Thermal and catalytic hydrocracking

Evaluation of a Two-Stage Thermal and Catalytic Hydrocracking Process for Athabasca Bitumen... 

Thermal and catalytic hydrocracking reactions have been reported to occur in cascade (Yang et al, 2011), that is, the vacuum residue is hydrocracked to form vacuum gas oil the vacuum gas oil hydrocracks to produce middle distillates, and so forth. Depending on the reaction conditions, occurrence of some path reactions can be more difficult, or they could not even be present. 

Kerosine, a distillate fraction heavier than naphtha, is normally a product from distilling crude oils under atmospheric pressures. It may also he obtained as a product from thermal and catalytic cracking or hydrocracking units. Kerosines from cracking units are usually less stable than those produced from atmospheric distillation and hydrocracking units due to presence of variable amounts of olefinic constituents. 

The preheated coal slurry (essentially liquefied) is sent to the reactor, where thermal and catalytic cracking, hydrogenation, and hydrocracking take place. These reactions occur rather slowly because fewer reactive bonds are involved in this stage, which produces distillate range small molecules. 

Froment, G.F. Kinetic modeling of complex processes. Thermal cracking and catalytic hydrocracking. In Chemical Reactor Technology for Environmentally Safe Reactors and Products, de Lasa, H.I, Dogu, G., Ravella, A., Eds. Kluwer Academic Publishers Dordrecht, 1992 409-424. 

KINETIC MODELING OF COMPLEX PROCESSES. THERMAL CRACKING AND CATALYTIC HYDROCRACKING... 

The present paper has outlined an approach for the detailed kinetic modeling of both thermal cracking and catalytic hydrocracking. The parallelism between the two cases is remarkable. Expressing the rate equations in terms of elementary steps and single events of either radical or carbenium ion chemistry keeps the number of rate parameters within practical limits. The approach should stimulate the commitment of oil and petrochemical companies to the improvement and refinement of their analytical means. 

Kinetic Modelling of Complex Processes. Thermal Cracking and Catalytic Hydrocracking P. Trambouze 409... 

Khorasheh, F., Rangwala, H.A., Gray, M.R., Dalla Lana, LG. 1989. Interactions between thermal and catalytic reactions in mild hydrocracking of gas oil. Energy Fuels 3 716-722. 

Yingxian, Z., Da, L. 2011. Kinetics and selectivity in thermal hydrocracking and catalytic hydrocracking of asphaltenes. China Petrol. Process. Petrochem. Technol. 13 24-31. 

Cracking is effected by one of three general methods thermal cracking, catalytic cracking, or hydrocracking. Each process has its own characteristics concerning operating conditions and product compositions. 

Hydrogen addition processes, catalytic hydroconversion (hydrocracking), fixed bed catalytic hydroconversion, ebullated catalytic bed hydroconversion, thermal slurry hydroconversion (hydrocracking), hydrovisbreaking, hydropyrolysis, and donor solvent processes. 

In the platforming process (Fig. 1), the feedstock is usually a straight-run, thermally cracked, catalytically cracked, or hydrocracked C6 to 200°C naphtha. The feed is first hydrotreated to remove sulfur, nitrogen, or oxygen compounds that would foul the catalyst, and also to remove olefins present in cracked naphthas. The hydrotreated feed is then mixed with recycled hydrogen and preheated to 495 to 525°C at pressures of 116 to 725 psi (0.8 to 5 MPa). Typical hydrogen charge ratios of 4000 to 8000 standard cubic feet per barrel (scf/bbl) of feed are necessary. 

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