As stated above - 2 15a 120v outlets would combine to a 15a 240v outlet.
But, for everyones safety, if you must do it, use a quick220 device or get with the landlord about authorizing you to hire an electrician and modifying the property. if it is near the breaker box it might now cost much money.
If anyone (landlord, their designee, family, friend) pulled out one of the plugs in the self made rig and was electrocuted it would be much bigger problems financially and mentally.