Molecular simulation of hydrodesulfurization of coal tar using Pd/ZSM‐5/γ‐Al₂O₃ catalyst

Abstract

In this study, all‐atom model of Pd/ZSM‐5/γ‐Al2O3 was developed and validated by comparing the experimental results of nitrogen adsorption isotherm, pore structure parameters, and powder X‐ray diffraction to our simulation results. Coal tar was simulated using dibenzothiophene (DBT), and tetralin (THN) in our study, and the product of coal tar hydrodesulfurization was modeled by H2S and n‐hexane (Hex). The adsorption and diffusion of the DBT, THN, and Hex on Pd/ZSM‐5/γ‐Al2O3 were investigated, and the simulation results were verified by differential thermogravimetric and X‐ray photoelectron spectroscopy results. The results demonstrated that DBT and THN mainly adsorbed to mesopores, and part of THN could also adsorb to micropores. Note that the mesopores allow the reactions of DBT, THN, and Hex to take place as they have large enough size, and micropores limit those reactions as those model molecules hardly adsorbed to micropores. In addition the acidity of the carrier weakens the heat of adsorption of H2S, making it easier to diffuse out of the catalyst and protect the active site. And our simulation results also show that the diffusion coefficient of H2S was much higher than other chemicals. As a consequence, the multichannel design and the choice of acidic carrier improved the sulfur tolerance of the catalyst.

Effect of Surface Structure and Adsorption Activity on Implanting of b-Oriented ZSM-5 Zeolite Film on Modified α-Quartz Substrate

“…The FC zeolite shortens the diffusion path and reduces diffusion resistance for the methanol, alkanes, and aromatic hydrocarbons to rapidly diffuses to the catalyst surface by the mesoporous. However, the single microporous structure has a negative impact on the ZSM-5 catalytic process due to its extremely narrow and elongated micro-channel arrangement which limits mass transfer and facilitated coke formation (Groen et al, 2010; Chu et al, 2019). The introduction of TiO 2 coating greatly promotes the formation of a dense and uniform b-oriented ZSM-5 zeolite film.…”

Zeolite Chemistry and Applications

“…The FC zeolite shortens the diffusion path and reduces diffusion resistance for the methanol, alkanes, and aromatic hydrocarbons to rapidly diffuses to the catalyst surface by the mesoporous. However, the single microporous structure has a negative impact on the ZSM-5 catalytic process due to its extremely narrow and elongated microchannel arrangement which limits mass transfer and facilitated coke formation (Groen et al, 2010;Chu et al, 2019). The introduction of TiO 2 coating greatly promotes the formation of a dense and uniform b-oriented ZSM-5 zeolite film.…”

“…There have been other several studies on PIM-1/UiO-66 MMM (Khdhayyer et al, 2017;Tien-Binh et al, 2018;Yu et al, 2019), however their scope was limited to membranes for gas separation applications. Several other studies have also reported on other types of MOF/Carbon composites such as MOF-5/expanded natural graphite (ENG) , MIL-101(Cr)/ZTC (Musyoka et al, 2016) and HKUST-1/graphene platelets (Hassan et al, 2019) (Marti et al, 2018) have been reported.…”