8yo constantly hurting younger brother

My 8 year old is autistic and is so aggressive to his 2 year old brother I just don't know how to deal with it anymore. This break from school has had me at breaking point I have to try and keep them separated at all times. He will hit/kick/push him just for going near him. He screams at him and my 2yo is really quite scared of him now.

No punishments have worked and i really don't know what to do but we can't carry on as we are. Has anyone been in a similar situation who can advise me what to do from here?