72
Water for Energy and Fuel Production
stable at 575°C. The activity decreased in the order: 30Co–10Ni > 40Co–20Ni >
20Co > 10Co–30Ni > 40Ni. The 40Ni showed the strongest resistance to deactivation, whereas all Co-containing catalysts showed higher activity than 40Ni catalyst.
The highest hydrogen yield was found for 30Co–10Ni catalyst in which xCo and Ni
are intimately mixed and dispersed in the HT-derived support.
Dong et al. [114] examined hydrogen production by steam reforming of ethanol
using potassium-doped 12CaO–7Al 2 O 3 catalysts. The conversion of ethanol and H 2
yield over C 12 A 7 O − /x%K catalyst mainly depended on the temperature, K-doping
amount, steam-to-carbon ratio, and contact time. Based on numerous types of catalyst analysis, the authors concluded that the active oxygen species and doped potassium play important roles in the steam reforming of ethanol over C 12 A 7 –O − /27.3%K
catalyst.
As shown earlier, the steam reforming of ethanol undergoes several reaction pathways depending on the catalysts and the reaction conditions. Therefore, the choice
of the catalyst plays a vital role in the reforming process. Navarro et al. [13] pointed
out that the reactions to avoid are C 4 and C 2 H 4 inductive of carbon deposition on
the catalyst surface. Thus, the catalysts that selectively produce hydrogen must
(1) dehydrogenate ethanol, (2) break the carbon–carbon bonds of surface intermediates to produce CO and CH 4 , and (3) reform these C 1 products to generate hydrogen.
As shown earlier, various oxide catalysts, metal-based catalysts (Ni, Co, Ni/Cu), and
noble metal-based catalysts (Pt, Pd, Rh) have proven to be active for steam reforming
of ethanol. The metallic function and the acid-based properties play an important
role in the steam reforming. A good review of hydrogen selectivity and coking resistance of various types of catalysts is given by Navarro et al. [13].
4.5.2.2 methanol
Methanol is an abundant chemical often produced from fossil fuels as well as biomass
[117–134]. Industrially, it is produced at 250°C–300°C temperature and 80–100 atm
pressure using a copper–zinc-based oxide catalyst. Methanol is an important feedstock for the production of hydrogen and hydrogen-rich syngas. While methanol can
be decomposed as
CH 3 OH → CO + 2H
0
2
∆ H 298 K = 90.1 kJ/mol
(4.57)
and this reaction is endothermic and can be catalyzed by a number of catalysts including Ni and Pd, in this chapter, we mainly focus on steam reforming of methanol.
Methanol is a good feedstock because of its easy availability, high-energy density,
and easy storage and transportation. Currently, a significant work is being carried out
for low-temperature steam reforming to produce high-purity hydrogen for power generation in FC in automobiles. The steam reforming of methanol follows the reaction:
CH 3 OH + H 2 O → CO 2 + 3H
∆
0
2
H 298 K = 49.4 kJ/mol
(4.58)
While a number of catalysts have been examined, commercial Cu/ZnO water–gas
shift reaction and methanol synthesis catalysts have been found to be effective for
steam reforming of the methanol. Copper on ZrO 2 support prepared by a numerous
Water for Energy and Fuel Production
stable at 575°C. The activity decreased in the order: 30Co–10Ni > 40Co–20Ni >
20Co > 10Co–30Ni > 40Ni. The 40Ni showed the strongest resistance to deactivation, whereas all Co-containing catalysts showed higher activity than 40Ni catalyst.
The highest hydrogen yield was found for 30Co–10Ni catalyst in which xCo and Ni
are intimately mixed and dispersed in the HT-derived support.
Dong et al. [114] examined hydrogen production by steam reforming of ethanol
using potassium-doped 12CaO–7Al 2 O 3 catalysts. The conversion of ethanol and H 2
yield over C 12 A 7 O − /x%K catalyst mainly depended on the temperature, K-doping
amount, steam-to-carbon ratio, and contact time. Based on numerous types of catalyst analysis, the authors concluded that the active oxygen species and doped potassium play important roles in the steam reforming of ethanol over C 12 A 7 –O − /27.3%K
catalyst.
As shown earlier, the steam reforming of ethanol undergoes several reaction pathways depending on the catalysts and the reaction conditions. Therefore, the choice
of the catalyst plays a vital role in the reforming process. Navarro et al. [13] pointed
out that the reactions to avoid are C 4 and C 2 H 4 inductive of carbon deposition on
the catalyst surface. Thus, the catalysts that selectively produce hydrogen must
(1) dehydrogenate ethanol, (2) break the carbon–carbon bonds of surface intermediates to produce CO and CH 4 , and (3) reform these C 1 products to generate hydrogen.
As shown earlier, various oxide catalysts, metal-based catalysts (Ni, Co, Ni/Cu), and
noble metal-based catalysts (Pt, Pd, Rh) have proven to be active for steam reforming
of ethanol. The metallic function and the acid-based properties play an important
role in the steam reforming. A good review of hydrogen selectivity and coking resistance of various types of catalysts is given by Navarro et al. [13].
4.5.2.2 methanol
Methanol is an abundant chemical often produced from fossil fuels as well as biomass
[117–134]. Industrially, it is produced at 250°C–300°C temperature and 80–100 atm
pressure using a copper–zinc-based oxide catalyst. Methanol is an important feedstock for the production of hydrogen and hydrogen-rich syngas. While methanol can
be decomposed as
CH 3 OH → CO + 2H
0
2
∆ H 298 K = 90.1 kJ/mol
(4.57)
and this reaction is endothermic and can be catalyzed by a number of catalysts including Ni and Pd, in this chapter, we mainly focus on steam reforming of methanol.
Methanol is a good feedstock because of its easy availability, high-energy density,
and easy storage and transportation. Currently, a significant work is being carried out
for low-temperature steam reforming to produce high-purity hydrogen for power generation in FC in automobiles. The steam reforming of methanol follows the reaction:
CH 3 OH + H 2 O → CO 2 + 3H
∆
0
2
H 298 K = 49.4 kJ/mol
(4.58)
While a number of catalysts have been examined, commercial Cu/ZnO water–gas
shift reaction and methanol synthesis catalysts have been found to be effective for
steam reforming of the methanol. Copper on ZrO 2 support prepared by a numerous