DFT and canonical ensemble investigations on the thermodynamic properties of Syngas and natural gas/Syngas mixtures

Density Functional Theory and canonical ensemble were used to investigate thermodynamic properties of Syngas and its mixture with natural gas. The following thermodynamic potentials were obtained: internal energy, enthalpy, entropy and Gibbs free energy for temperatures ranging from 0.5 K to 1500 K. It was observed that CO and H2 were the most stable Syngas components, possessing the ability to render Syngas less favorable to the temperature increase. Also, we verified that Syngas presents properties similar to an antiknock agent for natural gas, raising its resistance to temperature increases. Were determined the Poisson coefficients and Bulk modulus for Natural gas/Syngas mixtures and Shomate equation coefficients for some Syngas types, providing a more complete thermodynamic description for these gases. Additionally, thermodynamic potentials of combustion for Natural gas/Syngas mixtures were predicted, showing that this biofuel can reduce the calorific power of natural gas and makes its combustion less favorable due its antiknock behavior. However, a mixture with 30% of Syngas may be useful for natural gas combustion, since it present a calorific power between 73.41% and 79.49% of that of natural gas, which is a substantial fraction of energy released during combustion, showing good future prospects to the Natural gas/Syngas mixture to the renewable energy generation.