The heterogeneous and homogeneous combustion of C₃H₈/O₂/N₂ mixtures over Rh was investigated at pressures 1-6 bar, catalyst surface temperatures 680-1100 K and C₃H₈-to-O₂ equivalence ratios 0.25-0.52. Non-intrusive laser-based measurements were applied in a channel-flow catalytic reactor and involved 1-D Raman spectroscopy of major gas-phase species across the channel boundary layer for assessing the catalytic reactivity and planar laser induced fluorescence (PLIF) of the OH radical for monitoring homogeneous combustion. Simulations were carried out with a 2-D numerical code that included detailed hetero-/homogeneous chemical reaction mechanisms. By comparing the Raman-measured and predicted transverse profiles of the limiting C₃H₈ reactant, the suitability of a detailed surface reaction mechanism was initially evaluated and subsequently a one-step reaction was constructed, which was applicable for the C₃H₈ total oxidation over Rh at pressures 1 to 6 bar. The catalytic reactivity of C₃H₈ over Rh displayed a ∼p^0.14 pressure dependence, which was substantially lower than a previously reported ∼p^0.70 dependence over Pt. The weak pressure dependence of the C₃H₈ reactivity on Rh suggested caution when selecting catalysts for high-pressure power systems (recuperative microreactors, small-scale turbines) fueled with C₃H₈ or LPG (liquefied petroleum gas). Comparisons of PLIF-measured and predicted distributions of the OH radical indicated that the employed gas-phase reaction mechanism captured the onset of homogeneous ignition at pressures greater than or equal to 3 bar as well as the ensuing flame shapes. Predicted and measured homogeneous ignition distances agreed within 2.5% at 6 bar. With decreasing pressure, the predictions yielded gradually increasing but still modest underpredictions (up to 11.2% at 3 bar) of the homogeneous ignition distances. The key gas-phase reactions affecting homogeneous combustion at various pressures were finally identified.

在 1-6 bar 的压力、680-1100 K 的催化剂表面温度和 C ₃ H ₈ -to-O _{2条件下，研究了 C 3} H ₈ /O ₂ /N ₂混合物在 Rh 上的非均相和均相燃烧当量比 0.25-0.52。基于非侵入式激光的测量应用于通道流催化反应器，并涉及跨通道边界层的主要气相物质的一维拉曼光谱，用于评估 OH 的催化反应性和平面激光诱导荧光 (PLIF)用于监测均匀燃烧的自由基。使用包含详细异质/均质化学反应机制的二维数字代码进行模拟。通过比较限制性C ₃ H ₈反应物的拉曼测量和预测的横向轮廓，初步评估了详细表面反应机理的适用性，随后构建了适用于C ₃ H _{8的一步反应}在 1 至 6 bar 的压力下，在 Rh 上的总氧化。_{C 3} H ₈对Rh的催化反应性表现出～ p ^0.14的压力依赖性，这大大低于先前报道的对Pt的～ p ^{0.70依赖性。}_{C 3} H ₈反应性对 Rh的压力依赖性较弱，这表明在选择以 C ₃ H ₈为燃料的高压电力系统（回热式微反应器、小型涡轮机）的催化剂时要谨慎或 LPG（液化石油气）。PLIF 测量和预测的 OH 自由基分布的比较表明，所采用的气相反应机制捕获了在大于或等于 3 bar 的压力下均匀点火的开始以及随后的火焰形状。在 6 bar 时，预测和测量的均质点火距离在 2.5% 范围内一致。随着压力的降低，对均匀点火距离的预测逐渐增加，但仍然适度低估（在 3 bar 时高达 11.2%）。最终确定了影响不同压力下均质燃烧的关键气相反应。