Effect of flow rate on temperature in a Bi–P–O catalyst bed: Global enhancement by forced flow rate cycling

Effects of flow rate on reactivity of oxidative coupling of propylene with Bi2O3Bi2O3–P2O5P2O5 were investigated by reaction experiments and by model calculations. Although the conversion is lower at the higher flow rate because of the shorter contact time, there may be a case that when the temperature in the catalyst bed increases and it causes the reaction rate to accelerate. It is thought that the heat was accumulated in the catalyst bed when heat generation rate was much faster than the heat removal rate. The simple calculation based on the assumption of the pseudo-homogeneous phase indicated that the heat was not accumulated at the higher flow rate by the steady-state operation. However, heat wave emerged and accelerated the reaction after the flow rate was changed from the lower flow rate to the higher flow rate. Forced flow rate cycling, an operation where flow rate is changed periodically, was experimentally conducted. The time averaged conversion was slightly enhanced compared with the result from the steady-state operation at the flow rate of 100mLmin-1. In addition, even in the steady-state operation under the condition where a non-adiabatic reactor packed with only catalyst was used, the conversion and the yield of benzene became higher at the higher flow rate because of the temperature increase in the catalyst bed.