PS/2 keyboard with RS232 (DB9) workstation port
That PS/2 to serial adapter is meant only for mice that already have support for both PS/2 and RS232 interfaces built in, so the adapter only needs to connect correct wires to correct pins, so it does no signal conversion.
There is no way such an adapter or equivalent cabling can work with your PS/2 keyboard which has no built-in support for RS232 interface.