Besides reaction temperature, space-time-yield is an important factor for process efficiency. In order to optimize the space-time-yield of the acetone aromatization with Siralox 30, the weightto-flow ratio of catalyst mass W to acetone molar flow F is varied at 260 °C, the point of highest mesitylene selectivity. The acetone conversion and mesitylene yield increase for longer contact times which is represented by higher W/F ratios but mesitylene yield does not benefit from ratios higher than 12.5 gcat h mol -1 where it is 10.1 % (Figure ). The further increase in acetone conversion is a result of increased byproduct formation due to significantly longer catalyst contact times. The yield of mesityl oxide decreases for higher W/F ratios, indicating intermediate formation of the dimerization product and subsequent conversion to mesitylene. There was no significant effect of contact time on the formation of oligomers and isophorone. For a variation at 210 °C in liquid phase (Figure ), a constant increase in mesitylene yield to only 8 % was observed at a W/F ratio of 75. It can therefore be concluded that the increased reaction temperature leads to more efficient catalysis of the acetone condensation and thus allows for faster contact times compared to lower reaction temperatures. A reaction temperature of 260 °C and a W/F ratio of 12.5 gcat h mol -1 (corresponding to a WHSV of 4.66 h -1 ) are found as optimal conditions for the consistent formation of mesitylene with the ASA Siralox 30 in the continuous flow fixed-bed reactor.