Experimental and theoretical investigation of H-2 oxidation in a high-temperature catalytic microreactor

A sample and flexible quartz-glass-based microreactor design is presented f or high-temperature catalytic gas-phase reactions. The reactor was tested w ith the platinum-catalysed hydrogen oxidation reaction, withstanding extrem ely high reaction temperatures in excess of 1000 degreesC without ally sign s of degradation. Experimental results are compared to those from a previou s, alternative microreactor configuration, indicating substantially reduced heat losses. No homogeneous flames or explosions are observed under any re action conditions, indicating that homogeneous reactions can be very effect ively suppressed in a microreaction channel. A theoretical analysis of the explosion limits in the homogeneous H-2/O-2-system confirms that reactors w ith characteristic dimensions in the sub-millimetre range become intrinsica lly safe at ambient pressure conditions. Furthermore, the analysis shows th at the suppression of the explosive reaction behaviour in these microreacto rs can be traced to a kinetic quenching of the radical chain mechanism rath er than a thermal quenching due to increased heat transfer rates. (C) 2001 Elsevier Science Ltd. All rights reserved.