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their performance and carbon deposition. Rh − ZrO 2 has displayed a higher conversion and syngas yield compared to the Rh − CeO 2 catalyst due to high specific
surface area and small average Rh particle size of Rh − ZrO 2 catalyst. Rh − CeO 2
catalyst on the other hand has been suggested to have strong metal-support interaction when CeO 2 support was found encapsulating the Rh nanoparticles. The strong
metal-support interaction unfortunately has partially rendered the active sites of the
Rh catalyst in Rh − CeO 2 , resulting in a lower catalytic activity than that of
Rh − ZrO 2 . Nevertheless, the presence of CeO 2 has inhibited carbon formation due
to the mobility of oxygen species and oxygen vacancies of CeO 2 sites on the
Rh − CeO 2 catalyst. Meanwhile, the Rh − ZrO 2 deactivated faster than the
Rh − CeO 2 catalyst, which has been correlated to the sintering of Rh nanoparticles
and carbon deposition.
Ni-based catalysts and Rh catalysts are the primary catalysts employed for dry
reforming of glycerol. Regardless whether it is metal or noble catalyst, the aim of
catalyst selection is to achieve high catalytic activity and suppression of carbon
deposition during glycerol dry reforming. Additionally, supports and promoters
have been critically chosen to assist on providing catalyst with high surface area,
high catalyst dispersion, strong metal-support interaction, better carbon removal
due to oxygen species mobility, and basic site properties. As for the future, research
in glycerol dry reforming should focus on minimizing carbon deposition with more
attention on development of carbon-resistance catalysts.
7.3 Effects of Operating Conditions
Apart from catalyst used in GDR, operating conditions including reaction temperature, gas space velocity per gram of catalyst, and molar ratio of reactant carbon
dioxide to glycerol are also few important factors that need to be considered. In this
short review, the effect or reaction conditions in controlling the glycerol and CO 2
conversion, product yield, and catalyst deactivation were discussed. Understanding
the influence of operating conditions and thermodynamic behavior of the GRD are
required to design an efficient reactor system and proper catalyst in maximizing the
reactant conversion and product yield.
7.3.1 Effect of Reaction Temperature
Endothermic process behavior of glycerol dry reforming needs higher temperatures
at above 500 °C to favor the reaction and maximizing the syngas yield (Bulutoglu
et al. 2018). Glycerol reactant is likely to decompose at higher temperatures as its
molecule is thermally unstable (Valliyappan et al. 2008). This aspect was often
overlooked by previous GDR researchers, which in fact caused in imprecise results
on the catalytic activity performance. Bulutoglu et al. (2018) have highlighted this
7 A Short Review on Production of Syngas via Glycerol Dry Reforming
their performance and carbon deposition. Rh − ZrO 2 has displayed a higher conversion and syngas yield compared to the Rh − CeO 2 catalyst due to high specific
surface area and small average Rh particle size of Rh − ZrO 2 catalyst. Rh − CeO 2
catalyst on the other hand has been suggested to have strong metal-support interaction when CeO 2 support was found encapsulating the Rh nanoparticles. The strong
metal-support interaction unfortunately has partially rendered the active sites of the
Rh catalyst in Rh − CeO 2 , resulting in a lower catalytic activity than that of
Rh − ZrO 2 . Nevertheless, the presence of CeO 2 has inhibited carbon formation due
to the mobility of oxygen species and oxygen vacancies of CeO 2 sites on the
Rh − CeO 2 catalyst. Meanwhile, the Rh − ZrO 2 deactivated faster than the
Rh − CeO 2 catalyst, which has been correlated to the sintering of Rh nanoparticles
and carbon deposition.
Ni-based catalysts and Rh catalysts are the primary catalysts employed for dry
reforming of glycerol. Regardless whether it is metal or noble catalyst, the aim of
catalyst selection is to achieve high catalytic activity and suppression of carbon
deposition during glycerol dry reforming. Additionally, supports and promoters
have been critically chosen to assist on providing catalyst with high surface area,
high catalyst dispersion, strong metal-support interaction, better carbon removal
due to oxygen species mobility, and basic site properties. As for the future, research
in glycerol dry reforming should focus on minimizing carbon deposition with more
attention on development of carbon-resistance catalysts.
7.3 Effects of Operating Conditions
Apart from catalyst used in GDR, operating conditions including reaction temperature, gas space velocity per gram of catalyst, and molar ratio of reactant carbon
dioxide to glycerol are also few important factors that need to be considered. In this
short review, the effect or reaction conditions in controlling the glycerol and CO 2
conversion, product yield, and catalyst deactivation were discussed. Understanding
the influence of operating conditions and thermodynamic behavior of the GRD are
required to design an efficient reactor system and proper catalyst in maximizing the
reactant conversion and product yield.
7.3.1 Effect of Reaction Temperature
Endothermic process behavior of glycerol dry reforming needs higher temperatures
at above 500 °C to favor the reaction and maximizing the syngas yield (Bulutoglu
et al. 2018). Glycerol reactant is likely to decompose at higher temperatures as its
molecule is thermally unstable (Valliyappan et al. 2008). This aspect was often
overlooked by previous GDR researchers, which in fact caused in imprecise results
on the catalytic activity performance. Bulutoglu et al. (2018) have highlighted this
7 A Short Review on Production of Syngas via Glycerol Dry Reforming