Temperature calibration effect on FTS activity and product selectivity using Fe-MOF catalyst

A temperature calibration procedure for a fixed-bed reactor has been reported to investigate its outcome on the performance of Fischer-Tropsch Synthesis (FTS) utilizing metal-organic framework (MOF)-derived iron catalyst. It has been established that catalyst activation and activity are sensitive to reaction temperature. Elevated temperatures lead to deposition of CO as carbon expressed in misleading carbon balance and CO conversion (XCO) values. However, no systematic temperature calibration study for FTS was found in literature. In this work, a temperature probe was designed and assembled into the catalyst zone in the reactor to measure the catalyst temperature compared to the furnace sensor temperature. A large temperature gradient across the furnace caused by airflow through the furnace openings was considerably lowered by sealing the furnace openings. Calibration results indicate substantially different catalyst/furnace temperatures by up to 60 °C. Consequently, the catalysts showed different FTS activity, product selectivity and carbon balance before and after calibration. The olefin yield increased by up to 3.5-folds at lower temperatures and 46-folds at higher temperatures. Moreover, the methane selectivity decreased to half and C5+ selectivity was doubled in conjunction with the correction of carbon balance error. This study highlights the significance of temperature control for accurate FTS performance evaluation.