Iron-loaded small pore aluminosilicate zeolites and method of making metal loaded small pore aluminosilicate zeolites

An iron-loaded aluminosilicate zeolite-derived material having a maximum pore opening defined by eight tetrahedral atoms and having the framework type CHA, AEI, AFX, ERI, or LTA, obtained by a method comprising the steps of:

• (i) introducing mesoporosity into aluminosilicate zeolite crystallites by application of an aqueous alkali treatment to dissolve silica or application of an aqueous acidic treatment to dissolve alumina in the aluminosilicate zeolite crystallites;
• (ii) introducing the iron into the product of step (i) by wet impregnation or wet ion- exchange by contacting the product of step (i) with a mixture of an iron-containing reagent and a structure directing agent for the aluminosilicate zeolite;
• and
• (iii) closing the mesopores of the product of step (ii), thereby producing the iron-loaded aluminosilicate zeolite-derived material, wherein an ultraviolet-visible absorbance spectrum of the iron-loaded aluminosilicate zeolite-derived material comprises a band at approximately 280 nm, and, wherein a ratio of an integral, peak-fitted ultraviolet-visible absorbance signal measured in arbitrary units (a.u.) for the band at approximately 280 nm to an integral, peak-fitted ultraviolet-visible absorbance signal measured in arbitrary units (a.u.) for a band at approximately 340 nm is greater than about 2.