Q: Can I buy a T10 ticket at the RENFE train station at T1 ?
A: No. There is no RENFE train stop at Terminal 1 at Barcelona Airport (El Prat de Llobregat). You would need to transfer from Terminal 1 to Terminal 2B using the free airport shuttle bus. You would then be able to buy the T10 ticket from the RENFE train stop at Terminal 2.
The following links will help you plan your journey