Highly efficient steam reforming of ethanol (SRE) over CeO _x grown on the nano Ni _x Mg _y O matrix: H ₂ production under a high GHSV condition

Abstract

Summary Steam reforming of ethanol (SRE) over non‐noble metal catalysts is normally conducted at high temperature (>600°C) to thermodynamically favour the catalytic process and carbon deposition mitigation. However, high temperature inhibits water‐gas shift reaction (WGSR) and therefore restrains the yield of H2 and leads to the formation of an excessive amount of CO. The modification of non‐noble metal catalyst to enhance WGSR is an attractive alternative. In this study, CeOx was firstly loaded onto a nano‐scaled NixMgyO matrix and subsequently used as the catalyst for hydrogen production via SRE. Morphology of the catalyst materials was characterized by using a series of technologies, while H2‐temperature programmed reduction (H2‐TPR), CO‐temperature programmed deposition (CO‐TPD), and X‐ray photoelectron spectroscopy (XPS), were employed to study the surface nickel, ceria clusters, and their interactions. The catalytic activity and durability of the catalyst were studied in the temperature region of 500°C to 800°C. The CeOx‐coated nano NixMgyO matrix exhibited an outstanding hydrogen yield of 4.82 mol/molethanol under a high gas hourly space velocity (GHSV) of 200 000 hour−1. It is found that the unique Ni0‐CeOx structure facilitates the adsorption of CO on the surface and therefore promotes the effective hydrogen production via WGSR. Moreover, this modified NixMgyO matrix was found to be a more robust and anticoking nanocatalyst because of reversible switch between Ce4+ and Ce3+.

Structural Changes of Ni and Ni–Pt Methane Steam Reforming Catalysts During Activation, Reaction, and Deactivation Under Dynamic Reaction Conditions

“…50 Between 600 and 750 °C, the reacting species are reported to be Ni 2+ ions in the outermost layer and subsurface of mixed oxide phases. 48,51 At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO−MgO solid solution, 50,3,52 sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 .…”

“…At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO–MgO solid solution, ,, sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 . , The reduction of both phases, Ni x Mg y O and NiAl 2 O 4 , as well as of other Ni species cannot be clearly elucidated by an H 2 -TPR experiment but require a more detailed analysis as shown in the following discussion.…”

Structural Changes of Ni and Ni–Pt Methane Steam Reforming Catalysts During Activation, Reaction, and Deactivation Under Dynamic Reaction Conditions

“…50 Between 600 and 750 °C, the reacting species are reported to be Ni 2+ ions in the outermost layer and subsurface of mixed oxide phases. 48,51 At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO−MgO solid solution, 50,3,52 sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 .…”

“…At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO–MgO solid solution, ,, sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 . , The reduction of both phases, Ni x Mg y O and NiAl 2 O 4 , as well as of other Ni species cannot be clearly elucidated by an H 2 -TPR experiment but require a more detailed analysis as shown in the following discussion.…”

A mini review on recent progress of steam reforming of ethanol

“…Luo et al studied the role of CeO x loaded on Ni x Mg y O matrix. 99 The highly mobile oxygen species provided by CeO x is effective for coke removal, signicantly improving the stability in SRE. Meanwhile, CeO x benets CO adsorption and promotes WGS to achieve higher H 78 The as-prepared catalyst shows good activity and stability at 650 °C.…”

“…It is difficult for one single support to possess all these advantages, so rational doping and the addition of promoters are necessary. CeO 2 is a promising candidate as promoter 78,99,100 or supports. [101][102][103] Till now, carbon deposition cannot be absolutely eliminated.…”

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

“…Owing to the unique advantage of CeO 2 on oxygen storage, release and mobile capacity, the application of CeO 2 has attracted much attention during steam reforming process [222,223] . Luo et al [224] . adopted CeO 2 as shell to prepared CeO 2 ‐coated nano Ni x Mg y O catalysts, and found that the unique Ni 0 ‐CeO x structure is beneficial to the WGSR due to stronger CO adsorption and H 2 O activation, and inhibited methanation side reaction.…”

Structural Changes of Ni and Ni–Pt Methane Steam Reforming Catalysts During Activation, Reaction, and Deactivation Under Dynamic Reaction Conditions

“…50 Between 600 and 750 °C, the reacting species are reported to be Ni 2+ ions in the outermost layer and subsurface of mixed oxide phases. 48,51 At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO−MgO solid solution, 50,3,52 sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 .…”

“…At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO–MgO solid solution, ,, sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 . , The reduction of both phases, Ni x Mg y O and NiAl 2 O 4 , as well as of other Ni species cannot be clearly elucidated by an H 2 -TPR experiment but require a more detailed analysis as shown in the following discussion.…”

A mini review on recent progress of steam reforming of ethanol

“…Luo et al studied the role of CeO x loaded on Ni x Mg y O matrix. 99 The highly mobile oxygen species provided by CeO x is effective for coke removal, signicantly improving the stability in SRE. Meanwhile, CeO x benets CO adsorption and promotes WGS to achieve higher H 78 The as-prepared catalyst shows good activity and stability at 650 °C.…”

“…It is difficult for one single support to possess all these advantages, so rational doping and the addition of promoters are necessary. CeO 2 is a promising candidate as promoter 78,99,100 or supports. [101][102][103] Till now, carbon deposition cannot be absolutely eliminated.…”

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

“…Owing to the unique advantage of CeO 2 on oxygen storage, release and mobile capacity, the application of CeO 2 has attracted much attention during steam reforming process [222,223] . Luo et al [224] . adopted CeO 2 as shell to prepared CeO 2 ‐coated nano Ni x Mg y O catalysts, and found that the unique Ni 0 ‐CeO x structure is beneficial to the WGSR due to stronger CO adsorption and H 2 O activation, and inhibited methanation side reaction.…”

Structural Changes of Ni and Ni–Pt Methane Steam Reforming Catalysts During Activation, Reaction, and Deactivation Under Dynamic Reaction Conditions

“…50 Between 600 and 750 °C, the reacting species are reported to be Ni 2+ ions in the outermost layer and subsurface of mixed oxide phases. 48,51 At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO−MgO solid solution, 50,3,52 sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 .…”

“…At even higher temperatures, reduction peaks are mostly ascribed to the formation of the hardly reducible NiO–MgO solid solution, ,, sometimes also referred to as Ni x Mg y O z or NiMgO x , with a variable composition depending on the sample calcination temperature and the quantity of Ni present in the material. However, even though MgO represents the vast majority of the carrier material, the high reduction temperature was attributed in the literature to the possibly formed NiAl 2 O 4 . , The reduction of both phases, Ni x Mg y O and NiAl 2 O 4 , as well as of other Ni species cannot be clearly elucidated by an H 2 -TPR experiment but require a more detailed analysis as shown in the following discussion.…”

A mini review on recent progress of steam reforming of ethanol

“…Luo et al studied the role of CeO x loaded on Ni x Mg y O matrix. 99 The highly mobile oxygen species provided by CeO x is effective for coke removal, signicantly improving the stability in SRE. Meanwhile, CeO x benets CO adsorption and promotes WGS to achieve higher H 78 The as-prepared catalyst shows good activity and stability at 650 °C.…”

“…It is difficult for one single support to possess all these advantages, so rational doping and the addition of promoters are necessary. CeO 2 is a promising candidate as promoter 78,99,100 or supports. [101][102][103] Till now, carbon deposition cannot be absolutely eliminated.…”

Recent Status in Catalyst Modification Strategies for Hydrogen Production from Ethanol Steam Reforming

“…Owing to the unique advantage of CeO 2 on oxygen storage, release and mobile capacity, the application of CeO 2 has attracted much attention during steam reforming process [222,223] . Luo et al [224] . adopted CeO 2 as shell to prepared CeO 2 ‐coated nano Ni x Mg y O catalysts, and found that the unique Ni 0 ‐CeO x structure is beneficial to the WGSR due to stronger CO adsorption and H 2 O activation, and inhibited methanation side reaction.…”