氧对丙烷在HZSM－5上转化为轻质芳烃的影响

考查了不同温度下Ｏ＿２对丙烷在不同ＳｉＯ＿２／Ａｌ＿２Ｏ＿３比的ＨＺＳＭ－５上芳构化的影响。结果表明，Ｏ＿２的添加提高了丙烷转化率和芳烃选择性。讨论了不同ＳｉＯ＿２／Ａｌ＿２Ｏ＿３比与完全氧化活性之间的关系；结合临Ｈ＿２对丙烷转化的影响，推测氧除与气相氢作用外，还与催化剂表面氢物种作用，促进了烷烃活化，加速了对应烯烃的生成。提出了Ｏ＿２促进Ｃ＿４－Ｃ＿６等中间体转化；Ｏ＿２参与反应后抑制了氢转移反应。讨论了反应历程。

Effect of Oxygen on Propanc Aromatization over HZSM-5 Catalyst

The oxygen effect on the aromatization of propane on HZSM-5 zeolites with different SiO_2/Al_2O_3 ratio is studied.It is shown that addition of O_2 in the feeding gas promotes the conversionof propane to aromatic hydrocarbons. The relationship between acidity of HZSM-5 zeolite anddeep oxidation activity is discussed. From the result of H_2 effect on propane conversion,we cometo the conclusion that besides reacting with gaseous hydrogen,oxygen also reacts with hydrogenspecies adsorbed on the active sites of the catalyst,thus exerting the enhancement effect. The roleof oxygen can be described as follows:it takes part in the first stage of alkane activation,enhanc-ing the formation of corresponding olefines. It accelarates further convertion of the intermediatessuch as C_4-C_6 hydrocarbons. And the hydrogen transfer reaction is inhibited in the presence ofoxygen. A reaction mechanism concerning oxygen is proposed.