If you want to run off 24V, yet interface with an ADC, then you don't need a rail-to-rail op-amp, just one which will operate at the negative rail. There are plenty of op-amps which will do this and have a low offset voltage, which I presume is important: OPA234, LT1006, LT1013. If all you need is something cheap, then there's LM358 but the offset voltagemay be too high for your application.