The present invention relates to a catalytic composition comprising a noble metal on an acidic tungsten-containing mixed oxide, a method for producing the catalytic composition and the use of the catalytic composition as oxidation catalyst. The invention further relates to a catalyst shaped body, which has the catalytic composition on a support, a washcoat containing the catalytic composition according to the invention and the use of the washcoat to produce a coated catalyst shaped body.

To provide a reducer supply device that can be made compact and has excellent maintainability. The reducer supply device includes a nozzle unit that adjusts a flow rate of a reducer which is to be supplied to a NOx purification catalyst device; and a pump unit that supplies the reducer to the nozzle unit. The nozzle unit and the pump unit are arranged at positions offset from each other in top view.

A honeycomb filter includes: a honeycomb substrate having porous partition walls disposed so as to surround cells extending from an inflow end face to an outflow end face, an outer peripheral coating layer disposed so as to surround an outer periphery of the honeycomb substrate, and plugging portions that are disposed at any one of ends on the inflow end face and ends on the outflow end face, of the cells, wherein, the outer peripheral coating layer has an inflection point at which thermal expansion in thermal expansion behavior of the outer peripheral coating layer turns to contraction and a temperature T1 of which is 1000 to 1500 C., and the outer peripheral coating layer has a porosity P1 of 36 to 48%, and a thermal expansion coefficient C1 between 40 to 800 C. of 2.5 to 3.510.sup.6/ C.