Control of the product ratio of CO_2/(CO + CO_2) and inhibition of catalyst deactivation for steam reforming of gasoline to produce hydrogen

摘要

Factors controlling the product ratio of CO_2/(CO + CO_2) and methods for inhibiting deactivation of catalyst for steam reforming of gasoline were studied. Syngas (H_2 +CO) as major product was produced on Ni-Mo/Al_2O_3 and the major product on Ni-Re/Al_2O_3 was H_2 and CO_2 at the same reaction conditions. Hydrogen with a high CO_2/(CO + CO_2) ratio of about 92% was produced by coupling reaction of steam reforming and water gas shift on Ni-Re/Al_2O_3 catalyst at 805 K. The multifunctional activity of the bimetallic catalyst of Ni-Re/Al_2O_3 and the suitable reaction temperature were of crucial significance for the coupling reaction. Although no deactivation could be observed on both Ni-Mo/Al_2O_3 and Ni-Re/Al_2O_3 catalysts for steam reforming of sulfur-free fuels in about 200 h of time on stream, the activity and sulfur-tolerance of Ni-Re/Al_2O_3 was much better than the values of Ni-Mo/Al_2O_3 for steam reforming of sulfur-containing fuels because of the unique role of rhenium in the Ni-Re catalyst. The unique role of rhenium in Ni-Re catalyst was mainly because of alloying of rhenium with nickel to form bimetallic Ni-Re sites and interaction of rhenium with sulfur to form S-Re binds. The sulfur-tolerance of Ni-Re/Al_2O_3 for steam reforming of sulfur-containing gasoline was improved further by addition of a small amount of ZSM-5. The activity and sulfur-tolerance of Ni-Mo/Al_2O_3 was also enhanced by the addition of ZSM-5.