Hydrotreating regeneration

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. 

More severe hydrotreating, such as mild hydrocracking at an H2 partial pressure of >6.9 MPa (1000 psig) and temperature of >400° C, can stiU further reduce sulfur content in the FCC feed. Mild hydrocracking of a 25° API VGO reduced the sulfur content of the FCC feed 98%, from 1.7 wt % to 0.03 wt % (40). This reduction can be expected to lower the SO content in the FCCU regenerator flue gas by about 90%. 

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

Fluid catalytic cracking units present formidable emission control problems. Contaminants are present in both reactor product gas and regenerator flue gas. The reactor product contains hydrogen sulfide, ammonia, and cyanides, plus combined sulfur and nitrogen in the liquid products. Hydrogen sulfide, ammonia and cyanides are handled as part of the overall refinery waste water cleanup. The combined sulfur and nitrogen may be removed by hydrotreating. 

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. 

The changes in reactivity which may occur when solid solutions are formed are discussed in detail elsewhere [3], The support is necessarily very inert with respect to activation conditions. The element trapped in the solid solution will therefore be much less reactive. Consequently, only part of the active element contained in the precursor gets activated. Indeed, the loss of part of cobalt or nickel by reaction with y-AhC is of concern in hydrotreating reactions regeneration by calcination, which increases the proportion of the active elements trapped in the support as solid solution, decreases the amount of cobalt or nickel which can play a catalytic role. 

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. 

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