The maximum is €250 per payment between friends or €500 per payment to a retailer.
In addition to these minimum and maximum amounts, a daily maximum has also been put in place for every card linked to the Bancontact app: you can make payments of a maximum of €500 (€250 for payments between friends) and receive €500 per day and per card.
The total amount for all transactions with all cards in the app is also limited to a maximum of €500 for payments (max. €250 for payments between friends) and amounts received per day. These limits apply without prejudice to your bank card limits.
https://www.bancontact.com/en/faq/can-i-make-a-payment-or-receive-money-with-the-app-for-any-amount