Connecting time needed at PEK?

My daughter and I are looking to fly from UK (Heathrow) to Hong Kong, with a stop over in PEK, it is my first time arriving at PEK airport, there is 90 minutes connecting time to the flight to Hong Kong, I was wondering if it is enough?

Or maybe I should book the flight with 150 minutes connecting time instead to allow more time in events of delays?