Regeneration, hydrotreating catalysts

Hydrotreating/Hydroprocessing Heater stack gas (CO, SO, NO, hydrocarbons and PM), vents and fugitive emissions (HCs) and catalyst regeneration (CO, NO, SO,). 

Bogdanort, J. M., and Rase, H. F., Characteristics of a Commercially Aged Ni-Mo/AL203 Hydrotreating Catalyst Component Distribution, Coke Characteristics, and Effects of Regeneration. Ind. Eng. Chem. Prod. Res. Dev, 1986. 25 pp. 220-230. 

OptiCAT-plus A process for regenerating hydrotreating catalysts. It uses a fluidized-bed pretreatment to control the initial exotherms found in regeneration, followed by a moderate heat soak to eliminate sulfur and carbon. Developed in the 1990s by the Criterion Catalyst Company. 

Decoking and Regeneration of a Hydrotreating Catalyst by Supercritical Extraction... 

Advantages of In-situ Catalyst Regeneration. Replacement of hydrotreating catalysts is an expensive operation in refineries. 

Hydrotreating catalysts are usually alumina supported molybdenum based catalysts with cobalt or nickel promotors. By 1990, the demand for hydrotreating catalysts is expected to reach 80,000,000 pounds annually (1). The increased demand for these catalysts and the limitations on the availability and supply of the active metals increase the urgency to develop effective catalyst regeneration techniques. 

Solubilities of heavy hydrocarbons in supercritical fluids depend on the type of solvent (6). Moradinia and Teja (7) showed that the solubilities of solid n-alkanes (n-C2g, n-C Q, n-C ) are about ten times higher in supercritical ethane than in carbon dioxide. Therefore, it is reasonable to search and find an appropriate solvent which can disintegrate and dissolve the carbonaceous deposits from hydrotreating catalysts, resulting in their decoking and regeneration. 

In this project, the feasibility of catalyst regeneration by supercritical fluid extraction was studied. A spent catalyst from an industrial naphtha hydrotreater was extracted with tetrahydrofuran, pyridine, carbon dioxide, and sulfur dioxide under subcritical and supercritical conditions. The coke reduction and changes in the catalyst pore characteristics were measured and to a limited extent the catalyst activity was evaluated. It is shown that by supercritical extraction, the coke content of spent hydrotreating catalysts can be reduced and the catalyst pore volume and surface area can be increased. 

A spent resid hydrotreating catalyst was regenerated on a seni-commercial scale using a proprietary process in which the Nl+V metals were first extracted and Chen the catalyst was decoked (ref. 14). The catalyst was a high surface area GoCrNo/ganuna-alumina desulfurization catalyst that had... 

The quality of the regenerated catalyst was studied by means of Surface Area (SA) and Dynamic Oxygen Chemisorption (DOC). DOC has been proven previously to be an elegant technique for the evaluation of hydrotreating catalysts. Hydrodesulfurization activity has been correlated with the amount of oxygen chemisorbed at low temperature (5, 6). 

A spent commercial deactivated NiMo/Al203 hydrotreating catalyst, whose chemical analysis data are presented in Table 1, was used in this study. It was considered as a model of a spent industrial catalyst that is commonly discarded after its lifetime. The catalyst was employed in its sulfided form in hydrotreating of diesel fractions for about 3 years in a brazilian refinery. It was not regenerated during its lifetime and was kept in its original form (cylinder extrudates 5mm). 

Preheat, liquefaction preheater, hydrogen generation, hydrotreating, and solids-liquids separation Produce fractionation Catalyst regeneration... 

Catalytic cracking is another process to benefit from hydrotreating. The benefits are similar to those for reformate pretreatment longer runs, better cracking selectivity, and better product quality. Another advantage is reduced sulfur laydown on the cracking catalyst. Then, catalyst regeneration will contribute less sulfur dioxide to the atmosphere. 

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