A universal route to fabricate hierarchically ordered macro/mesoporous oxides with enhanced intrinsic activity

Abstract

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 NO_x 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.