The highest nitrobenzene conversion was measured for the use of TSS as acid (X54h = 75 %) after 54 h. While the overall conversion was lowest when no acid was used, the highest selectivity for quinaldine (SQui = 14 %) was measured for these conditions. With the suspended solid acid, a conversion of X54h = 55 % was obtained. Conversion with the immobilized solid acid was just slightly lower with X54h = 43 %.