Along with Akiva Bar-Nun and Simon Bauer, Sagan filed the Pressure Wave Synthesis of Aminocarboxylic Acids for a patent on October 2, 1970.
How does it work?
A homogenous vapor phase method for preparing aminocarboxylic acids by subjecting a gaseous mixture of compounds containing the elements of hydrogen, oxygen, carbon and nitrogen (with the latter two in reduced compounds), which are optionally mixed in an inert carrier gas to pressure wave heating and rapid expansion wave cooling. The products from the heating and cooling process are immediately withdrawn from the reaction chamber into a dilute aqueous solution of a mineral acid wherein the aminocarboxylic acids produced from the process are recovered.The patent was awarded on March 28, 1972.
While this is the only Sagan patent I found in Google's records, the search giant did show that he had influence in getting other inventions patented.
You may remember these from Cosmos: