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• A model for NH 3 -SCR based on kinetics and computational fluid dynamics (CFD). • Model validation with SCR by monolithic Cu-ZSM-5. • Inhibition of effect of hydrocarbons in engine emission tests. A simple kinetic model for the standard NH 3 -SCR reaction by Cu-ZSM-5 catalysts has been developed by assuming three reaction steps: NH 3 adsorption (desorption), reactions of adsorbed NH 3 with O 2 (NH 3 oxidation) and NO (NH 3 -SCR). The model is based on Arrhenius parameters for NH 3 -SCR and NH 3 oxidation by a powder catalyst, combined with models for heat and mass transport and parameters of monolithic catalysts. The model is validated with the experimental results, not included in the estimation of the model, for NH 3 -SCR by monolithic catalysts with different parameters (catalyst loading and cell density). NOx removal from diesel exhaust, generated by engine bench, was also carried out by using monolithic Cu-ZSM-5 and Cu-AFX catalysts. The results suggest the poisoning effect of hydrocarbons in the exhaust emissions on NOx conversion is more significant for Cu-ZSM-5 than Cu-AFX. [ABSTRACT FROM AUTHOR]

The kinetic modeling of NH 3 -SCR with a Cu-ion-exchanged chabazite (Cu-CHA) catalyst in steady-state reactions was investigated by a combination of flow reactor experiments and kinetic modeling with an in-house computational code. Here H-CHA and Cu-CHA monolith cylindrical catalyst specimens were used to identify the reactions at both Brønsted (H+) acid sites and Cu sites. Based on the proposals in the literature for NH 3 -SCR mechanism, a scheme for SCR and side reactions incorporating 17 reactions is proposed, and some of the reactions were verified by the experimental results here for the adsorption/desorption of NH 3 , unsteady-state reactions of the adsorbed NH 3 with NO 2 over the Cu-CHA and H-CHA, and NH 3 oxidation over Cu-CHA. The Arrhenius parameters for Standard, Fast, and Slow SCR reactions, NH 3 oxidation, NO oxidation to NO 2 , NO 2 decomposition to NO, and NH 3 desorption were obtained by kinetic experiments. This report develops a quantitative simulation model for SCR and side reactions, and the model was validated by experimental data for adsorption/desorption of NH 3 and NO 2 , steady-state SCR reactions (Standard, Fast, and Slow SCR), and side reactions (NH 3 and NO oxidation). The simulation model developed in this study can predict the steady-state SCR data and adsorption/desorption of NH 3 and NO 2 under unsteady-state. [Display omitted] • Investigations of reactions over Brønsted and Lewis acid sites by Cu-CHA and H-CHA catalysts. • The identified 17 kinds of important reactions were suggested through experiments. • Ammonia nitrate (NH 4 NO 3) production in Fast and Slow SCR reactions. • The developments of a kinetic SCR model considering energy transport, mass transport, diffusion, and chemical reactions. [ABSTRACT FROM AUTHOR]

Abstract: The mass-transfer processes in fiberglass were studied in the course of drying the saturated glass fabric sample. Experiments were carried out using an Avance DRX Bruker spectrometer equipped with a micro tomography device. Experimental signal intensities of fluids flowing at different velocities were obtained. A one-dimensional mathematical model was applied to calculate mass-transfer coefficients from experimental data. Dependencies Nu(Re) at the Reynolds number varied between 0 and 400 were obtained at different fluid velocities. The data obtained were compared to correlation dependencies for woven Pt/Pd gauzes and for rows of parallel cylinders. Numeric experiments of gas flow filtration at low Reynolds numbers (Re <1) were carried out using the CFD FLUENT software package. Fibrous material was represented as porous system consisting of bunches of parallel cylinders with varied distances between the cylinders. Dependence Nu(Re) was calculated at various parameters of system. [Copyright &y& Elsevier]

Proton exchange membrane fuel cells (PEMFC) are considered as electrochemical reactors, performances of which are regarded in the context of the various effects influencing FC output, such as mass transports, kinetic of electrode reactions and charge transfer in polymer electrolyte membrane (PEM). An experimental approach, involving the employment of impedance spectroscopy (IS), which allows a deep insight into the nature of these effects, is discussed and its applications to the different aspects of PEMFC functioning are reported. As examples of the use of IS in PEMFC studies, the investigations of the membrane conductivity and in situ studies of the anode and the cathode processes during FC operation are presented. [Copyright &y& Elsevier]

Polymerization of THF catalyzed by solid acid in the presence of acetic anhydride was studied. A moderate Lewis acid catalyst produces required PTME (PTMG-acetate) having adequate Mn. Zeolitic material is not suitable for this production because very high molecular weight PTME is co-produced. From this aspect, mixed oxide materials show good performance because only these have the required acidic character. Mass-transfer study suggests the importance of pore size of support and the homogeneity of active sites. They affect on the Mn and the Mw/Mn strikingly. The commercial technology has established by utilizing these results. [Copyright &y& Elsevier]