Question: acids which do not contain hydrogen?
Answer: From the Lewis theory, one can see that it is not necessary for an acid to have any protons, strictly speaking. The boron halides BF3, BCl3, BBr3, and BI3 are all Lewis acids and do not contain hydrogen. AlCl3 and AlBr3 are also common Lewis Acids used in Friedel-Crafts chemistry and do not contain hydrogen.