It's been done before, (mostly by countries that had no other options, ie. Imperial Japan, Nazi Germany and apartheid era South Africa), and in most cases was abandoned very quickly because it was not cost competitive. It's still not. That, and the fact that it's an environmental nightmare, is why it's still not in widespread use. Heck, if it were at all profitable China, with it's massive coal reserves and scant supplies of oil, would be all over it.
The patents are mostly expired now and the process is well understood. If there really is any money in it you should get together a group of investors. With the world demand for oil you'll be the next Bill Gates.