Acetic Acid Steam Reforming over Ni-Fe Catalyst: Complementary Roles of Iron and Reaction Pathways of Methane and CO

Steam reforming of acetic acid for hydrogen generation was investigated over bimetallic Ni-Fe catalysts,monometallic Ni and Fe catalysts to understand behaviours of nickel and iron during the reforming. Monometallic Fe is not active for acetic acid reforming but is important to transform the CO intermediate to H2 and CO2. Monometallic Ni is active for acetic acid reforming but is not stable with prolonged reaction time. The combination of these two metals with distinct catalytic capabilities makes the bimetallic Ni-Fe catalyst far superior to the monometallic Ni or Fe catalyst in terms of both activity and stability at the temperature as low as 623 K. The reaction pathways of the two gaseous by-products,methane and CO,were explored as well over the Ni-Fe catalyst. It was found that the 673 K was a critical temperature when the reaction pathways for both methane and CO started to shift. Below 673 K,methane mainly is formed from methanation of CO and CO2,while above this temperature methane is mainly formed from the decomposition of acetic acid. As for CO,below 673 K,it is mainly formed from the decomposition of acetic acid and the insufficient steam reforming of acetic acid. Above this temperature the reverse water gas shift reaction are the dominate way for CO formation.