Adsorbing Polynuclear Aromatics From a Reforming Process Using Adsorbents Containing Iron

PATENT

Adsorbing Polynuclear Aromatics From a Reforming Process Using Adsorbents Containing Iron

United States Patent Application 20110152589

Inventors:

Serban, Manuela (Glenview, IL, US)

Lapinski, Mark P. (Aurora, IL, US)

Moser, Mark D. (Elk Grove Village, IL, US)

Application Number: 12/701187

Publication Date:06/23/2011

Assignee: UOP LLC (Des Plaines, IL, US)

FIELD OF THE INVENTION

This invention generally relates to a process, for adsorbing polynuclear aromatics from one or more reforming process streams using at least one adsorption zone.

BACKGROUND OF THE INVENTION

Reforming is practiced widely throughout the world and is one of the most employed hydrocarbon processing reactions. In reforming, naphthene rings derived from paraffins are dehydrogenated into aromatic rings in the presence of a catalyst. The reformate will usually contain from 35 to 60 percent by weight of benzene, toluene and xylenes. Reforming catalysts are usually noble metals, such as platinum, or mixtures of platinum metals such as platinum and rhenium, on acidic supports such as alumina. Potential problems common to reforming processes include polynuclear aromatic (hereinafter may be abbreviated “PNAs”) content in the reformate and heat balance in the overall endothermic catalytic process.

If PNAs are not already present in the feed, they may be formed in the reforming processes. PNAs can form coke on the catalyst and foul units. Typically, PNAs include compounds having a plurality of fused aromatic rings and include compounds such as coronene and ovalene. As a result, it is desirable to remove PNAs from the one or more streams containing reformate to minimize catalyst deactivation through coking Adsorbent beds may be utilized to remove polynuclear aromatics from such reformate streams. After the adsorption capacity of the adsorbent is exhausted, the adsorbent may be disposed or regenerated.

U.S. Pat. No. 4,804,457 teaches the use of inter reactor PNA adsorption traps situated in a reforming process intermediate endothermic reforming reactors to remove any PNAs formed in the reforming process. The adsorption zone has an inorganic oxide selective for the separation of PNAs from mononuclear aromatics and normal paraffinic saturated hydrocarbons. The reference teaches that the separation to remove the PNAs from other hydrocarbons by adsorption is performed at a low temperature including from about 50° F. to 600° F.

U.S. Pat. No. 5,583,277 teaches that M41S, a molecular sieve, may be used to remove trace amounts of PNAs from reformate. U.S. Pat. No. 4,608,153 teaches the removal of PNAs using an iron-catalyst at high temperatures to selectively hydrogenate and hydrocrack the PNAs. GB1400545A teaches the removal of PNAs from gasoline or catalytic reformate using a graphite and alumina binder.

However, none of the references have provided a highly economical and efficient process for removing PNAs from one or more reformate streams. The process described herein calls for using carbon adsorbents in an adsorption zone located between at least two reforming reactors in a series of reactors, or in an adsorption zone located at the effluent of the last of a series of reforming reactors. The adsorption zone contains carbon adsorbent comprising iron. In one embodiment the activated carbon adsorbent comprises from about 1000 to about 50,000 ppm iron on a carbonaceous basis.

SUMMARY OF THE INVENTION

One embodiment of the invention is a process for adsorbing one or more polynuclear aromatics from at least one stream comprising reformate from a reforming zone using at least one adsorption zone, by passing at least a portion of at least one stream comprising reformate from the reforming zone through the adsorption zone wherein the adsorption zone comprises an activated carbon comprising iron and recovering reformate from the reforming zone having a reduced concentration of polynuclear aromatics. The reforming zone may be a series of reforming reactors and the stream comprising reformate may be at least a portion of the effluent of any of the reforming reactors in the series of reforming reactors. The PNAs may have three or greater fused rings, such as anthracenes, benz-antracenes, pyrenes, benzo-pyrenes, coronenes and ovalenes. Two adsorption zones containing activated carbon adsorbents comprising iron may be operated in a lead-lag mode of operation. The activated carbon adsorbent may comprise from about 1000 to about 50,000 ppm iron on a carbonaceous basis The activated carbon adsorbent may be coconut shell, coal, lignite activated carbons, wood activated carbons or mixtures thereof. An example is bituminous coal.

One or more of the PNAs are desorbed from the second activated carbon adsorbent comprising iron in the second adsorption zone by passing a petroleum fraction boiling in the range of about 200° C. to about 400° C. through the second adsorption zone. The temperature for desorbing at least one PNA from the second activated carbon adsorbent includes about 10° C. to about 500° C. and a pressure from about 170 kPa to about 21,000 kPa.

In another embodiment, the invention is a process for generating a hydrocarbon reformate with a reduced amount of polynuclear aromatic compounds. The process involves passing a heated hydrocarbon feed stream through a series of endothermic catalytic reforming reactors operated at a temperature of from about 427° C. to about 538° C. to reform the feed stream in the presence of a reforming catalyst to a hydrocarbon of higher octane value and to provide for at least one reforming reactor effluent containing polynuclear aromatic compounds. Next, the reforming reactor effluent is contacted with a first activated carbon adsorbent comprising iron effective to selectively adsorb the polynuclear aromatic compounds and to permit non-polynuclear aromatic hydrocarbons to pass over the first activated carbon adsorbent without being adsorbed and to form a first adsorbent bed effluent stream having a reduced amount of polynuclear aromatic compounds. The first adsorbent bed effluent stream may be passed to a final or second series of endothermic catalytic reforming reactors operated at a temperature of from about 427° C. to about 528° C. to reform the first adsorbent bed effluent stream to a hydrocarbon of higher octane value and to provide for a second reforming reactor effluent containing polynuclear aromatic compounds. A hydrocarbon reformate having a reduced content of polynuclear aromatic compounds may be recovered from the final or last of the series of reforming reactors. The feed stream may contain C6 to C12 naphtha having a boiling point in the range of about 38° C. to about 204° C. and the reformate has a higher octane than the feed. The invention may employ a second adsorption zone containing a second activated carbon adsorbent comprising iron where the first and second adsorption zones operate in a lead-lag mode of operation. One or more of the PNAs are desorbed from the second activated carbon adsorbent in the second adsorption zone by passing a petroleum fraction boiling in the range of about 200° C. to about 400° C. through the second adsorption zone. The petroleum fraction may be substantially in the liquid phase. The temperature for desorbing at least one PNA from the second activated carbon adsorbent may include a temperature from about 10° C. to about 500° C. and a pressure from about 170 kPa to about 21,000 kPa.

Yet another exemplary embodiment can be a refining or petrochemical manufacturing facility. Generally, the facility includes an adsorption zone, a hydrocracking zone, and a first fractionation zone. An adsorption zone may be adapted to receive a recycle oil having up to about 10,000 ppm, by weight, of one or more polynuclear aromatics and a light cycle oil, and the adsorption zone is adapted to send the light cycle oil downstream of a fluid catalytic cracking zone. Also, the reforming zone can be adapted to receive at least a portion of the recycle oil, in turn having no more than about 1,000 ppm, by weight, of one or more polynuclear aromatics from the adsorption zone and provide an effluent. The first fractionation zone may be adapted to receive at least a portion of the effluent and provide at least a portion of the recycle oil to the adsorption zone.

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Adsorbing Polynuclear Aromatics From a Reforming Process at Reaction Temperatures

PATENT

Adsorbing Polynuclear Aromatics From a Reforming Process at Reaction Temperatures

United States Patent Application 20110147265

Inventors:

Serban, Manuela (Glenview, IL, US)

Lapinski, Mark P. (Aurora, IL, US)

Moser, Mark D. (Elk Grove Village, IL, US)

Application Number: 12/701264

Publication Date:06/23/2011

Assignee: UOP LLC (Des Plaines, IL, US)

FIELD OF THE INVENTION

This invention generally relates to a process, for adsorbing polynuclear aromatics from one or more reforming process streams using at least one adsorption zone.

BACKGROUND OF THE INVENTION

Reforming is practiced widely throughout the world and is one of the most employed hydrocarbon processing reactions. In reforming, naphthene rings derived from paraffins are dehydrogenated into aromatic rings in the presence of a catalyst. The reformate will usually contain from 35 to 60 percent by weight of benzene, toluene and xylenes. Reforming catalysts are usually noble metals, such as platinum, or mixtures of platinum metals such as platinum and rhenium, on acidic supports such as alumina. Potential problems common to reforming processes include polynuclear aromatic (hereinafter may be abbreviated “PNAs”) content in the reformate and heat balance in the overall endothermic catalytic process.

If PNAs are not already present in the feed, they may be formed in the reforming processes. PNAs can form coke on the catalyst and foul units. Typically, PNAs include compounds having a plurality of fused aromatic rings and include compounds such as coronene and ovalene. As a result, it is desirable to remove PNAs from the one or more streams containing reformate to minimize catalyst deactivation through coking Adsorbent beds may be utilized to remove polynuclear aromatics from such reformate streams. After the adsorption capacity of the adsorbent is exhausted, the adsorbent may be disposed or regenerated.

U.S. Pat. No. 4,804,457 teaches the use of inter reactor PNA adsorption traps situated in a reforming process intermediate endothermic reforming reactors to remove any PNAs formed in the reforming process. The adsorption zone has an inorganic oxide selective for the separation of PNAs from mononuclear aromatics and normal paraffinic saturated hydrocarbons. The reference teaches that the separation to remove the PNAs from other hydrocarbons by adsorption is performed at a low temperature including from about 50° F. to 600° F.

U.S. Pat. No. 5,583,277 teaches that M41S, a molecular sieve, may be used to remove trace amounts of PNAs from reformate. U.S. Pat. No. 4,608,153 teaches the removal of PNAs using an iron-catalyst at high temperatures to selectively hydrogenate and hydrocrack the PNAs. GB1400545A teaches the removal of PNAs from gasoline or catalytic reformate using a graphite and alumina binder.

However, none of the references have provided a highly economical and efficient process for removing PNAs from one or more reformate streams. The process described herein calls for using activated carbon adsorbents in an adsorption zone located between at least two reforming reactors in a series of reactors, or in an adsorption zone located at the effluent of the last of a series of reforming reactors. The adsorption zone is able to operate at temperatures similar to those used in the reforming reactors, thus saving utilities by eliminating cooling and reheating steps required in previous processes.

SUMMARY OF THE INVENTION

One embodiment of the invention is a process for adsorbing one or more polynuclear aromatics from at least one stream comprising reformate from a reforming zone using at least one adsorption zone, by passing at least a portion of at least one stream comprising reformate from the reforming zone through the adsorption zone wherein the adsorption zone comprises an activated carbon and is operated at a temperature of at least 370° C. (700° F.) and recovering reformate from the reforming zone having a reduced concentration of polynuclear aromatics. The reforming zone may be a series of reforming reactors and the stream comprising reformate may be at least a portion of the effluent of any of the reforming reactors in the series of reforming reactors. The PNAs may have three or greater fused rings, such as anthracenes, benz-antracenes, pyrenes, benzo-pyrenes, coronenes and ovalenes. Two adsorption zones containing an activated carbon adsorbent may be operated in a lead-lag mode of operation. The activated carbon adsorbent may be coconut shell, coal, lignite activated carbons, wood activated carbons or mixtures thereof. An example is bituminous coal.

One or more of the PNAs are desorbed from the second activated carbon adsorbent in the second adsorption zone by passing a petroleum fraction boiling in the range of about 200° C. to about 400° C. through the second adsorption zone. The temperature for desorbing at least one PNA from the second activated carbon adsorbent includes about 10° C. to about 500° C. and a pressure from about 170 kPa to about 21,000 kPa.

In another embodiment, the invention is a process for generating a hydrocarbon reformate with a reduced amount of polynuclear aromatic compounds. The process involves passing a heated hydrocarbon feed stream through a series of endothermic catalytic reforming reactors operated at a temperature of from about 427° C. to about 538° C. to reform the feed stream in the presence of a reforming catalyst to a hydrocarbon of higher octane value and to provide for at least one reforming reactor effluent containing polynuclear aromatic compounds. Next, the reforming reactor effluent is contacted at a temperature of at least 370° C. (700° F.), with a first activated carbon adsorbent effective to selectively adsorb the polynuclear aromatic compounds and to permit non-polynuclear aromatic hydrocarbons to pass over the first activated carbon adsorbent without being adsorbed and to form a first adsorbent bed effluent stream having a reduced amount of polynuclear aromatic compounds. The first adsorbent bed effluent stream may be passed to a final or second series of endothermic catalytic reforming reactors operated at a temperature of from about 427° C. to about 528° C. to reform the first adsorbent bed effluent stream to a hydrocarbon of higher octane value and to provide for a second reforming reactor effluent containing polynuclear aromatic compounds. A hydrocarbon reformate having a reduced content of polynuclear aromatic compounds may be recovered from the final or last of the series of reforming reactors. The feed stream may contain C6 to C12 naphtha having a boiling point in the range of about 38° C. to about 204° C. and the reformate has a higher octane than the feed. The invention may employ a second adsorption zone containing a second activated carbon adsorbent where the first and second adsorption zones operate in a lead-lag mode of operation. One or more of the PNAs are desorbed from the second activated carbon adsorbent in the second adsorption zone by passing a petroleum fraction boiling in the range of about 200° C. to about 400° C. through the second adsorption zone. The petroleum fraction may be substantially in the liquid phase. The temperature for desorbing at least one PNA from the second activated carbon adsorbent may include a temperature from about 10° C. to about 500° C. and a pressure from about 170 kPa to about 21,000 kPa.

Yet another exemplary embodiment can be a refining or petrochemical manufacturing facility. Generally, the facility includes an adsorption zone, a hydrocracking zone, and a first fractionation zone. An adsorption zone may be adapted to receive a recycle oil having up to about 10,000 ppm, by weight, of one or more polynuclear aromatics and a light cycle oil, and the adsorption zone is adapted to send the light cycle oil downstream of a fluid catalytic cracking zone. Also, the reforming zone can be adapted to receive at least a portion of the recycle oil, in turn having no more than about 1,000 ppm, by weight, of one or more polynuclear aromatics from the adsorption zone and provide an effluent. The first fractionation zone may be adapted to receive at least a portion of the effluent and provide at least a portion of the recycle oil to the adsorption zone.

Free Full Text Source: http://www.freepatentsonline.com/y2011/0147265.html

A kinetic study of decalin selective ring opening reactions over Iridium supported on H-Beta zeolite catalyst

THESIS

A kinetic study of decalin selective ring opening reactions over Iridium supported on H-Beta zeolite catalyst

Alzaid, Ali H. (2011)

A Thesis Submitted In Partial Fulfillment Of The Requirements For The Degree Of Master Of Applied Science In The Faculty Of Graduate Studies (Chemical And Biological Engineering) The University Of British Columbia

Abstract:

Selective ring opening of naphthenic rings is the optimum process for reducing the cyclo-paraffin and aromatic content of gas oils in order to improve its quality and consequently its value.

The aim of this study was to examine the reaction rates of ring opening of a model multi-ring compound, namely decalin, using a bifunctional catalyst.

Three catalysts, Pd/H-Y-30, Ir/H-Beta-300 and Ir/H-Beta-25, were tested to examine the activity and yield of ring opened products at the same reaction conditions. The reaction was performed in a continuously-stirred, batch reactor at 350°C and 3 MPa H2 pressure. The results showed that Ir/H-Beta-25 had the highest activity and yield of ring opened products. By comparing the Ir/H-Beta-25 catalyst and the Ir/H-Beta-350 catalyst, it was concluded that higher activity was achieved with higher acidity, confirming the important role of catalyst acidity in selective ring opening. The effect of reaction conditions, namely temperature (275-350°C) and pressure (3-6 MPa), on the activity and product selectivity was also investigated. Results showed that as the temperature increased, the initial catalyst activity increased. Although the effect of pressure was minimal at 275°C, as the temperature increased, the effect of pressure became more significant and higher conversions were achieved at higher pressures. The concentration of ring opened products increased as the conversion increased for all temperatures and pressures. The ring opened product concentrations increased with increased temperature at 3 MPa. At 275°C, higher ring opened product concentrations were obtained at higher conversions as the pressure increased. Based on the experimental results, a Langmuir Hinshelwood (L-H) kinetic model for the ring opening of decalin was developed. The kinetic model assumed a bifunctional catalytic process in which hydrogenation/dehydrogenation reactions occurred on metal sites, whereas isomerization, ring-opening and cracking occurred on acid sites. The model parameters were estimated by minimizing the difference between measured experimental data and model predictions by the sum of least-squares method. The model was able to estimate the experimental results well, with a R2 of 0.8. Activation energies estimated from the model parameters showed that ring opening had the lowest activation energy (135.4 kJ/mol), whereas cracking had the highest (229.7 kJ/mol).

Free Full Text Source: https://circle.ubc.ca/handle/2429/35589

Ring Opening of Decalin on Iridium- and Platinum-Containing Zeolite Catalysts of the FAU-, MTW- and MWWType

THESIS

Ring Opening of Decalin on Iridium- and Platinum-Containing Zeolite Catalysts of the FAU-, MTW- and MWWType

Sandra Rabl (2011)

Universität Stuttgart

ABSTRACT

The aim of this work was to identify key factors which a high-performance catalyst should have to achieve high yields of open-chain decanes in the hydroconversion of cis-decalin

Polycyclic aromatics have an even higher tendency for the formation of particulates than one-ring aromatics, and they bring about various additional undesirable properties, such as poor ignition characteristics and cetane numbers, an increased propensity for soot formation and unfavorable cold-flow properties. For these reasons, the content of polycyclic aromatics in diesel fuels is limited by legislation to 8 wt.-%. Certain refinery streams, such as light cycle oil (LCO) from the FCC unit are rich in these undesired compounds and can be blended into diesel fuels only to a limited extent. A most attractive way for upgrading these refinery streams is the selective ring opening of polycyclic aromatics into alkanes, without degradation of the carbon number.

The aim of this work was to identify key factors which a high-performance catalyst should have to achieve high yields of open-chain decanes in the hydroconversion of cis-decalin. In order to reach this goal, the kind of the noble metal, the metal loading and the concentration and strength of the Brønsted acid sites in the zeolite catalysts were varied. For a safe identification of the desired open-chain decanes, n-decane was isomerized in separate experiments, and the mixture of iso-decanes thereby generated was co-injected with the liquid products from decalin hydroconversion.

All results suggested that a balance between the metal content and the concentration and strength of Brønsted acid sites was important and necessary. The catalysts could be divided into three categories: catalysts on which only hydrogenolysis on the metal took place; bifunctional catalysts on which the metal had only a dehydrogenation / hydrogenation function and the acid sites are responsible for the conversion of decalin and trifunctional catalysts on which mainly hydrogenolysis on the metal took place but also hints of a superimposition of bifunctional catalysis were visible. On nearly all catalysts open-chain decanes were obtained, but the best catalysts belonged to the group of trifunctional catalysts.

Free Full Text Source: http://elib.uni-stuttgart.de/opus/volltexte/2011/6266/

Platinum-free Catalysts for Selective Ring Opening and Ultra-deep Desulfurization

RESEARCH PROJECT

Platinum-free Catalysts for Selective Ring Opening and Ultra-deep Desulfurization

Principal Investigator: Natalia Semagina

University of Alberta

Website: www.ualberta.ca/~semagina/

Email: semagina@ualberta.ca

Project Number: COSI 2011-01

Projected Completion Date: March 31, 2014

Platinum-based catalysts have recently attracted considerable attention as active catalysts for ultra-deep desulfurization of fuels, with alloying used to increase their sulfur tolerance.

The current preparation methods of the bimetallic particles do not allow control over their structure, and often the most expensive Pt is accumulated in the nanoparticle core, which is inaccessible to reactants. This project is aimed to develop Pt-free bimetallic catalysts using recent advances in nanotechnology, enabling development of precisely controlled nanoparticles with core-shell or mixed-surface sites structure. The catalysts are believed to exhibit high activity, selectivity, and stability in ultra-deep desulfurization of refractory sulfur compounds and in selective ring opening of model fuel components.

Free Full Text Source: http://www.cosi.ualberta.ca/en/Research/BitumenSeparationandUpgrading/Platinum-free%20Catalysts%20for%20Selective%20Ring%20Opening%20and%20Ultra-deep%20Desulfurization.aspx

Selective ring opening of decalin with Pt–Ir/Al2O3 catalyst prepared by catalytic reduction

Catalysis Today, Article in Press, Corrected Proof

Selective ring opening of decalin with Pt–Ir/Al2O3 catalyst prepared by catalytic reduction

Silvana A. D’Ippolito (a), Viviana M. Benitez (a), Patricio Reyes (b), María C. Rangel (c) and Carlos L. Pieck (a)

pieck@fiq.unl.edu.ar

a Instituto de Investigaciones en Catálisis y Petroquímica (INCAPE) (FIQ-UNL, CONICET), Santiago del Estero 2654, 3000 Santa Fe, Argentina

b Facultad de Ciencias Químicas, Universidad de Concepción, Casilla 3-C, Concepción, Chile

c GECCAT, Instituto de Química, Universidade Federal da Bahia, Rua Barao de Geremoabo, s/n, Campus Universitário de Ondina, Federaçao, 40170-290 Salvador, Bahia, Brazil

Abstract

Reports a study of the reaction of selective ring opening using alumina supported Pt–Ir catalysts with and without Mg addition.

Catalysts were prepared by the method of catalytic reduction, having 1 wt% of Pt whereas the Ir content varied in the range 0.1–0.6 wt%. Electron diffraction shows that the method of preparation leads to catalysts with strong interaction between Pt and Ir being observed the presence of a solid phase of Pt–Ir. In catalysts without Mg no changes in the hydrogenolysis activity was observed as the Ir content increases. However, a decrease both in acidity and dehydrogenating activity was observed. In the Mg containing catalysts, the addition of Ir increases the acidity, the dehydrogenating and hydrogenolytic activity. Determined that for the isomerization reaction of n-pentane the addition of Ir improves the stability of the catalysts and formation of isomers of C5 in both series of catalysts (with and without Mg).

Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0920586111000782

Ring opening of cis-decalin on bifunctional Ir/- and Pt/La-X zeolite catalysts

Applied Catalysis A: General, Volume 400, Issues 1-2, 30 June 2011, Pages 131-141

Ring opening of cis-decalin on bifunctional Ir/- and Pt/La-X zeolite catalysts

Sandra Rabl (a), Andreas Haas (a), Dominic Santi (a), Cristina Flego (b), Marco Ferrari (b), Vincenzo Calemma (b) and Jens Weitkamp (a)

jens.weitkamp@itc.uni-stuttgart.de

a Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart, Germany

b Eni S.p.A., R&M Division, Via F. Maritano 26, 20097 San Donato Milanese, Italy

Abstract

Describes results of loading zeolite La-X with iridium or platinum by ion exchange with cationic complexes of the noble metals.

Resulting bifunctional catalysts were used for hydroconversion of cis-decalin in a high-pressure flow-type apparatus at temperatures between 200 and 255 °C and a hydrogen pressure of 5.2 MPa. Both Ir/La-X and Pt/La-X showed a high tendency for skeletal isomerization of decalin. An important isomer was formed by type A rearrangement, namely spiro[4.5]decane … Open-chain decane yields of up to 12% were achieved. The molar carbon number distributions of the hydrocracked products were M-shaped indicating mainly C–C bond cleavage of the ring opening products with one remaining naphthenic ring via carbocations and the paring reaction.

Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0926860X11002456

Thiotolerant Ir/SiO2–Al2O3 bifunctional catalysts: effect of support acidity on tetralin hydroconversion

Catal. Sci. Technol., 2011, 1, 408-412

Thiotolerant Ir/SiO2–Al2O3 bifunctional catalysts: effect of support acidity on tetralin hydroconversion

Salim Nassreddine, Santiago Casu, José Luiz Zotin, Christophe Geantet and Laurent Piccolo

Abstract

Reports results of tetralin hydroconversion over supported iridium catalysts under a pressure of 4 MPa in the presence of H2S in a continuous high-pressure gas-phase microreactor.

Decalin, naphthalene, ring-contraction bicyclic products and one-ring-opening products are formed. A screening of silica, alumina and amorphous silica–alumina (ASA) supports demonstrates that only ASA provides thiotolerance and ring opening/contraction selectivity to iridium nanoparticles. Shows that by testing Ir/ASA catalysts with various silica–alumina ratios but similar Ir particle size (1.5 nm), the intermediate concentration of silica (40 wt%) leads to the highest activity and selectivity, in correlation to the Brönsted acidity measured by infrared spectroscopy of adsorbed pyridine.

Full Text Source (Subscription or Fee): http://pubs.rsc.org/en/Content/ArticleLanding/2011/CY/c1cy00002k

Thiotolerant Ir/SiO2–Al2O3 bifunctional catalysts: Effect of metal–acid site balance on tetralin hydroconversion

Journal of Catalysis, Volume 278, Issue 2, 7 March 2011, Pages 253-265

Thiotolerant Ir/SiO2–Al2O3 bifunctional catalysts: Effect of metal–acid site balance on tetralin hydroconversion

Salim Nassreddine (a), Laurence Massin (a), Mimoun Aouine (a), Christophe Geantet (a) and Laurent Piccolo (a)

laurent.piccolo@ircelyon.univ-lyon1.fr

a Institut de recherches sur la catalyse et l’environnement de Lyon, IRCELYON, UMR 5256 CNRS & Université Lyon 1, 2 Avenue Albert Einstein, F-69626 Villeurbanne, France

Received 28 July 2010;  revised 15 October 2010;  accepted 16 December 2010.  Available online 26 January 2011.

Abstract

Describes investigation of hydroconversion of tetralin over iridium nanoparticles supported on amorphous silica–alumina (ASA) in a continuous high-pressure gas-phase micro-reactor in the presence of H2S

The bifunctional Ir/ASA catalysts have been submitted to sintering treatments. The samples have been characterized in order to tune the Ir particle size, tby HRTEM and XPS. Careful analysis of tetralin conversion products by comprehensive two-dimensional gas chromatography (GC×GC–MS) and NMR determines unambiguous compound families. Hydrogenation, dehydrogenation, ring-contraction products, and  one-ring-opening products are formed, without significant cracking. The catalysts exhibit stable activity in the presence of sulfur. As the mean particle size increases from 1.5 to 8 nm, the ring-opening/contraction selectivity increases dramatically.

 Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0021951710004288

FCC gasoline desulfurization using a ZSM-5 catalyst: Interactive effects of sulfur containing species and gasoline components

Fuel, Volume 90, Issue 5, May 2011, Pages 2016-2025

FCC gasoline desulfurization using a ZSM-5 catalyst: Interactive effects of sulfur containing species and gasoline components

Lisette Jaimes (a), Miguel Badillo (b) and Hugo de Lasa (a)

hdelasa@eng.uwo.ca

a Chemical Reactor Engineering Centre, Department of Chemical and Biochemical Engineering, Faculty of Engineering, University of Western Ontario, London, Ontario, Canada N6A 5B9

b Departamento de Ingeniería Química, Universidad de Zacatecas, Mexico

Abstract

Evaluates the influence of gasoline hydrocarbon components on thiophene conversion over H-ZSM5 zeolite. Describes experiments carried out in a CREC fluidized riser simulator under mild conditions using thiophene/hydrocarbon mixtures as representatives of gasoline. Results show a high and selective thiophene conversion, forming H2S, aromatics, alkyl-thiophenes, benzothiophene, and coke. Found that gasoline octane number is enhanced and olefin content reduced, accomplished with minimum gasoline losses. It is hypothesized that thiophene conversion takes place via ring opening and alkylation, with gasoline hydrocarbon components having key roles as hydrogen donors in thiophene ring opening reactions as well as co-reactants in thiophene alkylation. Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0016236110007015

The low temperature oxidation of Fosterton asphaltenes and its combustion kinetics

Fuel Processing Technology, Volume 92, Issue 5, May 2011, Pages 1056-1061

The low temperature oxidation of Fosterton asphaltenes and its combustion kinetics

Pulikesi Murugan (a), Thilakavathi Mani (a), Nader Mahinpey (a), and Koorosh Asghari (b)

nader.mahinpey@ucalgary.ca

a Dept. of Chemical and Petroleum Engineering, Schulich School of Engineering, The University of Calgary, Calgary, Canada, AB T2N 1N4

b Faculty of Engineering, University of Regina, Regina, SK S4S 0A2, Canada

Abstract

Examines the influence of low temperature oxidation (LTO) on Fosterton oil sand asphaltenes (FOSA).

Fosterton oil sand asphaltenes were subjected to air oxidation, at a low temperature for 6.33 hours in a fixed bed tubular reactor. Vent gases were analyzed for content of CO, CO2, and oxygen. The m ratio () of the fuel is obtained from effluent gas analysis. LTO residue was analyzed to determine its elemental composition. Low H/C ratio (0.8) found in LTO residue suggests that it contains condensed polynuclear aromatic rings. Thermal behavior and combustion kinetics of the residue was investigated using thermogravimetric analysis (TGA). Non-linear regression method was used to analyze the combustion reaction kinetics. Results indicate that the activation energy for the combustion of the asphaltene is 66.73 kJ/mol and the pre-exponential factor is 1.2 × 104 min-1.

Full Text Source (Subscription or Fee): http://www.sciencedirect.com/science/article/pii/S0378382011000063

Regio- and Stereoselective Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes

J. Am. Chem. Soc., 2011, 133 (15), pp 5794–5797

Regio- and Stereoselective Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes

Shingo Kobayashi, Louis M. Pitet, and Marc A. Hillmyer*

hillmyer@umn.edu

Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States

3-Substituted cis-cyclooctenes (3RCOEs, R = methyl, ethyl, hexyl, and phenyl) were synthesized and polymerized, and the polymers therefrom were hydrogenated to prepare model linear low density polyethylene (LLDPE) samples.

Ring-opening metathesis polymerization (ROMP) of the 3RCOEs using Grubbs' catalyst proceeded in a regio- and stereoselective manner to afford polyoctenamers [poly(3RCOE)] exhibiting remarkably high head-to-tail regioregularity and high trans-stereoregularity. Overall selectivity increases with the increasing size of the R substituent. Hydrogenation of poly(3RCOE)s affords precision LLDPEs with R substituents on every eighth backbone carbon.

Full Text Source (Subscription or Fee): http://pubs.acs.org/doi/abs/10.1021/ja201644v

Upgrading of light cycle oil by partial hydrogenation and selective ring opening over an iridium bifunctional catalyst

Research on Chemical Intermediates

Upgrading of light cycle oil by partial hydrogenation and selective ring opening over an iridium bifunctional catalyst

Dipali P. Upare, R. Nageswara Rao, Songhun Yoon and Chul Wee Lee

Abstract

An iridium catalyst supported on USY zeolite was evaluated for hydrotreating of light cycle oil (LCO) to reduce its aromaticity and improve its cetane index.

Products were analyzed by GC and 13C NMR spectrometry to determine quantitatively the aromatic carbon content and the increase in cetane index. It was found that addition of an appropriate amount of potassium was an effective way to optimize the acid properties of the catalyst. Results confirm that 0.9% (w/w) Ir/USY zeolite catalyst doped with 0.75% (w/w) K was highly suitable for partial hydrogenation and ring opening of LCO to improve cetane quality, thus increasing the extent of its blending ratio with the diesel pool.

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Stereoselective Ring-Opening Reactions of Epoxides in Water

Current Organic Synthesis, Volume 8, Number 3, June 2011 , pp. 319-329(11)

Stereoselective Ring-Opening Reactions of Epoxides in Water

Bonollo, S.; Lanari, D.; Marrocchi, A.; Vaccaro, L.

Abstract:

Water is an excellent reaction medium for the definition of highly chemically-efficient and environmentally friendly synthetic processes.

By exploiting the unique properties of water it has been possible to realize more selective and efficient processes than those performed in organic media. This includes the ring-opening of epoxides by nucleophiles. The review article examines the role of water in influencing the stereoselectivity of epoxide ring-opening reactions will be presented, including the most recent examples of enzyme-catalyzed processes.

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A comparative study of ring opening of naphthalene, tetralin and decalin over Mo2C/HY and Pd/HY catalysts

Applied Catalysis A: General, Volume 403, Issues 1-2, 22 August 2011, Pages 36-47

A comparative study of ring opening of naphthalene, tetralin and decalin over Mo2C/HY and Pd/HY catalysts

Shahrzad Jooya Ardakani, Kevin J. Smith , ,

Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada

Abstract

Reports that the conversion of naphthalene, tetralin or decalin to ring-opened products over Mo2C/HY, Mg- or K-Mo2C/HY, and a commercial Pd/HY catalyst.

Carbon deposition was lowest after reaction with decalin compared to naphthalene or tetralin for all the studied catalysts. The results suggest that the deposited carbon has species that are derived from naphthalene or tetralin, rather than decalin as its precursor, and the coke species are generated through bimolecular reactions on acid sites. The catalysts with higher hydrogenation activity, therefore, had lower deactivation rates.

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New Insights Into The Mechanism Of Alkene Metathesis

Rev. Roum. Chim., 2011, 56(4), 299-316

New Insights Into The Mechanism Of Alkene Metathesis

Carmen I. MITAN,* Valerian DRAGUTAN and Ileana DRAGUTAN

cmitan@yahoo.com

Institute of Organic Chemistry, Roumanian Academy, Spl. Independentei, 202 B, sect. 6, Bucharest, Roumania

The diversity of alkene metathesis reactions, presently applied to their full potential in synthesis of complex scaffolds and assemblies or as key steps in the total synthesis of natural products, demands a deep understanding of the intricate metathesis mechanism since not all of the catalysts are efficient for all of the substrates, nor do they trigger the identical mechanistic pathways, though they share the same main intermediates (the generally accepted metallacarbene and metallacyclobutane).

Metathesis processes are sometimes complicated by the occurrence of side reactions which result in a number of by-products. Unveiling the influence of reaction conditions, in particular of the catalytic system and the active species generated thereof during metathesis of a chosen substrate is important to obtaining high yields in the targeted product at low cost. The paper focuses on kinetic and mechanistic aspects reported to date for alkene metathesis induced by Ru-alkylidene complexes, concentrating on the interplay ligand dissociation – initiation step – overall catalytic activity, as determined by the catalyst structure.

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Hydro-conversion of 1-methyl naphthalene into (alkyl)benzenes over alumina-coated USY zeolite-supported NiMoS catalysts

Fuel, Volume 90, Issue 1, January 2011, Pages 182-189

Hydro-conversion of 1-methyl naphthalene into (alkyl)benzenes over alumina-coated USY zeolite-supported NiMoS catalysts

Joo-Il Park (a), Jihn-Koo Lee (b), Jin Miyawaki (a), Young-Kwang Kim (a), Seong-Ho Yoon (a), Isao Mochida (a)

yoon@cm.kyushu-.ac.jp

a Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 816-8580, Japan

b 121 Bio-venture Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoun-dong, Yuseong-gu, Daejeon 305-806, Republic of Korea

Abstract

To study ring opening reactions of 1-methyl naphthalene using NiMoS supported on ?-alumina and alumina-coated/mixed USY zeolites hydro-conversion reactions were carried out at 360 °C under 5 MPa of H2 pressure.

The catalysts were characterized using N2 BET, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), pyridine FT-IR, and high-resolution transmission electron microscopy (HR-TEM) to study the influence of morphological and acidic properties on hydrogenation (HYD) and hydrocracking (HC) reactions. NMACZ-2 (NiMoS supported on the minimum amount of alumina-coated USY zeolite) showed enhanced reactivity for HC and produced (alkyl)benzenes with the highest yield, of ca. 80% ... A large amount of decalin was produced through the HYD of tetralin without significant cracking, possibly due to the weak acid character of ?-alumina. Bulk phase Mo oxide species on NMAZ (physical mixture of alumina and USY zeolite), as well as deactivation of the catalysts due to coke formation over the naked zeolite surface, inhibited the ring opening of tetralin, decreasing the yield of (alkyl)benzene.

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Catalytic ringopening of decalin on Ir- and Pt-containing zeolite Y – Influence of the nature of the charge-compensating alkali cations

Microporous and Mesoporous Materials, Volume 146, Issues 1-3, December 2011, Pages 190-200

Special Issue - Corma60

Catalytic ringopening of decalin on Ir- and Pt-containing zeolite Y – Influence of the nature of the charge-compensating alkali cations

Dedicated to Professor Avelino Corma on the occasion of his 60th birthday

Sandra Rabl (a), Dominic Santi (a), Andreas Haas (a), Marco Ferrari (b), Vincenzo Calemma (b), Giuseppe Bellussi (b), Jens Weitkamp (a)

jens.weitkamp@itc.uni-stuttgart.de

a Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart, Germany

b Eni S.p.A., R&M Division, Via F. Maritano 26, 20097 San Donato Milanese, Italy

Abstract

Reports results of a study on the catalytic hydroconversion of cis-decalin at a hydrogen pressure of 5.2 MPa and temperatures ranging from 240 to 380 °C in a continuously operated fixed-bed reactor.

Two series of catalysts were used based on zeolite Y in which the alkali cations from lithium to cesium were introduced by ion exchange. One catalyst series contained 3 wt.% of iridium, the other the same amount of platinum. Both metals were introduced by ion exchange. Upon the reduction of the metals with hydrogen, Brønsted acid sites were formed, the strength of which decreased from the lithium to the cesium forms of zeolite Y, according to the Sanderson electronegativity concept.

The fastest reaction was the stereoisomerization of cis- to trans-decalin.

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The effect of Mg and K addition to a Mo2C/HY catalyst for the hydrogenation and ringopening of naphthalene

Catalysis Communications, Volume 12, Issue 6, 10 February 2011, Pages 454-458

Short Communication

The effect of Mg and K addition to a Mo2C/HY catalyst for the hydrogenation and ringopening of naphthalene

Xuebin Liu (a), Shahrzad Jooya Ardakani (a), Kevin J. Smith (a)

kjs@interchange.ubc.ca

a Department of Chemical and Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC, Canada V6T 1Z3

Abstract

Reports the effect of Mg (0.5–2 wt.%) or K (1 wt.%) added to a 20 wt.% Mo2C/HY catalyst for the hydrogenation and ring opening of naphthalene.

Both Mg-Mo2C/HY and K-Mo2C/HY increased naphthalene and coke-precursor hydrogenation whereas ring-opening selectivity was reduced compared to the Mo2C/HY. Metal dispersion and catalyst acidity are key parameters that determine bifunctional catalyst performance. Although Mg and K addition improved Mo2C dispersion they did not provide the optimum acidity needed for increased ring-opening selectivity.

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Selective Ring Opening of Methylcyclopentane and Methylcyclohexane Over Iridium Bifunctional Catalysts Supported on Surface Modified -Al2O3, SiO2 and Ultra Stable Y Zeolites

Catalysis Letters, Volume 141, Number 7, July 2011 , pp. 1047-1055(9)

Selective Ring Opening of Methylcyclopentane and Methylcyclohexane Over Iridium Bifunctional Catalysts Supported on Surface Modified ?-Al2O3, SiO2 and Ultra Stable Y Zeolites

Nageswara Rao, R. 1; You, Nansuk 2; Yoon, Songhun 2; Upare, Dipali 2; Park, Yong-Ki 2; Lee, Chul 3

chulwee@krict.re.kr

1: Analytical Chemistry Division, IICT, Tarnaka, Hyderabad, 500007, India

2: Green Chemistry Division, Petroleum Displacement Technology Center, Korea Research Institute of Chemical Technology, Daejeon, 305-600, Korea

3: Green Chemistry Division, Petroleum Displacement Technology Center, Korea Research Institute of Chemical Technology, Daejeon, 305-600, Korea

Abstract:

Presents investigation of selective ring opening of methylcyclopentane (MCP) and methylcyclohexane (MCH) over a series of Iridium catalysts supported on ?-alumina, silica and ultra-stable Y (USY) zeolites, and selective ring opening of methylcyclopentane and methylcyclohexane over a series of Iridium catalysts supported on surface modified by co impregnation of potassium of ?-alumina, silica and USY zeolites

On silica, the conversions were 10.7-16.6 and 10.4-14.0% with 96.9-99.0 and 93.3-99.1% selectivity. Potassium acted as a promoter in case of USY zeolites while suppressed of activity of Ir supported on ?-alumina and silica. The reaction conditions such as temperature, pressure, contact time and the feed/catalyst ratio were optimized. The evaluation of catalysts' activity and selectivity towards ring opening of MCP and MCH is of great importance in understanding which catalyst modification could be effective in treatment of gasoline/diesel feed stocks for improving octane/cetane rating and fuel quality.

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