Steam Reforming of Ethanol over Ni/Al₂O₃−La₂O₃ Catalysts Synthesized by Sol−Gel

Abstract

The activity of Ni/Al 2 O 3 -La 2 O 3 catalysts prepared by sol-gel process for hydrogen production using ethanol steam reforming was studied. The effect of Ni and La loading in the reaction activity and hydrogen selectivity was analyzed. The catalytic measurements were performed on a fixed-bed microreactor for a 6 h period; within this time, the catalysts showed partial deactivation. The catalyst containing 12 wt % La showed the highest yield to H 2 , but it also presented the highest deactivation. The other catalysts with the same Ni loading showed a decrease in H 2 yield over time. The increase of Ni loading from 5 to 10 wt % caused an increase in H 2 and CO yields in all La containing catalysts. The catalyst supported on sol-gel synthesized alumina showed the highest activity after 6 h on stream. This catalyst showed the lowest deactivation from all the systems that were studied. Polymeric and graphitic carbon were identified by DTA analysis of the spent catalysts. TGA analysis showed that the total coke deposited after reaction followed the trend: Ni/Al > Ni/12La ≈ Ni/8La > Ni/5La. However, less graphitic coke was identified on the catalysts as the lantana loading increased in the supports. Additionally, TEM results indicate that the radius of the graphite tubes decreased as the concentration of La in the support increased. A slight increase of H 2 and CO 2 yields was obtained when the water to ethanol mole ratio increased from 3 to 6. Higher deactivation was observed when more steam was fed to the reaction, even when lower carbon contents were determined by DTA-TGA analysis.

Monitoring Ni 0 and coke evolution during the deactivation of a Ni/La 2 O 3 –αAl 2 O 3 catalyst in ethanol steam reforming in a fluidized bed

“…Although noble metal catalysts perform well in SRE (particularly Rh-based catalysts, due to its activity for CAC bond breakage [14]), their high cost hardly justifies their practical application. Among the non-noble metal catalysts, Ni and Co are the most studied in the SRE process [15][16][17][18][19][20][21][22][23], showing high CAC bond breakage activity. The main inconvenience in the use of Ni and Co catalysts in hydrocarbons and oxygenates reforming processes is their activity in coke formation, although an increase in steam/ethanol molar ratio and temperature mitigates coke deposition because coke gasification is favored [17].…”

Morphological Effect of Pd Catalyst on Ethanol Electro-Oxidation Reaction

“…One possible way of obtaining energy from renewable sources involves the fermentation of organic matter to produce bioethanol, which is a low-toxicity liquid that features high power density (8 KWh/kg) and is easy to transport [2]. It has been suggested that instead of using bioethanol in internal combustion engines it could be used to generate hydrogen through steam-reforming reactions for more efficient fuel-cell applications [3,4,5]. An alternative way of producing energy from ethanol has recently been proposed.…”

Ni/La2O3 Catalysts for Dry Reforming of Methane: Insights into the Factors Improving the Catalytic Performance

“…The reason may be that La 2 O 3 is much excess and hydrophilic, thus part of the Ni species were easily embedded into La 2 O 3 and covered by La 2 O 3 around it, which prevents part of the Ni species from reducing. [40] To further confirm this, we have performed XRD experiment with the reduced 5Ni/La 2 O 3 -GNC after H 2 -TPR experiment. Apparently, Figure S3 exhibits that a new Ni 2 La 3 O 6.92 phase can be observed besides the metallic Ni phase.…”

“…Whereas, except that the amount of 5Ni/La 2 O 3 ‐GNC (1.11 mmol g cat −1 ) is close to this theoretical value, that of 5Ni/La 2 O 3 ‐PP (0.78 mmol g cat −1 ) and 5Ni/La 2 O 3 ‐TD (0.66 mmol g cat −1 ) is much lower than the theoretical value, indicating some Ni 3+ cations are difficult to be reduced from the LaNiO 3 perovskite crystalline structure, especially in 5Ni/La 2 O 3 ‐PP and 5Ni/La 2 O 3 ‐TD. The reason may be that La 2 O 3 is much excess and hydrophilic, thus part of the Ni species were easily embedded into La 2 O 3 and covered by La 2 O 3 around it, which prevents part of the Ni species from reducing …”