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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.
- Hexane isomers separation on an isoreticular series of microporous Zr carboxylate metal organic frameworksPublication . Henrique, Adriano; Maity, Tanmoy; Zhao, Hengli; Brântuas, Pedro; Rodrigues, Alírio; Nouar, Farid; Ghoufi, Aziz; Maurin, Guillaume; Silva, José A.C.; Serre, ChristianA series of isoreticular Zr carboxylate MOFs, MIL-140A, B and C, exhibiting 1D microporous triangular shaped channels and based on different aromatic dicarboxylate ligands (1,4-BDC, 2,6-NDC and 4,4′-BPDC, respectively), were investigated by chromatographic breakthrough experiments regarding their ability to separate hexane isomers (nC6/2MP/3MP/23DMB/22DMB). Both single and equimolar multicomponent experiments were performed at the temperatures 343, 373, and 423 K and a total hydrocarbon pressure up to 50.0 kPa using the MIL-140B form. The elution order is similar to that of the normal boiling point of the compounds nC6 > 2MP > 3MP > 23DMB > 22DMB. It is noteworthy that this material enables separation of the hexane isomers by class, linear > mono-branched > di-branched, with a selectivity (linear + mono-branched isomers/di-branched isomers) up to 10 at 343 K, decreasing, however, as the temperature increases. Grand canonical Monte Carlo simulations were further performed to gain insight into the adsorption/separation mechanisms, highlighting the crucial need to consider a tiny tilting of the organic linkers for capturing the experimental observations. The impact of the pore size was finally assessed through the comparison with MIL-140A and MIL-140C, respectively, based on multicomponent experiments at 343 K. We evidenced a significant decrease of the selectivity (about 2) in both cases while the loadings were decreased or increased for MIL-140A and MIL-140C, respectively. Additionally, MIL-140C was demonstrated to exhibit an uncommon shift in the elution order occurring between nC6 and 3MP, 3MP being the last compound to saturate in the column.
- Separation of hexane isomers in metal organic framework ZIF-8Publication . Henrique, Adriano; Karimi, Mohsen; 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.
- Fixed bed dynamics of multicomponent adsorption of pentane and hexane isomers in ZIF-8Publication . Brântuas, Pedro; Henrique, Adriano; Rodrigues, Alírio; Silva, José A.C.The separation of hydrocarbon mixtures is one of the most important topics in the petrochemical industry, including the separation of paraffins isomers in the C5/C6 range for the octane upgrading of gasoline. These processes separate low Research Octane Number (RON) linear paraffins, n-hexane (nC6) and n-pentane (nC5), from their respective branched isomers with higher RON content: 3-methylpentane (3MP), 2-methylpentane (2MP), iso-pentane (iC5), 2,3-dimethylbutane (23DMB) and 2,2-dimethylbutane (22DMB). In this context, metal organic frameworks (MOFs) have been studied for this process [1]. Due to their chemical and thermal stability, Zeolite Imidazolate Frameworks are of interest, specially ZIF-8 [2]. Septenary fixed bed breakthrough experiments of pentane and hexane isomers were performed with ZIF-8. The equimolar septenary studies were performed between 373 – 473 K and at a total hydrocarbon pressure of 25 kPa resulting in the following sorption hierarchy: nC6 > nC5 > 2MP > 3MP > iC5 > 23DMB > 22DMB as can be seen in Fig. 1 for the breakthrough experiment at 423 K. Results also show that the sorption of the linear nC5 and nC6 is equilibrium based in contrast with the sorption of branched isomers which is kinetically controlled. The equilibrium data were modelled by the Sips isotherm and the fitted parameters were used to simulate the breakthrough data through a mathematical model developed in a Matlab code using the method of lines (MOL).
- Separation of Branched Alkane Feeds with Metal-Organic FrameworksPublication . Henrique, Adriano; Brântuas, Pedro; Zafanelli, Lucas F.A.S.; Aly, Ezzeldin; Rodrigues, Alírio; Maurin, Guillaume; Serre, Christian; Silva, José A.C.The production of high-quality gasoline is currently achieved through the Total Isomerization Process that separates n/iso-paraffins in the pentane (C5) and hexane (C6) range while not reaching the ultimate goal of a research octane number (RON) higher than 92. This work demonstrates two promising alternatives/strategies using metal-organic frameworks (MOF) that lead to a novel adsorptive separation process to overcome this limitation. Here, the efficient discrimination of C5/C6 alkane isomers into valuable fractions of high RON (HRON – 2,3-dimethylbutane (23DMB; RON 105), 2,2-dimethylbutane (22DMB; RON 94), and isopentane (iC5; RON 93.5)) and low RON (LRON – n-pentane (nC5; RON 61.7), (nC6; RON 30), 2-methylpentane (2MP; RON 74.5), and 3-methylpentane (3MP; RON 75.5)) compounds is achieved.
- Separation of branched alkanes feeds by a synergistic action of zeolite and metal-organic frameworkPublication . Brântuas, Pedro; Henrique, Adriano; Wahiduzzaman, Mohammad; Wedelstedt, Alexander von; Maity, Tanmoy; Rodrigues, Alírio; Nouar, Farid; Lee, U-Hwang; Cho, Kyung Ho; Silva, José A.C.; Serre, Christian; Maurin, GuillaumeZeolites and metal-organic frameworks (MOFs) are considered as “competitors” for new separation processes. The production of high-quality gasoline is currently achieved through the total isomerization process that separates pentane and hexane isomers while not reaching the ultimate goal of a research octane number (RON) higher than 92. This work demonstrates how a synergistic action of the zeolite 5A and the MIL-160(Al) MOF leads to a novel adsorptive process for octane upgrading of gasoline through an efficient separation of isomers. This innovative mixed-bed adsorbent strategy encompasses a thermodynamically driven separation of hexane isomers according to the degree of branching by MIL-160(Al) coupled to a steric rejection of linear isomers by the molecular sieve zeolite 5A. Their adsorptive separation ability is further evaluated under real conditions by sorption breakthrough and continuous cyclic experiments with a mixed bed of shaped adsorbents. Remarkably, at the industrially relevant temperature of 423 K, an ideal sorption hierarchy of low RON over high RON alkanes is achieved, i.e., n-hexane ≫n-pentane ≫2-methylpentane > 3-methylpentane⋙ 2,3-dimethylbutane > isopentane ≈ 2,2-dimethylbutane, together with a productivity of 1.14 mol dm−3 and a high RON of 92, which is a leap-forward compared with existing processes.
- Separation of Branched Alkane Feeds with Metal-Organic FrameworksPublication . Henrique, Adriano; Brântuas, Pedro; Zafanelli, Lucas F.A.S.; Aly, Ezzeldin; Rodrigues, Alírio; Maurin, Guillaume; Serre, Christian; Silva, José A.C.The production of high-quality gasoline is currently achieved through the Total Isomerization Process that separates n/iso-paraffins in the pentane (C5) and hexane (C6) range while not reaching the ultimate goal of a research octane number (RON) higher than 92. This work demonstrates two promising alternatives/strategies using metal-organic frameworks (MOF) that lead to a novel adsorptive separation process to overcome this limitation. Here, the efficient discrimination of C5/C6 alkane isomers into valuable fractions of high RON (HRON – 2,3-dimethylbutane (23DMB; RON 105), 2,2-dimethylbutane (22DMB; RON 94), and isopentane (iC5; RON 93.5)) and low RON (LRON – n-pentane (nC5; RON 61.7), (nC6; RON 30), 2-methylpentane (2MP; RON 74.5), and 3-methylpentane (3MP; RON 75.5)) compounds is achieved.
- 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 Branched Alkanes Feeds by a Synergistic Action of Zeolite 5A and Metal-Organic Framework MIL-160(Al)Publication . Henrique, Adriano; Brântuas, Pedro; Zafanelli, Lucas F.A.S.; Aly, Ezzeldin; Rodrigues, Alírio; Maurin, Guillaume; Serre, Christian; Silva, José A.C.The total isomerisation process (TIP) developed by the universal oil products (UOP) for upgrading the octane rating of light hydrocarbon fractions, especially mixed feedstocks containing pentane (C5) and hexane (C6) isomers, is among the first and most successful adsorption processes applied in the industry. Typically, the light naphtha, characterised by a low research octane number (RON, ≈70), undergoes an incomplete catalytic isomerisation that generates an effluent containing unconverted linear paraffins, mostly n-pentane (nC5; RON 61.7) and n-hexane (nC6; RON 30), mixed with their respective branched isomers, i.e., isopentane (iC5; RON 93.5), 2-methylpentane (2MP; RON 74.5), 3-methylpentane (3MP; RON 75.5), 2,2-dimethylbutane (22DMB; RON 94), and 2,3-dimethylbutane (23DMB; RON 105). After that, the output of the isomerisation reactor is fed into an adsorber packed with zeolite (LTA type) that behaves as a molecular sieve, adsorbing only the linear paraffins (which are then recycled to the catalytic reactor for further processing). This results in a final branched isomerate product with an average RON ≈87–90. However, with the actual TIP process, the monobranched hexanes 2MP and 3MP represent up to 30% of the final product composition, which is detrimental to the octane improvement of gasoline for RON values higher than 90. Accordingly, this work shows a novel adsorptive separation process, based on the synergistic action of the zeolite 5A and the MIL-160(Al) metal-organic framework (MOF), to efficiently fractionate C5/C6 alkane isomers according to classes of high RON (HRON – 22DMB, 23DMB, and iC5) and low RON (LRON – nC5, nC6, 2MP, and 3MP) compounds.
- A microporous multi‐cage metal–organic framework for an effective one‐step separation of branched alkanes feedsPublication . Zhou, Lin; Brântuas, Pedro; Henrique, Adriano; Reinsch, Helge; Wahiduzzaman, Mohammad; Grenèche, Jean‐Marc; Rodrigues, Alírio; Silva, José A.C.; Maurin, Guillaume; Serre, ChristianThe improvement of the Total Isomerization Process (TIP) for the production of high-quality gasoline with the ultimate goal of reaching a Research Octane Number (RON) higher than 92 requires the use of specific sorbents to separate pentane and hexane isomers into classes of linear, mono- and di-branched isomers. Herein we report the design of a new multi-cage microporous Fe(III)-MOF (referred to as MIP-214, MIP stands for materials of the Institute of Porous Materials of Paris) with a flu-e topology, incorporating an asymmetric heterofunctional ditopic ligand, 4-pyrazolecarboxylic acid, that exhibits an appropriate microporous structure for a thermodynamic-controlled separation of hydrocarbon isomers. This MOF produced via a direct, scalable, and mild synthesis route was proven to encompass a unique separation of C5/C6 isomers by classes of low RON over high RON alkanes with a sorption hierarchy: (n-hexane >> n-pentane approximate to 2-methylpentane>3-methylpentane)(low RON)>>(2,3-dimethylbutane approximate to i-pentane approximate to 2,2-dimethylbutane)(high RON) following the adsorption enthalpy sequence. We reveal for the first time that a single sorbent can efficiently separate such a complex mixture of high RON di-branched hexane and mono-branched pentane isomers from their low RON counterparts, which is a major achievement reported so far.