Porous solids for biogas upgrading

In this work, we will present sorption equilibrium, kinetic and fixed bed data of CO2, CH4 in MOF-508b and zeolite 13X at 303, 323 and 343 K and partial pressures up to 4.5 bar. These data are fitted with appropriate isotherm models. At the same time single, binary and ternary breakthrough curves were measured to provide required data to develop and validate a mathematical model based on the LDF approximation for the mass transfer, which could be used in the design (simulation) of a cyclic adsorption processes (PSA) for the purification of biogas and CO2 sequestration

Porou solids for biogas upgrading and CO2 sequestration

In this work, we will present sorption equilibrium, kinetic and fixed bed data of CO2, CH4 in MOF-508b and zeolite 13X at 303, 323 and 343 K and partial pressures up to 4.5 bar. These data are fitted with appropriate isotherm models. At the same time single, binary and ternary breakthrough curves were measured to provide required data to develop and validate a mathematical model based on the LDF approximation for the mass transfer, which could be used in the implementation (simulation) of a cyclic adsorption processes (PSA) for the purification of biogas and CO2 sequestration

Adsorption technologies for BIOGAS upgrading and CO2 sequestration

Through this work it is shown that a new 13X zeolite can improve significantly the existing PSA technologies for BIOGAS upgrading with selectivities CO2/CH4 that can reach the value 34 and amounts adsorbed of CO2 around 5.2 mmol/g. A mathematical model was also developed and validated through experimental data to design PSA adsorption processes for biogas upgrading and CO2 sequestration.info:eu-repo/semantics/publishedVersio

Separation of Hexane Isomers in ZIF-8 by Fixed Bed Adsorption

The performance of porous metal organic framework ZIF-8 in the separation of all five hexane isomers (nC6, 2MP, 3MP, 23DMB, 22DMB) is evaluated through a series of multicomponent breakthrough adsorption experiments, at the temperatures of 373, 423, and 473 K and up to total hexane isomers pressure of 0.5 bar. The reported data show for all experiments the following sorption hierarchy: nC6 ≫ 2MP > 3MP ≫ 23DMB > 22DMB. At the temperature of 373 K and total hydrocarbon pressure of 0.5 bar the mixture loading of hexane isomers can go up to 2.15 mol·kg-1. In addition, at the same temperature the selectivities measured by the ratio of the loadings between linear plus monobranched (nC6, 2MP, 3MP) relatively to the dibranched (23DMB, 22DMB) isomers range between 34-55. The results also show that the sorption of nC6 is equilibrium based in contrast with the sorption of branched isomers which is kinetically controlled. The dibranched isomer 22DMB is practically excluded from the framework followed closely by 23DMB. The adsorption equilibrium experimental data are modeled by the Sips isotherm and the breakthrough data are simulated through a mathematical model developed in Matlab code using the method of lines (MOL), the results being in qualitative agreement. From the numerical simulations it was found that diffusivity of the branched paraffins in ZIF-8 is 2 orders of magnitude lower than for the linear nC6, and that the diffusivity of the dibranched paraffins is three times lower than for the monobranched ones. This work shows that ZIF-8 has the ability to purely separate the linear nC6 from its branched isomers and partially separate mono- from dibranched isomers if proper experimental conditions are setup, the result being important for the octane upgrade of gasoline.We acknowledge financial support from (1) Project ref POCI-01-0145-FEDER-016517 (PTDC/QEQ-PRS/3599/2014) funded by FEDER through COMPETE2020 and FCT; (2) AIProcMat@N2020 Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020, with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and (3) by Project POCI-01-0145-FEDER-006984 Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020, Programa Operacional Competiti-vidade e Internacionalização (POCI), and by national funds through FCT Fundação para a Ciência e a Tecnologia.info:eu-repo/semantics/publishedVersio

Sorption and kinetics of CO2 and CH4 in binderless beads of 13X zeolite

The sorption equilibrium of CO2 and CH4 in binderless beads of 13X zeolite has been investigated between 313 and 373 K and pressure up to 4 atm. The amount adsorbed of CO2 and CH4 is around 5.2 mmol/gads and 1.2 mmol/gads, respectively, at 313 K and 4 atm. Comparing these values with the ones in literature the value of CO2 is 20% higher than in CECA 13X binder pellets. It is also found that isotherms are pronounced Type I for CO2 and almost linear for CH4. The CO2 isotherms were modeled using a simple deviation from Langmuir isotherm that takes into account interaction between adsorbed molecules at adjacent sites (Fowler model) suggesting a moderate repulsion. Henry’s constants range from 143 to 11.1 mmol/gads.atm for CO2 and 0.45 to 0.27 mmol/gads.atm for CH4 between 313 and 373 K, respectively. The heats of sorption at zero coverage are 43.1 kJ/mol for CO2 and 9.2 kJ/mol for CH4. The sorption kinetics has been investigated by the Zero-Length Column technique (ZLC). Recipes to analyze ZLC desorption curves in pellets of adsorbents are reviewed and it is derived a criteria which indicates that for the sorption rate be measured macroscopically the time of the experiment (that should be above a few seconds) is directly calculated with the following expression: t0:1 7:02 10 2 r2c Dc. Based on such criteria it is shown that crystal diffusivity of CO2 in 13X can be measured macroscopically by ZLC, being the same measurement for CH4 practically impossible. The crystal diffusivity of CO2 measured experimentally is 5.8 10 15 m2/s and 1.3 10 15 m2/s at 373 and 313 K, respectively. These values are comparable to the ones measured by a frequency response and pulse chromatography techniques reported in literature. The ZLC desorption curves for CH4 were measured under an equilibrium regim

Hexane isomers sorption on the rigid framework MOF MIL-100(Cr)

In this work we studied the hexane isomers sorption on the MIL-100(Cr) [1]. The first part of the study was related to the pattern MIL-100(Cr) solid, the second dealt with the MIL-100(Cr) grafted with EtAp (Ethylamine pure) and the third with MIL-100(Cr)MEDA (Methyl ethylene diamine). The synthesis and characterization of MIL-100 (Cr), MIL-100(Cr)EtAp and MIL-100(Cr)MEDA was performed at Institut Lavoisier de Versailles. The separation and adsorption capacity of each MOF were evaluated through breakthrough experiments in a chromatographic system at LSRE using an equimolar mixture of four hexane isomers: n-hexane (nHEX) (RON 25), 3-methylpentane (3MP) (RON 75), 2,3-dimethylbutane (23DMB) (RON 103) and 2,2-dimethylbutane (22DMB) (RON 94) with the objective to the develop an adsorptive process to separate hexane isomers (kinetic diameter very similar) in order to improve the quality of gasoline measured by the octane number (RON)

Adsorption and separation of CO2/CH4 on binderless beads of 13X zeolite

The sorption equilibrium of CO2 and CH4 has been investigated on the binderless beads of 13X zeolite between 313 and 373 K and pressure up to 4 atm. The amount adsorbed of CO2 and CH4 is around 5.2 mmol/gads and 1.2 mmol/gads, respectively, at 313 K and 4 atm. Comparing these values with the ones in literature the value of CO2 is 20% higher than in similar 13X binder pellets

Resposta da quinoa (Chenopodium quinoa Willd.) a diferentes regimes hídricos e níveis de fertilização azotada nas condições agroecológica de Trás-os-Montes

A quinoa é considerada como uma cultura resistente a vários fatores bióticos e abióticos limitantes para produção agrícola, incluindo a seca, geada e salinidade. Sendo uma cultura de origem tropical, o cultivo em regiões de clima temperado e em particular de clima mediterrânico deve ser avaliado em diferentes condições agroecológicas. Este trabalho teve como objetivo avaliar o efeito do regime hídrico e da fertilizaçao azotada no crescimento e desenvolvimento da quinoa em Bragança, nordeste de Portugal. Para o efeito, a cultura foi instalada numa parcela da Escola Superior Agrária do Instituto Politécnico de Bragança (latitude: 41° 47' 52" N; longitude: 6° 45' 58" W e altitude: 693m) num delineamento experimental com quatro níveis de azoto (0, 67, 133 e 200 kg/ha1) e três regimes hídricos: sequeiro (RO); regadio, com dotação correspondente a 50% das necessidades de rega (RI); e 100% das necessidades de rega (R2). Durante a estação de crescimento avaliou-se o estado hídrico do solo e da planta nos diferentes regimes hídricos. Determinou-se o tempo térmico para as diferentes fases de desenvolvimento, e o índice de área foliar, através da medição da radiação intercetada pelo coberto. A ocorrência de temperaturas elevadas e dias longos (fotoperíodo) durante a condução do ensaio influenciaram o desenvolvimento da cultura com paragem desenvolvimento na fase de floração. O regime hídrico influenciou significativamente o estado hídrico das plantas. No tratamento sem rega, durante a floração, as plantas apresentavam uma condição de stresse hídrico muito severo com valores de potencial hídrico foliar de -2,3 MPa. Nos tratamentos com rega deficitária (50% ETc), mantiveram-se com valores de potencial hídrico próximos de -1,7 MPa revelando uma condição de stresse hídrico menos severo que as plantas não regadas. Os resultados do balanço hídrico mostraram que para o cenário sem rega o teor de água no solo esteve abaixo do limiar de rendibilidade ótima desde o 11° dia após a sementeira. Nas parcelas irrigadas com 50% da ETc, o teor de água no solo manteve-se acima do limiar de rendibilidade ótima até aos 40 dias após a sementeira. Nas parcelas irrigadas com 100% ETc o teor de água no solo manteve-se acima do limiar durante o ciclo da cultura. O regime hídrico influenciou deforma significativa a produção de biomassa. A maior produção verifícou-se em R2 (19, 51 Mg ha'), sem diferenças significativas para RI (17, 12 Mg hal), e ambos os regimes com produção significativamente superior a RO (4,3 Mg hal). A fertilização azotada afetou significativamente a biomassa produzida sendo que foi em N2 que se registou o valor médio mais elevado (16, 75 Mg ha') e em NO o menor (7,34 Mg ha'). A produtividade da água foi influenciada significativamente pelo regime hídrico com o tratamento de rega deficitária (RI) e nível de azoto N3 a apresentar o maior valor de produtividade da água (7,44 Kg/m').info:eu-repo/semantics/publishedVersio

Upgrading of the light naphata fraction with zeolite beta

Multicomponent adsorption of alkanes in the C5-C6 range was investigated in a sample of zeoliteBETA. 6-components breakthrough experiments were performed showing interesting properties forthe separation of the light naphtha fraction. The lower adsorption enthalpy of C5 alkanes was explored by a temperature sensibility analysis demonstrating that at 583 K C5/C6 equimolar mixture can be separated in a single step into low and high octane number (RON) fractions. The separation 23DMB/3MP can not be achieved in the case of mixtures with the typical composition of the isomerization products, but zeolite BETA still selective for 22DMB resulting in a slight increase of the RON comparatively to the final isomerate from the conventional processes

Octane upgrading of C-5/C-6 light naphtha by layered pressure swing adsorption

The performance of a layered pressure swing adsorption (PSA) process for the separation of high research octane number (HRON) paraffins from a C-5/C-6 light naphtha fraction is simulated with a detailed, adiabatic single column PSA model. A zeolite 5A layer is used for selective adsorption of the low RON linear paraffins, while a zeolite beta-layer is used to separate the intermediate RON 3MP from the H RON fraction. The effects of various independent process variables (zeolite 5A to zeolite beta ratio, purge to feed ratio, cycle time, operating temperature, and depressurization mode) on the key dependent process variables (product RON, H RON species recovery, HRON purity, and adsorbent productivity) are evaluated. It is demonstrated that an optimal zeolite 5A to zeolite beta ratio can improve the product average RON up to 1.0 point as compared to existing processes using zeolite 5A only. Moreover, process simulations demonstrated that increasing the operating temperature from 523 to 543 K results in an octane gain of 0.2 RON