The passport of Satam al Suqami who was on American Airlines flight 11 was recovered. From the 9-11 Commission report
The passport was recovered by NYPD Detective Yuk H. Chin from a male passerby in a business suit, about 30 years old. The passerby left before being identified, while debris was falling from WTC 2. The tower collapsed shortly afterwards. The detective then gave the passport to the FBI on 9/11.
This is found in endnote 109 on page 40 of this document.
This would suggest that the passport was blown out of the building and was found on the street.
As for the claim that nothing else of the planes content was recovered:
Photographic evidence of two men examining a seat cushion from flight 11.
To counter the argument that papers from the plane couldn't have survived here is a story from the NY Times about a letter that survived.
I doubt that will settle it with your friend but it might be a good place to start. For more debunking check out this site.