The Blues keeper, who was making his third appearance since moving to Coventry on an initial one month loan deal on 16th February, was dismissed by referee Jarnail Singh for a deliberate handball outside the penalty area four minutes before half time during the game between the two sides at Highfield Road last saturday.
Sky Blues boss Micky Adams had no goalkeeper on the bench and so midfielder Stephen Hughes took over between the sticks and Coventry held out for a 0-0 draw against the Potters.
After studying video evidence of the game, Coventry appealed the decision claiming that Benno was not denying Stoke a clear goalscoring opportunity.
However, the FA have deemed that Benno's handball was a "denial of an obvious goal scoring opportunity" and he now faces an automatic one game suspension for the red card offence.
Benno will miss Coventry's next game against Watford at Vicarage Road this weekend.