Ferhan Sami Atalay

Catalytic combustion of methylenechloride

The catalytic combustion of methylenechloride, one of the chloromethanes, was investigated on metal oxide catalysts coated on the monolith support or on the spherical alumina pellets, The prepared catalysts were tested at the different temperatures between 200 and 500°C and at varying GHSV values with an excess air of 216% The catalyst having the composition of 15% Cr2O3, 5% Ce2O3 and 80%γ-Al2O3 on the monolith was found to be ultimate due to the complete destruction of methylenechloride and to the highest mechanical stability. The operating conditions were proposed as 77778 h−1 for the GHSV, 216% for the excess air and 400–500°C for the temperature range to combust methylenechloride completely The dependency of the reaction on methylenechloride and oxygen partial pressures was searched, and it was determined that the rate was strongly dependent on oxygen partial pressure and weakly methylenechloride partial pressure. The reaction rate expression was derived using the mechanism proposed by Downie and the ...

Mathematical models for methane production in batch fermenters

Abstract This study reports an experimental and mathematical investigation of methane production from farm wastes in an anaerobic batch fermenter. Different growth models for the microorganisms are correlated and the relationship between methane production and substrate consumption rates are studied. Contois equation was determined to be the best fit model equation relating the specific growth rate to biodegradable volatile solids for substrate concentrations of 52, 73 and 91 gVS litre−1. Operating temperature, substrate concentration and volumetric retention time in the fermenter are determined to be the most important parameters for these processes.

Catalytic combustion of carbon tetrachloride.

The catalytic combustion of carbon tetrachloride (CCl4) by metal oxide catalysts coated on the monolith support was investigated. The prepared catalysts were tested at temperatures between 300 and 800 degrees C and at varying gas hourly space velocity (GHSV) values with an excess air ratio of 3100%. The catalyst, whose composition was 18% Cr2O3, 2% Ce2O3 and 80% gamma-Al2O3, was found to almost completely oxidize CCl4. The operating conditions proposed are 5702 h(-1) for GHSV, 3100% excess air and a temperature slightly higher than 800 degrees C. The reaction rate expression was found to be independent of oxygen partial pressure but strongly dependent on CCl4 partial pressure.

Esterification of acetic acid with methanol over a cation exchange resin

The esterification kinetics of acetic acid with methanol in the presence of ResinTech SACMP-H ion exchange resin as a heterogeneous catalyst were studied at temperatures of 303, 313 and 323 K. The effects of various parameters such as temperature, catalyst loading, stirrer speed and also the effect of the mole ratio of reactants, and the reaction mechanism, have been investigated in detail. The uncatalysed reaction was shown to be second-order reversible process. For heterogeneously catalysed reaction, three different kinetic models were applied to the experimental data, the best fit being the Eley-Rideal mechanism. It was found that ResinTech SACMP-H catalyst acts by reducing the activation energy from 58 to 48.2 kJ mol−1.

Kinetic Study of the Esterification of Acetic Acid with 1-Butanol Catalysed by Alumina-Supported Tungstophosphoric Acid

The kinetics of the esterification of acetic acid with 1-butanol in the presence of alumina-supported tungstophosphoric acid (TPA) was studied. The uncatalysed reaction was shown to proceed by a second-order mechanism. In the presence of the catalyst, the reaction was found to occur between an adsorbed alcohol molecule and a molecule of acid in the bulk fluid (Eley–Rideal mechanism). It was found that alumina-supported TPA is suitable for this reaction because the activation energy was reduced from 58.0 to 37.3 kJ mol−1. The catalyst was characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscope, nitrogen adsorption study and IR spectroscopy.

Determination of Adsorption and Kinetic Parameters for Butanol–Acetic Acid Esterification System Catalysed by Amberlyst 15

The esterification of acetic acid with butanol catalysed by Amberlyst 15 was studied over a range of catalyst loadings, temperature, molar ratio of reactants, stirrer speed and particle size of catalyst. The equilibrium constant was experimentally determined and the reaction was found to be exothermic. Swelling and adsorption studies were performed to estimate the adsorption constants. The values found for the adsorption constants follow the order: water > butanol > acetic acid > butyl acetate. Experimental kinetic data for the esterification were correlated with the Pseudohomogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Haugen-Watson (LHHW) models. The activity coefficients were calculated according to the UNIQUAC method. A possible mechanism of this reaction involved following the Eley-Rideal mechanism in which an adsorbed and protonated butanol molecule reacts with an acetic acid molecule in the bulk. The activation energy of the forward reaction was found to be 45.4kJ mol−1.

Catalytic Oxidation of Methanol to Formaldehyde

Methanol is a clean burning fuel, containing no sulphur or nitrogenous materials. It produces power with very low emissions compared to those of a natural gas-fired, combined-cycle unit. Methanol can also be used as a feedstock for more sophisticated processes in the petrochemical industry. In this study, catalytic oxidation of methanol to formaldehyde was investigated. For this purpose, laboratory type, fixed bed catalytic reactor was used. For this gas-phase reaction iron-molybdate catalysts supported by silica or alumina were used. On silica and alumina supports, different Mo/Fe ratios were investigated for three different residence times (W/FA0) and six different temperatures were tried. The analysis of liquid product was performed by using gas chromatograph. From the results of GC analysis and CO2 analyzer, conversion of methanol to formaldehyde, total conversion and selectivity to formaldehyde were obtained. After the determination of optimum operating conditions for this reaction, kinetic study was performed.

Catalyst Preparation and Testing for Catalytic Combustion of Chloromethanes

The catalytic combustion of methylenechloride, carbontetrachloride, and chloroform, three of the chloromethanes, was investigated on metal oxide catalysts prepared on the monolith support or on the spherical alumina pellets. The prepared catalysts were tested for methylenechloride and carbontetrachloride at the different temperatures and at varying GHSV values with an excess air ratios of 216% and 3100%, respectively. The catalyst having the composition of 15% Cr2O3, 5% Ce2O3 and 80% y-Al2O3 on the monolith was found to be ultimate due to the complete destruction of methylenechloride and to the highest mechanical stability. The operating conditions were proposed as 77778 h-1 for the GHSV, 216% for the excess air and 400–500 °C for the temperature range to combust methylenechloride completely. However the catalyst with a different active part composition (18% Cr2O3, 2% Ce2O3) satisfied nearly complete destruction of carbontetrachloride. The operating conditions were 5702 h-1 for the GHSV, 3100% for the excess air ratio and 800 °C for the temperature to combust carbontetrachloride. The catalytic oxidation of chloroform was investigated by the catalyst having the composition of 18% Cr2O3, 2% of Ce2O3 on monolith. The excess air was kept at a value of 4077%. The reactor temperature was changed between 200 and 300 °C.

Effect of temperature and catalyst type on the catalytic combustion of formaldehyde

In this study, the catalytic combustion of a volatile organic compound (VOC) namely formaldehyde on manganese oxide catalysts supported on silica or alumina, and on an industrial catalyst, i.e. a mixture of copper oxide and zinc oxide, was studied in the temperature range 125 – 225 °C. Formaldehyde was used as the aqueous solution. It was found that as the temperature was increased, the combustion of the produced and feed formaldehyde was enhanced whereas methanol combustion decreased. Also, the degree of conversion increased with the percentage of MnO in the catalysts.

An investigation of the production and lubricity characteristics of fatty acid esters.

The effects of operating parameters for the esterification of free fatty acids with butanol in the presence of sulfuric acid were studied. Experiments were carried out at catalyst loadings of 0.5, 1, and 7 wt% relative to reaction mixture, butanol/free fatty acids mole ratios of 1, 2, and 6 and the temperatures of 358, 368, and 378 K. Increase in reaction temperature, acid to alcohol ratio, and catalyst loading is found to enhance the conversion of free fatty acid. In this study, the prediction of esterification reaction mechanism is conducted by a complex acid model. The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. The energy of activation for the forward reaction was found to be 67.9 kJ/mol. Vegetable-based esters are potential biodegradable base stocks for environmentally friendly lubricants. The basic lubrication parameters, such as acid value, viscosity, viscosity index, color, copper strip corrosion, foaming, and demulsifying properties, were tested and compared well with commercial standards.