What Is a Titanium Reactor? Materials, Design & Applications Answering the core question: What is a titanium reactor, and why does it survive chloride and acid environments that destroy stainless steel? A titanium reactor is a vessel built from commercially pure (Grade 2) or alloyed (Grade 5, Ti-6Al-4V) titanium whose surface forms a self-healing TiO2 passive film just 1-10 nm thick. That film resists pitting in chloride concentrations above 20,000 ppm and in oxidizing acids