SBA-15 with varied pore size from 4 to 8 nm were synthesized by tuning the temperature of hydrothermal treatment

the supports were then used to load the active phase CrO

x

through a conventional impregnation method. The resulting catalysts were characterized by small/wide angle XRD

N

2

adsorption/desorption

FT-IR

TEM-EDX

XPS

TPR and CO

2

-TPD to study the feature of structure

surface chemical state

redox and basicity. It was found from these results that the metal species could be well dispersed on catalysts with larger pore size. Cr

6+

species could enter into the framework by substituting the Si atoms of SBA-15

and Cr

3+

mainly exist on extra framework. Pore size had profound effects on reducibility

surface composition and basicity. Cr

6+

species were necessary to activate the C-H bonds of alkanes

while the basicity played an important role in activating C-O bonds of CO

2

. The best performances were achieved over the sample Cr supported on SBA-15 with a pore diameter of 7 nm in oxidative dehydrogenation of ethane in the presence of CO

2

.