Influence of nitrogen on the catalytic behaviour of Pt/γ-Al ₂O₃ catalyst in glycerol reforming process

In the present work, deactivation behaviour of a Pt/γ-Al ₂O₃ catalyst used for converting glycerin/water mixture into hydrogen was investigated. It was shown that main reason for the catalyst activity drop is due to the carbon deposition over the catalyst surface. Interestingly, the catalyst suffered from faster deactivation in the case of nitrogen presence in the inlet stream. However, the catalytic stability of the catalyst could be greatly enhanced when nitrogen was phase out from the reaction atmosphere. In the reaction mixture containing 10 wt% glycerol, the deactivation constant of the catalyst decreased from d_A = -0.0516 mL/(min g_cat. h) under a condition with nitrogen to d_B = -0.0051 mL/(min g_cat. h) without nitrogen in the reaction bed. Catalytic evaluation and thermogravimetric analysis revealed that nitrogen was not only an inert carrier gas served as but also an accelerator for coking. A speculation model was proposed for explanation of the coking process over the catalyst with the nitrogen effect.