Answer:

The three chemical bonds in the exhaust gas are: CC Large π bond (bond energy 607. 0kJ / mol) and CH bond (bond energy 347.9 kJ / mol), UV photolysis of photon energy is sufficient to completely decompose them. Exhaust gas removal rate is related to many factors such as the concentration of waste gas, gas flow rate, and oxygen concentration, humidity and so on. It is easy to make the removal rate reach more than 95% with suitable debug. 

In practical application, the purification rate of benzene can reach more than 90%, toluene is generally about 80%, and xylene is about 70%. The difference between the three is determined by the total energy and the probability of breaking the methyl group.