Ni/Al2O3催化剂上CH4三重整反应-催化剂床层温度分布

Temperature profiles of fixedbed with Ni/Al2O3 catalyst were studied during the trireforming of methane in the temperature range of 750℃～950℃, 1 atm, and space velocity from 2000h－1 to 20000h－1. The effects of the furnace temperature (tf), space velocity, and the composition of feed stock on the thermal distribution were investigated. The results indicated that temperature grads of catalyst bed in the trireforming were lower than that in partial oxidation of methane. The temperature near the catalyst bed inlet (tmax) was 80℃ higher than tf at CH4/CO2/H2O/O2=50/12.5/12.5/25 and 2000h－1, whereas the temperature near the catalyst bed outlet was close to tf.Δtmax ( = tmax－tf) decreased with the decrease of space velocity (Δtmax=80℃ at 20000h－1; Δtmax=30℃ at 2000h－1). No distinct temperature grads were found near the catalyst bed inlet when there was no oxygen in feed. Under specific condition, tmin (the lowest temperature in the catalyst bed), which was about 30℃~40℃ lower than tf, can be observed in the bed. According to thermal distribution of the bed, the catalyst bed can be divided into three zones, oxygen adequate zone, oxygen inadequate zone, and oxygen absent zone. In oxygen adequate zone, methane combustion occurs only. In oxygen absent zone, methane reforming (carbon dioxide and steam reforming) takes places only. However, in oxygen inadequate zone, both reforming and partial oxidation of methane are present.