The heterogeneous and homogeneous combustion of fuel-lean CH₄/O₂/N₂ mixtures over PdO was investigated experimentally and numerically at equivalence ratios φ = 0.27–0.44, pressures 1–12 bar and surface temperatures 710–1075 K. In situ Raman measurements of major gas-phase species concentrations across the boundary layer of a channel-flow catalytic reactor assessed the heterogeneous reactivity, while planar laser induced fluorescence (LIF) of the OH radical monitored homogeneous combustion. Simulations were performed using a 2-D code with detailed heterogeneous and homogeneous reaction mechanisms. Comparisons between Raman-measured and predicted transverse profiles of major species mole fractions attested the atmospheric-pressure suitability of a detailed surface mechanism and allowed for the construction of a global catalytic step valid in the range 1–12 bar. The methane catalytic reaction rate exhibited an overall pressure dependence ∼p¹⁻ⁿ where the exponent n was itself a monotonically increasing function of pressure, rising from 0.58 at 3 bar to 1.02 at 12 bar. This resulted in a non-monotonic pressure dependence of the catalytic reaction rate in the range 1–12 bar, a behavior in stark contrast to other noble metals (Pt and Rh) where the methane reaction rates always increased with rising pressure. Surface temperatures remained well-below the PdO decomposition temperature at each corresponding pressure, owning largely to the “self-regulating” temperature effect of PdO, and this in turn mitigated homogeneous ignition. Simulations using the PdO decomposition temperatures as boundary conditions for the wall temperatures were further performed for practical CH₄/air catalytic reactors in power generation systems. It was shown that for p < 7 bar (a range relevant to microreactors) homogeneous ignition was altogether suppressed. For higher pressures relevant to gas-turbine burners, however, gaseous combustion ought to be considered in the reactor design.

贫燃料CH的多相和均相燃烧₄ / O ₂ / N _2分比的PdO的混合物进行了实验和数值在当量比研究φ  = 0.27-0.44，压力1-12巴和表面温度710-1075  K.我Ñ原位整个通道流催化反应器边界层上主要气相物种浓度的拉曼测量评估了异相反应性，而OH自由基的平面激光诱导荧光（LIF）监测了均匀燃烧。使用具有详细异质和均相反应机理的二维代码进行模拟。主要物种的拉曼测量和预测横向剖面的比较摩尔分数证明了详细表面机制的大气压适用性，并允许构建有效的整体催化步骤，范围为1–12 bar。甲烷催化反应速率显示出总体压力依赖性〜p ^{1 - n}，其中指数n本身就是压力的单调增加函数，从3 bar的0.58升高到12 bar的1.02。这导致催化反应速率在1-12 bar范围内非单调压力依赖性，这与其他贵金属（Pt和Rh）形成鲜明对比，后者的甲烷反应速率始终随压力的升高而增加。在每个相应的压力下，表面温度仍远低于PdO分解温度，很大程度上归因于PdO的“自调节”温度效应，从而减轻了均匀点火的可能性。对于实际的CH₄，进一步使用PdO分解温度作为壁温的边界条件进行了模拟。发电系统中的空气催化空气反应堆。结果表明，对于p  <7 bar（与微反应器相关的范围），完全抑制了均匀点火。但是，对于与燃气轮机燃烧器相关的更高压力，在反应堆设计中应考虑气体燃烧。