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- Separation of C5/C6 isomerate fractions in a mixed/layered bed of BETA/5A zeolitesPublication . Brântuas, Pedro; Karimi, Mohsen; Silva, José A.C.; Rodrigues, AlírioThe combustion quality of gasoline is measured by the research octane number (RON). When RON is high, the combustion occurs like a smooth explosion instead of a detonation and the performances of the motor are improved. Cracking, alkylation, isomerization and other process can be used to increase the RON of gasoline to about 90. The light straight-run (LSR) naphtha fraction produced by fractional distillation is one of the feedstocks used to produce gasoline. Its major constituents include C5 and C6 normal paraffins which have relatively low RON compared to their branched isomers. Therefore, octane upgrading commonly uses isomerization to rearrange the structure of the linear paraffins into branched components. The product stream from an isomerization reactor consists of hexane isomers: 2,2-dimethylbutane (22DMB), 2,3-dimethylbutane (23DMB), 2-methylpetane (2MP), 3-methylpentane (3MP), n-hexane (nHEX), as well as pentane isomers: iso-pentane (iPEN) and n-pentane (nPEN). Zeolite 5A is used to separate the linear isomers (nHEX and nPEN) from the branched isomers, returning them to the isomerization reactor for further processing, while the other isomers are retained as product. Denayer et al. [1] found that pentane and hexane isomers might be separated by chromatography according to their degree of branching using columns of zeolite beta, and some years before Huddersman and Klimczyk [2,3] indicated that zeolite beta in cation form (H, Ba) is an effective adsorbent for the separation of branched hexane isomers. Therefore, using both zeolites together should allow for a better separation of the high RON isomers (22DMB, 23DMB and iPEN) from the remaining isomers, specially the low RON isomers (nPEN and nHEX). Thus, four different adsorber bed configurations were studied: zeolite beta; a layered bed of zeolite 5A followed by zeolite beta; a layered bed first with zeolite beta followed by zeolite 5A; and, a mixed bed of both zeolites with the objective of analyzing the effect of each configuration on the adsorption and separation of alkane isomers.
- CO2 Capture in Chemically and Thermally Modified Activated Carbons Using Breakthrough Measurements: Experimental and Modeling StudyPublication . Silva, José A.C.; Karimi, Mohsen; Gonçalves, Carmem Natália de Pina; Díaz de Tuesta, Jose Luis; Rodrigues, Alírio; Gomes, HelderThe development of adsorption-based technologies for CO2 capture in the post combustion processes requires finding materials with high capacity of adsorption and low cost of preparation. In this study, the modification of a commercial activated carbon (Norit ROX 0.8), considered as a solid adsorbent for CO2 capture, and the effects of different methods of activations, chemically (hydrogen peroxide, sulfuric acid, nitric acid, and urea) and thermally (at 800 °C) on adsorption performance, have been investigated. Then, CO2 adsorption capacity was studied at different temperatures and pressures to evaluate the effects of various agents on sample performance. The textural properties of the samples were determined using adsorption−desorption isotherms of nitrogen at −196 °C. Finally, the obtained data were modeled by Response Surface Methodology (RSM) and Langmuir isotherm. The results showed that the prepared sample by successive treatments with nitric acid, urea, and thermal calcination has a higher uptake capacity than other modified samples.
- Uptake capacity of adsorbent materials derived from municipal solid waste for CO2 capture at post combustion conditionPublication . Díaz de Tuesta, Jose Luis; Karimi, Mohsen; Gonçalves, Carmem Natália de Pina; Silva, José A.C.; Gomes, Helder; Rodrigues, AlírioThe global climate change, as well as the accumulations of solid waste on landfills, are two of the primary issues nowadays, which it needs the significant attempts to reduce the impact on the ecosystem and environment from both of them [1]. In this work, the production of materials from organic solid waste is considered to produce adsorbent materials, which are assessed in the CO2 capture.
- Comparison between the ability of sulphuric acid, nitric acid and urea as chemical activators of commercial activated carbons for CO2 capturePublication . Gonçalves, Carmem Natália de Pina; Karimi, Mohsen; Díaz de Tuesta, Jose Luis; Silva, José A.C.; Rodrigues, Alírio; Gomes, HelderPhysical adsorption process has been considered as a promising technique for CO2 capture, due to low energy consumption and high efficiency. In this way, several adsorbents including activated carbons [1], zeolites [2] and MOFs [3] have been extensively studied for CO2 adsorption in the recent years. Activated carbon has attracted much attention, because of amorphous porous form, hydrophobic character and low energy for desorption [4]. To preparation of this adsorbent, physically (thermally) and chemically methods are the two main strategies. In the first method, the materials are carbonized in the temperature range of 400-850 0C, while in the second one by using some chemical components activation takes place by heating the mixture of precursor and dehydrating agent or oxidant. Hereby, based on BLUE Map Scenario of the International Energy Agency (IEA) [5], an activated carbon (Norit ROX 0.8) has been modified by using different chemical and thermal treatments, following the procedures described elsewhere [6]. In order to obtain adsorbents with smaller particle size, commercial activated carbon was first grinded and sieved to particle sizes ranging from 0.106 to 0.250 mm, resulting in a powder activated carbon (PAC). Three of the materials were prepared directly from the PAC sample by liquid phase treatments with hydrogen peroxide, sulphuric acid and nitric acid, resulting in PACHP, PACSA and PACNA materials, respectively. The treatment with hydrogen peroxide was performed wetting 25 g of PAC with 500 mL of hydrogen peroxide solution 30% (w/v) at room temperature for 24 h. In sulphuric acid oxidation, 25 g of PAC was immersed in 500 mL of 18 M acid solution for 3 h at 423 K. Oxidation with nitric acid was carried out boiling 25 g of PAC in 500 mL of 5 M nitric acid solution for 3 h. After the liquid phase treatments, all samples were thoroughly washed with distilled water until the neutrality of the rinsing waters and further dried in oven for 18 h at 383 K, resulting in samples PACHP, PACSA and PACNA, respectively. The other two samples were obtained in successive treatments of the PACNA material. 2 g of PACNA was immersed in 50 mL of 1 M urea solution and kept in a 125 mL stainless steel high pressure batch reactor under its own atmosphere at 473 K for 2 h, the recovered solids being thoroughly washed with distilled water until the neutrality of the rinsing waters, and further dried overnight in oven at 383 K, resulting in the PACNAU material. Then, a gas phase thermal treatment was applied, in which 1 g of PACNAU was heated, under a N2 flow (100 cm3 min−1), at 393 K, 673 K and 873 K during 60 min at each temperature and then at 1073 K for 240 min, resulting in the PACNAUT material.
- Thermally and chemically activated biochar obtained in mechanical biological treatment plants for carbon dioxide adsorptionPublication . Karimi, Mohsen; Brântuas, Pedro; Henrique, Adriano; Gonçalves, Carmem Natália de Pina; Silva, José A.C.; Rodrigues, AlírioIn this study, based on the scopes of CCS strategy and municipal solid waste management, a novel Integrated Environment Management (IEM) strategy has been proposed. In this way, the obtained compost in the mechanical biological treatment from municipal solid wastes has been considered as a source of adsorbents for CO2 capture. In this way, the maturated compost waste was modified by liquid phase treatment with sulfuric acid and thermal treatment at 800 ºC. Then, the prevalent operational conditions of post-combustion processes have been considered to find the best prepared samples for CO2 capture.
- Separation of hexane isomers in metal organic framework ZIF-8Publication . Karimi, Mohsen; Henrique, Adriano; Brântuas, Pedro; Silva, José A.C.; Rodrigues, AlírioThe performance of porous metal organic framework ZIF-8 in the separation of all five hexane isomers (nHEX, 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 partial pressures of 0.5 bars. The reported data shows for all experiments the following sorption hierarchy: nHEX >> 2MP > 3MP >> 23DMB > 22DMB. It is also demonstrated that the sorption of nHEX is equilibrium based in contrast with the sorption of branched isomers which is kinetic controlled. The experimental data is also simulated through a mathematical model developed in MATLAB code, being the results in qualitatively agreement. This paper shows that it possible to separate the hexane isomers in ZIF-8 by classes linear/mono-branched/di-branched if proper experimental conditions are set-up, being the result of importance for the octane upgrading of gasoline.
- Equilibrium adsorption of CO2, CH4 and N2 on BETA zeolites at post-combustion operational conditionsPublication . Karimi, Mohsen; Brântuas, Pedro; Henrique, Adriano; Silva, José A.C.; Rodrigues, AlírioThe adsorption equilibrium and kinetics of CO2,CH4, and N2 on three types of BETA zeolites were investigated at different temperatures and a defined partial pressure range from dynamic breakthrough experiments. The adsorbed amount followed the decreasing order of CO2>CH4>N2 for all studied materials. For the same ratio of SiO2/Al2O3, the Na-BETA-25 zeolite showed a higher uptake capacity than H-BETA-25, due to the presence of a Na+cationic center. Comparing the same H+compensation cation, zeolite H-BETA-25 expressed a slightly higher adsorption capacity than H-BETA-150. Regarding the selectivity of gases, based on their affinity constants, H-BETA-150 displayed the best ability. The adsorption kinetics was considered using the zero-length-column (ZLC) technique.
- Breakthrough measurement of carbon dioxide adsorption on lowcost activated carbons derived from solid wastesPublication . Karimi, Mohsen; Díaz de Tuesta, Jose Luis; Gonçalves, Carmem Natália de Pina; Silva, José A.C.; Rodrigues, Alírio; Gomes, HelderIn this study, based on the scopes of CCS strategy and municipal solid waste management, a novel Integrated Environment Management (IEM) strategy has been proposed. In this way, the obtained compost in the mechanical biological treatment from municipal solid wastes has been considered as a source of adsorbents for CO2 capture. In this way, the maturated compost waste was modified by liquid phase treatment with sulfuric acid and thermal treatment at 800 0C. Then, the prevalent operational conditions of post-combustion processes have been considered to find the best prepared samples for CO2 capture.
- A cochonilha negra, Saissetia oleae, como alimento para larvas e adultos de Chrysoperla carnea s.l.Publication . Villa, Maria; Mahzoum, Abdelkader; Benhadi-Marín, Jacinto; Pereira, J.A.As larvas de Chrysoperla carnea s.l. (Stephens) são amplamente utilizadas em programas de luta biológica devido à sua ação como predadores de insetos. Por sua vez, os adultos alimentam-se de meladas de hemípteros, pólen e néctar de flores. No olival são potenciais predadores de várias pragas. Assim, neste agroecosistema a existência de recursos alimentícios é essencial para manter as populações de C. carnea e melhorar a sua ação numa perspetiva de proteção biológica por conservação. A cochonilha negra, Saissetia oleae (Olivier), é uma praga secundaria da oliveira em grande parte da região mediterrânica. A existência desta praga pode proporcionar recursos alimentícios para as diferentes fases de desenvolvimento de C. carnea, nomeadamente, as ninfas como presas para alimentação das larvas do predador, e as meladas que o adulto excreta como fonte de energia para adultos. Assim, o objetivo deste trabalho foi avaliar o potencial de S. oleae como alimento para larvas e adultos de C. carnea. Para avaliar o efeito nas larvas, foram disponibilizadas diferentes densidades de ninfas de S. oleae a larvas de C. carnea, e avaliadas taxas de consumo; para os adultos, foram disponibilizadas meladas excretadas por S. oleae e avaliada a sobrevivência, em ambos os sexos, e fecundidade em fêmeas. Verificou-se que as larvas de C. carnea consomem eficientemente ninfas de S. oleae. Por sua vez nos adultos, o consumo de meladas melhora a sua sobrevivência em comparação ao controlo (água), mas não a reprodução, o que estará relacionado com a inexistência de proteína necessária para a formação de ovos. Assim, numa estratégia de proteção biológica por conservação, baixos níveis populacionais da praga podem contribuir para a manutenção e aumento de crisopídeos no olival
- Functional response of Chrysoperla carnea (Neuroptera: Chrysopidae) to Saissetia oleae (Olivier) (Hemiptera: Coccidae)Publication . Mahzoum, Abdelkader; Villa, Maria; Benhadi-Marín, Jacinto; Pereira, J.A.Lacewings are common biocontrol agents against a wide range of agricultural pests. These predators are highly voracious against soft-bodied preys such as juveniles of scale insects. In this context, the present work aims to study the use of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) as biological control agent against Saissetia oleae (Olivier) (Hemiptera: Coccidae). For that, we studied the functional response of the larval instars of C. carnea to nymphs of S. oleae. Increasing densities (3, 5, 10, 15, 25 and 40) of S. oleae nymphs were offered to the three larval stages of C. carnea in a controlled laboratory environment. After 24 hours, the number of S. oleae consumed by C. carnea larva was recorded and the functional response calculated. The three larval stages of C. carnea displayed a type II functional response behavior. Prey consumption by C. carnea larvae increased with high S. oleae densities. Moreover, younger larvae showed a lower predation rate in comparison with the older ones. The search rate and handling time of the third instar larvae were lower than those of the younger larval instars, and the simulated max. attack rate of the third instar larvae was higher than those of the first and second instar larvae. Our results suggest that all larval stages of C. carnea could be important in S. oleae biological control in olive orchards, although the third larval stage of the predator was more efficient in reducing S. oleae densities than first and second C. carnea larval instars.