# Glycerol Steam Reforming in a Pilot Plant: Effect of Temperature and Catalyst Load
## 1 Introduction
Equally, hydrogen production through ethanol and glycerol steam reforming was carried out with Ir, Co and Ni catalysts supported on CeO\({}_{2}\), finding that the former (Ir/CeO\({}_{2}\)) provided a full conversion of glycerol at 400 \({}^{\circ}\)C, whereas the total conversion for Co/CeO\({}_{2}\) and Ni/CeO\({}_{2}\) took place at 425 and 450 \({}^{\circ}\)C, respectively [34]. Another study pointed out the role of promoters such as Mg, Zr, Ce or La in Ni-Al\({}_{2}\)O\({}_{3}\) catalysts, increasing the hydrogen selectivity during the process and obtaining the full conversion of glycerol at 600 \({}^{\circ}\)C (at atmospheric pressure) and a space velocity of 2.5 h\({}^{-1}\). Ni, Ir and Co were effective for CeO\({}_{2}\), with a total conversion of glycerol and 90% selectivity for hydrogen at 550 \({}^{\circ}\)C [35]. For additional hydrogen purification, membrane reactors can be used to increase the hydrogen percentage in the final gas, with Pd-Ag membranes being one of the most popular alternatives for this purpose [23]. Thus, glycerol turns out to be a good candidate to be a renewable source for hydrogen production. Its conversion to hydrogen (depending on the use of purification technologies such as membrane reactors or pressure swing adsorption [36; 37]) or synthesis gas can be reached through reforming processes such as steam reforming (SO), partial oxidation or gasification (PO), autothermal reforming (ATR), aqueous-phase reforming (APR) and steam reforming with supercritical water (SCW). These chemical routes depend on the properties of the catalyst used, generally Ni, Pt and Ru (which favors hydrogen production), as well as the temperature, pressure and reagent ratio. Hence, these factors should be considered when the H\({}_{2}\) yield is evaluated for each process [23]. However, not many studies at a semi-industrial scale or using pilot plants have been observed, as many works show innovative trends that are interesting but only focused on a laboratory scale. Specifically, as observed in Table 2, there are two main trends when it comes to steam reforming applied to glycerol (mainly obtained from biodiesel):  
* Firstly, the possible implementation of GSR in a biorefinery context based on biodiesel production was mainly assessed through simulations of integrated processes, proving that hydrogen production could contribute to the total yield found in these systems. In that sense, more works focused on semi-industrial or industrial levels could complement these works to prove the efficiency of GSR in real contexts. * Secondly, the development of new catalysts, including promoters such as La (included in this work), Ce or Mg, to improve the duration of their activity. Also, different kinds of supports, including nanocatalysts, have been considered to make the chemical conditions more efficient and stable over time. Thus, it is essential to improve the efficiency of GSR at an industrial level, to compete with traditional technologies. Considering the above, the aim of this work was to carry out the steam reforming of glycerol in an experimental facility at a semi-industrial scale, trying to assess the effect of the temperature and catalyst load to obtain suitable gasification powers, paying attention to the feasibility of the Ni-based catalyst applied to this facility. Specifically, the outlet gas flow was optimized, as well as the hydrogen mole fraction and power. On the other hand, the selection of the best temperature and catalyst percentage to obtain the best catalytic performance was another specific objective, with different NiO concentrations used for that purpose and comparing them with non-catalytic tests. Finally, considering these comparisons, our aim was to establish the optimum operating conditions for the semi-industrial plant according to the gas flow, hydrogen mole ratio, lower calorific value and power. Thus, the real implementation of glycerol steam reforming at a semi-industrial scale is proposed, with useful information about the feasibility of this process.