Purification structure including a catalysis system supported by a zircon in reduced state

A filtration structure, comprising:

• an array of longitudinal adjacent channels of mutually parallel axes separated by porous filtering walls comprising a porous inorganic material, wherein said channels are alternatively plugged at one or other of the ends of the structure so as to define inlet channels and outlet channels for a gas comprising NOx to be filtered, and so as to force said gas to pass through the porous filtering walls separating the inlet channels from the outlet channels,
• wherein said filtration structure comprises a catalytic system comprising at least one noble metal or transition metal that reduces the NOx and a support material wherein the support material has formula (I):
• (ZrO2-x)1-y(M2O3-x)y (I),
• wherein:
• M is Y3+, Sc3+, or a rare earth cation of valency 3;
• x is greater than 0.005 and less than 0.5;
• and
• y is greater than 0 and less than 2;
• or
• wherein the support material has formula (II):
• (ZrO2-x)1-y′(M′O1-x)y′ (II),
• wherein:
• M′ is Ca2+or Sr2+;
• x is less than 0.5;
• and
• y′ is greater than 0 and less than 2.