Recovery of green hydrogen from natural gas grids

Hydrogen (H2) can play an essential role as clean energy in a sustainable future. For example, H2 can store surplus renewable power when the grid cannot soak it, help to decarbonize heavy industry and long-distance transport and replace fossil fuels as a zero-carbon feedstock in chemicals and fuel production. However, H2 as an energy source is only sustainable if its production is free of carbon emissions. In this sense, green hydrogen produced via electrolysis of water powered by renewable energy sources (solar, wind, hydroelectricity, or biomass) is a vital strategy to reduce CO2 emissions levels. The global concern to replace fossil fuels is reflected by a forecast of more than $300 billion in H2 investments through 2030, motivating studies to enable its use. One of the main barriers to set-up the use of green hydrogen produced from renewables is its transportation to the end-users. To surpass this issue, the use of the existing natural gas networks has been proposed for distributing green hydrogen. There are at least three main advantages of using the existing natural gas pipelines, namely: (i) the use of existing ones avoids large investments to build new ones, (ii) H2 can be transported by long distance cheaply ($0.1/kg for up to 500 km), and (iii) H2 can be used directly without chemical conversion required. 2 However, a new technology to recover green hydrogen from natural gas grids needs to be developed to allow the pure distribution of H2 and CH4. In this context, the present work seeks to identify strategies to develop a new separation technology based on adsorption processes to recover green hydrogen from natural gas grids.info:eu-repo/semantics/publishedVersio

Single- A nd multicomponent fixed bed adsorption of CO2, CH4, and N2in binder-free beads of 4A zeolite

Single- A nd multicomponent adsorption fixed bed breakthrough experiments of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on commercial binder-free beads of 4A zeolite have been studied at 313, 373, and 423 K and a total pressure of up to 5 bar. The ternary experiments (CO2/CH4/N2) show a practically complete separation of CO2 from CH4/N2 at all the temperatures studied, with selectivity at 313 K of CO2 around 24 over CH4 and 50 over N2. The adsorption equilibrium data measured from the breakthrough experiments were modeled by the dual-site Langmuir isotherm, and the breakthrough results were simulated with a fixed bed adsorption model taking into account axial dispersion, mass-transfer resistances, and heat effects. The mathematical model predicts with a good accuracy the systematic behavior of the single- A nd multicomponent breakthrough results based on the independent parameters calculated from well-established correlations and intracrystalline diffusivities for zeolite 4A available in the literature. The results showed in the present work evidence that the binder-free beads of zeolite 4A can be employed to efficiently separate CO2 from CO2/CH4/N2 mixtures by fixed bed adsorption.The authors would like to acknowledge (i) Kristin Gleichmann and Chemiewerk Bad Koestritz GmbH for kindly providing the binder-free beads of zeolite 4A studied in this work and (ii) the comments and suggestions of the anonymous reviewer of this paper that help us to improve significantly the contents and analysis of the results. The authors acknowledge the financial support from (1) Project “VALORCOMP” (ref.0119_VALORCOMP_ 2_P), financed through INTERREG V A Spain Portugal (POCTEP) 2014−2020, under the European Regional Development Fund by FCT; (2) Project POCI-01-0145-FEDER006984-Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020, Programa Operacional Competitividade e Internacionalização (POCI), and by national funds through FCTFundação para a Ciência e a Tecnologia; (3) Foundation for Science and Technology (FCT, Portugal) and ERDF under Programme PT2020 to CIMO (UID/AGR/ 00690/2019); (4) National funding by FCT, Foundation for Science and Technology, through the individual research grant SFRH/BD/140550/2018 of Mohsen Karimi; (5) National funding by FCT, Foundation for Science and Technology, through the individual research grant SFRH/BD/148525/2019 of Adriano Henrique; and (6) The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio

Binder-free zeolite 4A for biogas upgrading and CO2 capture

To keep global warming below 2 ºC in the coming 30 years, the development and valorization of renewable sources of energy and also the CO2 capture from coal-fired power plants are important steps for the transition to a clean energy economy. Biogas is a sustainable and renewable source of energy from the anaerobic decomposition of organic matter and, together with natural gas, they are a more environmentally friendly alternative. The presence of CO2 in the biogas composition can reach up to 40 vol.%, which reduces biogas calorific value, impairs its transport via pipelines, and, consequently, limits its use [1]. CO2 released from coal-fired power plants has been contributing to a massive 73% of annual emissions for the energy sector [2]. This value could be reduced by attaching a recovery unit downstream of these power plants to recover CO2, avoiding its emissions. Among the processes available to recover CO2 and purify biogas, the adsorption is easy to operate, efficient to provide high recovery and purity, and more economical when compared to absorption and cryogenic separations, which have intensive energy consumption. Therefore, this work seeks to evaluate the adsorption equilibrium and dynamic separation of CO2, CH4, and N2 on binder-free zeolite 4A in conditions of interest to biogas upgrading and CO2 capture from the post-combustion stream.info:eu-repo/semantics/publishedVersio

Simulation of fixed bed adsorption for biogas upgrading

Great efforts have been devoted to developing clean sources of energy that can contribute to keeping global warming below 2ºC in the coming 30 years. Biogas is a renewable source of energy that can be easily produced by the treatment of agricultural, municipal, and industrial wastes. Furthermore, biogas can be a decentralized alternative to produce clean energy in Portugal and India, as both have a large quantity of feedstock. The second main component of biogas is CO2, which decreases its heating value practically by half relative to natural gas. Therefore, biogas needs to be upgraded (by removing CO2) to obtain biomethane that can be either injected into natural gas networks or directly used as a vehicle fuel. In this way, adsorption processes are a promising alternative to biogas upgrading as it presents a lower energy cost, is easy to operate, can provide higher purity and recovery, as compared to other methods, and especially for the possibility of regenerating the adsorbent material without generating by-products. In this view, this work seeks to develop an adsorption simulator to study the separation of CO2/CH4/N2 mixtures in a fixed bed. To achieve this objective, a mathematical model has been developed to describe the adsorption of mixtures in a fixed bed solved through numerical methods available in the literature. The adsorption mathematical model, derived from mass and energy conservation laws, was implemented in a personal computer to predict the dynamic behavior of the adsorption process. Moreover, this mathematical model includes both effects of axial dispersion and mass-transfer resistances considering an overall effective rate mass-transfer (KLDF) from the linear driving force model. The numerical implementation was performed in MATLAB® simulation environment. To solve the mathematical model the method of lines was used, being the spatial coordinates discretized by orthogonal collocation, and the resulting ordinary and algebraic differential equations were solved with a stiff integrator, ode15s, available in the MATLAB library. The implemented model was tested and validated by simulating experimental data of fixed-bed adsorption of CO2, CH4, and N2 on binder-free zeolite 4A and KY performed in our laboratory. In summary, the simulator implemented in this work is a versatile tool to describe the adsorption process and is useful in processes simulation.info:eu-repo/semantics/publishedVersio

Binder-free zeolite 4A for biogas upgrading and CO2 capture

To keep global warming below 2 ºC in the coming 30 years, the development and valorization of renewable sources of energy and also the CO2 capture from coal-fired power plants are important steps for the transition to a clean energy economy. Biogas is a sustainable and renewable source of energy from the anaerobic decomposition of organic matter and, together with natural gas, they are a more environmentally friendly alternative. The presence of CO2 in the biogas composition can reach up to 40 vol.%, which reduces biogas calorific value, impairs its transport via pipelines, and, consequently, limits its use [1]. CO2 released from coal-fired power plants has been contributing to a massive 73% of annual emissions for the energy sector [2]. This value could be reduced by attaching a recovery unit downstream of these power plants to recover CO2, avoiding its emissions. Among the processes available to recover CO2 and purify biogas, the adsorption is easy to operate, efficient to provide high recovery and purity, and more economical when compared to absorption and cryogenic separations, which have intensive energy consumption. Therefore, this work seeks to evaluate the adsorption equilibrium and dynamic separation of CO2, CH4, and N2 on binder-free zeolite 4A in conditions of interest to biogas upgrading and CO2 capture from the post-combustion stream.info:eu-repo/semantics/publishedVersio

Novel insights into activated carbon derived from municipal solid waste for CO2 uptake: synthesis, adsorption isotherms and scale-up

Recently, developing bio-based carbon materials due to the surface chemistry and a large spectrum of pore structures have received much attention. In the present work, a series of activated carbon (AC) adsorbents were synthesized from the compost derived by the mechanical/biological treatment of municipal solid wastes and evaluated regarding their CO2uptake. The AC samples were characterized by sulfuric acid and calcination by N2at 400 and 800 °C. Then, the CO2uptake capacities were evaluated by dynamic breakthrough experiments in a temperature range of 40-100 °C and pressures up to 3 bar. The presented data were properly described by Langmuir model and it was revealed that the CMSW-S-800 sample, treated with sulfuric acid and activated at 800 °C, has the highest CO2uptake capacity with an amount adsorbed around 2.6 mol/kg at 40 °C. In the next step, a mathematical model has been developed to match the experimental dynamic breakthrough data and design a pressure swing adsorption (PSA) cyclic process to evaluate the capacity and potential of the best AC sample for CO2adsorption. The results arising from this work showed a possible route for the application of the compost as a source of activated carbon for the sorption of greenhouse gases.This work was financially supported by: Project POCI-01-0145- FEDER-006984 – Associate Laboratory LSRE-LCM funded by FEDER through COMPETE2020 Programa Operacional Competitividade e Internacionalização (POCI) and project “VALORCOMP" (ref.0119_VALORCOMP_2_P), financed through INTERREG V A Spain Portugal (POCTEP) 2014-2020 –by national funds through FCT, and Project NORTE-01-0145- FEDER-000006, supported by Norte’s Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund, also it received financially support from CIMO under UID/AGR/00690/2019. M. Karimi acknowledges PhD research grant awarded under Project: SFRH/BD/140550/2018 by Foundation for Science and Technology (FCT, Portugal). In addition, Authors would like to appreciate Prof. Helder T. Gomes and Dr. Jose L. Diaz de Tuesta from CIMO for their collaboration in VALORCOMP project.info:eu-repo/semantics/publishedVersio

Fixed bed adsorption of CO2, CH4, and N2 and their mixtures in potassium-exchanged binder-free beads of Y zeolite

The adsorption of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) has been studied on potassium-exchanged (95%) binder-free beads of Y zeolite through single, binary, and ternary fixed bed breakthrough experiments, covering the temperature range between 313 and 423 K and a pressure of up to 350 kPa. At 313 K and 350 kPa, the single-component data obtained showed that the amounts adsorbed of CO2, CH4, and N2 are around 6.42, 1.45, and 0.671 mol kg-1, respectively. The binary experiments CO2/N2 carried out under typical post-combustion conditions show a selectivity of CO2 over N2 around 104. The ternary experiments resulted in the selectivities of CO2 over CH4 and N2 around 19 and 45, respectively. The adsorption equilibrium data have been modeled by the dual-site Langmuir model, and the breakthrough experiments were numerically simulated with a suitable dynamic fixed bed adsorption model. The model predicts with good accuracy the systematic behavior of all breakthrough experiments. The results shown in the present work prove that the potassium-exchanged binder-free beads of Y zeolite enhance the amount adsorbed of CO2 at low partial pressure over other alkali metal-exchanged faujasites and efficiently separate it from binary (CO2/N2) and ternary (CO2/CH4/N2) mixtures by fixed bed adsorption.The authors thank the Foundation for Science and Technology (FCT, Portugal) and ERDF under Programme PT2020 to CIMO (UID/AGR/00690/2019) and POCI-01-0145- FEDER006984-Associate Laboratory LSRE-LCM. The authors also thank the Foundation for Science and Technology (FCT, Portugal) under Programme PTDC 2020 * 3599-PPCDTI * Engenharia dos Processos Químicos project PTDC/EQUEPQ/0467/2020. Last, the authors thank the Foundation for Science and Technology (FCT, Portugal) through the individual research grants SFRH/BD/148525/2019 for A.H. and DFA/BD/7925/2020 for L.F.A.S.Z.info:eu-repo/semantics/publishedVersio

3D-printed activated carbon for post-combustion CO2 capture

The applicability of 3D-printed activated carbons for their use to CO2 capture in post-combustion streams and the influence of activation conditions on CO2 uptake and CO2 to N2 selectivity were studied. For two monoliths with the same open cellular foam geometry but low and high burnoff during activation, a series of fixed-bed breakthrough adsorption experiments under typical post-combustion conditions, in a wide range of temperature (313 and 373 K), and partial pressure of CO2 up to 120 kPa were carried out. It is shown that the higher burnoff during activation of the 3D printed carbon enhances the adsorption capacity of CO2 and N2 due to the increased specific surface area with sorption uptakes that can reach 3.17 mol/kg at 313 K and 120 kPa. Nevertheless, the lower burnoff time on monolith 1 leads to higher selectivity of CO2 over N2, up to 18 against 10 on monolith 2, considering a binary interaction to a mixture of CO2/N2 (15/85 vol%) at 313 K. The single and multicomponent adsorption equilibrium is conveniently described through the dual-site Langmuir isotherm model, while the breakthrough curves simulated using a dynamic fixed-bed adsorption linear driving force model. Working capacities for the 3D printed carbon with lower burnoff time lead to the best results, varying of 0.15–1.1 mol/kg for the regeneration temperature 300–390 K. Finally, consecutive adsorption-desorption experiments show excellent stability and regenerability for both 3D printed activated carbon monoliths and the whole study underpins the high potential of these materials for CO2 capture in post-combustion streams.Generally, the authors are thankful to Dr. M. Rückriem and Dr. A. Schreiber from Microtrac Retsch GmbH for the kind support with nitrogen physisorption and mercury porosimetry measurements. The authors acknowledge the joint financial support from Fundação para a Ciência e a Tecnologia (FCT), in Portugal, and the Deutscher Akademischer Austauschdienst (DAAD), in Germany. Foundation for Science and Technology (FCT, Portugal) and ERDF under Programme PT2020 to CIMO (UIDB/00690/2020) and POCI-01-0145-FEDER006984-Associate Laboratory LSRE-LCM. Foundation for Science and Technology (FCT, Portugal) under Programme PTDC 2020 * 3599-PPCDTI * Engenharia dos Processos Químicos * project PTDC/EQU-EPQ/0467/2020. Foundation for Science and Technology (FCT, Portugal), through the individual research grants SFRH/BD/148525/2019 for Adriano Henrique and DFA/BD/7925/2020 for Lucas F. A. S. Zafanelli.info:eu-repo/semantics/publishedVersio

Embryonic dormancy in seeds of Bactris gasipaes Kunth (peach-palm)

Bactris gasipaes is a domesticated palm whose fruits are of great importance for the Amazonian people and whose heart of palm is also receiving economic interest in other brazilian and Latin America regions. The aim of this study was verify embryonic dormancy and its correlation with first cataphyll emergence in B. gasipaes seeds collected from four plants at Manaus city and four others at Coari city, both in the Amazonas state, Brazil. After extraction and cleaning, some of the seeds (4 replications of 25 per plant) were sown in a seedbed with a sawdust and sand mixture as substrate, and embryos (4 replications of 10 per plant), after extraction, were inoculated into half strength Murashige and Skoog cultures. Were used 100 seeds and 40 embryo per treatment. Whole seed and embryo germination varied between the different source plants and locations, with the greatest difference observed for the emergence of first cataphyll from seeds in the seedbed. For the most part of variables, results of seed and embryo were positively associated, namely, as one went up the other also, and vice versa. These results suggesting that, at least in part, seed dormancy in Bactris gasipaes is associated with embryonic dormancy. © 2017, Associacao Brasileira de Tecnologia de Sementes. All rights reserved