Petroleum coke catalyst

Combifining A petroleum refining process which removes asphaltenes, sulfur, and metals from residues, before further treatment. The catalyst is an activated petroleum coke in a fluidized bed, operated under hydrogen pressure at 380 to 420°C. 

Petroleum coke is the residue left by the destructive distillation (thermal cracking or coking) of petroleum residua. The coke formed in catalytic cracking operations is usually nonrecoverable because of adherence to the catalyst, as it is often employed as fuel for the process. The composition of coke varies with the source of the crude oil, but in general, is insoluble on organic solvents and has a honeycomb-type appearance. 

Five types of commercially available petroleum hydrotreating catalysts were evaluated. The properties of catalysts are listed in Table V. All catalysts were presulfided before being coked. 

The following test materials have often been used FCC catalysts, aluminium oxide, silica gel, glass beads, silica or quartz sand, sea sand, coal and coal ash, petroleum coke, metal powders, resin particles, boric acid, and magnesite powder. Mean particle size ranges from 11 /un to 1,041 /rm, and particle density, from 384 kg/m3 to 7,970 kg/m3. According to Geldart s classification (1973), most of these materials belongs to Class A, some to Class B, and a few to Class D or C, as listed in Table II. 

In many refineries thermal cracking processes are used to convert residues into lighter products. Low value petroleum coke is a product from the more severe cracking processes. The H-Oil process made it possible to convert the asphaltenic carbonizable portion of the residue to higher value liquid products rather than coke. In the H-Oil process an ebullated bed of catalyst is used to convert lower value heavy oil into upgraded higher value products in the presence of hydrogen. The ebullated bed reactor is an expanded bed of catalyst maintained in constant motion by the upward flow of liquid. The reactor behaves as a well mixed continuously stirred tank reactor. 

The conversion takes place in the absence of catalyst, around 1500 C on a fluidized bed of petroleum coke to achieve complete conversion of the reactants. The molar yields are about 85 to O per cent in relation to both propane and ammonia. 

Catalytic cracking is a process for the conversion of heavy petroleum cuts into gasoline. The catalyst is constituted of microspheres of about 60 /zm diameter contains 10 to 40 % of an acid Y zeolite (REY, USHY...) dispersed in a matrix (clay + binder). This catalyst circulates rapidly in the unit, its contact time with oil in the riser reactor (T 530 0) being of several seconds. The coked catalyst (about 1 wt % coke) is transported to the regenerator where the introduction of air makes possible, in a few minutes the combustion of coke at high temperature (about 700 C). The use of heavier and heavier feeds creates several problems during the regeneration steps ... 

Kariya et al. performed dehydrogenation of methylcyclohexane and other cycloalkanes over platinum, palladium and rhodium monometallic and platinum/palladium, platinum/rhodium, platinum/molybdenum, platinum/tungsten, platinum/rhenium platinum/osmium and platinum/iridium catalysts supported on both petroleum coke active carbon and on alumina between 375 and 400 °C [279]. The platinum catalyst supported by petroleum active carbon showed the highest activity. While platinum was the most active monometallic catalyst, its activity could be increased by addition of molybdenum, tungsten and rhenium. 

A completely new approach for BTX production has emerged in recent years. It converts to paraffins into aromatics using a modified ZSM-5 zeoHte catalyst which contains gallium (19). An example of this approach, the Cyclar process, has been in commercial operation by British Petroleum at Grangemouth, Scotiand since August 1990 (20). It uses C —feed and employs UOP s CCR technology to compensate for rapid catalyst coking. 

The most dominant catalytic process in the United States is the fluid catalytic cracking process. In this process, partially vaporized medium-cut petroleum fractions called gas oils are brought in contact with a hot, moving, freshly regenerated catalyst stream for a short period of time at process conditions noted above. Spent catalyst moves continuously into a regenerator where deposited coke on the catalyst is burnt off. The hot, freshly regenerated catalyst moves back to the reactor to contact the hot gas oil (see Catalysts, regeneration). 

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