# Glycerol Steam Reforming in a Pilot Plant: Effect of Temperature and Catalyst Load
## 3 Results and Discussion
### Non-Catalytic Glycerol Steam Reforming at Different Temperatures  
Concerning GSR without the catalyst addition, Figure 5 shows the main results obtained for this experiment at different temperatures, including the gas flow and hydrogen composition in the outlet gas.  
Figure 4: Stabilization test for glycerol steam reforming (reaction conditions: water to glycerol ratio = 0.7; flow = 40 mL/min; T = 750 \({}^{\circ}\)C).  
Figure 5: Flow (**a**) and hydrogen percentage (**b**) in outlet gas in glycerol steam reforming without catalyst addition at different temperatures (reaction conditions: water to glycerol ratio = 0.7; inlet flow = 40 mL/min).  
As observed in Figure 5a, there was a considerable increase in the gas flow generated with the temperature, from 16.04 to 30.93 L/min at 750 and 950 \({}^{\circ}\)C, respectively. Compared with previous experiments at the same chemical conditions, the results obtained in this work at 950 \({}^{\circ}\)C were higher, proving that the improvements introduced in the glycerol steam reforming system were effective. Concerning hydrogen production (Figure 5b), its percentage increased with the temperature at the same water/glycerol ratio and feed flow, obtaining slightly higher values compared to previous studies at 950 \({}^{\circ}\)C. This could be due to the fact that alumina without a catalyst addition allowed the chemical modification and enrichment in hydrogen. Previous studies did not include any support addition, which provoked a continuous load loss. These hydrogen percentages are in accordance with the literature, where yields ranging from 37 to 99.7% were observed depending on the catalyst used [26]. Regarding the low heating value (LHV) and power, Figure 6 shows the main results obtained. Thus, it can be concluded that, at the same steam/glycerol ratio and inlet flow, higher heating values were obtained at lower temperatures (15,772 kJ/m\({}^{3}\)N at 750 \({}^{\circ}\)C), which could be due to the higher CO and hydrocarbon percentage under these conditions, whereas an increase in the temperature provoked the chemical conversion of hydrocarbons to hydrogen (as observed in Figure 5b) and CO\({}_{2}\), with the latter not contributing to the LHV calculation and therefore decreasing its value.  
On the other hand, the power increased with the temperature (from 4216 W at 750 \({}^{\circ}\)C to 6325 W at \({}^{\circ}\)C) due to its relationship with the outlet gas flow according to Equation (6):  
\[\mathrm{Power}=\mathrm{Q}_{\mathrm{outletgas}}\times\mathrm{LHV} \tag{6}\]  
where \(\mathrm{Q}_{\mathrm{outletgas}}\) is the flow of the outlet gas and LHV is the low heating value. Therefore, the influence of the flow gas, which considerably increased with the temperature, as observed in Figure 5a, is higher compared to the LHV (which showed an opposite trend with the temperature). Again, previous studies, where the process was not optimized, offered lower power values compared to the present work, with a 4.43% decrease. This way, it can be concluded that the improvements included in this work implied a better performance when it comes to glycerol steam reforming, as a better outlet gas flow, hydrogen percentage and power values were found compared to equivalent previous studies.  
Figure 6: Power and low heating value (LHV) in glycerol steam reforming without catalyst addition (reaction conditions: water to glycerol ratio = 0.7; inlet flow = 40 mL/min).