In this study, catalyst of rutile titanium dioxide nanoparticles (rTiO2-NP) has been investigated for the removal and reduction of unburned hydrocarbons as benzopyran. To evaluate and calculate the thermodynamic properties of this aim, pollutants are closed to the nanoparticles and converted them into other products and the carbon dioxide molecules are simulated in the 12th steps. The geometrical structure of all stages is optimized by Density Functional Theory (DFT) method based on B3LYP/6-31G. The structure of rutile titanium dioxide nanoparticles, there are several different locations on it as the cross bridge Ti-O and Ti-Ti, the thermodynamic properties of these conversions and locations are calculated by a semi empirical method (ZINDO/S). The results shown these interactions are exothermic and spontaneous. The total energy (kcal/mol) for conversion benzopyran on Ti-O bond is lower than Ti-Ti bond. Therefore the probability of interaction with Ti-O is more. This phenomenon dramatically increases the electrical conductivity of the nano-particles, suggesting that the rTiO2-NP may be potential sensor for benzopyran gaseous molecule detection.