Effect of intraparticle diffusion-reactions at reverse flow reactors. Cases study: Methane catalytic oxidation

Abstract

Abstract Reverse Flow Reactor (RFR) is a fixed bed reactor whose direction of flow changes at a certain time periodically. To obtain an overview of the flow direction changing on the RFR effect on the reaction rate, the intraparticle diffusion reaction factor needs to be assessed. The flow that changes in RFR causes the value of tortuosity to behave dynamically so that the reaction rate also changes dynamically. The model approach that involves intraparticle diffusion reactions is to determine the effectiveness factor. The procedure used is to estimate the effectiveness of the simulated reaction, which allows obstacles due to intraparticle diffusion to be considered at each point of the reactor without using numerical integration of the diffusion equation in the pellet (catalyst). The results obtained show that the conversion of methane gas changes over time. This change can be approached by assuming the total reaction rate in bulk is constant, but the total reaction rate in the catalyst varies depending on the intraparticle diffusion reaction, which is indicated by the value of effectiveness factor. The dynamic effectiveness factor behaviour can be approximated by the 6th degree polynomial equation as follows: 6.38e-13*t6 + 3.23e-10*t5 – 5.84e-8*t4 + 4.34e-6*t3 – 9.91e-5*t2 – 0.0004*t + 0.1781