The reference for a patent looks like this:
Inventor surname, initial. (year). Title of patent. Country of registration and patent number.
Hornung, A., Apfelbacher, A. (2009). Biomass Processing. UK patent GB 2460154 A.
The following search tools will allow you to find patents. There are sometimes many versions of similar patents, so if you have a patent number or other reference number, this is often the best way to search.