Residues hydroconversion

The residue hydroconversion process applies to both atmospheric and vacuum residues. 

Typical Feedstocks Performance and product properties from residue hydroconversion (to be continued). 

American Petroleum Institute atmospheric residue atmospheric residue hydroconversion American Society for Testing and Materials Association pour la Valorisation des Huiles Lourdes Anstalt fur Verbrennungskraftmaschinen List Bureau of Mines Correlation Index bromine number... 

The Residue Hydroconversion process (Figure 9-27) is a high-pressure fixed-bed trickle-flow hydrocatalytic process. The feedstock can be desalted, atmospheric, or vacuum residue. 

W.C. Van Zijll Langhout, P.B. Kwant and G.J. Lambert, The development of Shell s Residue Hydroconversion Process, Symp. on Oil Refining, Sept. 30-Oct. 4, 1985, La Plata, Argentina. 

Our main purpose for developing residual hydroconversion catalyst is the upgrading of petroleum residue, decomposition of asphaltenic components and hydrocracking of hydrocarbons to obtain useful middle distillates from petroleum residue. Through extensive studies on HDS catalysts, hydroconversion was determined to be entirely dependent on reaction temperature [2]. On the other hand, coking and metal deposition onto catalyst were reported to occur under such high temperatures as to decrease catalyst activity and shorten catalyst life [5,6,7,8]. 

Mosby et al. reported a seven-lump residue hydroconversion model. Lumped models for steam cracking of naphtha and gas oils can be found in Dente and Ranzi s review. The literature aboimds with FCC kinetic models, with the number of lumps being three four °, five, six , eight, ten °. 

Other technologies have been proposed in order to overcome the difficulties linked to metals deposit. Moving bed processes have been developed to continuously replace the catalyst. Shell has developed the bunker flow reactor, operating concurrently. This technique can be used for hydrodemetallization as well as for residue hydroconversion (HCON process). 

Scheffer, B., van Koten, M.A., Robschlager, K.W., de Boks, F.C. 1998. The shell residue hydroconversion process Development and achievements. Catal. Today 43(3-4)2 11-22A. 

Feedstocks are light vacuum distillates and/or heavy ends from crude distillation or heavy vacuum distillates from other conversion processes visbreaking, coking, hydroconversion of atmospheric and vacuum residues, as well as deasphalted oils. 

Intermediate feedstock preparation processes such as direct hydroconversion of vacuum residues, solvent deasphalting, improved coking will also make their appearance. 

There are commercial processes for the direct upgrading of residues under high severe hydroconversion conditions. Other alternatives consider the previous hydrotreatment of the residue, so that the hydrocracking stage does not need to be so harsh. Otherwise, residue conversion could also proceed via carbon rejection methods, these processes fall out the scope of the present book and will not be considered here. However, it is important to mention than VR coking is seen as a more economical alternative than HDP, especially for the more heavy crudes, for which concentrations of metals and nitrogen would require the toughest conditions. 

Recovery of catalyst from converted oil. Another way to process the residues is to add hydrogen to effect hydroconversion which avoids the formation of a large quantity of asphalt Solid catalyst is formed afterward by reaction. Membrane filtration is used to separate the converted oil from the catalyst This makes it possible to partially recycle the catalyst to the reactor. Alumina and zirconia membranes with pore diameters ranging from 30 to 600 nm have been tested for this application. The membrane with a pore diameter of 30 nm yields a stable flux and a catalyst retention better than 98% [Deschamps et al., 1989). Concentration polarization is significant and requires a high crossflow velocity and temperature to overcome it. 

We attempted to compare our results to earlier reports for catalytically active Si-VPI-5 samples, however, relevant results for a direct comparizon were not found. Martens et al. [6] and Kraushaar-Czametzki etal. [13] reported their results for Pt/Si-VPI-5 bifunctional catalysts in the isomerisation of n-decane [6], and in the hydroconversion of n-heptane, respectively. Davis et al. also used metals supported on VPI-5 to test catalytic reactions [12]. Our main interest were the cracking capability and the selectivity to useful fuel fractions, using the Si-VPI-5 catalysts in reactions of trans-decalin (model compound) or atmospheric residue. 

A basic concept of the catalyst combination system is that pretreatment catalyst, such as HDM catalyst, loaded in the upper section of a reactor removes the deactivation components included in feed residual oils, and it protects the desulfurization catalyst and the hydroconversion catalyst loaded in the latter section of reactor. Several bench plants which had multi-reactor systems and intermediate product sampling systems were operated to investigate the deactivation behavior and metal accumulation of each catalyst. The required temperature and the metal accumulation can be calculated through the analysis of each intermediate product for sulfur levels and metal levels. 

Gauthier T, Danial-Fortain P, Merdrignac I, Guibard I, Quoineaud A-A. Studies on the evolution of asphaltene structure during hydroconversion of petroleum residues. Catal. Today 2008 130 429-438. 

An evaluation of preparation parameters and their impact on catalyst production is presented along with an electron microscopy characterization of the actual active phase generated during hydroconversion of a deasphalted vacuum residue. Finally, the potential interest of this catalytic stem is illustrated by an evaluation of its performance in hydroconversion of a petroleum residue. 

The very high yields of carbonaceous solids and the low metal contents obtained when the electrical discharge is established into a heavy hydrocarbon exclude the generation of a catalyst precursor directly in the feeding line of a hydroconversion reactor it would produce an excessive amount of carbonaceous solids. It must be kept in mind that the catalyst is destined to conversion of residues, therefore the introduction of excessive amount of useless material must be kept to a minimum. 

Bianco, A.D., Panariti, N., Carlo, S.D., Beltrame, P.L., and Camit, P. 1994. New developments in deep hydroconversion of heavy oil residues with dispersed catalysts. 2. kinetic aspects of reaction. Energy Euels, 8, 593-597. 

Bearden, R. 1997. MICROCAT-RC Technology for hydroconversion upgrading of petroleum residues. Division of Petroleum Chemistry, American Chemical Society, San Francisco, CA, April 13-17. 

---