596
the mesoporous support pore which inhibits N 2 adsorption during BET analysis
[68]. Similar type of behavior was observed for Cu-MCM-41 [33]. All isotherms
were type IV with H1 hysteresis loop based on IUPAC classification. Capillary
condensation was observed between the relative range of 0.6 to 0.8 for KIT-6 and
Ce-Cu/KIT-6 [63]. This result showed the existence of large channel-like pores that
fall between a narrow range (0.6–0.8) [69]. Same type of isotherm was observed for
Pd-Zn on mesoporous alumina synthesized by impregnation method [64]. After
addition of Pd and Zn, the surface area decreases due to pore blockage of the support. Steep inflection, observed between the relative pressure range of 0.45 to 0.7,
suggests the mesoporosity of the materials. Deshmane et al. [34] used mesoporous
TiO 2 -supported Pd catalyst for methanol steam reforming. All the isotherms belong
to type IV. H2-type hysteresis loop often attributed to disordered and nonuniform
pore size distribution was observed for mesoporous TiO 2 support. The hysteresis
loop changed from H2 to H4 type (indicative of a combination of narrow-slit mesopores and inner micropores) after incorporation of metal into the support. Tajrishi
et al. [66] prepared SBA-15-supported Cu-Ce-Zr-Zn catalyst and found the same
type of isotherm observed by Eswaramoorthi and Dalai [61]. After addition of metals, the isotherm was preserved, but the pore size of the nanocatalysts was less uniform and ordered, compared with that of SBA-15 [70]. MCM-41 and Cu-loaded
MCM-41 catalysts were synthesized by Deshmane et al. [34] where the pores were
blocked upon addition of Cu (Fig. 1). Small pores are blocked first which increases
the pore size [71]. Similar kind of phenomena was reported by Abrokwah et al. [33].
2.2.2 Comparison of SRM Activity of Different Mesoporous Supported Catalysts.
Table 2 shows the activities of Cu- and Pd-based mesoporous supported catalysts for
the methanol steam reforming. Cu-based catalyst is very common in methanol steam
reforming [73–75]. Apart from Cu-based catalysts, Pd can also be used in SRM [76, 77].
Eswaramoorthi and Dalai [61] and Tajrishi et al. [66] investigated Pd- and
Cu-based SBA-15 (mesoporous silica) catalysts for SRM. Both catalysts showed
good catalytic activity in SRM. However, Cu-based catalyst containing Ce and Zr
yielded better methanol conversion and hydrogen selectivity at the same reaction
temperature. So, it can be concluded that other metals, Ce and Zr, play an important
role in Cu dispersion. Mesoporous Ce-Zr supported Cu-based catalyst, and its activity in SRM was also studied by Jampa et al. [62]. The catalyst showed good catalytic activity in terms of methanol conversion and hydrogen selectivity. Different Cu
loading (10 and 15 wt%) on the same mesoporous silica (MCM-41)-supported catalysts were synthesized by Abrokwah et al. [33] and Deshmane et al. [34]. The optimum metal loading of 15% Cu showed the best catalyst activity at a fixed
temperature, indicating that the Cu loading plays an important role in catalyst activity. Another type of mesoporous silica (KIT-6)-supported Cu-based catalyst, prepared by Taghizadeh et al. [63] yielded 100% H 2 selectivity and 92.2% methanol
conversion. They reported that the catalyst activity increased due to the incorporation of Ce into the catalyst. Mesoporous TiO 2 supported Pd catalyst showed 98%
methanol conversion and 95% H 2 selectivity [65]. They reported that good catalytic
activity depends on metal-support interactions. Abrokwah et al. [33] studied time on
stream of different metals supported MCM-41 catalysts for 40 h at 300 °C (Fig. 2).
They found that Cu-supported catalyst gave promising results based on the analysis.
S. Bepari et al.
the mesoporous support pore which inhibits N 2 adsorption during BET analysis
[68]. Similar type of behavior was observed for Cu-MCM-41 [33]. All isotherms
were type IV with H1 hysteresis loop based on IUPAC classification. Capillary
condensation was observed between the relative range of 0.6 to 0.8 for KIT-6 and
Ce-Cu/KIT-6 [63]. This result showed the existence of large channel-like pores that
fall between a narrow range (0.6–0.8) [69]. Same type of isotherm was observed for
Pd-Zn on mesoporous alumina synthesized by impregnation method [64]. After
addition of Pd and Zn, the surface area decreases due to pore blockage of the support. Steep inflection, observed between the relative pressure range of 0.45 to 0.7,
suggests the mesoporosity of the materials. Deshmane et al. [34] used mesoporous
TiO 2 -supported Pd catalyst for methanol steam reforming. All the isotherms belong
to type IV. H2-type hysteresis loop often attributed to disordered and nonuniform
pore size distribution was observed for mesoporous TiO 2 support. The hysteresis
loop changed from H2 to H4 type (indicative of a combination of narrow-slit mesopores and inner micropores) after incorporation of metal into the support. Tajrishi
et al. [66] prepared SBA-15-supported Cu-Ce-Zr-Zn catalyst and found the same
type of isotherm observed by Eswaramoorthi and Dalai [61]. After addition of metals, the isotherm was preserved, but the pore size of the nanocatalysts was less uniform and ordered, compared with that of SBA-15 [70]. MCM-41 and Cu-loaded
MCM-41 catalysts were synthesized by Deshmane et al. [34] where the pores were
blocked upon addition of Cu (Fig. 1). Small pores are blocked first which increases
the pore size [71]. Similar kind of phenomena was reported by Abrokwah et al. [33].
2.2.2 Comparison of SRM Activity of Different Mesoporous Supported Catalysts.
Table 2 shows the activities of Cu- and Pd-based mesoporous supported catalysts for
the methanol steam reforming. Cu-based catalyst is very common in methanol steam
reforming [73–75]. Apart from Cu-based catalysts, Pd can also be used in SRM [76, 77].
Eswaramoorthi and Dalai [61] and Tajrishi et al. [66] investigated Pd- and
Cu-based SBA-15 (mesoporous silica) catalysts for SRM. Both catalysts showed
good catalytic activity in SRM. However, Cu-based catalyst containing Ce and Zr
yielded better methanol conversion and hydrogen selectivity at the same reaction
temperature. So, it can be concluded that other metals, Ce and Zr, play an important
role in Cu dispersion. Mesoporous Ce-Zr supported Cu-based catalyst, and its activity in SRM was also studied by Jampa et al. [62]. The catalyst showed good catalytic activity in terms of methanol conversion and hydrogen selectivity. Different Cu
loading (10 and 15 wt%) on the same mesoporous silica (MCM-41)-supported catalysts were synthesized by Abrokwah et al. [33] and Deshmane et al. [34]. The optimum metal loading of 15% Cu showed the best catalyst activity at a fixed
temperature, indicating that the Cu loading plays an important role in catalyst activity. Another type of mesoporous silica (KIT-6)-supported Cu-based catalyst, prepared by Taghizadeh et al. [63] yielded 100% H 2 selectivity and 92.2% methanol
conversion. They reported that the catalyst activity increased due to the incorporation of Ce into the catalyst. Mesoporous TiO 2 supported Pd catalyst showed 98%
methanol conversion and 95% H 2 selectivity [65]. They reported that good catalytic
activity depends on metal-support interactions. Abrokwah et al. [33] studied time on
stream of different metals supported MCM-41 catalysts for 40 h at 300 °C (Fig. 2).
They found that Cu-supported catalyst gave promising results based on the analysis.
S. Bepari et al.