Ternary Oxide Catalysts Research Articles

The Production of Methacrylic Acid by the Vapor-Phase Aldol Condensation over V–Si–P Ternary Oxide Catalyst

Abstract The vapor-phase aldol condensation of propionic acid with formaldehyde was performed over a V–Si–P ternary oxide catalyst of atomic ratio of 1:2:2.2. The one-pass yield of methacrylic acid was 55 mol% on the charged formaldehyde basis at the propionic acid/formaldehyde molar ratio of 2. The maximum yield of methacrylic acid remained unchanged with the variation in temperature and the dilution of reactants, but it increased with the propionic acid/formaldehyde ratio; the yield reached 82 mol% at the propionic acid/formaldehyde ratio of 6. The effects of reaction variables such as temperature, concentrations of propionic acid, formaldehyde, water vapor, methacrylic acid, and oxygen, and propionic acid/formaldehyde ratio were examined.

The Effects of the Reaction Variables on the Yields of Acrylic Acid and Methyl Acrylate in the Reaction of Acetic Acid with Methanol in the Presence of Oxygen

Abstract The effects of the reaction variables on the yields of the aldol condensation products, i.e., acrylic acid and methyl acrylate, in the reaction of acetic acid with methanol in the presence of gaseous oxygen was studied using a V–Ti–P ternary oxide catalyst with an atomic ratio of 1:2:6, respectively. The best catalyst performance was obtained with an oxygen/methanol molar ratio of between 0.5 to 0.75. The yield of acrylic acid decreased with increasing the methanol concentration, while that of methyl acrylate increased; the sum of the two yields increased with methanol concentration above 360°C. The feed rate did not have much effect on the yield, except at high conversions. Better catalytic performance was observed with longer contact times at lower temperatures than with shorter contact times at higher temperatures.

Dehydrogenation of ethylbenzene and ethylcyclohexane over mixed ternary oxide catalysts containing tio 2-zro 2

the ternary metal oxides, combining Ti0 2-Zr0 2 with the other first period transition metal oxides, were prepared by coprecipitation method. The The effects of the prereduction of the ternary oxides were studied. The acid-base dehydrogenation activities were decreased by prereduction. However, t

Acidic Property and Oxidation Activity of MoO3-V2O5-P2O5 Ternary Oxides

Abstract The relationship between the acid-base properties and the oxidation activity of a series of ternary oxide catalysts, MoO3–V2O5–P2O5, with different V/Mo composition and a constant phosphorus content, P/(Mo+V)=0.1, was investigated. The acidity was determined by means of the NH3 adsorption and by studying the catalytic activity for acid-catalyzed reactions, such as dehydration of isopropyl alcohol and isomerization of 1-butene, in the presence of an excess of air. A new acidic site is generated by the combination of two binary oxides, i.e., MoO3–P2O5 and V2O5–P2O5, and a broad maximum in the acidity occurs at V/(Mo+V)=0.4–0.9. The basic property is so small that no satisfactory data can be obtained from the adsorption of acidic molecules such as CO2, SO2, and acetic acid. The catalysts, regardless of composition, are inactive for reactions which are accelerated by basic sites, such as oxidative dehydrogenation of isopropyl alcohol to acetone, oxidative decomposition of formic acid to CO2, and oxidation of methanol to CO2. The oxidation activities for butadiene and methanol can be tied to the acidity of the catalysts.

The Synthesis of Acetic Acid by Catalytic Oxidation of Butene

Catalytic oxidation of 1-butene l for a., 6etic acid was studied over vanadium oxide catalysts supported on silica in the presence of steam at temperature range of 200N300C.Binary and ternary oxide catalyst systems containing SnO2, WO3 and TiOdii as the second or the thild componenntt exhibited selective formation of acetic acid, w, hile both activisy and selectivity wer6 poor in the absence of these promoters. The selectivity to qcetic acid -was dependent mainly on the reaction temperature and the catalyst compositig. n, but ip. depepde. pt of the Conversiori of butene. Over the catalyst of V-Sn-W (1: 1: 0.5) oxide on silica, acetic acid was produced with se1 vity, of 50-55% and 45-50%at 225. C and 250, respectively,

The application of differential thermal analysis technique to the study of single, binary and ternary oxide catalyst systems

The authors have reviewed the salient features of the thermal behavior of the following systems: Excellent correlations have been obtained in most of the systems between the thermal characteristics of the solids, as revealed by DTA, and their specific surface areas and catalytic activity.