424
addition of zinc on the Cu-Al 2 O 3 catalyst reduces the metal size and increases the
metal dispersion [40, 41]. This increases the Cu catalyst activity, hence preferred
over the Ni-based catalyst [40]. The addition of ZrO 2 on Cu/Zn/Al 2 O 3 catalyst
reduces the CO yield [40, 42] which is desirable for membrane reformer application. To reduce the CO selectivity, other supports such as CeO 2 [43], ZnO-Al 2 O 3 /
CeO 2 -ZnO [39, 41, 43], ZrO 2 [44], and MgO [45] are also studied extensively. As
stated earlier it is important to understand the interaction between the impregnated
metal and support to determine complete functionality of any catalyst. The physiochemical property of the combined support and metal significantly affects the surface reaction. It either modifies the electrical property of the metal or promotes the
intermediate formation. In Cu and Ni monometallic catalysts with different support,
CO formation is observed in the range of 3–18%. The same was around 25–35% for
Pd- and Ru-based catalyst supported on Alumina, zirconia, or ceria support.
However, Pd supported on In 2 O 3 , ZnO, and Ga 2 O 3 shows less than 5% CO selectivity [39]. The alloy formation was mainly responsible for such a vast change in CO
selectivity.
Recently, Bimetallic catalysts have gained more attention for methanol steam
reforming. Due to the formation of alloy, the bimetallic catalyst shows diverse electrical and chemical properties in comparison to their base metals. Based on the
metal properties, temperature, support, and oxidative or reductive environment different structure of bimetallic catalysts can be observed. Mostly hetero-atom and
nano-alloys structures are reported in the literature [40] which shows the distinct
property. It is reported that the addition of Cu in Ni-based catalysts can reduce the
coking and metal sintering [42]. The addition of Fe in Ni-CeO 2 catalyst is also studied and found that the addition of Fe reduces the CO formation. Recently, Sharma
et al. [46] have shown that the addition of Fe to Cu on Alumina-zinc-zirconia support shows no CO till 400 °C temperature at atmospheric pressure. Such a catalyst
is quite suitable for the membrane reformer application. However, the life and performance of such catalyst at high pressure need to be rigorously tested.
The metal-supported catalyst normally used for glycerol steam reforming
includes Ir [47], Ru [48], Pt [49], Ni [50], and Pd [51]. Zhang et al. [47] obtained
the complete conversion of glycerol at 400 °C using Ir/CeO 2 with 85% H 2 selectivity, while selectivity with Co/CeO 2 and Ni/CeO 2 were observed 88% and 75% at
425 and 450 °C respectively. They have also verified the presence of a small amount
of CH 4 at the outlet. For each catalyst, maximum hydrogen selectivity was obtained
at the highest temperature of 550 °C. Dave and Pant [52] reported H 2 yield 3.7–3.9
with increasing temperatures from 600 to 700 °C by steam reforming at 82% and
100% conversion, respectively, using Ni/CeO 2 and Ni-ZrO 2 /CeO 2 . Adhikari et al.
[53] synthesized the Ni-based catalyst on different supports: MgO, CeO 2 , and TiO 2 .
They have studied the effect of support on hydrogen selectivity at 600 °C and
WGFR of 9. The order for H 2 selectivity was observed as follows: CeO 2
(70%) > 4MgO (40%) > 4TiO 2 (15%). Chiodo et al. [54] compared the performance
of Rh- and Ni-based catalyst supported on γ-alumina. It was found that the Rh-based
catalyst was more active compared to the Ni-based catalyst. However, for both the
catalysts (Rh/Al 2 O 3 and Ni/Al 2 O 3 ) coke formation was observed at all the
R. K. Upadhyay
addition of zinc on the Cu-Al 2 O 3 catalyst reduces the metal size and increases the
metal dispersion [40, 41]. This increases the Cu catalyst activity, hence preferred
over the Ni-based catalyst [40]. The addition of ZrO 2 on Cu/Zn/Al 2 O 3 catalyst
reduces the CO yield [40, 42] which is desirable for membrane reformer application. To reduce the CO selectivity, other supports such as CeO 2 [43], ZnO-Al 2 O 3 /
CeO 2 -ZnO [39, 41, 43], ZrO 2 [44], and MgO [45] are also studied extensively. As
stated earlier it is important to understand the interaction between the impregnated
metal and support to determine complete functionality of any catalyst. The physiochemical property of the combined support and metal significantly affects the surface reaction. It either modifies the electrical property of the metal or promotes the
intermediate formation. In Cu and Ni monometallic catalysts with different support,
CO formation is observed in the range of 3–18%. The same was around 25–35% for
Pd- and Ru-based catalyst supported on Alumina, zirconia, or ceria support.
However, Pd supported on In 2 O 3 , ZnO, and Ga 2 O 3 shows less than 5% CO selectivity [39]. The alloy formation was mainly responsible for such a vast change in CO
selectivity.
Recently, Bimetallic catalysts have gained more attention for methanol steam
reforming. Due to the formation of alloy, the bimetallic catalyst shows diverse electrical and chemical properties in comparison to their base metals. Based on the
metal properties, temperature, support, and oxidative or reductive environment different structure of bimetallic catalysts can be observed. Mostly hetero-atom and
nano-alloys structures are reported in the literature [40] which shows the distinct
property. It is reported that the addition of Cu in Ni-based catalysts can reduce the
coking and metal sintering [42]. The addition of Fe in Ni-CeO 2 catalyst is also studied and found that the addition of Fe reduces the CO formation. Recently, Sharma
et al. [46] have shown that the addition of Fe to Cu on Alumina-zinc-zirconia support shows no CO till 400 °C temperature at atmospheric pressure. Such a catalyst
is quite suitable for the membrane reformer application. However, the life and performance of such catalyst at high pressure need to be rigorously tested.
The metal-supported catalyst normally used for glycerol steam reforming
includes Ir [47], Ru [48], Pt [49], Ni [50], and Pd [51]. Zhang et al. [47] obtained
the complete conversion of glycerol at 400 °C using Ir/CeO 2 with 85% H 2 selectivity, while selectivity with Co/CeO 2 and Ni/CeO 2 were observed 88% and 75% at
425 and 450 °C respectively. They have also verified the presence of a small amount
of CH 4 at the outlet. For each catalyst, maximum hydrogen selectivity was obtained
at the highest temperature of 550 °C. Dave and Pant [52] reported H 2 yield 3.7–3.9
with increasing temperatures from 600 to 700 °C by steam reforming at 82% and
100% conversion, respectively, using Ni/CeO 2 and Ni-ZrO 2 /CeO 2 . Adhikari et al.
[53] synthesized the Ni-based catalyst on different supports: MgO, CeO 2 , and TiO 2 .
They have studied the effect of support on hydrogen selectivity at 600 °C and
WGFR of 9. The order for H 2 selectivity was observed as follows: CeO 2
(70%) > 4MgO (40%) > 4TiO 2 (15%). Chiodo et al. [54] compared the performance
of Rh- and Ni-based catalyst supported on γ-alumina. It was found that the Rh-based
catalyst was more active compared to the Ni-based catalyst. However, for both the
catalysts (Rh/Al 2 O 3 and Ni/Al 2 O 3 ) coke formation was observed at all the
R. K. Upadhyay