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Stable hydrogen production from ethanol through steam reforming reaction over nickel-containing smectite-derived catalyst.

Yoshida H, Yamaoka R, Arai M - Int J Mol Sci (2014)

Bottom Line: The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition.Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite.The Ni-containing smectite-derived catalyst contains, after H2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H2.

View Article: PubMed Central - PubMed

Affiliation: . yoshida@chem.kumamoto-u.ac.jp.

ABSTRACT
Hydrogen production through steam reforming of ethanol was investigated with conventional supported nickel catalysts and a Ni-containing smectite-derived catalyst. The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition. Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite. The Ni-containing smectite-derived catalyst contains, after H2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H2.

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Time profiles of selectivity to CH3CHO (a); CO (b); CH4 (c); C2H4 (d) and CO2 (e) over different Ni catalysts given at 500 °C.
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ijms-16-00350-f007: Time profiles of selectivity to CH3CHO (a); CO (b); CH4 (c); C2H4 (d) and CO2 (e) over different Ni catalysts given at 500 °C.

Mentions: Time profiles of the product selectivity were examined to further discuss the carbon deposition (Figure 7). At the beginning of the reaction over SM(Ni35) and Ni35/SM, high selectivity to CO and CH4 (Figure 7b,c) and low selectivity to CH3CHO and CO2 (Figure 7a,e) were obtained; the dehydrogenation of ethanol to C1 species (Equation (2)) and the decomposition of CH3CHO (Equation (3)) took place rapidly, but further reaction of C1 species with water, the steam reforming of CH4 (Equation (4)) and the water gas shift reaction (Equation (5)) should be slower than the former reactions. During the reaction, the selectivity to CH3CHO and CO2 tended to increase (Figure 7a,e) while that to CO and CH4 decreases (Figure 7b,c), implying that the decomposition of CH3CHO to CO and CH4 (Equation (3)) was suppressed by carbon deposition compared with the other reactions. Therefore, one can say that CO and CH4 formed from CH3CHO induced the side reactions to form the carbon deposition on the catalyst (Equations (8) and (9)), which suppressed the further decomposition of CH3CHO and resulted in the catalyst deactivation. Vicente et al. [26,27] investigated the steam reforming of ethanol over Ni/SiO2 catalyst, and they noted that CO and CH4 formed by the decomposition of CH3CHO were the precursors of the filamentous coke deposited on the Ni surface. For the three catalysts prepared by impregnation, the selectivity to CO against that to CH4 was higher, and this means that the rate of CH4 steam reforming is faster than the water gas shift reaction. For the smectite-derived SM(Ni35) catalyst, however, the selectivity to CO against that to CH4 was relatively lower compared with the case of Ni35/SM, which indicates that the reactivity of CO was enhanced by Ni nanoparticles in the framework of the smectite structure.


Stable hydrogen production from ethanol through steam reforming reaction over nickel-containing smectite-derived catalyst.

Yoshida H, Yamaoka R, Arai M - Int J Mol Sci (2014)

Time profiles of selectivity to CH3CHO (a); CO (b); CH4 (c); C2H4 (d) and CO2 (e) over different Ni catalysts given at 500 °C.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307250&req=5

ijms-16-00350-f007: Time profiles of selectivity to CH3CHO (a); CO (b); CH4 (c); C2H4 (d) and CO2 (e) over different Ni catalysts given at 500 °C.
Mentions: Time profiles of the product selectivity were examined to further discuss the carbon deposition (Figure 7). At the beginning of the reaction over SM(Ni35) and Ni35/SM, high selectivity to CO and CH4 (Figure 7b,c) and low selectivity to CH3CHO and CO2 (Figure 7a,e) were obtained; the dehydrogenation of ethanol to C1 species (Equation (2)) and the decomposition of CH3CHO (Equation (3)) took place rapidly, but further reaction of C1 species with water, the steam reforming of CH4 (Equation (4)) and the water gas shift reaction (Equation (5)) should be slower than the former reactions. During the reaction, the selectivity to CH3CHO and CO2 tended to increase (Figure 7a,e) while that to CO and CH4 decreases (Figure 7b,c), implying that the decomposition of CH3CHO to CO and CH4 (Equation (3)) was suppressed by carbon deposition compared with the other reactions. Therefore, one can say that CO and CH4 formed from CH3CHO induced the side reactions to form the carbon deposition on the catalyst (Equations (8) and (9)), which suppressed the further decomposition of CH3CHO and resulted in the catalyst deactivation. Vicente et al. [26,27] investigated the steam reforming of ethanol over Ni/SiO2 catalyst, and they noted that CO and CH4 formed by the decomposition of CH3CHO were the precursors of the filamentous coke deposited on the Ni surface. For the three catalysts prepared by impregnation, the selectivity to CO against that to CH4 was higher, and this means that the rate of CH4 steam reforming is faster than the water gas shift reaction. For the smectite-derived SM(Ni35) catalyst, however, the selectivity to CO against that to CH4 was relatively lower compared with the case of Ni35/SM, which indicates that the reactivity of CO was enhanced by Ni nanoparticles in the framework of the smectite structure.

Bottom Line: The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition.Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite.The Ni-containing smectite-derived catalyst contains, after H2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H2.

View Article: PubMed Central - PubMed

Affiliation: . yoshida@chem.kumamoto-u.ac.jp.

ABSTRACT
Hydrogen production through steam reforming of ethanol was investigated with conventional supported nickel catalysts and a Ni-containing smectite-derived catalyst. The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition. Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite. The Ni-containing smectite-derived catalyst contains, after H2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H2.

Show MeSH