Challenges and strategies for optimization of glycerol steam reforming process

Abstract

The steam reforming of the main biodiesel by-product, glycerol, has been catching up the interest of the scientific community in the last years. The use of glycerol for hydrogen production is an advantageous option not only because glycerol is renewable but also because it's use would lead to the decrease of the price of biodiesel, thus making it more competitive. Consequently, the use of biodiesel at large scale would significantly reduce CO2 emissions comparatively to fossil fuels. Moreover, hydrogen itself is seen as a very attractive clean fuel for transportation purposes.Therefore, the industrialization of the glycerol steam reforming (GSR) process would have a tremendous global environmental impact. In the last years, intensive research regarding GSR thermodynamics, catalysts, reaction mechanisms and kinetics, and innovative reactor configurations (sorption enhanced reactors (SERs) and membrane reactors (MRs)) has been done, aiming for improving the process effectiveness. In this review, the main challenges and strategies adopted for optimization of GSR process are addressed, namely the GSR thermodynamic aspects, the last developments on catalysis and kinetics, as well as the last advances on GSR performed in SERs and MRs.

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

“…H 2 , CO, CO 2 and CH 4 on the one hand and glycerol, acetic acid, and methanol on the other were selected as possible steam reforming products and non-consumed reagents, respectively, for the Gibbs energy minimisation calculations [4,[20][21][22][23][24]. In addition, the thermodynamic formation of solid C was considered negligible under the operating conditions employed, which is in accordance with the results of other thermodynamic studies [5,[24][25][26][27]. The results were analysed by means of an ANOVA test with 95% confidence and the relative influence of the operating variables was calculated using the cause-effect Pareto principle.…”

“…The first consists of its purification to obtain high purity glycerol for use in, for example, the food, cosmetics and pharmaceutical industries [1,3]. The second option is to upgrade crude glycerol to produce different value-added chemicals and/or energy using different valorisation routes such as gasification, steam reforming, aqueous phase reforming and supercritical reforming, among others [4,5]. This work is focused on H 2 production from crude glycerol, a biodiesel by-product, which consists not only of glycerol but also of many other chemicals [1].…”

Thermodynamic analysis of Glycerol Steam Reforming for hydrogen production with in situ hydrogen and carbon dioxide separation

“…The thermodynamic analysis was performed for temperatures in the range of 600-800 K, pressures between 1-5 atm and WGFRs between 3-9 (realistic operation conditions for hydrogen selective membranes [6,7] and carbon dioxide sorbents [5,8,9], which are close to those typically employed in the GSR [10,11]) ; the study considered also hydrogen removal fractions in the range of 0-0.99 and a carbon dioxide removal fraction of 0.99 (for the reasons explained in a posterior section). For all the cases, the yields of hydrogen, methane, carbon dioxide and carbon monoxide were analyzed.…”

“…Moreover, although CO2 might affect membrane permeability towards H2, this is not very pronounced as, for instance, it occurs with CO, and such effect is reversible (thus, as long as CO2 is removed, high permeability towards H2 is restored) [4]. The main requirement is that operating conditions, namely in terms of temperature, are compatible for the GSR catalyst, CO2 sorbent and H2-selective membrane, which is the case [5].…”

Effect of Active Metal Supported on SiO2 for Selective Hydrogen Production from the Glycerol Steam Reforming Reaction

“…10175 reforming (APR) (Cortright et al 2002;Manfro et al 2011;Menezes et al 2011;Tuza et al 2013), and supercritical water (SCW) reforming reactions (Byrd et al 2008;Gutiérrez Ortiz et al 2013;Pairojpiriyakul et al 2013). However, steam reforming has attracted the most attention, partially due to the fact that the process is widely used in industry, and it would require only minor alterations in existing systems if the feedstock was changed from natural gas or naphtha to glycerol (Silva et al 2015). Based on this background, a comparative study of the catalytic performances of nickel (Ni), cobalt (Co), and copper (Cu) supported on silica catalysts, for the glycerol steam reforming reaction, is reported in this study.…”