Does anyone know if we can use this power supply PW48V-12V85W to convert a 2116 to DC power?
The original AC one should be this one:
https://mikrotik.com/product/up1302c_12
with 10.8 A @12 V it is much more powerful than the 7 A @12V of the PW48V-12V85W, though the 7x12=84 W (or 85 ) are just the same as the max 83W of the CCR 2116:
https://mikrotik.com/product/ccr2116_12g_4splus#fndtn-specifications
Hard to say if the AC power supply is actually oversized and the 48 V one is just right.
Since the 2116 is not a cheap, entry level router, I presume that it will be used in a professional environment, I would ask for an official statement by Mikrotik support and/or local distributor as replacing the PSU with another one might affect the warranty and/or safety of the device.
Yes, we use these in the 2116
Just to confirm your answer, you were able to use the 48V inside the CCR2116-12G-4S?
Yes, the PW48V-12V85W works electrically and people are using it with the CCR2116, but it provides less current than the original PSU. It is likely fine under normal load, but there is less headroom. For production use, confirm with MikroTik or your distributor since swapping the PSU can affect warranty and long term reliability.