both mine were also 6 months when they could reliably get past 45 mins. the good thing was that they could go to sleep on their own at the start of the nap. for us it was the transition that was the problem. sometimes just putting a hand on them would work other times I would need to pick up for a couple of minutes and put back down other times they just woke up.
that's not to say that yours will take that long. working on them being able to go to sleep independently at the outset is the first step!!