Not in the hands of an experienced chemist, the yield depends mostly on how good the aspiring chemist is when it comes to crystallize the oil to a yellow mass. I'd say evaporate all the solvent under vacuum, and shake the remaining oil with water to dissolve any remaining catalyst, and if the nitropropene crystals does not form right away, then just put the washed organic solution in the freezer until crystals form (perhaps with scraping the sides of the beaker with a glass rod). Then recrystallize the yellow mass from a minimum amount of boiling methanol or IPA, and chill in the freezer before filtering and drying. The recrystallization greatly improves the ability to store the nitropropene without decomposition, and it also removes any water from the mix. The resulting crystals should look like frozen white whine afterwards (very light yellow).
Please get back to us with a detailed lab report when you're done.