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- Biochar in carbon sequestrationPublication . Shirzad, Mohammad; Karimi, Mohsen; Rodrigues, Alírio; Silva, José A.C.The increase of carbon dioxide emissions and the global warming consequences is today a considerable environmental concern. On the contrary, the rapid growth in the energy consumption throughout the world has exacerbated the CO2 emissions to the atmosphere. Accordingly, carbon capture sequestration and utilization have been considered as a potential emission mitigation strategy. In this way, several strategies and technologies including: absorption, membranes, adsorption etc. have been proposed, which adsorption technology using solid sorbents due to the lower environmental side-effects also lower energy consumption is one of the most favorable strategies. However, despite the significant efforts made for developing novel solid adsorbents for CO2 mitigation, still the elements of cost and synthesis have remained as main challenges. To this end, biochar carbon materials have been employed as a source of adsorbent through CO2 capture and sequestration process not only to satisfy these factors but also as a pathway to the solid waste management. Herein, the key concepts on the carbon capture and sequestration also adsorption processes have been discussed. Next, the capability of biomass/biochar as a low-cost origin of potential adsorbent is extensively discussed.
- Carbon dioxide separation and capture by adsorption: a reviewPublication . Karimi, Mohsen; Shirzad, Mohammad; Silva, José A.C.; Rodrigues, AlírioRising adverse impact of climate change caused by anthropogenic activities is calling for advanced methods to reduce carbon dioxide emissions. Here, we review adsorption technologies for carbon dioxide capture with focus on materials, techniques, and processes, additive manufacturing, direct air capture, machine learning, life cycle assessment, commercialization and scale-up.
- Designing a simple volumetric apparatus for measuring gas adsorption equilibria and kinetics of sorption. Application and validation for COPublication . Karimi, Mohsen; Rodrigues, Alírio; Silva, José A.C.The screening of adsorbents (zeolites, MOFs, ACs, etc) requires the measurement of adsorption equilibria and kinetics at the milligram scale. In this regard, a volumetric apparatus (constant volume variable pressure – batch adsorber) has been developed for studying adsorption equilibria and kinetics of sorption. Its validation was accomplished by studying the adsorption equilibria of carbon dioxide (CO2), methane (CH4) and nitrogen (N2) and the kinetics of sorption of CO2 on commercial binder-free 4A zeolite. The data collected has an acceptable agreement with already published values by a gravimetric and breakthrough flow technique. The isotherms were modeled using Sips model from low pressure till 8 bar at 303, 343 and 373 K. The sorption kinetics of CO2 was measured from the uptake rate experiments and fitted with a solid-film linear-driving-force model (LDF). It was observed that the LDF mass transfer coefficients increase with pressure and temperature. Finally, the statistical analysis of the data was performed by Response Surface Methodology (RSM) to determine the interactions among process variables such as temperature and pressure in the respective gas adsorption equilibria data.
- Moving bed reactors: challenges and progress of experimental and theoretical studies in a century of researchPublication . Shirzad, Mohammad; Karimi, Mohsen; Silva, José A.C.; Rodrigues, AlírioMoving bed reactors (MBRs) have been proposed as a sign of significant progress in the reaction engineering area for performance improving and energy saving. Since their advent in 1890, the MBRs have attracted a wide acceptance in different industries, while they were first developed for the drying industries. The progress that this technology has made during its evolution led to the introduction of these reactors as a pioneer strategy in other industries including petroleum, petrochemical, pyrolysis, and biomass industries. In the traditional reaction systems, the process performance decreases during the operational conditions, while MBRs have obviated this drawback by having an all-around permanent acceptable efficiency. In this context, the present work provides an overview on the evolution of MBRs by investigating the main experimental and theoretical studies. In this way, the experimental studies have typically taken into account operational conditions and production rates of different products, while in the theoretical research, modeling, and simulation of conventional processes, the evaluation of novel configurations and the optimization techniques have been investigated. In the end, some suggestions are proposed to modify the traditional MBRs as helpful ideas for further studies.
- 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.
- Analyses of adsorption behavior of CO2, CH4, and N2 on different types of BETA ZeolitesPublication . Henrique, Adriano; Karimi, Mohsen; 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. Response surface methodology (RSM) was applied to evaluate the interactions between adsorption parameters and to describe the process.
- Fixed bed adsorption of CO2, CH4, and N2 and their mixtures in potassium-exchanged binder-free beads of Y zeolitePublication . Aly, Ezzeldin; Zafanelli, Lucas F.A.S.; Henrique, Adriano; Pires, Marcella Golini; Rodrigues, Alírio; Gleichmann, Kristin; Silva, José A.C.; Golini Pires, MarcellaThe 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.
- 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.
- Biomass as a source of adsorbents for CO2 capturePublication . Karimi, Mohsen; Rodrigues, Alírio; Silva, José A.C.CO2 capture and global warming have become the major anxiety of mankind in recent decades, and many researchers attempt to find the best strategies for these challenges. Besides the nature of global warming, the rapid increase of population and high consumption of energy have intensified this problem.
- Novel insights into activated carbon derived from municipal solid waste for CO2 uptake: synthesis, adsorption isotherms and scale-upPublication . Karimi, Mohsen; Zafanelli, Lucas F.A.S.; Almeida, João P.; Ströher, Gylles R.; Rodrigues, Alírio; Silva, José A.C.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.