The model predicted well the results and can be used for scale-up. Fatty acid epoxides are obtained by epoxidation of fatty acids and esters with hydrogen peroxide. Carbonation of fatty acid epoxides with CO 2 is an important topic in the development of environmentally friendly technologies for the production of chemical intermediates, polymers and fuel components. Very precise kinetic and mass transfer studies on the carbonation of a tall-oil model component, epoxidized methyl oleate were carried out in an autoclave operating at 20–60 bar CO 2 and 100–160 °C. SBA-15(0.12)-4PPI was used as the grafted heterogeneous catalyst. The reaction times were 0–23 h and the stirring rates were varied between 200 and 1000 rpm to study the gas–liquid mass transfer of CO 2. The main reaction product was the carbonate, while some amounts of ketone were formed as a side product via the Meinwald rearrangement. Five rival reaction mechanisms were considered, based on the concept of interaction between the Lewis and nucleophilic sites on the catalyst surface. A multiphase reactor model including the interaction of intrinsic kinetics and gas–liquid mass transfer effects was developed to determine the parameters from the experimental data. The model reproduced the experimental data very well, giving a perspective for process scale-up. [ABSTRACT FROM AUTHOR]

• Transformations of glucose to 1,2-propylene glycol. • Mechanical mixture of ZnO and Ru/C as catalysts in the presence of hydrogen. • The optimal temperature for glucose transformation to propylene glycol is 165 °C. • Thermodynamic analysis of possible reactions. • Kinetic modelling of a complex reaction network gave a reliable description of data. Transformations of glucose to 1,2-propylene glycol were studied over a mechanical mixture of ZnO and Ru/C catalysts in the presence of hydrogen. Different reaction conditions were evaluated by changing the reaction temperature and hydrogen pressure. In addition to the cascade mode of operation, also separate steps in the overall reaction network, such as hydrogenation of pyruvaldehyde and hydroxyacetone to 1,2-propylene glycol were investigated. Fructose as a starting material was also studied resulting in a propylene glycol yield of 37.5%. The optimal temperature for glucose transformation to propylene glycol was found to be 165 °C. The influence of temperature on the catalytic behavior was more prominent than the effect of hydrogen pressure. Thermodynamic analysis of glucose transformation to 1,2-propylene glycol was performed and a plausible kinetic model reflecting a complex reaction network was developed being able to describe the data in a reliable way. [ABSTRACT FROM AUTHOR]

Stearoyl ethanolamine was synthesized by amidation of stearic acid with ethanolamine in solventless conditions. Iron containing heterogeneous catalysts supported on SiO 2 , Al 2 O 3 , Beta (BEA), ZSM-12 (MTW) and Ferrierite (FER) were used in this work. Sn-modified Ferrierite and H-Ferrierite were also studied for comparison. Fe-modified catalysts synthesized using solid state ion-exchange and evaporation impregnation methods, were thoroughly characterized with X-ray powder diffraction, scanning electron microscope, FTIR with pyridine, nitrogen adsorption, energy dispersive X-ray microanalysis and Mössbauer spectroscopy. The highest conversion was obtained with Fe-H-FER-20 at 140 °C in 1 h giving 61% conversion and 98% selectivity towards the desired amide. The catalytic performance in terms of turnover frequency per mole of iron was achieved with the catalyst exhibiting the largest amount of Fe 3+ species, optimum acidity and a relatively low Brønsted to Lewis acid site ratio. [ABSTRACT FROM AUTHOR]

The direct amination of dodecanol with ammonia to dodecylamine was investigated over carbon supported ruthenium, palladium, platinum, iridium and osmium catalysts. The influence of ammonia and hydrogen pressures was investigated. It was found that ammonia pressure did not influence the reaction, while extra hydrogen in the reaction mixture was beneficial for dodecanol conversion and dodecylamine selectivity. A dodecylamine yield of 83.8% was achieved with Ru/C catalyst at 150 °C, 4 bar ammonia and 2 bar hydrogen after 24 h reaction. Zero reaction order in ammonia typically implies that the rate limiting step is not related to amination, but rather to a preceding dehydrogenation step. Experimentally observed unusual positive order in hydrogen in dehydrogenation was related to deactivation by surface coking. Partial surface regeneration requires presence of hydrogen, thus explaining a positive reaction order towards this reactant. A detailed analysis of kinetic regularities, which due to specificity of the reaction mechanism could be done separately for activity and selectivity, allowed advancing a mathematical model adequately describing experimental observations. [ABSTRACT FROM AUTHOR]

Benzodioxinols, compounds with 6-membered heterocycles containing two oxygen atoms, exhibit promising analgesic activity. In the current study, synthesis of dioxinol via two-step approach including Prins cyclization of isopulegol with benzaldehyde to tetrahydropyran and its ring-rearrangement to dioxinol was investigated. Different acidic and basic catalysts were studied in the second step and the highest selectivity toward dioxinol was achieved using mesoporous Ce-composite material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nonanoic acid esterification promoted by Amberlyst-15 and Amberlite IR120. • Amberlyst-15 is more active than Amberlite IR120. • Internal mass transfer limitation was always present. • Amberlite IR120 shows a more ideal fluid-dynamics than Amberlys-15. • The industrial feasibility was successful in PBR with Amberlite IR120. Nonanoic acid is considered a feedstock of growing interest due to the promising applicability of its derivatives. It can be obtained from vegetable oils, one of the products of oleic acid oxidation. Recently, a very interesting application of the ester obtained from nonanoic acid esterification with 2-ethylhexanol was found. In fact, it showed excellent properties as solvent for varnishes. The aim of this work was the kinetic investigation of the nonanoic acid esterification with 2-ethylhexanol in batch and continuous reactors, promoted by Amberlyst-15 and Amberlite IR120 resins, and to demonstrate the technical feasibility of the mentioned technology in flow systems. A mathematical model was developed to simulate the collected experimental data taking into account all the phenomena appearing in the system: intrinsic kinetics, mass transfer and flow pattern. Experiments were also conducted in the continuous packed bed reactor to compare the catalyst performances and validate the results obtained in the batch reactor. The best nonanoic acid conversion (85%) was obtained fixing T = 363 K, Q = 4.17·10−9 m3/s with an alcohol:acid molar ratio of 5:1 using Amberlyst-15 as heterogeneous catalyst. [ABSTRACT FROM AUTHOR]