FYI, LH has a nice list of lounges available on their site and you can choose the city and "Star Gold" for the lounge list.

For Beijing they only list the Air China Biz & First lounge, which is "Terminal 2, Restricted area, departure level ( 2nd floor ) oppsite to main airport duty free shop".

I've only flown into PEK, not out of there yet, but after being in some of the business/first lounges I've seen at smaller domestic airports so far in China (KMG, SHA, etc) I'm fully prepared to be underwhelmed.

I'll be on UA 850 PEK-ORD on Sat 4 June. PM me if you're on that flight and want to meet up in the lounge