Analysis and Modeling of a Monolithic Reactor

Abstract

This work reports the results of experimental and theoretical investigations of NO decomposition in a catalytic monolith reactor. Monolithic catalysts are composed of a commercial cordierite substrate (Corning Inc.) and copper containing ZSM-5 zeolite (Si/Al = 40; 1.92 % Cu). Laboratory scale activity tests were carried out in the integral monolith reactor, operating under atmospheric pressure at different temperatures (573-773 K) and at various space times. The reactor performance was modeled using several mathematical models. The kinetics of NO decomposition was described by a LHHW type rate equation. The parameters of the monolith reactor models were estimated from experimental data using a modified differential method and Nelder-Mead method of non-linear optimization. It was found that the behavior of the experimental monolithic reactor was mainly limited by interphase mass transfer. The 2D heterogeneous model with distributed parameters was determined to be the most suitable mathematical model for detailed consideration of physico-chemical processes occurring in the catalytic monolith reactor.

Structural sensitivity of NO decomposition over a V-O-W/Ti(Sn)O2 catalyst

“…This can be explained by the fact that desorption of the oxygen released by decomposition from the surface of the zeolite catalyst is not rate determining step in the overall reaction mechanism. However, with increasing concentration of oxygen contained in the feed gas conversion of NO to N 2 over Cu-ZSM-5 decreased, as already reported [11].…”

Analysis of the mass transfer controlled regime in automotive catalytic converters

“…This reveals that the model assumptions that the washcoat is infinitely thin (no internal diffusion limitations) and that the wall reaction is infinitely fast are not satisfied, and thus the conversion is in fact lower than that predicted by considering pure external mass transfer controlled conditions. It does appear that in the case of an automotive catalyst, the conversion, even at high temperatures, is not solely external mass transfer controlled [21,22]. Under these circumstances, the experimental data reveals that the use of asymptotic values for the Sherwood number in 1D models leads to an overestimation of the catalytic converter performance.…”

Physicochemical Studies on Polyurethane/Siloxane Cross-Linked Films for Hydrophobic Surfaces by the Sol–Gel Process

“…The activation energy for the decomposition process of castor oil polyurethane/siloxane film samples was calculated by the Kissinger method using the following equation: − ln ( β T max 2 ) = − italicE normala italicR italicT max + { ln ⁡ A R E a + ln false[ n false( 1 − α max false) n − 1 false] } where β = heating rate, T max = temperature corresponding to the maximum degradation, A = pre-exponential factor, E a = activation energy, α max = maximum conversion, n = order of the reaction, and R is the universal gas constant. A plot of ln(β/ T max 2 ) versus 1/ T max should give a straight line with the slope being − E a / R .…”