Preparation of the printed catalyst. Using either ABS or ABS-(carbon fiber) fiber, the porous cartridge was printed (see above). The cartridge was then connected to a vacuum line (protected by a sodium bicarbonate trap) using teflon tubing and a screw cap. Fuming sulfuric acid was drawn up into the cartridge until it filled the interior volume (ca. 5 mL, H2SO4 with 15% SO3). The vacuum was broken and the acid was allowed to drain from the cartridge. These steps were then repeated twice and the process was again done, drawing the fuming sulfuric acid up from the opposite end. The ABS-SO3H printed catalyst was then flushed three times with the reaction solvent (3x15 mL).