Parametric and kinetic studies on deactivation and regeneration of hydrotreating catalysts in solvent refined coal upgrading process and an evaluation of the liquid vaporization effects on hydrotreater performance
Catalysts used in hydrotreating the solvent refined coal were rapidly deactivated during the initial stages of processing. The major cause of deactivation appears to be the deposition of carbonaceous material on the catalyst. A simulated aging technique involving a series of reactions on the same batch of catalyst and a model compound activity test were developed and used to study the effects of process conditions, feedstock characteristics, catalyst properties, and catalyst pretreatment on initial catalyst deactivation. The variables shown to increase the rate of deactivation are: increased catalyst loading, high reaction temperature, low hydrogen pressure, unsulfiding the catalyst, and high concentrations of preasphaltenes and insoluble organic matter in the feedstock. The loss in catalyst surface area during the aging process was substantial, being as high as 95%. A simple kinetic model, including a first-order catalyst deactivation rate, was applied to upgrading of two-coal derived feedstocks. A catalyst deactivation mechanism was proposed which involves the adsorption and surface reaction of coke precursors on catalytic active sites. Catalyst regeneration of aged catalysts from the LC-Finer and the ITSL process has been accomplished through oxidative treatment followed by presulfiding. A parametric study has been performed to identify the optimum regeneration conditions. The degree of regeneration appears to be dependent on the feed material and reaction history of the catalyst. Liquid vaporization affects the hydrotreater performance significantly. The hydrotreater is simulated to study the effects of the solvent volatility, hydrogen flow rate, feed concentration, temperature, and pressure. A gradientless reactor system was designed, built, and used to verify the key result ofthe simulation study.
- OSTI ID:
- 6744329
- Country of Publication:
- United States
- Language:
- English
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