High Selectivity of Medium Distillates in Fischer–Tropsch Synthesis Using Dual Bed

A dual bed was used as an alternative to favor Fischer–Tropsch Synthesis (FTS) selectivity towards products with higher added value (C 10 –C 20 ), as waxes produced on metallic sites may be cracked on acid sites. For the FT catalyst, the use of SiC as support favors heat transfer and temperature maintenance due to its high thermal conductivity. Concerning acid catalyst, mesoporous zeolite tends to increase accessibility to sites and cracking of heavier molecules. Therefore, mesopores were created from the pristine NaY zeolite using a sequence of acid and alkaline post-treatments. The catalysts were characterized by N 2 physisorption, XRD, TPR, SEM/EDS, TGA, Raman, and XRF. Three configurations: Co/SiC (A), Co/SiC + Meso Y zeolite (B) and physical mixture of two catalysts (C), were evaluated in an FTS reactor at 483 K, 2.0 MPa, H 2 /CO = 2. The highest selectivity to diesel and lubricants, with a stable CO conversion of 10%, was obtained with configuration B. The association of mesoporous Y zeolite with Co/SiC catalyst contributed to cracking heavy products (C 21+ ), favoring low methane formation and yields above 30% kerosene and diesel. Graphic Abstract