Engineering the Framework Cobalt and Hierarchical Pores of Aluminophosphates for Enhanced Performance in n-Butene Skeletal Isomerization

An effective method is proposed to synthesize a hierarchical Co-doped AlPO4 molecular sieve (CoAIP-CTAB). For the obtained zeolite, both framework and extra framework Co are firstly established and identified by X-ray absorption fine structure (XAFS). The percentage of framework Co (P-O-Co-O-P) is estimated to be 82%. Due to the hierarchical structure and abundant Co sites in the framework, CoAIP-CTAB nanocrystals have shown high catalytic activity and stability for the catalytic conversion of n-butenes to isobutene at mild temperature (350 degrees C) without gas dilution. This novel synthesis strategy may inspire the design of similar types of industrial zeolite catalysts for selective reactions.