Can we print SAP spool into PDF format?

Yes, you can print SAP spool into PDF format by using report RSTXPDFT4.  Just create a spool request for any printer, even if it is dummy.

Now do the following:
1. Go to transaction SE38, fill with RSTXPDFT4 then execute.
2. In the first screen give the spool request number, you will get the spool request number in transaction SP01. And then enter the filename of the pdf you want it to be downloaded as.
3. Save it to your desktop and view it as a pdf.