Methane oxidative coupling in a novel riser simulator reactor

The aim of the present work is the development of a heterogeneous kinetic model for the isomerization and disproportionation of 1,2,4-TMB. With this end, experiments are conducted in a novel CREC riser simulator loaded with an FCC catalyst. FCC catalysts were prepared using HY zeolites having different crystallite sizes, namely,0.4 and 0.9 µm. The observed distributions of products are reviewed considering potential shape-selectivity effects and hindered diffusion of products. The adopted modeling strategy allows for the calculation, with little ambiguity, of adsorption constants; heats of adsorption; and kinetic constants, such as energies of activation and preexponential factors.

Section: Modeling the Catalytic Disproportionation And Isomerization ...mentioning

confidence: 99%

Catalytic Conversion of 1,2,4-Trimethylbenzene in a CREC Riser Simulator. A Heterogeneous Model with Adsorption and Reaction Phenomena

Atias

Tonetto

Lasa

2003

“…In this operation, methane always contacts a very small amount of oxygen both on the catalyst surface and in the gas phase. Methane reacts under "starving oxygen condition" that suppresses the further oxidation of C 2 products (Pekediz and de Lasa, 1994).…”

Section: Introductionmentioning

confidence: 99%

A Comparative Simulation Study on Oxidative Coupling of Methane in Fixed-Bed and Membrane Reactors

Kao

Lei

Yue

1997

Oxidative coupling of methane (OCM) on a conventional fixed-bed reactor (FBR) and a ceramic dense membrane reactor (DMR) packed with Li/MgO catalyst is analyzed using plug-flow reactor models. The validity of OCM kinetic equations employed in the modeling is confirmed by excellent agreement between the simulation and experimental data for OCM on FBR. For FBR, a high methane to oxygen feed ratio favors the OCM reaction, with a low C2 yield because of insufficient oxygen supply. The highest C2 yield achieved with a feed mixture consisting of 70% methane and 30% oxygen is 20.7% at a selectivity of 53% and operating temperature of 750 °C. The C2 yield and selectivity increase slightly at a higher operating temperature. The optimal feed ratio does not change with temperature. DMR is made of a mixed-conducting ceramic membrane tube packed with an OCM catalyst. The membrane tube separates the methane and oxygen feed. The oxygen concentration in the DMR is much lower and more uniform than that in the FBR because of the different reactant feeding mode and logarithemic dependence of oxygen flux on oxygen partial pressures of the dense ceramic membrane. This results in a significantly increased C2 selectivity and yield for the DMR as compared to the FBR.

“…To feed the reactants to the CREC riser simulator, a gas injector initially developed by Pekediz was employed. This gas injector allows the feeding of the reactant mixture with different compositions at essentially instantaneous conditions with time lags of not more than 0.1−0.2 s. This gas injector had the following components: (a) a Plexiglas barrel (23 mm i.d.)…”

Section: Experimental Methodsmentioning

confidence: 99%

Catalytic Dry Reforming of Methane in a CREC Riser Simulator Kinetic Modeling and Model Discrimination

Solh

Jarosch

Lasa

2003

The present study deals with catalytic dry methane reforming in a fluidized Chemical Reactor Engineering Centre (CREC) riser simulator and with the modeling of the obtained results using several kinetic rate equations. Experiments were designed and developed using a statistical criterion that optimizes the effort expended for model discrimination. From the eight models originally considered, six of them were initially found to fit the data. However, only one of them was later on retained using model discrimination. Results of the study show that both the adsorption of methane and the adsorption of carbon dioxide play an important role in determining the observed rate of the methane dry reforming reaction and suggest that methane and carbon dioxide adsorb on different sites of the catalyst. The study is also valuable in providing a sound rate equation applicable in the context of a Catforming process under current development at the CREC of the University of Western Ontario.