Kinetic analysis of molecular weight growth of olefin pyrolysis

Gas phase chemistry directly affects SOFC performance in several ways. For example, alkane pyrolysis produces smaller alkanes, alkenes, and H2. Any remaining parent alkanes, as well as the smaller alkanes and alkenes can then react within the catalytic porous anode. Another way is that molecular-weight-growth reactions can lead to deposit formation, decreasing the efficiency and the life of the SOFC. Therefore, it is necessary to characterize the thermal decomposition of the fuel and determine its impact on SOFC operation. Pyrolysis experiments were performed for 1-butene and isobutylene under fuel cell conditions. Products were analyzed by either gas chromatograph or by a mass spectrometer. Residence times were ∼5 seconds and the temperatures were varied such that a wide range of conversion was observed. The two fuels have different conversions and produced different products. Experimental data will be compared to the detailed kinetic model predictions, emphasizing the difference between the molecular weight growth products and suggesting possible pathways.