In the name of Allah, the most compassionate, the most merciful
According to Shia Islam, it is not Haram or impermissible to sell alcohol for industrial purposes. So, totally, there are diverse kinds of alcohols, therefore it depends upon its kind which would be deemed as the haram one or the halal one (which can have positive and permissible using such as industrial using...).
شیخ انصاری، مکاسب، ص 3، سطر 23; (Sheikh Ansari, Makaseb, pg.3, line23)
As well as this, to the best of my knowledge if I'm not mistaken -- concerning the last part of the query --, the sort of alcohol in the Urf (custom) can be effective too. Namely, e.g. if X-alcohol in the custom is not famous as drinkable alcohol (albeit rarely someones drink it) but is well-known for its industrial consumption not as a normal drinkable alcohol, subsequently (AFAIR) it would be permissible to deal ... and vice versa.
Let's elucidate the issue with giving an short/simple example; and it'll be more clarified for you if you adopt the previous illustration with the following example: e.g., the fruit "X" is sold/bought as a normal fruit, but its leaf doesn't normally/customarily have interchange (albeit can be eatable in specific circumstances...). So, the issue of industrial/drinkable alcohol can be adopted with such example, namely the custom is significant in its circumstances about its impressibility or ...