Mint Extract: If you favor neither the smell of citrus nor vanilla, you can perhaps use mint extract instead. Pour several drops of mint extract on a couple of cotton wools. Toss the cotton wools inside the confined space and leave them for a couple of days.
Charcoal: Charcoal is on the top of the list of smell deodorizers as it is one of the best absorbent agents that can soak up the bad odor. Charcoal is also widely used as water filters and in most odor-removing commercial products. You can put a medium-sized chunk of charcoal inside your smelly patio for instance, and leave it there for a couple of days. You will notice that it can effectively remove the trash can smell.