Can my family and I travel on a 72hr or 144 hr visa free transit

We are UAE residents (expat) flying from Abu Dhabi to Hong Kong for 6 days, from Hong Kong we fly to Chengdu for 3 days and then return to Abu Dhabi. we are taking a one way ticket with internal airline from HK to Chengdu.

We fly to Chengdu from Hong Kong on 26th October 1350hrs arrive (air china) one way, and fly out 29th 2105hrs from Chengdu (Etihad) back to UAE.
would we be eligible for 72hr free transit.
British passport holders.
thank you
Sam