Hydrotreating of oil fractions

Jorge Ancheyta Anton Alvarez-Majmutov and Carolina Leyva  

Catalytic hydrotreating (HDT) is a mature technology used in the petroleum refining industry for the upgrading of hydrocarbon streams for the last 60 years. For conventional distillate 

HDT is carried out under a wide range of operating conditions. The severity of the process is adjusted depending on the properties of the feed and required product composition. The main process variables are pressure, temperature, hydrogen-to-oil (H2/oil) ratio, and space velocity. Each variable affects the process in different ways therefore, the set of operating conditions must be carefully adjusted to achieve an efficient operation. 

The reactions that take place during the HDT process are hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodearomatization (HDA), hydrodeoxygenation (HDO), 

Multiphase Catalytic Reactors Theory, Design, Manufacturing, and Applications, First Edition. Edited by Zeynep Ilsen Onsan and Ahmet Kerim Avci. 2016 John Wiley Sons, Inc. Fubli ed 2016 by John Wiley Sons, Inc. 

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Koltai T, Dobrovolszky, T6t6nyi P, in Proc. 2nd Fur. Symp.Hydrotreating a. Hydrotreating of Oil Fractions (Forment GF, Dehnon B, Grange P, eds.) Elsevier, 1999, p. 137. 

Mederos, F.S. 2010. Dynamic modeling and simulation of a three-phase reactor for hydrotreating of oil fractions, PhD thesis, IMP Postgraduate School, Mexico. 

The illustrated unit can be used to study vapor-phase reforming of kerosene fractions to high octane gasoline, or hydrogenation of benzene, neat or in gasoline mixtures to cyclohexane and methylcyclopentane. In liquid phase experiments hydrotreating of distillate fractions can be studied. The so-called Solvent Methanol Process was studied in the liquid phase, where the liquid feed was a solvent only, a white oil fraction. 

The oxidation of thiophene sulfides combined with a selective separation process of oxidized products, for example by adsorption on inert materials, might offer an alternative to deep hydrotreating for desulfurization of oil fractions. On these grounds, the oxidation of disulfides has gained considerable interest [149]. Owing to the nature of sulfur impurities, large-pore and even more mesoporous Ti-silicates would be appropriate catalysts. 

Koltai T, Galsan V, Tetenyi P, React Kinet Catal Lett 67 391, 1999. Kogan VM, Parfenova NM, in Proc. 1st Eur.Symp. Hydrotreating a. Hydrocracking of Oil fractions (Proment GF, Delmon B, Grange P, eds.) Elsevier B.V. 1997, P. 449. 

Figure 2. Product aromatic content vs. hydrogen consumption hydrotreating whole SRC-II oil at various severities group type calculated from GC or MS of individual fractions (%) ICR 106, (O) ICR 113...

The results from the supercritical hydrotreatment experiments are superior in almost every respect to conventional hydrotreatment experiments (without the use of solvent). Under similar conditions, supercritical hydrotreating produced better products, for example less gas yield (10 vs 25 ), more of light oil fraction, <300F, (55 vs 35 ) and less coke formed on the catalyst surface (0.3 vs 3.8 based on the feed). For... 

Runs 9 and 10 were carried out to study the effect of an aliphatic solvent such as n-heptane in supercritical hydrotreating of topped crude. Comparing the results from Runs 6 and 7 in which toluene was used as the solvent, the nitrogen contents in heavy oil fractions are much lower for the heptane runs than the toluene runs. The sulfur contents are about the same. Thus, one can conclude that an aliphatic solvent is better solvent for hydrodenitrogenation than the aromatic solvent. The reason is that the aromatic solvent was competing for hydrogenation (about 1 wt of the toluene was converted to methyl cyclohexane). 

The character and hydrocarbon-type composition of several syncrudes have been investigated by adaptation of methods developed for heavier fractions of petroleum crude oils. The methods are reviewed briefly, and results are summarized for five coal liquids and a hydrotreated shale oil Refining requirements for removal of heteroatoms, especially nitrogen, and conversion of polynuclear aromatics are discussed in relation to the composition of the syncrudes and the character of refined products to be expected. A preliminary report is given on the preparation of liquid samples from coals of widely different rank to permit more systematic correlation of hydrocarbon character with coal source in relation to refining. 

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