Biochar is a reactive carrier as it may be partially gasified with steam in steam reforming

which could influence the formation of reaction intermediates and modify catalytic behaviors. Herein

the Ni/biochar as well as two comparative catalysts

Ni/Al

2

O

3

and Ni/SiO

2

with low nickel loading (2% (mass)) was conducted to probe involvement of the varied carriers in the steam reforming. The results indicated that the Ni/biochar performed excellent catalytic activity than Ni/SiO

2

and Ni/Al

2

O

3

as the biochar carrier facilitated quick conversion of the -OH from dissociation of steam to gasify the oxygen-rich carbonaceous intermediates like C=O and C-O-C

resulting in low coverage while high exposure of nickel species for maintaining the superior catalytic performance. In converse

strong adsorption of aliphatic intermediates over Ni/Al

2

O

3

and Ni/SiO

2

induced serious coking with polymeric coke as the main type (21.5% and 32.1%

respectively)

which was significantly higher than that over Ni/biochar (3.9%). The coke over Ni/biochar was mainly aromatic or catalytic type with nanotube morphology and high crystallinity. The high resistivity of Ni/biochar towards coking was due to the balance between formation of coke and gasification of coke and partially biochar with steam

which created developed mesopores in spent Ni/biochar w

hile the coke blocked pores in Ni/Al

2

O

3

and Ni/SiO

2

catalysts.