Bologna hotel recommendations

https://www.allegroitalia.it/en/espresso-bologna-3/

This modern hotel is part of a moderate-priced Italian chain. The central train station is a long block away and it faces the bus terminal. It's an easy walk to the central plazas of Bologna. Decent buffet breakfast; small lobby bar open late.
For more choices, try Google Maps. Put in the train station name and hit Nearby to find adjacent hotels. You do want to be on the city side of the train station. Also the shuttle to the airport has a main stop at the station.

Historic city center, Hotel Novecento, wonderful place and location.

Nothing is going to be close to both the train station and the city center, as they're too far apart.

If your budget can allow it, I had a lovely stay at the Art Hotel Commercianti: https://en.art-hotel-commercianti.com/ To get from there to the train station, I took a taxi or bus (both easy).

As Harold mentioned, the hotel and Centro Storico are not convenient to each other. Jump into a cab at the station and the Centro is about €7. My partner and I stayed at Albergo Centrale Bologna, which is in the center. It was inexpensive, convenient to all sites had a decent buffet breakfast and my room was good sized, quiet and clean. I would definitely stay there again on another visit. It's classified as a two star hotel but we could not understand it not being a three star. It was superior than some three star properties that we have stayed at in Italy.

I very much enjoyed my time in Bologna but, I've dropped the Albergo Centrale from my list of places to stay.

While I did not have any problems with my stay, I had recommended the place to some close friends, in which they had an incident where they caught a maid riffling through their bags. They stepped-out of the hotel but, upon hitting the streets, she realized she forgot her packable shopping bag. They turn around and go back up to their room, upon entering there was a housekeeper with a guilty look on her face; door was not propped open, nor was there a cleaning supply trolley outside. Asking what she was doing there (at 5pm) she replied she was dropping off some towels. Friend goes to her bag to retrieve her shopping bag and notices the purchased ornaments that were wrapped-up in paper and taped-up, had been opened and appeared to have been hurriedly wrapped back up.

They reported the incident to the front desk and the person shrugged it off as a misunderstanding she was delivering 'complementary towels'. They checked-out and found another location, no effort made by the hotel to remedy the situation. They surmised the front desk clerk was in cahoots with the housekeeper.

Not sure if this is the location you desire but we stayed at Hotel Corona D'Oro and it was awesome.

Thanks to all for youre suggestions!