Construction and optimization of molecular multidimensional model of Changqing petroleum residue

Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) are used to characterize the chemical structure of Changqing petroleum residue molecules, and the average molecular structure is established. The vibrational frequency of the average molecular structure is calculated by the channel to obtain the calculated infrared spectrum, which verifies the rationality of the model. The density at the lowest energy of the system is obtained by molecular dynamics (MD) simulation. The number of aromatic carbon atoms in the molecular structure reach 60% by fitting the peaks of the infrared spectrum, and the length of the aliphatic hydrocarbon chain is calculated from the content ratio of CH3/CH2 to be 0.718. Oxygen-containing functional groups include hydroxyl, carbonyl, carboxyl and ether bonds; nitrogen elements exist in the form of primary amines, pyridines and pyrroles. Finally, a relatively reasonable two-dimensional molecular structure is constructed, and the molecular formula is C223H237O19N3. Put 20 optimized molecules (49.7 × 49.7 × 49.7Å3) into the periodic box, and through molecular dynamics simulation, the density of the lowest point of total potential energy is obtained as 0.85 g/cm3.