VISION TECNOLOGICA / VOL. 6 Nº 1, 1998 15

ISAL™: HIGH QUALITY GASOLINE

Nelson Martínez, Rodolfo Bruno Solari, José Armando Salazar and Arturo Mogollón

ISALTM, the technology developed by PDVSA-Intevep y UOP, offers refiners an excellent opportunity to upgra-de low-quality FCC naphtha for use in gasoline pool. The technology is based on typical hydrotreating flow

schemes, and thus ease of operation and reliability are inherent to the process. Because the degree by whichthe available naphtha can be improved is dependent on the naphtha source, UOP and Intevep will provide thenecessary information for specific processing requirements, since improvement of available naphtha dependson the source. Based on its wide experience in hydroprocessing technologies, UOP is well placed to offer ISALTM

as a solution for improving the quality of FCC gasoline.

ISALTM es una tecnología desarrollada por PDVSA-Intevep y UOP que ofrece una excelente oportunidad a losrefinadores de mejorar la nafta de FCC de baja calidad a fin de incorporarla a su “pool” de gasolinas. La tec-

nología está basada en los esquemas típicos de flujo de hidrotratamiento que proporcionan una fácil operacióny confiabilidad al proceso. Tanto UOP como Intevep proveen toda la información necesaria relacionada conrequerimientos específicos de procesamiento, en vista de que el grado en el que se puede mejorar la nafta dis-ponible depende de su origen. Basado en su amplia experiencia en tecnologías de hidroprocesamiento, UOPestá en capacidad de ofrecer ISALTM como una solución para mejorar la calidad de la gasolina de FCC.

Today, the refining industry is facing the need for cleaner fuels. Because FCC gasoline isa major component of many gasoline pools, refiners need to reduce the sulfur and olefincontent in the FCC gasoline. In many cases, hydrotreating is the only technology avail-

able to achieve adequate quality improvement. However, according to common wisdom, themajor drawback to hydrotreating FCC gasoline is the resultant loss of octane that occurs whenolefins and some of the aromatics are saturated. This octane reduction can be in excess of 10numbers, (R+M)/2.

If a refiner can live with this loss of octane, then FCC gasoline hydrotreating may be sufficient,and UOP is pleased to discuss the use of UOP Unionfiningsm technology for this application.However, when a loss of octane cannot be tolerated UOP and Intevep believe that our pilotplant and commercial database on FCC gasoline hytrotreating puts us in the unique position ofbeing able to discuss the advantages of the process ISAL™ over conventional hydrotreating.This allows UOP and PDVSA-Intevep to recommend the option that is most suitable to a par-ticular refiner’s needs.

ISAL™ PROCESS DESCRIPTION

The reactor circuit configuration in ISAL™ is quite similar to that used in simple hydrotreatingprocesses. The feed naphtha is mixed with hydrogen and processed across a fixed bed ofcatalyst at moderate temperatures and pressures. Reaction products are separated and hydro-gen-rich to the reaction section. The naphtha stabilizer can be used for RVP adjustment tomeet final product specifications.

Refining Division, PDVSA-Intevep

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ISAL™ and Octane Recovery

The purpose of the ISAL™ is to recover the octane lost bysimple hydrotreating FCC gasoline. To keep the yield lossand hydrogen consumption to a minimum, ISAL™ utilizesselective isomerization reactions for full recovery of feedoctane. While there is also some selective conversion of

high molecular weight and low octane hydrocarbons intolighter components, these reactions are minimized in orderto keep yield loss to a minimum. The result is a productwith improved octane and minimum yield loss and hydro-gen consumption. For full recovery of feed octane, the Cs+yield is expected to be in excess of 95 vol%.ISAL™ can be adapted to different refinery applications.Refiners can choose to hold motor octane number (MON) ofISAL™ effluent at a value equivalent to MON of untreatedFCC gasoline. Also, refiners could select to control rese-arch octane (RON), so that no loss occurs across ISAL™unit, or at a slight gain or loss, depending upon the pooloctane requirements.

Characteristics of ISAL™

ISAL™ reduces the naphtha sulfur and nitrogen content,and also the naphtha olefin content. It diminishes thenaphtha T-90, and it does not increase the aromatics con-tent. It can maintain or increase naphtha octane.ISAL™ upgraded FCC naphtha is specifically suited tomeet reformulated gasoline specifications in today's globalmarket.

INVESTMENT

Investment required for installing ISAL™ in a refinerytoday depends on the feedstock and processing severity.For sweet virgin naphtha feedstock, investment cost issimilar to that of a simple naphtha hydrotreater. For moredifficult feeds, such as cracked naphthas, investment ishigher. As reference, the estimated erected cost of a 10,000bpsd heavy FCC naphtha ISAL™ process unit is US$MM

28,000 BPSD 26,412 BPSD

Feed: FCC-C9+ Product: C5+°API: 40.3 °API: 43Sulfur: 1420 wppm Sulfur <100 wppmNitrogen: 154 wppm Nitrogen: <1 wppmOlefins: 13.9 wt% Olefins: 0.5 wt%MON: 79.2 MON: 80.8RON: 88.6 RON: 87.1RVP: 1.2 RVP: 4.0

ISAL™UNIT

ISAL™, which is the result of recently completed jointdevelopment work between PDVSA-Intevep and UOP, is ahydroprocessing technology designed to improve thequality of FCC gasoline with no loss in octane.

Fig. 1. Sulfur reduction using conventional way.

VISION TECNOLOGICA / VOL. 6 Nº 1, 1998 17

14. This cost is based on US Gulf Coast installation duringthe 1st quarter of 1996.

ISAL™ applied to light FCC naphthas

Light FCC naphthas have been traditionally treated bychemical processes to reduce sulfur (10-15 wt%), as shownin Fig. 1, or sent to etherification to produce oxygenatesfrom the C5-C6 iso-olefins (23-25 vol% reduction of total

olefins content); however, given the restrictions on theozone formation, potential forming compounds, such as ole-fins, need to be removed to a larger extent than the levelachieved by any of the two processes described. An exam-ple of light FCC naphtha from a Venezuelan refinery is pre-sented in Table 1.

Notice that using ISAL™ in a low severity range (Figs. 2and 3), this stream can be desulfurized up to 40 wt% and

Fig. 2. Low severity ISALTM for light FCC naphthas.

Fig. 3. Low severity ISALª for light FCC naphthas.

18 VISION TECNOLOGICA / VOL. 6 Nº 1, 1998

olefins removal can reach up to 30 vol% with insignificantyield or octane penalties. Such option clearly would addmore flexibility, as shown in Fig. 4, to the refiner foradjusting specifications in his gasoline blending system,while complying with EPA regulations.

Nelson Martínez. Chemist, University ofPoitiers, France (1973); master in physicoche-mistry in the same university; PhD in chemistryin the University of Reading, 1978; master inmanagement of technology, MIT, 1993. He hasbeen leader of catalysis group in Intevep, andhas coordinated several projects on catalyticcracking, new catalytic supports, and catalyst

commercialization. He was manager of Process DevelopmentDepartment of Intevep. In 1994 Dr. Martínez was named mem-ber of the New York Science Academy. He was assigned in 1995to the Strategic Planning Coordination of PDVSA to work in thetechnology management corporate group. He is presently work-ing as specialist in catalysis.

Rodolfo Bruno Solari. B.S. in chemical engine-ering, Universidad de Chile, 1970; PhD in che-mical engineering, University of California atDavis, 1974. In 1980 he joined Intevep where hehas successively worked as process developmentsection head, reÞning process dept. manager,and heavy oil upgrading program manager. Dr.

Solari has been technology leader of heavy and extra-heavy oilactivities, and he is part-time lecturer at Universidad SimónBolívar (USB). He is specialist in heavy oil upgrading. In 1991,he became the recipient of UNESCO Science Award.

José Armando Salazar. B.S. in chemical engine-ering, Tulsa University; master & PhD in che-mical engineering from the same university. Forover twenty one years, he has been working inR&D of reÞning processes. He is currently lead-er of the hydroprocessing group in monitoringprojects for catalytic reforming and hydrotreat-ing units of all PDVSA reÞneries, as well as in

technical assistance in the catalytic reforming area. Dr. Salazarparticipated in the ISALª conceptual engineering, and he is atpresent in charge of providing ISALª estimates according toreÞners requirements.

Arturo Mogollón. B.S. in chemical engineering, UniversidadCentral de Venezuela (UCV). In 1980 he joined Intevep«s PilotPlant Department, where he worked as leader of pilot plantsstart-up teams, and was member of engineering task forces tocarry out pilot plants basic design. He was involved in R&Dactivities in ßuid drying/incineration processes for HDHªspent catalysts. Since 1994 he has been participating in thehydroprocessing group, where he leads R&D experimental pro-grams to test catalyst for lube base oil upgrading, to assessUOP«s Unicracking technology for VGO hydrocracking, and forthe evaluation of new approaches to ISALª.. At present, Mr.Mogollón is assigned to Citgo Lemont ReÞnery, where he isworking as process technologist, assisting the reÞnery«s hydro-treating group.

Properties Light FCC naphtha(Distillate range 80-245°F)

Total olefins, vol% 52

IC5= 7.3

IC6= 11.4

Diolefins, vol% 1.2

Naphthalenes, vol% 10.1

Aromatics, vol% 2.9

Total sulfur, wppm 350

Sulfur (mercaptans, wppm) 9

Table 1. Light FCC naphtha properties.

Fig. 4. Sulfur and oleÞn reduction using ISALª.