Capture of volatilized vanadium and tungsten compounds in a selective catalytic reduction system

A method of treating diesel exhaust gas, comprising:

• providing a selective catalytic reduction catalyst system comprising:
• a catalyst material comprising:
• a majority phase comprising a titania-based support material, and a minority phase comprising a catalyst component comprising at least one oxide of vanadium, silicon, tungsten, molybdenum, iron, cerium, phosphorous, copper or manganese;
• and
• a capture material comprising a majority phase for capturing a minority phase comprising volatile oxides or hydroxides originating from the catalyst material, wherein the minority phase of the capture material maintains a total fractional monolayer coverage on the majority phase of the capture material of about 5 or less;
• and
• wherein the capture material is positioned in a mixture with the catalyst material, or is located downstream of the catalyst material;
• and
• exposing the diesel exhaust gas to the selective catalytic reduction catalyst system wherein the capture material removes substantially all volatile oxides and hydroxides originating from the catalyst material from the diesel exhaust gas.