微细通道内氢气辅助甲烷催化氧化的数值模拟

Numerical Simulation of Hydrogen Assisted Lean Methane Catalytic Oxidation in a Micro-Channel

对微圆管内低浓度氢气、甲烷混合气在铂表面的催化氧化进行了数值模拟,重点研究了添加氢气对甲烷反应的影响机理.结果表明,氧气占据空位活性中心抑制了甲烷的吸附,导致较高的催化着火温度;氢气的掺入可以降低甲烷氧化反应的起始温度和着火温度;在铂催化剂表面,甲烷的催化氧化发生在氢气的燃烧过程中,氢气在燃烧过程中消耗氧气,为甲烷的反应提供必需的空位活性中心(Pt(s));甲烷的着火主要受其自身的激发,甲烷着火以前,壁面活性中心几乎全被氧占据,而甲烷着火以后,O(s)和Pt(s)同为主要壁面组分.

The catalytic oxidation of fuel-lean CH4-H2 mixtures over Pt was investigated numerically in a micro-channel,focusing on the impact of the adition of H2 on CH4 reaction in principle.The results show that the surface sites Pt（s）are covered by O2,inhibiting the adsorption of CH4 and resulting in a high ignition temperature.The added H2 can decrease the initial reaction temperature and ignition temperature of CH4.The catalytic oxidation of CH4 on Pt occurs during the combustion of H2.The reaction of H2 and O2 provides CH4 with necessary uncovered surface sites（Pt（s））.The ignition of CH4 is mainly promoted by itself.Before CH4 ignition,the catalytic surface is mainly covered by O2,while after ignition,the main surface species are O（s）and Pt（s）.