A quick answer... yes, you can, but I think poswdered sugar has a little bit of corn
starch in it, to make it light and fluffy as opposed to the heavier texture of granulated sugar, so you have to use more of the confectioners.
Try using almost twice as much than the granulated called for in the recipe. I'd start with 1/3 cup if your recipe lists 1/4 cup granulated, then add more if you don't mind it a tiny bit sweeter. Or better yet, if you have a kitchen scale, weigh it. Then you'll be sure you have the right amount of sugar. Oh, but you don't have granulated sugar to compare it to - so I guess that won't work for you now, but maybe in the future.
I doubt if you'll come out it a different texture for the bread, especially if your recipe has yeast in it. I've done it in a pinch and have never noticed a difference.