Processes hydroprocessing

Table 2. General Process Characteristics for Hydroprocessing Various Feedstocks...

Reclamation, Disposal, and Toxicity. Removal of poisons and inorganic deposits from used catalysts is typically difficult and usually uneconomical. Thus some catalysts are used without regeneration, although they may be processed to reclaim expensive metal components. Used precious metal catalysts, including automobile exhaust conversion catalysts, are treated (often by the suppHers) to extract the metals, and recovery efficiencies are high. Some spent hydroprocessing catalysts may be used as sources of molybdenum and other valuable metals. 

Hydroprocesses Hydrogen is chemically stable and relatively unreactive at ordinary temperatures most processes utilizing it require a catalyst. Above 500°C it reacts readily with oxygen and confined flammable mixtures explode violently if ignited Main hazards fire, explosion, metallurgical problems arising from hydrogen attack... 

It has been mentioned in an earlier chapter that nickel deposits are basically of two types sulfidic and lateritic (oxide). The scenario of nickel extraction from nickel sulfide concentrates and nickeliferrous pyrrho tite (these two are the two products of physical beneficiation of nickel sulfide ores), and from limonitics and gamieritics (these are the common lateritic ores) has been presented in Figure 5.6. It can be seen that nickel is extracted from its various sources by pyro, pyro-hydro and hydroprocessing. The account given here pertains to the latter two processes applied to the various nickel sources. 

Manufacturing high quality fuels would require not only more hydroprocessing but also other chemical processing. In the immediate future, most of the refinery investments are made to cope with these requirements and particularly involve hydrotreatment processes. However, commercially available technology does not have all the answers to the market needs. Some niches are open for new technology development. 

Cooper, B. H. Sogaard-Anderson, P., and Nielsen-Hannerup, P., Production of Swedish class I diesel using dual-stage process,in Catalytic Hydroprocessing of Petroleum and Distillates, M.C. oballa, S.S.S. editor. 1994, Marcel Dekker New York. pp. 279-290. 

Takeuchi, C. Fukui, Y. Nakamura, M., and Shiroto, Y., Asphaltene Cracking in Catalytic Hydrotreating of Heavy Oils. 1. Processing of Heavy Oils by Catalytic Hydroprocessing and Solvent Deasphalting. Ind. Eng. Chem. Proc. Des. Dev, 1983. 22(2) pp. 236-42. 

Arosat [Aromatics saturation] A hydroprocessing process developed by C-E Lummus. 

DCH (1) [Direct contact hydrogenation] A process which uses catalytic hydroprocess-ing to re-refine spent lubricating oils to produce clean fuel, lubricating oil base stocks, or hydrocarbon feedstock for cracking. Developed by UOP but not commercialized as of 1991. 

Hydrorefining A general name for petroleum refining processes using hydrogen gas. See also Hydroprocessing. 

Metrex A process for recycling spent hydroprocessing catalysts. Developed in 1993 by Metrex BV. 

Sulfur is removed from a number of refinery process off-gas streams (sour gas) to meet the sulfur oxide emissions limits of the Clean Air Act and to recover salable elemental sulfur. Process off-gas streams, or sour gas, from the coker, catalytic cracking unit, hydrotreating units, and hydroprocessing units can contain high concentrations of hydrogen sulfide mixed with light refinery fuel gases. 

Transition metal sulfide units occur in minerals in nature and play an important role in the catalytic activity of enzymes such as hydrogenase and nitrogenase. Industrial processes use transition metal sulfides in hydroprocessing catalysis. Both the metal and the sulfur sites in these compounds can undergo redox reactions which are an important part of their reactivity. Thus, the electronic situation of the ReS4 anion and related complexes is of considerable interest and has been evaluated applying quantum chemical methods. 

---