Cat cracker bottoms

An Exxon cat cracker bottom pitch was extracted with solvents of varying solubility parameter in order to evaluate the relationships which exist between extraction conditions and the characteristics of the extracted product. The precursor pitch possessed a carbon/ hydrogen ratio of 1.49 and a alculatedO, overall average solubility parameter of 10.48 reflux quinoline insolubles content of the pitch was 2.3% and the refluxing toluene insolubles were at a level of 20.3%. The pitch was not optically anisotropic. Upon heating in N2 to 530 C in a TGA, a coke yield of 37% was obtained. 

VARIATION IN COKE YIELD OF EXTRACTION CAT CRACKER BOTTOM PITCHES AS A FUNCTION OF THE SOLUBILITY PARAMETER OF THE EXTRACTION SOLVENT... 

VARIATION IN C/H VS THE SOLVENT SOLUBILITY PARAMETER FOR VARIOUS CAT CRACKER BOTTOM PITCH FRACTIONS... 

VARIATION IN GLASS TRANSITION TEMPERATURE FOR EXTRACTED CAT CRACKER BOTTOM PITCH FRACTIONS AS A FUNCTION OF THE EXTRACTION SOLVENT SOLUBILITY PARAMETER... 

Figure 10 DENSITY AND CRYSTALLITE SIZES OF CARBON FIBER PRODUCED FROM A CAT CRACKER BOTTOM PITCH EXTRACTED WITH A SOLVENT HAVING A...

Furnace carbon black is produced from the incomplete combustion of what is called carbon black oil feedstock, which consists of heavy aromatic residue oils. In the United States this oil is commonly the bottoms from catalytic cracker units. They are commonly referred to as cat cracker bottoms and contain relatively low hydrogen content (and conversely high carbon content). In Europe and other locations, the carbon black oil used is commonly a byproduct of high-temperature steam cracking of such products as naphtha, gas condensate, and gas oil to produce ethylene, propylene, and other olefins. Here, no catalysts are used in the cracking process. These types of carbon black oils are mainly unsaturated hydrocarbons. A third source of carbon black feedstock is coal tar, which is commonly used in China to manufacture carbon black. 

Feedstocks are usually either cat cracker bottoms from a petroleum cracking unit or tars from steam cracking for polyethylene production. Coal tars are commonly used as feedstocks to produce carbon black in China. 

Thermal carbon blacks are a particular subclass of carbon black. Unlike the much more common furnace blacks just discussed, thermal carbon blacks are derived from the pyrolysis (thermal decomposition) of natural gas feedstock, not cat cracker bottoms as with furnace blacks. Worldwide there is probably less than 1 billion pounds of thermal carbon black produced each year. This production from natural gas results in a carbon black with a significantly larger particle size. 

Coal tar is the distant third most likely feedstock used to produce furnace carbon blacks (next to cat cracker bottoms and ethylene tars ). There is some use of coal tar in China to manufacture carbon black for rubber applications. 

DO is the heaviest product from a cat cracker. DO is also called slurry oil, clarified oil, bottoms, and FCC residue. Depending on the refinery location and market availability, DO is typically blended into No. 6 fuel, sold as a carbon black feedstock (CBFS), or even recycled to extinction. 

Nearly every cat cracker experiences some degree of coking/fouling. Coke has been found on the reactor walls, dome, cyclones, overhead vapor line, and the slurry bottoms pumparound circuit. Coking and fouling always occur, but they become a problem when they impact throughput or efficiency. 

Decanted Oil, Slurry, Clarified Oil, or Bottoms is the heaviest and often the lowest priced liquid product from a cat cracker. 

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