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<p>This study evaluates the efficiency of non-oxidative regeneration strategies for removing coke deposits from spent catalysts. Solid-state nuclear magnetic resonance and Fourier-transform infrared spectroscopy were used to characterize the structural and compositional properties of the coke. A two-step regeneration process combining accelerated solvent extraction (ASE) and hydrotreatment (HT) was applied at pilot scale. The aliphatic carbon content of the coke decreased from 39% in untreated samples to 17% after ASE and further to 3% following wet HT. Dry HT, involving heated hydrogen under pressure, promoted the formation of light hydrocarbons such as methane and ethane by disrupting carbon–catalyst bonds. Wet HT refers to utilizing a mixture of hydrogen and hydrogen sulfide gas under high-temperature and pressure, and dry and wet HT methods removed substantial amounts of coke, while Dry HT proved remarkably effective, eliminating over 72% of the deposited coke. However, HT-severe conditions (HT-S1) increased coke aromaticity. These findings provide practical insights into the development of non-oxidative regeneration protocols for spent refinery catalysts, thereby minimizing catalyst degradation while enhancing coke removal efficiency.</p>

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Solid-state 13C NMR analysis of regenerated and coked catalyst under dry and wet hydrotreatment

  • 期刊论文

  • 发表日期：

    2025年7月24日

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  • Narjes Ghaloum,
  • Salim Ok

摘要

This study evaluates the efficiency of non-oxidative regeneration strategies for removing coke deposits from spent catalysts. Solid-state nuclear magnetic resonance and Fourier-transform infrared spectroscopy were used to characterize the structural and compositional properties of the coke. A two-step regeneration process combining accelerated solvent extraction (ASE) and hydrotreatment (HT) was applied at pilot scale. The aliphatic carbon content of the coke decreased from 39% in untreated samples to 17% after ASE and further to 3% following wet HT. Dry HT, involving heated hydrogen under pressure, promoted the formation of light hydrocarbons such as methane and ethane by disrupting carbon–catalyst bonds. Wet HT refers to utilizing a mixture of hydrogen and hydrogen sulfide gas under high-temperature and pressure, and dry and wet HT methods removed substantial amounts of coke, while Dry HT proved remarkably effective, eliminating over 72% of the deposited coke. However, HT-severe conditions (HT-S1) increased coke aromaticity. These findings provide practical insights into the development of non-oxidative regeneration protocols for spent refinery catalysts, thereby minimizing catalyst degradation while enhancing coke removal efficiency.