Adsorption of Prototypical Asphaltenes on Silica: First-Principles DFT Simulations Including Dispersion Corrections

Abstract

In this work, we explore the interaction between some prototypical asphaltene and porphyrin molecules with a fully hydroxylated (0001) surface of α-quartz by means of theoretical calculations based on the density functional theory (DFT) under periodic boundary conditions. The influence of dispersion forces, adsorption geometries, and size of the side chain is analyzed. The inclusion of London dispersion forces is overriding as they increase the interaction by about 1 order of magnitude. All of the considered molecules strongly interact with the hydroxylated surface and prefer to adsorb in a parallel position instead of vertically. It is also found that adsorption energy always increases with larger side chains because dispersion interactions also augment. Interestingly, in the case of porphyrin, the less stable isomer in the gas phase is the preferred one after adsorption, which is substantiated by a differential stabilization induced by the surface. Finally, we present a comparative study of the adsorption of these model molecules in terms of energy per area unit and energy per interacting π electron.

Advances and Challenges in the Molecular Characterization of Petroporphyrins

“…141,144,145 Several studies have focused on the interaction between metalloporphyrins and solid surfaces. [146][147][148] Adsorption onto surfaces is either undesirable due to side effects on the whole production chain or required for the formation of sieves or traps of metal compounds. These calculations implement periodic DFT calculations.…”

The Application of Quantum Mechanics in Reactivity of Molecules

“…In this work, the authors used molecular and PDFT simulations with GGA-PW91 [59] functional to optimize the adsorption geometries of various asymmetric meso-substituted porphyrins on TiO 2 and determine their electronic properties. While TiO is the extensively used oxide support for many PDFT simulations involving porphyrin binding, supports like ZnO [125] and SiO 2 [126] are also studied. In the case of ZnO, the support was used as an alternative for TiO in dye sensitized solarcells and PDFT calculations were used to understand the charge transfer characteristics.…”

“…In the case of ZnO, the support was used as an alternative for TiO in dye sensitized solarcells and PDFT calculations were used to understand the charge transfer characteristics. SiO 2 -porphyrin [126] studies are used to determine the binding strength for porphyrins to SiO 2 support for application as a trapping agent in petroleum industry.…”

Structure, Properties, and Reactivity of Porphyrins on Surfaces and Nanostructures with Periodic DFT Calculations

“…In this work, the authors used molecular and PDFT simulations with GGA-PW91 [59] functional to optimize the adsorption geometries of various asymmetric meso-substituted porphyrins on TiO 2 and determine their electronic properties. While TiO 2 is the extensively used oxide support for many PDFT simulations involving porphyrin binding, supports like ZnO [125] and SiO 2 [126] are also studied. In the case of ZnO, the support was used as an alternative for TiO 2 in dye sensitized solarcells and PDFT calculations were used to understand the charge transfer characteristics.…”

“…In the case of ZnO, the support was used as an alternative for TiO 2 in dye sensitized solarcells and PDFT calculations were used to understand the charge transfer characteristics. SiO 2 -porphyrin [126] studies are used to determine the binding strength for porphyrins to SiO 2 support for application as a trapping agent in petroleum industry.…”