Design of nanocomposites with cobalt encapsulated in the zeolite micropores for selective synthesis of isoparaffins in Fischer–Tropsch reaction

A new strategy for the synthesis of metal–zeolite nanocomposite materials containing metal nanoparticles only in the zeolite pores is proposed. These materials were first prepared by zeolite impregnation with metal salts which resulted in metal species located both inside the zeolite pores and on the zeolite outer surface. Then, the metal oxide nanoparticles on the external zeolite surface were selectively extracted by larger heteropolyacid molecules which cannot enter the zeolite pores. The use of cobalt–zeolite nanocomposites with cobalt nanoparticles selectively encapsulated in the zeolite pores led to significantly higher selectivity to C5–C12 branched hydrocarbons in Fischer–Tropsch synthesis with the maximum ratio of isoparaffins to n-paraffins of 5.8.