(469e) A Hybrid Catalytic Membrane Reactor for Destruction of a Chemical Warfare Simulant

Authors: 
Motamedhashemi, M., University of Southern California
Nair, N., University of Southern California
Egolfopoulos, F., University of Southern California
Tsotsis, T. T., University of Southern California

Abstract

The possibility of the use of chemical weapons has been increased in recent years both as a result of potential terrorist attacks and of ongoing international conflicts. The focus of our research is the development of a novel, hybrid catalytic membrane reactor which consists of a flow-through catalytic membrane reactor (FTCMR) integrated with a surface-flow based membrane separator (SFMS) in order to reduce significantly the load on the FTCMR, to achieve complete oxidation of chemical warfare agents (CWAs) at trace levels, applicable in integrated individual protection system (IPS) for civil and military applications. As a part of this research, a catalytic tubular alumina membrane is prepared via impregnation with commercial H2PtCl6.H2O solutions, and is utilized in a FTCMR for the catalytic oxidation of dimethyl methylphosphonate (DMMP) in air. DMMP is known as a chemical precursor for the more toxic gas Sarin (GB), and has been widely used to simulate its characteristics. 

Experiments are reported for different DMMP feed concentrations (150-1000 ppm) and reactor temperatures (373-573K), which demonstrate the potential advantage of the FTCMR in the complete catalytic oxidation of this important CWA simulant. Complete destruction of low and high concentrations of DMMP was achieved at lower temperatures compared to the values obtained in this study for a wall-coated plug-flow (monolith) reactor containing the same amount of catalytic metal.

A mathematical model has also been developed in order to provide a better understanding of the fundamental transport phenomena underpinning the FTCMR operation.  It makes use of the Dusty Gas Model, which incorporates in an appropriate fashion continuum and Knudsen diffusion, and viscous flow as the mechanisms for gas transport through the porous membrane being utilized in the FTCMR.  The model is used for identifying the advantages of the FTCMR concept compared to the wall-coated catalytic monolith, and also for investigating some of the limitations, which may exist in applying this concept for the complete oxidation of chemical warfare simulants.  The results of the model support the superiority of the FTCMR concept over the more conventional (plug-flow) monolith reactor.

These preliminary experimental and theoretical results indicate that the hybrid membrane reactor concept shows promise for application in the design of individual-protection systems (e.g., gas masks) for soldiers and other military personnel, as well as in the design of collective-protection systems for military armored vehicles and buildings.