Study On Dry Reforming Of Methane With Ni-Co/HZSM-5 Catalysts

Reforming of methane,which is used to produce syngas?CO and H₂?,is one of the most important way of methane conversion for high value-added products.Dry reforming of methane,which gained widespread concern from researchers,can utilize two greenhouse gases methane?CH4?and carbon dioxide?CO2?,and the H₂/CO ratio of products is appropriate for F-T synthesis.On the basis of thermodynamic and carbon deposition behavior of DRM,Ni/HZSM-5 catalysts with 10 wt% loading amount and x wt%Ni-y wt%Co/HZSM-5?x+y=10?were prepared by a wet impregnation method and an excessive impregnation method respectively.10 wt%Ni-5 wt%MgO/HZSM-5 catalysts were prepared by a wet impregnation method.The effect of calcination temperature,space velocity,reaction temperature,bimetallic Ni-Co mass ratio on dry reforming of methane were studied.The catalysts were characterized by BET,H₂-TPR,NH₃-TPD,XRD,TG-DTG techniques.The main results are as follows:?1?Ni/HZSM-5 catalysts with 10 wt% loading amount were prepared by a wet impregnation method.The results indicate that the catalyst shows better activity and stability for dry reforming of methane with larger specific surface area,smaller Ni crystallite size and mediate stronger acidity.?2?x wt%Ni-y wt%Co/HZSM-5?x+y=10?catalysts were prepared by an excessive impregnation method.The reaction performance of Ni-Co bimetallic catalysts is significantly improved,especially mNi:mCo = 6: 4.The DRM reaction activity and stability over 6 wt%Ni-4 wt%Co/HZSM-5 is even better than metal Ni catalysts.?3?10 wt%Ni/HZSM-5 and 10 wt%Ni/Al2O3 were prepared by an excess impregnation method.The results indicate that lower calcination temperature is beneficial to coke reduction.The catalyst deactivation is slower at high reaction temperature.The amount of carbon deposition associated with calcination temperature of 500 oC is measured to be 20.33% whereas 27.25% carbon deposition is obtained on the spent catalyst calcinated at 700 oC.The carbon is amorphous.The catalyst prepared by an excess impregnation method has higher activity and stability of DRM than by a wet impregnation method.