Loads of sympathy Lorien - my two are 22 mnths age gap, and I shudder to remember that period when the baby starts to get mobile.
We didn't do "special toys", though some friends did with success. Other people encouraged the older child to play at the table, in their room, or even in a playpen so as to have space not to be molested by the baby brother.
I think it's vital to have a zero tolerance of aggression at this stage, though it is very hard as he is so young. Do keep on with time-outs. But can you do some positive encouragement as well? Start by aiming really, really low: "If you are nice and kind to your brother for the next 5 minutes, then: you can watch your favourite video/I'll take you to the park/you can have a sticker, or whatever". Children this young often do respond well to a very simple sticker chart. Once he gets the hang of it, extend the target time. Above all, try and catch him being good, and praise him and reward him immensely.
I don't think I was particularly good at this at this stage, because I just feel so much sympathy for the elder child who has their privacy invaded by this little beast, who can't communicate with language, but shoves, pushes, and snatches ... and it's the elder one who's in trouble when they shove back!
IME this stage lasted about a year - sorry! But once the baby started talking it got a lot better.
Anyway, to end on a happy note - my two are now 4 and 6, and love being with one another now, and play together really nicely. IMO you're in the worst stage at the moment, for this age-gap. You've just got to get through it! Good luck!