9V powering to the safest maximum brightness of 4 IR LEDs in series
Assuming the IR LEDs have 'typical' values from the datasheet, their forward voltage is 1.4 V.

Four such diodes in series then has a forward voltage of 5.6 V, you have a 9 volt source and a 22 ohm resistor. The current is therefore (9 - 5.6) / 22, or 154mA. This is too much according to the datasheet. It may work for now, but expect the life of the LEDs to be shortened.

A better solution would be to use a constant current source, or an LED driver to drive them. Running at the absolute maximum from the datasheet is acceptable, but you may get better reliability by backing off from it a little, run at say 80% of max current.