Preliminary expenses are which account?

Ideally preliminary expenses (I assume you mean start-up or pre-operating costs) should be expensed as incurred as per IAS 38.69.

In case you are not reporting as per IFRS it is a Real account.

Good day!

The benefit  of preliminary expenses is long term so it is treated as intangible asset and are shown in balance sheet.. So the correct account is Real account.

As per IAS- Nominal Account.