丙烷脱氢反应过程的研究Ⅲ.不锈钢空管反应器中氧的影响

Dehydrogenation of Propane Ⅲ. Effects of Oxygen in Tubular Stainless Steel Reactor

采用不锈钢空管反应器，在350～700℃时测定不同氧加入量下丙烷及丙烯的热解转化率和产物分布。实验结果表明，受不锈钢管器壁催化作用的影响，低温时丙烷和丙烯主要发生完全氧化反应，氧转化率可达100%，CO2的生成量取决于氧加入量；温度高于650℃时，丙烷和丙烯的气相自由基反应显现，经部分氧化和无氧热解产生的H2、CO及烃类物质增多；氧加入促进了丙烷和丙烯的热解转化，但对高温时丙烷生成丙烯的选择性不利；含氧气氛中丙烯的自由基反应能力仍弱于丙烷。不锈钢管器壁的污染影响实验表明，器壁材料的碎片化以及焦炭类物质的存在，导致了高温时丙烯完全氧化能力大幅下降，部分氧化以及深度脱氢性能显著增强，氧加入量高时丙烯可全部转化。

The pyrolysis of C3H8 and C3H6 with different addition of O2 in a tubular stainless steel reactor was investigated in the temperature range of 350-700℃. The results showed that, at low temperature,the wall surface of the reactor exhibited its catalysis for the combustion of both C3H8 and C3H6,the conversion of O2 could reach 100% and the generation of CO2 entirely depended on the addition of O2. The generation of both CO and H2 appeared at higher than 650℃,which enhanced the partial oxidation and the O2-free pyrolysis of C3H8 and C3H6 based on the free-radical reaction mechanism. The presence of O2 could promote the pyrolysis of C3H8 and C3H6,but was not beneficial to the selectivity to C3H6 from the C3H8 pyrolysis at high temperature. The effects of the contaminant of the reactor wall on the oxidative pyrolysis of C3H6 were investigated. It was revealed that the complete combustion of C3H6 was severely weakened while both the partial oxidation and the deepdehydrogenation of C3H6 were significantly strengthened at high temperature after the reactor wall was contaminated.