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The conversion of syngas into higher alcohols was examined using bimetallic Rh-Co, Rh-Cu, and multimetallic RhCuPd catalysts, all of which were supported on ZrO 2. This process was also studied using a MnOx-promoted Rh/SiO 2 catalyst. These experiments were conducted within a temperature range of 225–300 °C, under a pressure of 30 bar, and with a H 2 /CO ratio of 2. The catalysts were characterized using a variety of physicochemical methods, including Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Carbon Monoxide Diffuse Reflectance Infrared Fourier Transform Spectroscopy (CO DRIFTS). The Rh particle sizes in the fresh catalysts were found to be less than 3 nm. The Rh-Co catalyst supported on ZrO 2 exhibited the highest selectivity to ethanol, achieving 38 % at a CO conversion rate of 58 % at 275 °C. This catalyst also demonstrated a chain growth probability of 0.35 for alcohols. A slightly higher chain growth probability was observed with the Rh-MnOx/SiO 2 catalyst, although this also resulted in the formation of substantial amounts of acetic acid. Interestingly, this acetic acid could be converted into ketones when RhMnOx was used in conjunction with Pd/ZrO 2. [Display omitted] • Bimetallic zirconia supported Rh-Co, Rh-Cu, and multimetallic RhCuPd catalysts for conversion of syngas into higher alcohols • Extensive catalyst characterization. • 38 % selectivity to ethanol at 58 % CO conversion at 275 °C on Rh-Co/ZrO 2. • Rh-MnOx/SiO 2 catalyst resulted in substantial amounts of acetic acid. • Acetic acid could be converted into ketones when RhMnOx is combined with Pd/ZrO 2. [ABSTRACT FROM AUTHOR]

Zinc-modified alumina catalysts for methyl chloride synthesis were prepared with varying zinc loadings: from 2.4 to 21.1 wt%. The influence of the zinc loading, zinc precursor and the pH of the impregnation on the physico-chemical properties of the catalyst, and on the catalyst activity and selectivity for methyl chloride (MeCl) synthesis was investigated. The prepared catalysts were thoroughly characterized by FTIR, TEM, physisorption and EDX. On the alumina surface, both molecular and bulk zinc species are created upon zinc loading. The surface area of the catalyst decreases steadily with zinc loading. Bulk zinc species dominate on the catalyst starting at a zinc loading of 9.4 wt% and the amount of Lewis acid sites (LAS) decreases. A shift in the acid site type takes place upon zinc modification. Sites assigned to stronger LAS are eliminated while zinc-based weaker acid sites started to predominate. The shift in acidity increases the selectivity and activity of methyl chloride synthesis, which was demonstrated in a series of experiments in a laboratory-scale fixed bed reactor. [ABSTRACT FROM AUTHOR]

Highlights: [•] Activity, selectivity and stability have been tested for all catalysts. [•] Influence of zinc modification on surface area and pore volume was investigated. [•] Activity and selectivity have been correlated with the catalysts acid properties. [•] Zinc species on the catalyst surface have been characterized by EDX, TEM and XPS. [•] Spent catalysts were characterized by N2-physisorption, FTIR, EDX and XRD. [ABSTRACT FROM AUTHOR]

Abstract: A kinetic investigation of dimethyl carbonate (DMC) synthesis from methanol and CO2 over ZrO2–MgO was performed by using butylene oxide as a chemical trap for the water formed during the reaction. The effect of the catalyst amount, the stirring speed, the temperature, as well as the amount of butylene oxide on the reaction rate and the selectivity to DMC was studied. The analysis of the reaction pathway suggests that DMC and butylene glycol are formed via the reaction of adsorbed mono-methoxycarbonate intermediate and methoxybutanol or methanol. A kinetic model was developed based on the reaction mechanism and it was in agreement with the experimental data. The apparent activation energy for the formation of DMC was 62kJ/mol. [Copyright &y& Elsevier]

Abstract: The kinetics in the one-pot synthesis of R-1-phenyl ethylacetate starting from acetophenone have been systematically investigated by using different amounts of hydrogenation catalyst and an immobilized enzyme simultaneously. The kinetic results revealed that there is interference between their catalytic performance indicating that these catalysts were not acting independently but in concert. The reaction mechanism was very complex, since besides the consecutive reactions, hydrogen-acylation, also dehydration of an intermediate product, (R,S)-1-phenylethanol occurred leading to styrene and its instantaneous hydrogenation to ethyl benzene. This work presents the kinetic regularities, quantitative understanding of which remains a challenge. [Copyright &y& Elsevier]

Abstract: Possibility of the cyclic voltammetry (CV) in characterization of supported VIII group metal catalysts was studied. The emphasis was laid on Pd catalysts. A standard procedure for CV measurements was proposed and validated. Reasons causing cumbersome behavior of copper underpotential deposition (UPD) were revealed. The relative surface areas of metal catalysts on conductive and non-conductive supports were measured. [Copyright &y& Elsevier]

Abstract: A kinetic study of the reduction of NO by n-octane performed isothermally (200°C) at steady state conditions over an active Ag/alumina catalyst was carried out in the presence of hydrogen. The mathematical model was based on a supposed reaction mechanism, which among other steps includes molecular adsorption of NO and CO as well as dissociative adsorption of H2 and O2. Formation of CO2 is assumed to go through oxidation of CO. A comparison between experimental data and simulations revealed that the developed mathematical model is able to describe the observed reduction of NO in presence of H2 sufficiently well. [Copyright &y& Elsevier]

Abstract: Hydrogen assisted n-octane-SCR under lean conditions over a 1.91wt.% Ag/alumina catalyst was studied. The kinetic behaviour of the catalytic reaction at 200°C at steady state conditions was examined in the concentration range: , 0.5 and 1vol.%, P NO =375, 500 and 1000ppm, P octane =187.5, 375 and 500ppm and , 3 and 6vol.%. The results showed that all the rates increased along the increasing H2 concentration with the reaction order equal to 0.4 in NO and 1.4 in octane at 0.5vol.% hydrogen concentration. Moreover it was observed that the effect of hydrogen was more predominant on the NO to N2 reduction than varying reactant (NO, C8H18) concentration. The main mechanistic effect of hydrogen in significantly improving the low temperature performance of silver/alumina catalysts in HC-SCR cannot only be attributed to the reduction of surface nitrates with hydrogen suggesting its involvement in the catalytic cycle of NO reduction. [Copyright &y& Elsevier]

Abstract: The kinetics and mechanism of the reduction of NO and N2O by H2 over Ag/Al2O3 were studied with transient step response and isotope exchange techniques. Dissociation of hydrogen and deuterium was observed on the Ag/alumina catalyst. The reduction of NO with hydrogen gave N2 as the main product and N2O, NH3 and H2O as by-products, while the catalyst showed low activity for the self-decomposition of NO and N2O. To clarify the reaction mechanism for the reduction of NO with hydrogen parameter estimation and modeling was carried out. [Copyright &y& Elsevier]

An alumina supported silver catalyst was studied with a transient step-response technique for the reduction of NO and N2O with H2. Dissociation of hydrogen and deuterium was observed on the Ag/alumina catalyst and a kinetic model was proposed for the isotopic exchange between H2 and D2. The proposed model describes the observed dissociation and isotope exchange reaction sufficiently well. [Copyright &y& Elsevier]

Selective double bond isomerization of linoleic acid to cis-9,trans-11-conjugated linoleic acid and trans-10,cis-12-conjugated linoleic acid (CLA) was performed batchwise under kinetic control at 165 °C in an n-decane solution. Commercial H2-preactivated Ru/Al2O3 catalyst (6.19 wt.% Ru) and two H2-preactivated Ru/Al2O3 catalyst samples that were prepared by incipient wetness impregnation of γ-Al2O3 with two different precursors of ruthenium, i.e. ruthenium(III) chloride trihydrate (RuCl3·3H2O, 3.27 wt.% Ru) and ruthenium(III) acetylacetonate (Ru(acac)3, 2.97 wt.% Ru), were investigated to study the effect on catalytic activity and isomerization selectivity of residues remaining on the catalyst surface from the impregnation step. Catalyst characterization was done by nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy–energy dispersive X-ray analysis (SEM–EDX), and temperature programmed desorption of hydrogen techniques. Impregnation of γ-Al2O3 with ruthenium(III) acetylacetonate resulted in a remarkably higher selectivity towards the desired cis-9,trans-11- and trans-10,cis-12-conjugated linoleic acid isomers compared to that shown by impregnation of γ-Al2O3 with ruthenium(III) chloride trihydrate. [Copyright &y& Elsevier]