Vietnam to Beijing to Canada

We are Canadians currently working in Beijing under a Z Chinese visa. But we are planning on leaving Beijing to travel to South East Asia in a few months, causing us to cancel our Work Z. We are leaving some luggage in Beijing while we go traveling. Causing us to come back through Beijing on a flight from Vietnam to collect our luggage, then getting on a flight from Beijing back to Canada the next day. Are we still able to use the 72-hour free transit?