Thanks for thinking about recycling this rather than just doing the easy thing and putting it in the landfill. You could try searching for a metal recycler near you. If they pay you, it might not be a lot, but it would be better than just the landfill. I'd urge people to consider doing this even if they don't pay you, because ti is a useful metal. For example, Leder Brothers is near where I live in the United States, and they say they will purchase scrap titanium (and other specialty metals.)
I'm not sure exactly what keywords to use, however. On Google Maps, the business type for Leder Bros was "Recycling center." "Scrap metal recycling" may also show results. I'm not sure if all metal recyclers will take titanium.
Ti wasn't listed on the website of one other metal recycler I visited, but this one did list Ti. See the other answer for a German term to use, as the OP is likely from Germany.
I should point out one thing - you asked the frame manufacturer about repair options, but I am not sure how many frame manufacturers are set up to repair Ti frames, and bike shops might not know about Ti frame repairers. Single builders might consider it. Ticycles.com explicitly offers repair services. It might still not be economical to repair, but it's something you could consider in addition to trying to recycle.