Where can I find the "10 merits of life liberation" in the Tripitaka? I searched, but I couldn't find, where these "10 merits of life liberation" are included in the Tripitaka.

Here you can find the "10 merits" I mentioned: Why do Buddhists practise life liberation?

There is also a Pali verse I found about this, but it's not in English, and also I don't study Buddhism in English normally -- so'll be thankful if anyone can point out where it is in the tripitaka.

I guess it may be in the therapadana part, according to that Pali verse -- I can't write it clearly in English letters as I found it only in Sinhala letters, but nearly it's like this:


  abhayadanan dhatwana - jaththuno bhayajjite
  dasanisanse anubhomi - kammanuchchawike mama
This is a bit delicate, because the list of ten you have mentioned includes statements such as:


  
  One will have abundant offsprings for future generations.
  One will easily attain what one wishes.
  


With #4, since monastics are generally celibate as part of the Vinaya, there would be no "abundant offspring" in the literal sense. Perhaps in the spiritual sense would might have "offspring", but with the wording, that would be a bit of a stretch.

With #5, this also a bit in contradiction with all the suttas such as SN12.23 that clearly state that craving leads to suffering. Wishing is a tricky word to use. One might wish for a Ferrari or one might wish for a spiritual path. 

Compare your referenced list of ten with a list of ten from the DN33 sutta:


  A mendicant has given up five factors, possesses six factors, has a single guard, has four supports, has eliminated idiosyncratic interpretations of the truth, has totally given up searching, has unsullied intentions, has stilled the physical process, and is well freed in mind and well freed by wisdom.


Indeed, why would a Liberated One wish for anything? Grasping a wish, one searches for the fulfillment of that wish. And above we have clearly stated that there is no more searching.

Note, that one might argue that the list you've quoted is a list for lay practitioners. However even here, we have AN8.61 with Ugga the Householder happily choosing celibacy:


  I’ve undertaken the five training rules with celibacy as fifth


I would recommend reading AN8.61 yourself to understand how far the list you have linked differs from what the Pali Canon shows in the suttas.

When lay instructions differ from monastic instructions it is always good to understand the differences so that we our practice progress rather than regresses. 

Advantage #5 is very close to the following quote from DN33. Yet the following quote provides more context. One must be ethical and pure.


  The heart’s wish of an ethical person succeeds because of their purity.


This is a very important consideration. When we live by violence, that is impure. WHen we give fearlessness, we are being ethical. So item #5 should be read in the context of being ethical. It does not stand alone.

DN33 goes on to say:


  If only, when my body breaks up, after death, I would be reborn in the company of well-to-do aristocrats or brahmins or householders!


So yes, in the context of Right View, one will easily attain what one wishes simply because what one wishes for is Right. This is where the precepts come in for lay practitioners:


  It’s when a noble disciple doesn’t kill living creatures, steal, commit sexual misconduct, lie, or use alcoholic drinks that cause negligence
  --an5.179


The following warning from DN33 also indicates that being rich, young and healthy and having abundant offspring is a temporary condition with uncertain outcome. One must focus on Right View:


  It is not because of endowment with family, wealth, or health that sentient beings, when their body breaks up, after death, are reborn in a good place, a heavenly realm.
  It is because of endowment with ethics or view that sentient beings, when their body breaks up, after death, are reborn in a good place, a heavenly realm.


The list of 10 therefore does have concrete roots in the suttas. The suttas mostly deal with monastic study. They do also have instruction for lay practitioners. The lay instructions are usually quite terse and somewhat restrictive. Indeed, many lay practitioners would have trouble following the first five precepts (e.g., avoid alchohol?). Because of this, one might list out the advantages of following the first five precepts. I believe the list you have referenced is one such list. It is a list of advantages to be gained from following the path of:


Right View
Right Thought
Right Speech
Right Action
Right Livelihood
Right Effort
Right Mindfulness
Right Immersion