Activation of desulfurization and denitrogenation processes using substituted Cu (100) stepped surfaces as potential adsorbent: Ab Initio and MD Investigations

This study employs first-principles calculations based on density functional theory (DFT) and reactive molecular dynamics (ReaxFF) to explore the trapping mechanisms of sulfur and nitrogen compounds in thiophene (C4H4S) and pyridine (C5H5N) molecules, respectively, via adsorption on substituted Cu (100) stepped surfaces. Through a comprehensive analysis using DFT and MD simulations, we delve into various critical aspects, including interaction energies, charge transfers, changes in electron density, the influence of water molecules on adsorption, and the regeneration capacity of adsorbents. Further, we employed these methods to evaluate the adsorption behavior of thiophene and pyridine molecules on Pt/Rh-doped Cu (100) stepped surfaces.
To summarize the preference of adsorption, we found that the Cu (100) stepped surface exhibits a stronger inclination towards thiophene compared to pyridine. In contrast, Pt–Cu and Rh–Cu surfaces exhibit higher pyridine adsorption compared to thiophene, with pyridine being notably more favored on the Rh–Cu surface by approximately 62 kJ/mol. This highlights the superior detection capability of pyridine over thiophene. As for regeneration capacity, our investigation suggests that nearly all studied surfaces possess a significant capacity for regeneration. Furthermore, results from MD simulations in combination with the potential of mean force (PMF) simulations at 300 K, aligned with DFT calculations, confirmed the adsorption configurations of thiophene and pyridine. This analysis demonstrated the competitive advantage of thiophene over pyridine in adsorption and highlighted the inhibitory effect of water on pyridine adsorption on the Cu (100) surface.
In real applications, the Cu (100) stepped surface has the potential to serve as an efficient adsorbent and suitable material to facilitate the desulfurization and denitrogenation processes.

Audience Take Away Notes: 

• Understand how sulfur and nitrogen compounds in thiophene and pyridine molecules interact with substituted Cu (100) stepped surfaces
• By understanding the interaction mechanisms and the effect of doping, researchers and engineers can design catalysts with improved efficiency and selectivity for trapping sulfur and nitrogen compounds
• The detailed explanation of DFT and ReaxFF techniques will enable researchers to apply these methodologies to other molecular systems and adsorption problems
• Academics and industrial researchers can adopt and adapt the advanced simulation techniques presented, leading to more robust and accurate research outcomes
• The research opens pathways for innovative catalytic systems that can be applied in different industrial contexts, from refining to pollution control