Cracking of heavy oils

Example 3 Thermal Cracking of Heavy Oils (Visbreaking)... 

As one more common example of liquid fuels present reference may be drawn to liquified petroleum gas (LPG) or bottled gas or refinery gas. This fuel is obtained as a by-product during the cracking of heavy oils or from natural gas. It is dehydrated, desulfurized and traces of odours organic sulfides (mercaptans) are added in order to identify whether a gas leak has occurred. Supply of LPG is carried out under pressure in containers under different trade names. It consists of hydrocarbons of great volatility such that they can occur in the gaseous state under atmospheric pressure, but are readily liquifiable under high pressures. The principal constituents of LPG are n-butane, iso-butane, butylene and propane,... 

P. O Connor, A.C. Pouwels and J.R. Wilcox "Evaluation of Resid FCC Catalysts" Symposium on Catalytic Cracking of Heavy Oils, paper 242E,... 

The higher ethylene yields observed in the DCC type processes has led developments towards the catalytic cracking of heavy oils to ethylene. A typical yield from cracking a gas oil (b.p. 229-340°C) with 45% paraffins, 35.7% naphthenes and aromatics 18.2% is illustrated in Table 10.5". 

Several attempts were made to prepare pillared smectites with sufficient hydrothermal stability for use as active components in catalysts for catalytic cracking of heavy oil fractions. Although improvements were made, none of the attempts resulted in pillared materials stable enough to withstand the hydrothermal conditions found in the regenerator of a commercial FCC. One type of materials studied, i.e. alumina-montmorillonites, may be attractive alternatives to the active matrices, often alumina, currently used in FCC-catalysts designed for cracking of heavy oils. The alumina-montmorillonites can, perhaps, not be considered to be bona fide pillared smectites as they have considerably larger pores and a wider pore-size distribution than what is characteristic for pillared smectites. 

Figure 16. Changes in product yields of catalytic cracking of heavy oil obtained by the pyrolysis of poly-ethylene using REY zeolite.

A. R. Songip, T. Masnda, H. Kuwahara, and K. Hashimoto, Kinetic stndies for catalytic cracking of heavy oil from waste plastics over REY zeolite. Energy Fuels 8, 136 (1994). 

CATALYTIC CRACKING OF HEAVY OIL OVER SOLID-ACID CATALYSTS... 

A rare earth metal-exchanged Y-type (REY) zeolite catalyst was found to be an effective catalyst for the catalytic cracking of heavy oil. The influence of the reaction conditions and the catalytic properties of REY zeolite on the product yield and on gasoline quality have been described above. In this section, a reaction pathway is proposed for the catalytic cracking reaction of heavy oil, and a kinetic model for the cracking reaction is developed [14,33]. 

It is however necessary to remember that products from cracking of heavy oils are highly unsaturated and therefore they have to be further submitted to hydrofining. 

M. G. Yang, I. Nakamura and K. Fujimoto. Hydro-thermal cracking of heavy oils and its model compound. Catalysis Today, 43, 273-280 (1998). 

D.M. Stockwell, W.M. Jaglowski, and G.S. Koemer. Symposium on Catalytic Cracking of Heavy Oils. 1992 AIChE Annual Meeting, paper 242C, 1-6 November 1992. 

The repeated irradiation of the products of radiation-induced cracking of heavy oil and bitumen at the high dose rates do not provide considerable yields of light fractions and usually leads to additional polymerization of the product (Zaikin and Zaikina 2008a). 

Zaikin, Y.A. and Zaikina, R.F. 2010. Polymerization as a limiting factor for light product yields in radiation cracking of heavy oil and Bitumen. Radiat. Phys. Chem. In press. 

Zaikina, R.F., Zaikin, Y.A., and Nadirov, N.K. 1997. Mechanisms and kinetics of radiation-induced thermal cracking of heavy oil fractions. Oil and Gas, Kazakhstan 2 83-100. 

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