Chemical Engineering (Council of Physical Sciences)
50 %
Ortelius classification: Applied chemistry
Panel
Chemistry 1
Department or equivalent
Institute of Isotopes, Hungarian Academy of Sciences
Participants
Chamam, Mounir Geszti, Tamásné Győrffy, Nóra Horváth, Anita Nagy, Norina Szarvas, Tibor
Starting date
2008-01-01
Closing date
2012-06-30
Funding (in million HUF)
40.141
FTE (full time equivalent)
7.49
state
closed project
Summary in Hungarian
In Hungary there are several gas wells for methane which contain large amount of carbon dioxide (> 30 %). Earlier studies have shown that the carbon deposition results in several non-desirable structures on the catalyst surface. When the carbonaceous deposit is allowed to be graphitized it becomes fully non-reactive, its removal can be achieved only by oxidation. Sometimes carbon whiskers are formed which migth causes destruction of the metal particles and its top metal appears. As it appears the major drawback of the present reaction is the excessive carbon formation. In the proposed research 3 important reactions play crucial role in the process: water-gas shift reaction, Boudouard reaction, the coke formation. The first priority is the catalyst design in which we prevent the coke formation, or if coke is already formed, its removel during the reaction is accelerated. (i) We aim at developing carbon-resistant catalyst family either by modifying the support, or using bimetallic catalysts. This can be achieved by altering the way of preparation which should be well designed. The higher the metal dispersion, the better the catalyst is, however, the high temperature makes the small metal particles to agglomerate. Thus, the metal particles must be stabilized either by oxide spacing between particles, or by alloying it or by strong metal- support interaction. The pretreatment serves this latter process. Once coke is formed on the catalyst, the Boudouard reaction can be utilized to react with the existing CO2 in the gas stream to produce CO. Small amount additives to e.g. Ni can be useful in this reaction. The experimental strategy concerns with these four points and the target is to design and develops a catalyst working at optimum performance.
Summary
In Hungary there are several gas wells for methane which contain large amount of carbon dioxide (> 30 %). Earlier studies have shown that the carbon deposition results in several non-desirable structures on the catalyst surface. When the carbonaceous deposit is allowed to be graphitized it becomes fully non-reactive, its removal can be achieved only by oxidation. Sometimes carbon whiskers are formed which migth causes destruction of the metal particles and its top metal appears. As it appears the major drawback of the present reaction is the excessive carbon formation. In the proposed research 3 important reactions play crucial role in the process: water-gas shift reaction, Boudouard reaction, the coke formation. The first priority is the catalyst design in which we prevent the coke formation, or if coke is already formed, its removel during the reaction is accelerated. (i) We aim at developing carbon-resistant catalyst family either by modifying the support, or using bimetallic catalysts. This can be achieved by altering the way of preparation which should be well designed. The higher the metal dispersion, the better the catalyst is, however, the high temperature makes the small metal particles to agglomerate. Thus, the metal particles must be stabilized either by oxide spacing between particles, or by alloying it or by strong metal- support interaction. The pretreatment serves this latter process. Once coke is formed on the catalyst, the Boudouard reaction can be utilized to react with the existing CO2 in the gas stream to produce CO. Small amount additives to e.g. Ni can be useful in this reaction. The experimental strategy concerns with these four points and the target is to design and develops a catalyst working at optimum performance.
Final report
Results in Hungarian
A kutatás célja újszerű, stabilis nanoméretű Ni katalizátorok fejlesztése volt, melyeken korlátozható az ártalmas szénlerakódás keletkezése a metán száraz reformálása során. Hordozóként MgAl2O4 spinelt vagy Ce-Zr-oxidot választva, a Ni, NiCo, NiRh vagy NiAu fémrészecskék bevitele szol-gél, szol illetve impregnálás módszerével történt. A szol-gél technikát alkalmazva, a Ni komponens Ce-Zr-oxidmátrixba való beágyazódásával kis és stabilis Ni részecskék keletkeznek. Ennek következtében a reformálási reakcióban képződött szén mennyisége jelentősen lecsökkent a megfelelő impregnált mintához képest, hiszen a jól diszpergált nikkel és az oxid szoros kölcsönhatása elősegítette a felületi szén eltávozását a gázfázisba. A tartós aktivitás biztosításához azonban nagy, robosztusabb Ni részecskék jelenléte is szükséges ezen a hordozón. Az impregnált 8%Ni/MgAl2O4 mintán szénburok és nanocsövek keletkezése lassú dezaktiválódáshoz vezetett, míg a szol-módszerrel készített 4%Ni/MgAl2O4 katalizátoron csökkent a széndepozitum mennyisége. A kevés Au-t tartalmazó szolos mintákon a legaktívabb és legstabilabb 4%Ni/MgAl2O4 katalizátorhoz képest megnövekedett, viszont 3 wt% Au esetén csökkent szénképződés figyelhető meg. Az eredmények szerint a szolban keletkezett NiAu kétfémes vagy ötvözet részecskék jelentős szerkezetváltozáson mennek keresztül az oxidáció/redukció és a katalitikus reakció során. Az arany aktivitást csökkentő hatása mind az impregnálás, mind a szolos módszer esetén megfigyelhető.
Results in English
Our aim was to develop new Ni-based catalysts with nanosized particles stable at high temperature for long time and tolerant to the presence of carbon deposited in methane dry reforming. MgAl2O4 or Ce-Zr-oxide were chosen as supports, and Ni, NiCo, NiRh or NiAu particles were formed by sol-gel process, traditional impregnation or a newly developed sol-method. When Ni was built in the CeZr-oxide matrix by sol-gel technique, the small size of metal could be better maintained and the carbon formation was dramatically decreased compared to the case when Ni was impregnated on the same type of support, because the intimate contact of oxide and the finely dispersed Ni facilitates carbon gasification. However, sintered, robust metallic or bimetallic particles seem to be important in long term stability. On impregnated 8%Ni/MgAl2O4 sample the catalyst slowly deactivated due to the formation of graphite shell around nickel particles and carbon nanotubes. Using 4%Ni/MgAl2O4 prepared by sol technique, the amount of surface coke could be decreased. Small amount of Au increased the amount of carbon deposited on sol samples, while 3wt% Au decreased it compared to the parent 4%Ni/MgAl2O4 which exhibited the best activity and stability. Significant restructuring of AuNi sol-samples is suggested to happen during oxidation/reduction treatment and during catalytic run. In general, the presence of gold introduced by impregnation or sol method retarded the catalytic dry reforming reaction.
László Guczi, Györgyi Stefler, Alain Kiennemann, Agnieszka Pietraszek: CH4 DRY REFORMING WITH CO2: CHARACTERIZATION OF SURFACE CARBON SPECIES FORMED ON CeOx-ZrOy BASED NI, NI-CO AND NI-RH CATALYSTS, AECHI Meeting 2010, 2010
L. Guczi, G. Stefler, O. Geszti, I. Sajó, Z. Schay and A Tompos: METHANE DRY REFORMING WITH CO2: A STUDY ON SURFACE CARBON SPECIES, North American Catalysis Society Meeting, San Francisco, 2009, 2009
Anita Horváth, Györgyi Stefler, Alain Kiennemann, Agnieszka Pietraszek and László Guczi: Correlation between preparation methods and surface carbon formed in CH4 and CO2 dry reforming on Ni-based catalysts, 240. ACS Meeting Boston 2010 August, 2010
A. Horváth, Gy. Stefler, O. Geszti, A. Kiennemann, A. Pietraszek, L. Guczi: Methane dry reforming with CO2 on CeZr-oxide supported Ni, NiRh and NiCo catalysts prepared by sol-gel technique: relationship between activity and coke formation, Catalysis Today 169 pp. 102-111, 2011
László Guczi, Goran Boskovic, and Erno Kiss: Bimetallic Cobalt Based, Catal Rev. Sci. Eng. 52 pp. 133-203, 2010
A. Horváth, L. Guczi: Methane dry reforming under realistic conditions on solgel and impregnated Ni, NiMe samples: activity and coke formation, előadás (meeting Dublin), 2010
Anita Horváth, Györgyi Stefler, Alain Kiennemann, Agnieszka Pietraszek and László Guczi: A comparative study on CH4 dry reforming with CO2 performed on Ni/MgAl2O4 and Ni/Ce-Zr-oxides, 9th Novel Gas Conversion Symposium, May 31th-June 3rd, 2010, Lyon 2010, 2010
L. Guczi, G. Stefler, O. Geszti, I. Sajó, Z. Schay and A. Tompos: METHANE DRY REFORMING WITH CO2: A STUDY ON SURFACE CARBON SPECIES, Catalysis Society Meeting, South Africa, előadás, 2008
A. Horvath, Gy. Stefler, V. La Parola, L. F. Liotta, G. Pantaleo, A. M. Venezia, L. Guczi: Development of AuNi bimetallic catalysts for CO2 reforming of methane, Proc. of Final Workshop of the COST D36 Action, pp. 51-52 2011.05.18-05.20. Fuengirola, Spain, 2011
A. Horváth, Gy. Stefler, G. Sáfrán, V. La Parola, L. F. Liotta, G. Pantaleo, A. Venezia, L. Guczi1: Comparative study on Au-modified Ni/MgAl2O4 catalysts for dry reforming of methane, 15th International Congress on Catalysis, Münich, 2012 July 1-6, 2012
A. Horváth, Gy. Stefler, G. Sáfrán, V. La Parola, L. F. Liotta, G. Pantaleo, A. Venezia, L. Guczi: Au-modified Ni/MgAl2O4 catalysts: the influence of preparation method on catalyst structure and behavior in methane dry reforming, írás alatt, 2012
Guczi László, Stefler Györgyi, Geszti Olga, Sajó István, Pászti Zoltán, Tompos András, Schay Zoltán: Methane dry reforming with CO2: A study on surface carbon species, Appl. Catal. A: Gen. 375 pp.236-246, 2010
