It's not common, but notable in chemistry. You sometimes burn/melt stuff for analysis in Pt/Au bowls because it's known that ceramics could introduce (soluble) contaminants (leeching sodium from glaze, metals and glass 'fluxing' around alumina dust - that level of analytic pedantism). For 'chemically inert' reason, gas-phase synthesis may necessitate piping and vessels made of platinum or Pt/Rh or Pt/Ir alloys, but I can't give you a reaction example off-hand. I also got to use Pt/Nb anode and Pt/Ir 'combustion mantle' (that fine mesh around a flame, like on old-timey gas lamps) in organic synthesis, but the latter was hella niche even by the "Pt alloys in lab" category. And it wasn't used for catalyst either; I needed to cleanly keep the water away with flame, with this somehow being the least stupid setup. You don't alloy platinum for anything but jewelry and catalysts, that I know of.