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Low and high-pressure ring opening of indan over 2 wt.% Pt, Ir and bi-metallic Pt25Ir75/boehmite catalysts prepared from microemulsion systems
KTH, Superseded Departments, Chemical Engineering and Technology.
KTH, Superseded Departments, Chemical Engineering and Technology.
KTH, Superseded Departments, Chemical Engineering and Technology.
KTH, Superseded Departments, Chemical Engineering and Technology.
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.

Place, publisher, year, edition, pages
2004. Vol. 262, no 2, 189-200 p.
Keyword [en]
ring opening (selective), hydrogenolysis, bi-metallic catalyst, platinum, iridium, boehmite, indan, cetane number improvement
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-8869DOI: 10.1016/j.apcata.2003.11.026ISI: 000221314100008Scopus ID: 2-s2.0-2142815744OAI: oai:DiVA.org:kth-8869DiVA: diva2:14340
Note

QC 20101014

Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Ring-opening catalysts for cetane improvement of diesel fuels
Open this publication in new window or tab >>Ring-opening catalysts for cetane improvement of diesel fuels
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
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:nbn:se:kth:diva-537 (URN)91-7178-221-4 (ISBN)
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

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