I recently purchased a surface mounted motion detector porch light for my front porch. I currently have a recessed porch light. I have tried finding deep boxes that will allow me to mount this light but I am having no luck.I purchased a box, although it is more for hollow walls and is not even big enough in diameter, nor deep enough.

Can anybody help me with this???

Look for something called a "plaster ring", a "mud ring", or most correctly, an "extension ring". This is a box designed for just this problem.

It's basically a standard size electrical box, except without a back (so it looks like a empty ring). They are designed so you just screw them down onto the existing box, and they extend it out to be flush with the wall. Then you can attach your regular fixture, cover plate, etc. onto the extended box.

They are available at any well-stocked hardware store. When you go to the store, you will need to know the size & shape of the existing box in the wall (4" square, octagon, single-gang outlet, etc. -- taking a life-size tracing of the existing box to the store is real helpful), and you need to know the depth of the existing box in the wall -- how much extension do you need to bring it out flush with the wall.

This is a real common thing in redoing house wiring, and easy to handle.