Experimental and theoretical investigation of the heating characteristic of C3H6 catalytic combustion over Pt/Al2O3 catalyst

Abstract

The purpose of this study is to investigate the effect of C3H6 catalytic combustion on the heating characteristic over DOC, tracking C3H6 conversion efficiency (XC3H6) and gas mixture temperature to optimize the control strategy during active DPF regeneration. The temperature programmed oxidation and constant temperature oxidation test were conducted on a fixed-bed quartz reactor with a uniformly coated Pt/Al2O3 catalyst. The comparative effects of temperature and C3H6 concentration on the DOC performance including the light-off activity, XC3H6 and heating characteristic were systematically discussed. Experimental results showed that XC3H6 was weakened with higher C3H6 concentration in low-temperature conditions, for C3H6 easily adhering to the active site surface of the catalyst and exhibiting a inhibitory effect on self-catalytic oxidation. In high-temperature conditions, XC3H6 did not decrease with the addition of C3H6 concentration, for the adsorption effect of C3H6 weakened. DOC outlet temperature rise response characteristics in constant temperature oxidation test could be divided into three stages: slow start stage/temperature rise delay stage, acceleration stage and stabilization stage. In the test under oxygen-enrich conditions, there was a nearly linear relationship between the DOC outlet temperature rising amplitude and C3H6 concentration, as the addition of C3H6 led to the more participation of C3H6 in the oxidation reaction to release heat. The order of temperature rising amplitude of C3H6/O2/H2O/N2 at 300, 400 and 500 °C was θ300 °C>θ400 °C>θ500 °C, respectively, which was closely related to C3H6 combustion in front of the DOC.