Eligible for 72h visa? BCN-PEK-HKG-PEK-BCN

Hello
I have booked a roundtrip ticket from Barcelona to Beijing and also am in the process of getting a one-entry China visa. However, it just came up that I need to be in Hong Kong for a few days. Since I must enter China twice but only applied for a one entry visa my question is if i somehow can i make use of the 72/144 hour twov on either:

BCN-PEK-HKG
or
HKG-PEK-BCN

for the first or second entry to Beijing.

Thanks a lot for your help

PS: I am German, living in Spain.