194
et al. 2018). These results proved that higher CO 2 consumption will lead to negative
impact on the glycerol conversion and hydrogen yield since the process favors the
RWGS reaction (Bulutoglu et al. 2018; Wang et al. 2009).
Excessive CO 2 molecule tends to react with hydrogen that is previously produced from the main GDR reaction and from water Eq. (7.1). This leads to the limitation of glycerol conversion and hydrogen yield but favors the formation of carbon
monoxide. Wang et al. (2009) reported that at CO 2 -to-glycerol ratio less than 1, the
hydrogen production increases with the increase of reaction temperature. Harun
et al. (2019) observed that the formation rates of the hydrogen and carbon monoxide
dropped as the CO 2 -to-glycerol ratio increased from 3 to 5. This trend was probably
due to the thermodynamic limitation of GDR itself while competing with side species of light hydrocarbon to form the syngas.
Numerous works have been conducted to study the effects of operating conditions on catalytic reforming of glycerol, and these literatures have highlighted the
benefits and limitation faced by the process. However, important targets in terms of
high reactant conversion and product yield as well as coking elimination have yet to
be achieved. Here are some suggestions that might be considered to achieve the
targets:
(i) To design an efficient reactor structure by considering heat transfer coefficient,
reaction rate, endothermic reaction, and temperature gradient of the reactor.
Several reactors types can be proposed and studied to improve the catalytic gas
reaction including fluidized bed reactor, catalytic wall reactor, solar reactor,
and membrane reactor.
(ii) To introduce a vacuum condition to the reactor which could potentially reduce
the reaction temperature since low reaction temperature would minimize the
catalyst deactivation due to coking and sintering.
(iii) To develop kinetics model which can be further used to validate results obtained
from the experimental data. From the model, an accurate reaction conditions
required to achieve higher catalytic activity can be predicted.
(iv) To develop a coke-resistance catalyst that also able to inhibit undesired side
reactions, i.e., RWGS.
7.4 Thermodynamic Analysis of Glycerol Dry Reforming
Thermodynamic analysis is important to predict the behavior of syngas synthesis
from glycerol dry reforming. Wang et al. (2009) have conducted a study on thermodynamic analysis of glycerol dry reforming using Gibbs free energy minimization
method. In their study, reaction equilibrium constant, K p , of Eqs. (7.2), (7.3), (7.4),
(7.5), (7.6), (7.7), (7.8), (7.9) and (7.10) at different temperatures has been determined from Eq. (7.11):
S. Z. Abidin et al.
et al. 2018). These results proved that higher CO 2 consumption will lead to negative
impact on the glycerol conversion and hydrogen yield since the process favors the
RWGS reaction (Bulutoglu et al. 2018; Wang et al. 2009).
Excessive CO 2 molecule tends to react with hydrogen that is previously produced from the main GDR reaction and from water Eq. (7.1). This leads to the limitation of glycerol conversion and hydrogen yield but favors the formation of carbon
monoxide. Wang et al. (2009) reported that at CO 2 -to-glycerol ratio less than 1, the
hydrogen production increases with the increase of reaction temperature. Harun
et al. (2019) observed that the formation rates of the hydrogen and carbon monoxide
dropped as the CO 2 -to-glycerol ratio increased from 3 to 5. This trend was probably
due to the thermodynamic limitation of GDR itself while competing with side species of light hydrocarbon to form the syngas.
Numerous works have been conducted to study the effects of operating conditions on catalytic reforming of glycerol, and these literatures have highlighted the
benefits and limitation faced by the process. However, important targets in terms of
high reactant conversion and product yield as well as coking elimination have yet to
be achieved. Here are some suggestions that might be considered to achieve the
targets:
(i) To design an efficient reactor structure by considering heat transfer coefficient,
reaction rate, endothermic reaction, and temperature gradient of the reactor.
Several reactors types can be proposed and studied to improve the catalytic gas
reaction including fluidized bed reactor, catalytic wall reactor, solar reactor,
and membrane reactor.
(ii) To introduce a vacuum condition to the reactor which could potentially reduce
the reaction temperature since low reaction temperature would minimize the
catalyst deactivation due to coking and sintering.
(iii) To develop kinetics model which can be further used to validate results obtained
from the experimental data. From the model, an accurate reaction conditions
required to achieve higher catalytic activity can be predicted.
(iv) To develop a coke-resistance catalyst that also able to inhibit undesired side
reactions, i.e., RWGS.
7.4 Thermodynamic Analysis of Glycerol Dry Reforming
Thermodynamic analysis is important to predict the behavior of syngas synthesis
from glycerol dry reforming. Wang et al. (2009) have conducted a study on thermodynamic analysis of glycerol dry reforming using Gibbs free energy minimization
method. In their study, reaction equilibrium constant, K p , of Eqs. (7.2), (7.3), (7.4),
(7.5), (7.6), (7.7), (7.8), (7.9) and (7.10) at different temperatures has been determined from Eq. (7.11):
S. Z. Abidin et al.