Scientific publications

Scientific peer-reviewed papers

All the open access scientific publications of FLEDGED project are available in the FLEDGED community on Zenodo.

Optimised production of tailored syngas from municipal solid waste (MSW) by sorption-enhanced gasification (Martinez I., Grasa G., Callén M.S., Lopez J.M., Murillo R., Chemical Engineering Journal, Volume 401, 2020)
Sorption-enhanced gasification (SEG) is a promising indirect gasification route for the production of synthetic fuels since it allows the H2, CO and CO2 content of the resulting syngas to be adjusted. This SEG process has been successfully demonstrated at pilot scale for lignocellulosic biomass and other agricultural and forest waste products, mainly focusing on H2-rich gas production. Within this work, the potential application of the SEG process to a material derived from municipal solid waste (MSW) as feedstock is experimentally demonstrated in a 30 kWth bubbling fluidised-bed (BFB) gasifier. The influence of the sorbent-to-biomass ratio, steam excess and gasification temperature has been carefully analysed in order to understand their effect on SEG performance. Moreover, main conditions able to affect the resulting syngas composition, specifically in terms of H2, CO and CO2 content, have been indicated. Gasification temperature turned out to be the variable that most influenced syngas composition due to the limiting mechanisms associated with the carbonation of the CaO used as bed material. This operating variable also determined biomass conversion, together with solids residence time in the gasifier, resulting in a wide variation of fixed carbon conversion under the studied conditions. Finally, tar yield and composition were evaluated as a function of temperature and the sorbent-to-biomass ratio used, resulting in tar contents as low as 7 g/Nm3 (dry gas), consisting mainly of 1-ring aromatic compounds.
Sorption enhanced dimethyl ether synthesis for high efficiency carbon conversion: Modelling and cycle design (van Kampen J., Boon J., Vente J., van Sint Annaland M., J. of CO2 Utilization, Volume 39, 2020)
Dimethyl ether is one of the most promising alternative fuels under consideration worldwide. Both the conventional indirect DME synthesis and the improved direct DME synthesis process are constrained by thermodynamics, which results in limited product yield, extensive separations and large recycle streams. Sorption enhanced DME synthesis is a novel process for the production of DME. The in situ removal of H2O ensures that the oxygen surplus of the feed no longer ends up in CO2 as is the case for direct DME synthesis. As a result CO2 can be converted directly to DME with high carbon efficiency, rather than being the main byproduct of DME production. The sorption enhanced DME synthesis process is a promising intensification, already achieving over 80 % single-pass CO2 conversion for a non-optimized system. The increased single-pass conversion requires less downstream separation and smaller recycle streams, especially for a CO2-rich feed. A key optimization parameter for the process performance is the adsorption capacity of the system. This capacity can be improved by optimizing the reactive adsorption conditions and the regeneration procedure. In this work, a detailed modelling study is performed to investigate the impact of various process parameters on the operating window and the interaction between different steps in a complete sorption enhanced DME synthesis cycle, and to compare its performance to other direct DME synthesis processes. The development of sorption enhanced DME synthesis, with its high efficiency carbon conversion, could play a significant role in the energy transition in which the carbon conversion will become leading.
Experimental investigation on sorption enhanced gasification (SEG) of biomass in a fluidized bed reactor for producing a tailored syngas (Martínez I., Kulakova V., Grasa G., Murillo R., Fuel, Volume 259, 2020)
Synthetic fuel production from renewable energy sources like biomass is gaining importance driven by the ambitious targets for reducing greenhouse gas emissions worldwide. Sorption enhanced gasification (SEG)
proposes carrying out the gasification of biomass in the presence of a CO2 sorbent, which allows producing a syngas with a suitable composition for a subsequent synthetic fuel production step. This study aims at analysing the effect of different operating parameters (e.g. steam-to-carbon (S/C) ratio, CO2 sorption capacity and sorbent-to-biomass ratio) in the syngas composition and char conversion obtained in a 30 kWth bubbling fluidized bed gasifier, using grape seeds as feedstock. The importance of reducing the formation of higher hydrocarbons through a high steam-to-carbon ratio and using a CO2 sorbent with high sorption capacity is assessed. C3-C4 and unsaturated C2 hydrocarbons contents below 1%vol. (in dry and N2 free basis) can be achieved when working with S/C ratios of 1.5 at gasification temperatures from 700 to 740 °C. Varying the amount of the CO2 separated in the gasifier (by modifying the temperature or the CO2 sorption capacity of the sorbent) the content of H2, CO and CO2 in the syngas produced can be greatly modified, resulting in a module M=(H2-CO2)/(CO+CO2) that ranges from 1.2 to almost 3.
Steam separation enhanced reactions: Review and outlook (van Kampen J., Boon J., van Berkel F.P.F. Vente J., van Sint Annaland M., Chemical Engineering Journal, Volume 374, 2019)
Enhancement by steam separation is a promising process intensification for many types of reactions in which water is formed as a byproduct. For this, two main technologies are reactive vapor permeation (membrane technology) and reactive adsorption. Both can achieve significant conversion enhancement of equilibrium limited reactions by in situ removal of the by-product steam, while additionally it may help protecting catalysts from steam-induced deactivation.
In general, reactive permeation or reactive adsorption would be preferable for distinctly different process conditions and requirements. However, although some advantages of reactive steam separation are readily apparent from a theoretical, thermodynamic point of view, the developments in several research lines make clear that the feasibility of in situ steam removal should be addressed case specifically and not only from a theoretical point of view. This includes the hydrothermal stability of the membranes and their permselectivity for reactive steam permeation, whereas high-temperature working capacities and heat management are crucial aspects for reactive steam adsorption. Together, these developments can accelerate further discovery, innovation and the rollout of steam separation enhanced reaction processes.
Reversible deactivation of γ-alumina by steam in the gas-phase dehydration of methanol to dimethyl ether (Boon J., van Kampen J., Hoogendoorn R., Tanase S., van Berkel F.P.F.,van Sint Annaland M., Catalysis Communications, Volume 119, 2019)
Acidic γ-Al2O3 is an active catalyst for the dehydration of methanol to dimethyl ether (DME). However, the produced steam reduces the activity. In this work, the influence of the exposure of γ-Al2O3 to steam on the catalytic activity for methanol dehydration has been determined. At 250 °C and increasing stream partial pressure the conversion of γ-Al2O3 into γ-AlO(OH) is observed at a p(H2O) of 13–14 bar. As a consequence, the catalytic activity decreases, reducing the rate of methanol dehydration to around 25%. However, this conversion is reversible and under reaction conditions γ-AlO(OH) converts back to γ-Al2O3, recovering its catalytic activity.

Conference abstracts

2017 - TMFB2017 - 5th International Conference on Tailor-Made Fuels from Biomass
A novel sorption enhanced dimethyl ether synthesis (SEDMES) process is presented using a solid adsorbent to remove produced water in situ. SEDMES experiments from feed mixtures of H2, CO, and CO2 have shown an increased yield of DME, an improved selectivity to DME over methanol, and a strongly reduced CO2 content in the product. Consequently, SEDMES will reduce the downstream separation effort and minimise the recycle streams. Within the European Horizon 2020 project FLEDGED, synthesis gas from biomass gasification will be used as feedstock for the separation enhanced DME-synthesis.

Other FLEDGED concept related publications

Flexible sorption enhanced gasification (SEG) of biomass for the production of synthetic natural gas (SNG) and liquid biofuels: Process assessment of stand-alone and power-to-gas plant schemes for SNG production (Martìnez I., Romano M., Energy, Volume 113, 2016)
A flexible sorption enhanced gasification (SEG) process is assessed in this work, where CaO-based material circulating between gasifier and combustor reactors is adjusted for fulfilling the syngas composition requirements according to the downstream fuel synthesis process. A case study of a synthetic natural gas (SNG) production plant based on this SEG process is presented, which has been analysed under different conditions of gasification temperature or solid circulation. A possible integration of this plant with an electrolysis system for power-to-gas application for balancing the electric grid is also proposed and assessed. SNG production efficiencies as high as 62% (LHV-based) have been found for the production of SNG with final CH4 content of 98%. Excess energy recovered from the process streams can be used for producing electricity in a steam turbine, covering the electric demand in the plant. If credits associated to electricity production are considered, equivalent SNG production efficiencies higher than 70% have been calculated. Efficiencies reported in this work are in the upper limit of the range found in the literature for non-SEG concepts, which require an intermediate conditioning step of WGS and CO2 removal. When coupled with an electrolyser, power-to-gas efficiencies of about 60% have been calculated, in line with stand-alone power to gas methanation systems.
Modelling of indirect steam gasification in circulating fluidized bed reactors (Kari Myöhänen, Juha Palonen, Timo Hyppänen, Fuel Processing Technology, Volume 171, 2018)
The indirect steam gasification in circulating fluidized bed reactors was studied by modelling. The object of study was a coupled 12 MWth gasifier-combustor system, which was fired by woody biomass. The heat for the steam-blown gasifier was produced in the air-blown combustor and transported by circulating solids between the interconnected reactors. The system was modelled by a semi-empirical three-dimensional model, which simulated the fluid dynamics, reactions, and heat transfer in the coupled process. The studied cases included different temperature levels, which were controlled by the amount of additional fuel feed to the combustor. The model concept can be later applied to study sorption enhanced gasification, which is a promising method for sustainable production of transport fuels to substitute fossil based fuels.