Tri-reforming of methane over Ni@SiO_2 catalyst

摘要

A nickel-silica core@shell catalyst was applied for a methane tri-reforming process in a fixed-bed reactor. To determine the optimal condition of the tri-reforming process for production of syngas appropriate for methanol synthesis the effect of reaction temperature (550-750 ℃), CH_4:H_2O molar ratio (1:0-3.0) and CH_4:O_2 molar ratio (1:0-0.5) in the feedstock was investigated. CH_4 conversion rate and H_2/CO ratio in the produced syngas were influenced by the feedstock composition. Increasing the amount of steam above the proportion of CH_4:H_2O 1:0.5 reduced the H_2:CO molar ratio in produced syngas to ～1.5. Increasing oxygen partial pressure improved methane conversion to 90% at 750 ℃. At low ～550 ℃ reaction temperature the tri-reforming process was not effective with low hydrogen production (H_2 yield ～20%) and very low ＜5% CO_2 conversion. Increasing reaction temperature increased hydrogen yield to ～85% at 750 ℃. From all the tested reaction conditions the optimal for tri-reforming over the ll%Ni@SiO_2 catalyst was: feed composition with molar ratio CH_4:CO_2:H_2O:O_2:He 1:0.5:0.5:0.1:0.4 at T = 750 ℃. The results were explained in the context of characterisation of the catalysts used. The obtained results showed that the tri-reforming process can be applied for production of syngas with composition suitable for methanol synthesis.