Stanka Zrnčević

Catalytic reduction of NOx over Cu/ZSM-5 catalyst

Catalytic decomposition of NO on Cu/ZSM-5 catalyst was carried out in tubular fixed-bed reactor at atmospheric pressure. The influence of temperature and flow rate on the reaction rate was investigated. The kinetic model of reaction was proposed and compared with the literature results. The formation of NO2 during the catalytic decomposition of NO was also monitored. Therefore, additional experiments were performed aimed at examining the kinetics of NO oxidation under the same reaction conditions. Both kinetic models were used to develop the reactor model and to describe quantitatively the behavior of the overall reaction system. Satisfactory degree of correlation between experimental data and values predicted by reactor model has been achieved.

Phenol oxidation with hydrogen peroxide using Cu/ZSM5 and Cu/Y5 catalysts

Phenol oxidation with hydrogen peroxide using Cu/ZSM5 and Cu/Y5 catalysts In this work, catalytic activity and stability of Cu/Y5 and Cu/ZSM5 zeolites in phenol oxidation with hydrogen peroxide were examined. The catalyst samples were prepared by the ion exchange method of the protonic form of commercial zeolites. The catalysts were characterized by the powder X-ray diffraction (XRD), AAS, while the adsorption techniques were used to measure the specific surface area. The thermal programmed desorption of NH3 (NH3-TPD) was used for measuring the total number of acid sites formed on the surface of zeolites. Catalytic performance of the prepared samples was monitored in terms of phenol, hydrogen peroxide and total organic carbon (TOC) conversion, by-product distribution and a degree of copper leached into the aqueous solution. It was found that the activity of Cu/Y5 catalyst was generally higher than that of Cu/ZSM5 and that unlike Cu/ZSM5, Cu/Y5 catalyzed phenol oxidation more completely.

Reaction and Mass Transfer Effects in a catalytic monolith reactor

Zeolite-based monoliths (Cu/ZSM-5 on cordierite) are prepared and used to catalyze direct decomposition of nitrogen monoxide. Two-dimensional heterogeneous model is applied to describe the behavior of the monolith reactor, with the emphasis on the features introduced due to coupling of flow, mass transfer and chemical reaction. The proposed model has been verified by comparing computer simulation data with laboratory experimental data. It is shown that both inter- and intraphase diffusion limitations have to be considered when modeling complex reactor configuration, such as monolith reactors, especially when monolith with thicker catalytic layer are used at higher temperatures.

Kinetics of no decomposition over Cu/ZSM-5 catalyst

AbstractThe kinetics of catalytic decomposition of NO over Cu/ZSM-5 catalyst has been studied in an integral flow reactor at atmospheric pressure. Kinetic analysis is based on the assumption that the surface reaction represents the rate-determining step. On the basis of theoretical considerations of different interactions between reactants and catalyst, and experimental evidences, three different mechanistic kinetic models were chosen. Also a power-law model was tested. The best agreement has been achieved with the model

Catalytic hydrogenation in the process of 2-((1-benzylpiperidin-4-yl) methyl)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride synthesis I. Catalyst screening and finding the optimal reaction conditions

r_S = \frac{{k \cdot C_{NO} ^2 }}{{\left( {1 + \sqrt {K_D ^1 \cdot C_{O_2 } } } \right)^2 }}

Kinetics of Catalytic Wet Peroxide Oxidation of Phenolics in Olive Oil Mill Wastewaters over Copper Catalysts

The liquid phase hydrogenation of 2-((1-benzyl-1, 2, 3, 6-tetrahydropyridin-4-yl)methylene)-5, 6-dimethoxy-2, 3-dihydroinden-1-one hydrochloride (1) over a 5 % Pt/C industrial catalyst was studied experimentally in a batch slurry reactor using methanol as a solvent. The catalyst was characterized by the adsorption techniques for specific surface area and pore volume, and by XRD for crystallinity. To investigate the intrinsic kinetics of the reaction, the effect of temperature, catalyst loading, hydrogen partial pressure and (1) concentration on the initial rate of hydrogenation was studied. The analysis of initial rate data showed that the gas-liquid, liquid-solid, and intraparticle mass-transfer resistances were not significant. The reaction scheme of (1) hydrogenation was proposed for the kinetic modelling. Apparent rate constants for all hydrogenation steps were calculated using a first order kinetic approach resulting in good agreement between the experimentally obtained and predicted concentrations. From the temperature dependence of rate constants, the activation energies of various reaction steps were calculated. The averaged activation energy of these steps was found to be 31.1 kJ mol-1.

Catalytic Wet Peroxide Oxidation of Olive Oil Mill Wastewater over Zeolite Based Catalyst

1 Catalytic hydrogenation of 2-((1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)methylene)-5,6-dimethoxy-2,3-dihydroinden- 1-one hydrochloride () to 2-((1-benzylpiperidin-4-yl)methyl)-5,6-dimethoxy-2,3-dihydroinden- 1-one hydrochloride (2) was investigated in the batch-slurry reactor. The 5% Pt/C catalyst was chosen to search the optimal reaction conditions because of its higher catalytic activity compared to other catalysts used in the work. To investigate the catalyst activity, selectivity and stability, the effect of agitation speed, catalyst loading, solvent, temperature, hydrogen pressure and catalyst reuse were studied. The initial rate of hydrogenation increases with the increase of catalyst loading, with the temperature and solvent polarity, if alcohols were used as solvents. The hydrogenation rate decreases with higher hydrogen pressure and that was explained by competitive adsorption of both reactants. The results also indicate that 5% Pt/C is a promising catalyst for 1 hydrogenation because at relatively mild reaction conditions selectivity towards main product was high (98%) and catalyst maintains its activity during successive runs.