Effect of CTAB on the Oxidation of Furfural to Maleic Acid over Hierarchical CoAPO-5 Catalysts

A series of hierarchical CoAPO-5 molecular sieves was hydrothermally synthesized using cetyltrimethylammonium bromide (CTAB) as the template. The structural properties of CoAPO-5 molecular sieves with different amount of CTAB, including AFI-0.10, AFI-0.25, AFI-0.35, AFI-0.45 and AFI-0.55 were all characterized by XRD, SEM, N2 adsorption-desorption and NH3-TPD. The catalytic performance of as-prepared CoAPO-5 molecular sieves for the oxidation of furfural to maleic acid was investigated. Research results indicated that the structure characteristics as well as the catalytic performances of CoAPO-5 molecular sieves were strongly affected by CTAB amount. Among those hierarchical CoAPO-5 catalysts, AFI-0.45 sample exhibited highest maleic acid yield of 85.9% at 60℃ after 3 h reaction. In addition, the stability of AFI-0.45 was proved persistent for subsequent cycles.