Replacing Tantalum capacitor?
I would guess that \$22\mu F\$ is the minimum capacitance that the application can use.

Part characteristics can differ as their voltage rating increases, so be careful not to go 'too' high. (Don't put a 100V capacitor where there once was a 16V part). I would wager that if you can get something between \$22 \mu F\$ and \$47 \mu F\$ in 25V, you'll be fine.

You may also be able to use multilayer ceramic capacitors in parallel to get \$ 22\mu F\$ - just don't use electrolytic. Electrolytic capacitors are not 'high speed' due to their intrinsic parasitic characteristics.