Is there a way to track a stolen iPhone using the IMEI?

Sorry, but no, you cannot track it by IMEI. And since the phone has already been removed the phone from your account, you can't track it at all. The only way it could have been removed is if:

Whoever took your phone knew your Passcode, Apple ID and Password

Find My was not enabled before it went missing

If your phone was removed from your Apple ID, either you did not have a passcode on the phone, or you provided your personal information to the person who had your phone, likely in an email or message. Or, stated another way.....you were scammed.

Apple does not use IMEI to track the phone because the information is not all that reliable., but your carrier does use this information to track cell phone tower use.

The downside.......you will need a court order to obtain this information from your carrier.

It's a pretty simple process:

• Turn on Find My
• Back up your phone. Cannot be done after it is stolen. It is set by default to backup, so you would need to have turned that off yourself.
• Don't give out your Passcode/Password

Just by following those 3 things, all your data is safe and you will be able to track your device. No one will be able to get into your phone and no one will be able to remove your phone from your Apple ID. You will find that Apple cares deeply about protecting users data and offers many tools to do that, but you just need to use them.