Zakah has its own due recipients and all those recipients are clarified in the Qur’an. The one who pays the zakah does not have the right to stipulate that it should be spent in a certain way. The spending of zakah money here is left to those who run the institutions which receive the zakah money and their estimation to what they think will be for the good of their society.
The European Council for Fatwa and Research, states the following: One should look into the matter as follows: What can be distinguished as obligatory zakah should be distributed according to the instructions given in the following Qur’anic verse: (The alms are only for the poor and the needy, and those who collect them, and those whose hearts are to be reconciled, and to free the captives and the debtors, and for the cause of Allah, and (for) the wayfarers; a duty imposed by Allah. Allah is knower, Wise.) (At-Tawbah 9: 60)

The payer of zakah does not have the right to stipulate that it should be spent in a specific way.
Those who run these institutions shall dispose of this portion of the fund in the way mentioned in the above verse and according to what they think will be for the good of their society. What is not distinguished as obligatory zakah must have been intended to be spent on the particular project that the donor was asked to donate for. In this case the donor is a waqif (giver of an endowment), and the condition of the waqif should be observed and the fund should be spent the way he or she had indicated. Therefore, if the donor is identified and can be asked for permission, the duty is to do so. If this is impossible, but it is possible to secure the permission of the group of donors—similar to the funds collected from the worshipers in the mosques, for example—let it be done. If none of these alternatives is possible, there is then no objection to spending the fund on a project similar to the one for which it was collected. The leading principle in all that is the saying of Allah Almighty, (So keep your duty to Allah as best ye can) (At-Tagabun 64:16).