Highly-dispersed metallic Ru nanoparticles sputtered on H-beta zeolite for directly converting syngas to middle isoparaffins

For coping with the increasing petroleum crisis, an efficient conversion of syngas (CO + H₂) to gasoline-ranged isoparafins has been paid more and more attention. Here, we report a metallic bifunctional catalyst for this conversion, consisting of highly dispersed Ru nanoparticles (NPs) and H-Beta zeolite support, prepared by a self-made polygonal barrel-sputtering process. The HRTEM and chemisorption results indicated that sputterd Ru NPs exhibited a high metal dispersion of 31.2% with a narrow diameter of 2-4 nm. These metallic Ru NPs were bonded with the acidic zeolite by a weakly physical force, clearly different from the conventional impregnated one. Without any reduction pretreatment, the Ru/H-Beta catalyst could be directly used in Fischer-Tropsch synthesis, showing a CO conversion of 1.6 times as much as the impregnated one. Furthermore, the short distance between sputtered Ru and acidic sites nearby was responsible for the enhanced C_iso/C_n ratio of 4.6, the highest value of gasoline-ranged hydrocarbons among the relevant reports.