Direct hydroxylation of benzene to phenol by nitrous oxide on amorphous aluminium-iron binary phosphates

Abstract The effect of iron content (Fe/Al molar ratio = 0.01–1 equivalent to the iron percentages from 0.5 to 20.5 wt%) and thermal treatment (450–650 °C) of aluminium-iron phosphates, prepared by an ammonia gelation method, on their catalytic performances in the one-step hydroxylation of benzene to phenol by N 2 O, has been investigated. The solids have been characterized by ICP-MS, EDX, XRD, DRIFT, DR UV–V, XPS, and N 2 adsorption techniques. The results obtained showed the critical role of iron content in the catalytic behaviour of binary phosphates while thermal treatment hardly had effect. Phosphates with a lower amount of iron exhibited the best yield to phenol that was similar to those reported in the literature for Fe-MFI type catalysts. Thus, yield to phenol of 22% (0.7 g Phe /g cat  h) at 350 °C has been achieved on the binary phosphate with Fe/Al = 0.02 (1 wt% of iron) calcined a 450 °C, in which highly dispersed iron species exist.