Chef and Foreman

Sorry I'm a newbie. I want to use Foreman to manage Chef. Is it possible
to install Foreman without puppet? Should Foreman be on a different server
then my Chef server?

As I run my environments with Puppet, I only can say this from experience
of a colleague trying to run Foreman without Puppet and only Ansible: No,
completly without Puppet will not work, using the foreman-installer (which
utilizes Puppet) gives you the best installation experience, Puppet can not
be removed from the GUI, but you should be able to add Chef and use this as
your choice of configuration management solution.