Construction and evaluation of chemical structure model of Huolinhe lignite using molecular modeling

Molecular model construction plays an important role in gaining insight into the thermal conversion process and reaction mechanism of lignite. Based on element analysis, solid-state ¹³C nuclear magnetic resonance (¹³C NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR), a Huolinhe (HLH) lignite two dimensional (2D) molecular model was initially constructed. Concentrations of main covalent bonds were employed to adjust and examine the molecular model. The advantage of this approach is not only that it can solve the problem of selecting a representative isomer in constructing the model but also that it considers the essence of chemical reaction. The three dimensional (3D) minimum energy configuration was obtained by molecular mechanics (MM) and molecular dynamics (MD) calculation in Materials Studio package (Accelrys). Finally, the sequence of bond-cleavage from DTG analysis and molecular simulations were used to verify the rationality of proposed model. In general, this work has opened pathways in studying the lignite thermal reaction process at the molecular scale.