Joanna10, 22 y.o. is a great age for a cat. He was obviously well loved and had excellent care. Always so very very hard to let an old friend go.
I expect your 9 y.o. cat is spraying because of the stress he is feeling over missing his cat friend. If they were close good friends, cats do grieve. It's his way of saying he's upset with the change, tho it's always good to have vet check for any possible urinary problem. If he's fine physically, then you'll know it's stress for sure.
I think he would probably stop spraying if you got him a playmate---
a girl spayed kitty around 4-5 mos. old would be ideal. He would likely adjust better and be more accepting of an older kitten than an adult. Another male kitten may have him continue to spray to assert his dominance. It would be good to hear an update, so let us know how it goes. All the best!