What is the maximum baud rate that ADM2587EBRWZ can use with RS422?

Maximum baud rate with ADM2587EBRWZ is 500,000 baud. 115,200 baud is supported, over a cable length of up to 1.2 kilometers. 

The same is true for the ADM2563E, which features significant improvements over the ADM2587E in ESD and noise immunity, footprint, temperature range. 

https://www.analog.com/en/products/adm2563e.html

Regards,

Neil