Design of a Hierarchical Meso/Macroporous Zeolite‐Supported Cobalt Catalyst for the Enhanced Direct Synthesis of Isoparaffins from Syngas

A hierarchical meso/macroporous zeolite-supported Co catalyst (Co/ASB) was designed and employed for the direct synthesis of isoparaffins. The hierarchical porous zeolite (ASB) was developed by a steam-assisted crystallization method using alumina-modified meso/macroporous silica as the precursor. Structural characterization indicated that the as-synthesized ASB exhibited nanosized β-zeolite crystallites and a hierarchical meso/macroporous structure. The activity of the Co/ASB catalyst was much higher than that of conventional Co catalysts supported on SiO2 (Co/SiO2) and H-β-zeolite (Co/B). A high isoparaffins selectivity of 30.5 % was obtained from Co/ASB because of the hydrocracking/isomerization of long-chain hydrocarbons at the strong acidic sites of the β-zeolite. Furthermore, as a result of the fast diffusion of syngas in the unique hierarchical pores, the methane selectivity of Co/ASB was lower than that of Co/B.