Evaluation of SiC-porcelain ceramics as the material for monolithic catalyst supports

Journal of Advanced Ceramics, Sep 2014

Mechanical and thermal properties of SiC-porcelain ceramics were studied in the wide SiC content range of 0–95%. Microstructure evolution, shrinkage at sintering, porosity, mechanical strength, elastic modulus, coefficient of thermal expansion (CTE) and thermal conductivity were studied depending on SiC content. The optimal sintering temperature was 1200 °C, and the maximum mechanical strength corresponded to SiC content of 90%. Parametric evaluation of the ceramic thermal shock resistance revealed its great potential for thermal cycling applications. It was demonstrated that the open-cell foam catalyst supports can be manufactured from SiC-porcelain ceramics by the polyurethane foam replication process.

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Evaluation of SiC-porcelain ceramics as the material for monolithic catalyst supports

Oleg SMORYGO 1 Alexander MARUKOVICH a Vitali MIKUTSKI 1 Vladislav SADYKOV 0 0 Boreskov Institute of Catalysis , 5, Lavrentiev Ave., 630090, Novosibirsk, Russia 1 Powder Metallurgy Institute , 41, Platonov Str., 220005, Minsk, Belarus Mechanical and thermal properties of SiC-porcelain ceramics were studied in the wide SiC content range of 0-95%. Microstructure evolution, shrinkage at sintering, porosity, mechanical strength, elastic modulus, coefficient of thermal expansion (CTE) and thermal conductivity were studied depending on SiC content. The optimal sintering temperature was 1200 , and the maximum mechanical strength corresponded to SiC content of 90%. Parametric evaluation of the ceramic thermal shock resistance revealed its great potential for thermal cycling applications. It was demonstrated that the open-cell foam catalyst supports can be manufactured from SiC-porcelain ceramics by the polyurethane foam replication process. Introduction Efficiency of catalytic process with strong heat flux (e.g., hydrocarbon steam reforming) is strongly dependent on the catalyst thermal conductivity. Catalysts supported on the metal alloy monolithic supports ensure effective heat transfer in reactors thus providing a uniform temperature distribution (both axial and radial), and this affects overall catalyst performance [13]. Low robustness of metallic catalyst supports due to corrosive degradation in the reaction media (600900 , water vapor, decomposition products of hydrocarbon, aggressive admixtures) limits their practical application [1,4]. This problem does not arise when the catalyst supports are made from various oxide ceramics exhibiting excellent corrosive resistance [57]. Conventional oxide ceramics, * Corresponding author. E-mail: however, have low thermal conductivity which can be the cause of strong temperature gradients within catalytic reactor, and local hot zones can appear resulting in the catalyst sintering and its fast deactivation [8]. The use of the silicon carbide catalyst supports in the hydrocarbon steam reforming and other strongly endothermic or exothermic process [9] looks promising taking into account their attractive combination of high thermal conductivity and excellent corrosive resistance. The data in Ref. [10] demonstrated that the substitution of the alumina foam catalyst supports by the silicon carbide ones results in the increase of the cobalt based catalyst selectivity from 54% to 80% due to more uniform temperature distribution in the reactor. Extensive application of SiC catalyst supports is restrained by the considerable manufacturing cost resulting from high sintering temperature of above 2100 [11]. Ceramic materials with high SiC content (up to 90%95%) and high mechanical strength (450500 MPa) as well as SiC foam catalyst supports can be synthesized via liquid phase sintering with sintering aids like Al2O3Y2O3 [12,13]. This process is often classified as low temperature sintering, but actually the sintering occurs at rather high temperatures of 17001800 . Besides, the process implies protective sintering atmospheres in order to prevent SiC oxidation, which also contributes to the product manufacturing cost. That is why many efforts were undertaken during the last decade to develop compositions ensuring SiC based ceramics at much lower sintering temperatures. It was found that ceramic materials with high SiC content and reasonable mechanical properties can be synthesized by sintering in air with alkali or alkali-earth silicate sintering aids at temperatures as low as 11001200 [1419]. Various sintering aids containing alkali oxides were successfully applied in these researches: porcelain and its polishing residues, bentonite, and art glass. Potentially, if a reasonable combination of mechanical and thermal properties can be attained, this type of ceramics can have a great commercial potential as the material for monolithic catalyst supports: its low manufacturing cost is predetermined by cheap initial materials and low sintering temperature without special protective atmosphere. However, no study performed complex analysis of mechanical and thermal properties of this type of ceramics before, and no study estimated this type of ceramics as the material for monolithic catalyst supports. Besides, the referred papers presented experimental data on different and rather narrow SiC content ranges, and hence the authors did not report on the evolution of microstructure and properties in the whole SiC content range. In this paper, we studied sintering regimes, microstructure evolution, and mechanical and thermal properties of SiCporcelain ceramics in the wide SiC content range of 095%. Complex analysis of properties that influence the performance in thermal cycling applications was performed, and SiCporcelain ceramics potential as the catalyst support material was analyzed via parametric evaluation. It was demonstrated that open-cell ceramic foam catalyst supports can be manuf (...truncated)


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Oleg Smorygo, Alexander Marukovich, Vitali Mikutski, Vladislav Sadykov. Evaluation of SiC-porcelain ceramics as the material for monolithic catalyst supports, Journal of Advanced Ceramics, 2014, pp. 230-239, Volume 3, Issue 3, DOI: 10.1007/s40145-014-0114-0