Duvets and pillows are classified as textiles.
Although most textiles are suitable for recycling due to hygiene reasons duvets and pillows aren’t.
This should be placed in the general waste bin.
If you have NEW unused and unwanted items these can be donated to charity. If you have used ones which are in good condition perhaps you could donate them to an animal shelter – check with your local centre first. Textile banks do not accept used pillows and duvets for hygiene reasons.