There are programs and online services that could convert the PDFs to images or other formats. I don’t know if any specifically designed to do this security purposes.
I don’t know if this is a possibility in your environment, but since the exploits are almost all for Adobe Reader, what about just standardizing on a different PDF viewer for users’ desktops? One with a minimum of features should be less vulnerable to attack.
What happens if a user downloads a malicious PDF from a website?