An interesting page here. What did Thomas know about Islam? There are two specific references in his works. One at the beginning of Summa contra gentiles, written for Dominicans who were going to preach in Muslim territories, the other, De rationibus fidei contra Saracenos, Graecos et Armenos ad Cantorem Antiochenum*, where Thomas considers the main objections which Muslims make to the Catholic Faith, such as the possibility of the Trinity and of the Incarnation, the wisdom of the Crucifixion and human liberty before divine predestination.
There are some interesting summaries of which Islamic philosophers and which of their works are mentioned by Thomas, and which of their works he appears not to have known.
See also Joseph Kenny's website here. Many translations of Aquinas.
*Now in parallel Latin-English at the Logic Museum.