Open Access
Effect of oxygen addition, reaction temperature and thermal treatments on syngas production from biogas combined reforming using Rh/alumina catalysts
(Elsevier, 2019) Navarro Puyuelo, Andrea; Reyero Zaragoza, Inés; Moral Larrasoaña, Ainara; Bimbela Serrano, Fernando; Bañares, Miguel A.; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Dry reforming and partial oxidation of biogas were studied using 0.5 wt.% Rh/Al2O3 catalysts, both inhouse prepared and commercial. The effects of O2 addition on syngas yield and biogas conversion were studied at 700 C using different O2/CH4 ratios in the gas feeding stream: 0 (dry reforming), 0.12, 0.25, 0.45 and 0.50. The highest CH4 conversion, H2 yield and H2/CO molar ratio were obtained with an O2/CH4 ratio of 0.45, even though simultaneous valorization of both CH4 and CO2 could be best attained when the O2/CH4 ratio was 0.12. Increased biogas conversions and syngas yields were obtained by increasing reaction temperatures between 650 and 750 C. A detrimental influence on catalytic activity could be observed when the catalyst was subjected to calcination. Increasing the hold time of the thermal conditioning of the catalyst under inert flow altered Rh dispersion, though had no significant impact on catalyst performance in the dry reforming of methane at 700 C and 150 N L CH4/(gcat h). Characterization of spent samples after reaction by Raman spectroscopy revealed the presence of carbonaceous deposits of different nature, especially on the commercial(named as Rh com) and calcined (Rh calc) catalysts, though oxygen addition in the biogas feed significantly reduced the amount of these deposits. The Rh catalysts that had not been calcined after impregnation (Rh prep) did not present any noticeable characteristic peaks in the G and D bands. In particular, scanning transmission electron microscopy (STEM) images of the spent Rh prep sample revealed the presence of very highly dispersed Rh nanoparticles after reaction, of particle sizes of about 1 nm, and no noticeable C deposits. Combined oxy-CO2 reforming of biogas using highly dispersed and low metal-loading Rh/Al2O3 catalysts with low O2 dosage in the reactor feed can be used to effectively transform biogas into syngas.
Open Access
Remarkable performance of supported Rh catalysts in the dry and combined reforming of biogas at high space velocities
(Elsevier, 2024) Navarro Puyuelo, Andrea; Atienza Martínez, María; Reyero Zaragoza, Inés; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Dry and combined (with O2) reforming of synthetic biogas were studied at 700 °C using 0.5 % Rh catalysts prepared by impregnation on different supports: γ-Al2O3, SiO2, TiO2, ZrO2 and CeO2. Gas hourly space velocity (GHSV) was varied between 150 and 700 N L CH4/(gcat·h), and two O2/CH4 molar ratios of 0 and 0.12 were studied. Rh/Al2O3 catalysts (prepared using two different commercial supports here denoted as Sph and AA) presented the highest biogas conversion and syngas yields under both dry and combined reforming conditions. Catalytic activities were as follows: Rh/AA ≈ Rh/Sph > Rh/SiO2 > Rh/ZrO2 ≈ Rh/CeO2 > Rh/TiO2. The effect of catalysts’ calcination pre-treatment at relatively low (200 °C) and high temperatures (750 °C) was also studied. Calcination at high temperatures had a detrimental effect on both dry and combined reforming activities. However, a positive effect on the reforming activities and syngas yields was observed when the catalysts were calcined at 200 °C, especially under biogas combined reforming conditions: higher CH4 conversions and syngas yields could be achieved, as well as increasing CO2 conversions, though at the expense of lower H2/CO molar ratios.
Open Access
Oxidative steam reforming of glycerol. A review
(Elsevier, 2021) Moreira, Rui; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Ferreira, Abel; Sánchez, José Luis; Portugal, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This review article presents the state-of-the-art on the catalytic oxidative steam reforming (OSR) of glycerol to produce syngas. Concerning the different technologies proposed for the catalytic OSR of glycerol, the following key points can be highlighted: (1) the robustness is much higher than other reforming technologies, (2) several catalysts can work with low deactivation, some of which can recover almost full activity by suitable regeneration, (3) syngas production by catalytic OSR of glycerin is higher than with concurrent technologies, (4) their scaling-up remains an unrealized task, (5) the thermodynamics of the process has been sufficiently covered in the literature, (6) there is a significant lack of kinetic and mechanistic studies that could help gaining deeper insight on the process, (7) novel concepts and reactor designs must be proposed for their development at larger scales, (8) new catalyst formulations must be developed for attaining higher resistance against oxidation and (9) process intensification could help developing them at larger scales.
Open Access
Rutas y retos para la valorización de biogás
(Universidad Libre (Colombia), 2017) Navarro Puyuelo, Andrea; Reyero Zaragoza, Inés; Moral Larrasoaña, Ainara; Bimbela Serrano, Fernando; Gandía Pascual, Luis; Química Aplicada; Kimika Aplikatua
Las tecnologías de digestión anaerobia para procesar corrientes residuales (fracción orgánica de residuos de vertedero, lodos de estaciones depuradoras de aguas residuales, purines, etc.) han originado un incremento de la producción de biogás. El biogás está compuesto principalmente por metano y dióxido de carbono, aunque contiene otros componentes minoritarios e impurezas que obligan a efectuar tratamientos para su purificación y acondicionamiento. Existen diversas alternativas para el aprovechamiento y la valorización de este gas, como son: su utilización directa en la generación de energía calorífica y/o eléctrica, su conversión a biometano, y la producción de gas de síntesis (H2+CO), que posteriormente permite producir combustibles líquidos y/o compuestos químicos de interés como el metanol. En este trabajo se presenta una revisión general de las alternativas de valorización de biogás, con énfasis en los procesos de reformado catalítico, tales como el reformado seco o con vapor de agua y procesos de reformado combinado incluyendo la oxidación parcial.
Open Access
Clean syngas production by gasification of lignocellulosic char: state of the art and future prospects
(Elsevier, 2021) Moreira, Rui; Bimbela Serrano, Fernando; Gil-Lalaguna, Noemí; Sánchez, José Luis; Portugal, Antonio; Institute for Advanced Materials and Mathematics - INAMAT2
Using lignocellulosic char instead of the original biomass avoids the need for costly cleaning and conditioning stages of the producer gasification gas. However, lignocellulosic char gasification has been less extensively studied than gasification of lignocellulosic biomass, and a review of published works on this topic was missing. In this review the present status of char gasification technologies and their future prospects are critically discussed, including possible research opportunities. To date, most studies on char gasification have been performed in thermogravimetric analyzers (TGA) or TGA-like experimental setups. The major setback of TGA and TGA-like equipment is that they do not mimic the actual reaction conditions occurring in gasification reactors, which impedes a direct extrapolation of the findings during the scale-up of different gasification technologies. For this reason, in this literature review focus was put on studies undertaken in industrially relevant reactors, both in batch and continuous configurations. Overall, char gasification can be deemed a valid alternative for clean syngas production, contributing to an integral valorization of lignocellulosic residues within different biorefinery schemes. Of these, process intensification by microwave heating offers interesting opportunities for research and scaling-up, though efforts must be directed toward developing continuous microwave-assisted gasification processes.