A universal route to fabricate hierarchically ordered macro/mesoporous oxides with enhanced intrinsic activity†
Hierarchically ordered macro/mesoporous oxides and mixed oxides have been fabricated by adopting a dual-templating [poly(methyl methacrylate) colloidal microspheres and Pluronic P123] strategy and a wet ammonia gas infiltration–precipitation route to solidify metal precursors in situ. This is especially suitable for mixed oxides that can be prepared by a co-precipitation method using ammonia as the precipitation agent. The as-prepared Ce–Ti mixed oxides have a desirable homogeneous distribution of the components and exhibit excellent intrinsic activity for the selective catalytic reduction of NOx with NH3 under an exceptionally high gas hourly space velocity of 500 000 mL g−1 h−1, which confirmed the contribution of the macropores to small-molecule reactions. Furthermore, hierarchically macro/mesoporous Mn, Cr, Ti, La, Y, Sn, Zn, Ni and Co oxides have been fabricated on a large-scale to illustrate the universal applicability of this method.