Reductive Gaseous (H₂/NH₃) Desulfurization and Gasification of High-Sulfur Petroleum Coke via Reactive Force Field Molecular Dynamics Simulations

Abstract

The use of high-sulfur petroleum coke (petcoke) as raw material in the carbon industry requires an effective desulfurization process. Hydrodesulfurization (HDS) and NH 3 gaseous desulfurization are the most effective approaches. However, the S/N removal and the gasification ability of HDS and NH 3 desulfurization have not been well-explored. Here, petcoke transitions were examined using the reactive force field simulation approach at a constant volume and temperature (3000 K for 250 ps). The S/N removal and transformations in HDS were thiophenic S → C 1−4 S, H 1−2 S → H 2 S, and pyrrolic and pyridinic N → C 1−4 N → HCN. Given the large H 2 production from NH 3 decomposition, the S/N removal and transformations in NH 3 desulfurization were similar to those of HDS. However, NH compounds (NH 3 ) directly bonded with C atoms in petcoke, adding to the coke yield but adding an additional heteroatom challenge with utilization after NH 3 desulfurization. Produced C 1−4 N (CN, mostly) and H 2 were transformed into H x C 1−4 N (0 < x < 5). The final stable gaseous compounds were HCN and H 2 S. For NH 3 treatment, some NH compounds bonded with C atoms, resulting in an increased N content after NH 3 desulfurization (higher coke yield compared to HDS).

Structural Evolution of High-Rank Coals during Coalification and Graphitization: X-ray Diffraction, Raman Spectroscopy, High-Resolution Transmission Electron Microscopy, and Reactive Force Field Molecular Dynamics Simulation Study

“…The ReaxFF is a bond-order based empirical potential, which can describe the bond formation and dissociation of molecules during the simulations. The detailed description of potential functions of ReaxFF can be found in ref , which has been progressively improved by incorporating parameter sets and successfully applied to the combustion, oxidation, and pyrolysis of hydrocarbons, − formation of C black and soot nanoparticle during the acetylene pyrolysis and fuel combustion, , and carbonization process of hydrocarbons and polymers. − In the present study, the newly developed ReaxFF referred to as CHON-2019 was used, which has simulated the carbonization process of raw polymer precursors …”

Investigation of Petroleum Coke Gasification with CO2/H2O Mixtures and S/N Removal Mechanism via ReaxFF MD Simulation

“…Petroleum coke (petcoke) is a valuable oil refinery product derived from delayed coking of carbon–hydrogen compounds (such as petroleum asphalt and residual oil). As fuel, it is competitive because of the price advantage, extraordinary heat value (30.25–34.91 MJ/kg), high carbon (>80 wt %), and low ash (<1.5 wt %) content. − Nonetheless, due to the continuous decline in crude oil quality in recent years, petcoke high in S (>4 wt %) and N (∼1 wt %) content gradually dominates in the application of petcoke. − The extensive S and N elements in these petcoke are attributed to a large quantity of SO x and NO x emission and can aggravate environmental pollution . As a result, the direct energy use of petcoke is doomed.…”

“… 1 − 3 Nonetheless, due to the continuous decline in crude oil quality in recent years, petcoke high in S (>4 wt %) and N (∼1 wt %) content gradually dominates in the application of petcoke. 4 − 6 The extensive S and N elements in these petcoke are attributed to a large quantity of SO x and NO x emission and can aggravate environmental pollution. 7 As a result, the direct energy use of petcoke is doomed.…”

The Effects of Physical-Chemical Evolution of High-Sulfur Petroleum Coke on Hg0 Removal from Coal-Fired Flue Gas and Exploration of Its Micro-Scale Mechanism

“…In addition, it is crucial to combine the methods of DFT and ReaxFF to actually present the HSPC for the simulation of activation and further Hg 0 removal. Furthermore, Zhong et al [ 87 ] introduced the H 2 and NH 3 to the desulfurization of HSPC. The result illustrated that under a pyrolysis atmosphere, regardless of H 2 or NH 3 , the sulfur removal pathway occurred that C 1 –4 –S decomposed and then transformed to H 2 S, which was different from the effects of those reductive atmospheres.…”