Abstract:

The self-sustained combustion of toluene on the Cu-Ce-Zr based catalysts with different activity has been carried out in a micro-tube with inner diameter of 4 mm. It was shown that the lean-combustion limits over CuCe_0.75Zr_0.25O_x-BC catalyst with the higher activity were less than that on CuCe_0.75Zr_0.25/TiO₂ catalyst at the same flow rate, and the minimum of equivalence ratio (?) was 0.024 under the flow rate of 200 ml/min. The residence time of the mixed gas on the catalyst surface declined with the increasing of flow rate, making the highest surface wall-temperature range shift to the back of catalyst bed. Toluene could maintain self-sustained combustion even when the heat loss was as high as 91.9%. Combined with the theoretical model, the heat transport of toluene self-sustained combustion in micro-tube was calculated. The self-sustained combustion in a fixed-bed reactor was realized with reducing the upper limit of temperature runaway s impacts for the reactor and catalysts.

Key words: self-sustained combustion, Cu-Ce-Zr based catalyst, toluene, lean-combustion limit, heat transfer, microscale, fixed-bed

摘要：

在内径4 mm的微型反应器内对两种活性不同的Cu-Ce-Zr基催化剂进行甲苯自持燃烧的贫燃极限研究和热量计算。研究结果表明，活性高的CuCe_0.75Zr_0.25O_x-BC催化剂的贫燃极限小于活性低的CuCe_0.75Zr_0.25/TiO₂催化剂的贫燃极限，当流量为200 ml/min时，其当量比?值最小，为0.024。混合气在催化剂表面的停留时间随混合气流量的增大而缩短，使得催化自持燃烧的壁温高温区向催化剂床层后端移动，且壁温高温区温度随催化剂活性的增高而降低。在散热率高达91.9%的情况下，甲苯仍可维持稳定的自持燃烧状态。同时结合微管反应实验结果和理论计算，在有效降低飞温上限对反应器和催化剂的影响下实现了甲苯在固定床反应器中的自持燃烧。

关键词: 自持燃烧, Cu-Ce-Zr基催化剂, 甲苯, 贫燃极限, 传热, 微尺寸, 固定床