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Ring-opening catalysts for cetane improvement of diesel fuels
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The global oil refining industry with its present product distribution essentially shifted towards fuels such as gasoline and diesel will most likely hold the fort for considerable time. However, conditions are changing and refinery survival will very much depend on long-term planning, process and product flexibility and being at the frontiers of refining technology, a technology where catalysts play leading roles. Today oil refiners are faced with the challenge of producing fuels that meet increasingly tight environmental specifications, in particular with respect to maximum sulphur content. At the same time, the average quality of crude oil is becoming poorer with higher amounts of aromatics, heteroatoms (sulphur and nitrogen) and heavy metals. In order to stay competitive, it is of decisive importance for refiners to upgrade dense petroleum fractions of low quality to highly value-added products. A practicable route, for example, is upgrading the catalytic cracking by-product Light Cycle Oil (LCO) into a high-quality diesel-blending component in a two-step catalytic process. In the first step the LCO is hydrotreated over a Pt Pd based acidic catalyst bringing about heteroatom and aromatic reduction and isomerization of C6 to C5 naphthenic structures. In the second step these naphthenic structures are selectively opened over an Ir-based catalyst to improve the cetane value.

The present thesis is mainly devoted to the second catalytic step of LCO upgrading and was partly conducted within the framework of the European Union project RESCATS.

From the patent literature it is evident that iridium-based catalysts could be good candidates for ring-opening purposes. A literature survey covering ring opening of naphthenic structures made in the beginning of the project (in 2001), showed the need for extending investigations to heavier hydrocarbons, more representative of the diesel fraction than model compounds such as alkylated mono C5 and C6 naphthenic rings frequently employed in previous academic studies.

Ring-opening catalysts, mainly Pt-Ir based, were synthesised at KTH by two different techniques: the microemulsion and the incipient wetness techniques. Paper I is a review of the microemulsion technique and its applications in heterogeneous catalysis. Characterization of catalysts was performed employing a multitude of techniques including quantitative TPR, TEM-EDX, XPS, CO FT-IR, NH3-DRIFTS and XRF etc. Catalytic screening at 325 oC and atmospheric pressure with hydrogen and pure indan as model substance was conducted to investigate ring-opening activity in terms of conversion and selectivity to desired cetane-boosting products. This development process is the topic of Papers II-IV. The possible industrial implementation of the best catalyst candidate is demonstrated in Paper V.

When designing a catalytic system aimed at refining petroleum, it is crucial to monitor the evolution of the sulphur distribution throughout the different stages of the process so that catalyst properties and reaction parameters may be optimised. The final section of this thesis and Paper VI are devoted to high-resolution sulphur-distribution analysis by means of a sulphur chemiluminescence detector (SCD) following gas chromatographic separation.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , xiv, 74 p.
Series
Trita-KET, ISSN 1104-3466 ; R222
Keyword [en]
ring opening (selective), naphthenic structure, indan, light cycle oil (LCO), cetane, Pt-Ir catalyst, microemulsion, XPS, TPR, TEM, DRIFTS, sulphur analysis, GC-SCD
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-537ISBN: 91-7178-221-4 (print)OAI: oai:DiVA.org:kth-537DiVA: diva2:14345
Public defence
2005-12-09, D3, Lindstedtsvägen 5, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20101014Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2010-10-14Bibliographically approved
List of papers
1. Preparation of catalysts from microemulsions and their applications in heterogeneous catalysis
Open this publication in new window or tab >>Preparation of catalysts from microemulsions and their applications in heterogeneous catalysis
2004 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 265, no 2, 207-219 p.Article in journal (Refereed) Published
Abstract [en]

Microemulsions have a wide range of applications from oil recovery to synthesis of nanoparticles. The first implementation of water-in-oil (w/o) microemulsions for synthesis of nanoparticles was introduced in 1982 and concerns nanoparticles of noble metals for catalytic uses. Since this time, the method has been employed quite extensively in the field of catalysis, from room-temperature reactions such as butene isomerisation to high-temperature reactions such as catalytic combustion of methane.The present review paper will introduce the term microemulsion with emphasis on the microemulsion properties essential for heterogeneous catalyst preparation followed by a general description of the mode of catalytic materials prepared from microemulsions. Several examples of the use of these materials in heterogeneous catalysis are then described. It is shown that nanoparticles obtained from microemulsions have specific properties with respect to size, size distribution and surface structure. Consequently, these particles are in some cases superior regarding catalytic activity and/or selectivity

Keyword
microemulsion, nanoparticles, catalyst preparation, catalysis
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8868 (URN)10.1016/j.apcata.2004.01.014 (DOI)000221855400008 ()2-s2.0-2442563677 (Scopus ID)
Note
QC 20101014Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2011-09-26Bibliographically approved
2. Low and high-pressure ring opening of indan over 2 wt.% Pt, Ir and bi-metallic Pt25Ir75/boehmite catalysts prepared from microemulsion systems
Open this publication in new window or tab >>Low and high-pressure ring opening of indan over 2 wt.% Pt, Ir and bi-metallic Pt25Ir75/boehmite catalysts prepared from microemulsion systems
2004 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 262, no 2, 189-200 p.Article in journal (Refereed) Published
Abstract [en]

A bi-metallic 2 wt.% Pt25Ir75/boehmite catalyst has been synthesized from a microemulsion system and characterized in detail with techniques including TPR, XPS, SEM and TEM-EDX. Additional reduction treatment changes the structural phase of the support as well as the character of the metal particles. TEM-EDX revealed unexpectedly large agglomerates with platinum clusters lying on top of iridium plate-like clusters. The catalytic activity with respect to ring opening of indan was Studied at 325 degreesC and atmospheric pressure and compared with the catalytic performance of corresponding monometallic Pt and Ir/boehmite catalysts. The bi-metallic 2wt.% Pt(25)lr(75)/boehmite catalyst was also tested in a more realistic environment for industrial applications, i.e. at high pressure (40 bar). In essence, the obtained catalytic results indicated superior catalytic activity for the Ir and Pt-Ir catalysts. Concerning selectivity the product distribution varied widely, with hydrogenation and selective ring opening being the most prominent reactions for high pressure and atmospheric pressure conditions, respectively. At atmospheric pressure, all catalysts were slightly deactivated whereas at high pressure, the Pt-Ir catalyst showed a high operating stability with no deactivation.

Keyword
ring opening (selective), hydrogenolysis, bi-metallic catalyst, platinum, iridium, boehmite, indan, cetane number improvement
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8869 (URN)10.1016/j.apcata.2003.11.026 (DOI)000221314100008 ()2-s2.0-2142815744 (Scopus ID)
Note

QC 20101014

Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2016-11-24Bibliographically approved
3. Catalytic ring opening of naphthenic structures Part I. From laboratory catalyst screening via pilot unit testing to industrial application for upgrading LCO into a high-quality diesel-blending component
Open this publication in new window or tab >>Catalytic ring opening of naphthenic structures Part I. From laboratory catalyst screening via pilot unit testing to industrial application for upgrading LCO into a high-quality diesel-blending component
Show others...
2006 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 299, 1-13 p.Article in journal (Refereed) Published
Abstract [en]

The present investigation shows the most relevant results obtained during a joint academic and industrial effort to develop new effective catalysts for upgrading light cycle oil (LCO) into a high-quality diesel-blending component. Bench-scale atmospheric pressure screening with indan over 12 different Pt-Ir-based ring-opening catalysts prepared by the incipient wetness technique showed that the relative amount of iridium and the choice of support material are factors that mainly influence the activity but also the initial and final product distribution. Moreover, TPO-TG-MS analyses of the spent catalysts revealed that for ceria-based catalysts there is a correlation between the amount of iridium, the amount of coke deposits and the resulting catalytic activity: increasing the iridium load results in less carbonaceous deposits and hence higher catalytic activity due to the intrinsic hydrogenolysis/hydrogenation properties of iridium that effectively destroy coke precursors. The catalytic properties of the chosen catalyst candidate, with the formula 2 wt.% Pt5Ir95/CeO2, were examined more closely in a pilot unit under industrially employed conditions with a tetralin/cetane model feed mixture and the real feed pre-hydrotreated LCO (HDT-LCO). As the operating pressure is increased from atmospheric to industrial high-pressure conditions, i.e. 40 bar, coking tendencies are supressed. Moreover, the dominating reaction pathway for the model feed changes from ring-opening to hydrogenation; still, ring-opening is gradually observed as the temperature exceeds approximately 300 degrees C. Simultaneously with ring-opening, consecutive cracking reactions are observed and these must be closely monitored and carefully balanced in order to reduce liquid yield losses.Results obtained at high pressure employing the HDT-LCO show that catalyst performance is slightly impaired, most likely due to sulphur poisoning. In spite of this, the catalyst candidate shows very promising catalytic properties and as the majority of current and forthcoming diesel quality specifications are exceeded, implementation of this catalyst in industrial operation is feasible.

Keyword
ring opening, hydrogenolysis, Pt-Ir catalyst, HDT-LCO, diesel quality improvement
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8870 (URN)10.1016/j.apcata.2005.09.023 (DOI)000234691000001 ()2-s2.0-29144438145 (Scopus ID)
Note

Uppdaterad från "accepted" till published: 20101014. QC 20101014

Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2013-04-11Bibliographically approved
4. Catalytic ring opening of naphthenic structures: Part II - in-depth characterization of catalysts aimed at upgrading LCO into a high-quality diesel-blending component
Open this publication in new window or tab >>Catalytic ring opening of naphthenic structures: Part II - in-depth characterization of catalysts aimed at upgrading LCO into a high-quality diesel-blending component
2006 (English)In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 299, 14-29 p.Article in journal (Refereed) Published
Abstract [en]

The present paper delves into physical and chemical characterization of surface and bulk properties of the twelve 2 wt.% PtxIry catalysts employed in Part I for ring opening of naphthenic structures. The support materials (ceria, alumina, silica, silica-alumina, zirconia, H-SA and magnesia) were investigated using X-ray diffraction (XRD) for phase identification and adsorption/desorption of nitrogen to obtain the specific surface area and pore size distribution. The catalyst preparation via the incipient wetness technique was closely monitored and the final catalysts were examined by means of X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS) and quantitative TPR followed by dynamic pulse chemisorption of CO, Fourier transform infrared spectroscopy (Fr-IR) of adsorbed CO and NH3-DRIFTS. The XPS analyses are particularly comprehensive and involve all the catalysts in their fresh, reduced and spent states. The combined results from TPR, XPS and Fr-IR of adsorbed CO reveal that metallic Pt-Ir alloys are formed directly upon mild reduction.

Keyword
catalyst characterization, XPS, TPR, CO chemisorption, FT-IR, Pt-Ir, platinum, iridium, ceria
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8871 (URN)10.1016/j.apcata.2005.10.050 (DOI)000234691000002 ()2-s2.0-29144481798 (Scopus ID)
Note

Uppdaterad från "accepted" till published: 20101014. QC 20101014

Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2013-04-05Bibliographically approved
5. New effective ceria-based bimetallic precious metals ring-opening catalysts for diesel quality improvement, with special emphasis on cetane enhancement: First-to-invent patent-type document registered at notary offices, Spain & France
Open this publication in new window or tab >>New effective ceria-based bimetallic precious metals ring-opening catalysts for diesel quality improvement, with special emphasis on cetane enhancement: First-to-invent patent-type document registered at notary offices, Spain & France
(English)Manuscript (Other academic)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8872 (URN)
Note
QC 20101014Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2010-10-14Bibliographically approved
6. Characterization of alkylated aromatic sulphur compounds in light cycle oil from hydrotreated vacuum gas oil using GC-SCD
Open this publication in new window or tab >>Characterization of alkylated aromatic sulphur compounds in light cycle oil from hydrotreated vacuum gas oil using GC-SCD
2004 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 86, no 2, 223-234 p.Article in journal (Refereed) Published
Abstract [en]

A light cycle oil (LCO) fraction in the boiling point range 220-337 degreesC was successfully characterized in detail with respect to 29 individual aromatic sulphur compounds and total sulphur content using high-resolution gas chromatography with sulphur chemiluminescence detection (HRGC-SCD). The resulting chromatogram, although very complex with hundreds of different alkyl-substituted aromatic sulphur derivatives, was well resolved owing to the high performance Equity-1 column and the optimised GC method. A shift in the sulphur distribution towards the heavier homologues was observed due to the origin of the LCO, derived from hydrotreated vacuum gas oil.

Keyword
aromatic sulphur compounds, light cycle oil (LCO), analysis, high-resolution gas chromatography (HR-GC), sulphur chemiluminescence detector (SCD)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-8873 (URN)10.1016/j.fuproc.2004.03.001 (DOI)000225142900010 ()2-s2.0-4944265298 (Scopus ID)
Note

QC 20101014

Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2016-11-24Bibliographically approved

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