Egg-shell Type Research Articles

AUTOMATIC IDENTIFICATION OF ISOLATED CALCIFICATIONS AND THEIR ACCUMULATIONS ON MAMMOGRAMS

Although microcalcinates usually are hyperattenuated, which makes them hyperintensive on mammograms, breast cancer is characterized by their small size, which, combined with the small size of their clusters, makes it difficult to identify them, especially against a dense background, which is often noted in fibrous changes in the breast parenchyma. The purpose of the study is to create and evaluate the effectiveness of the block for automatic identification of calcifications and their accumulations on mammograms. Material and methods. Mammograms of patients with suspicious (136 mammograms of 67 patients), as well as benign (299 mammograms of 151 patients) calcifications of various types were analyzed using a proprietary software package. Research results. After analyzing benign calcifications, the system marked all cases (100%) of calcified sediment, rod-shaped, vascular calcifications; 33 out of 36 (92.7%) cases of dystrophic, 66 out of 70 cases (94.3%) of rounded and 12 out of 15 (80%) cases of point calcifications in all patients; as well as 2 out of 3 cases of cutaneous calcifications in 1 out of 2 patients, 103 out of 106 (97.2%) cases of flaky calcifications in 51 out of 52 (98.1%) patients and 19 out of 22 cases (86.4%) of eggshell type calcifications in 10 out of 11 patients (90.9%). Among suspicious calcifications, the system marked 33 out of 39 cases (84.6%) of large heterogeneous calcifications, all 6 cases of small linear branching calcifications and 37 out of 39 (94.9%) cases of small polymorphic calcifications in all patients, as well as 30 out of 36 (83.3%) cases of amorphous calcifications in 15 out of 16 (93.7%) patients and 12 out of 16 (75.0%) cases of small linear calcifications in 6 out of 8 (75.0%) patients. All cases of unmarked suspicious calcifications corresponded to high-intensity soft-tissue shadows associated with indistinctly defined calcifications, which were labeled by the MammCheck II system previously developed by the authors. The frequency of false positive labels was 0.31 per mammogram. Conclusions. Benign calcifications were marked on 282 out of 299 images (94.3%) in 148 out of 151 (98.0%) patients, suspicious calcifications – on 118 out of 136 images (86.8%) in 64 out of 67 patients (95.5%).

Quantum Chemical Calculations of m-Toluidine and Investigation of Its Adsorption on Eggshells

Aromatic nitro compounds, which have good water solubility, are one of the essential industrial pollutants, highly toxic and non-biodegradable, and adversely affect human health, aquatic life, and the environment. For this reason, eliminating these harmful organic compounds has become a subject of great importance and is frequently studied. In this study, we have investigated the adsorption of m-toluidine on three types of eggshells characterized by FT-IR and FT-Raman spectroscopy. Also, the theoretical analysis of these harmful organic was determined using density functional theory on GAUSSIAN 09 software program. Molecular electrostatic analysis, Infrared and Raman vibrational bands, frontier molecular orbitals, and molecular geometry were investigated for this purpose.

Recycling of Chicken Egg Shells into Nanopowder: Synthesis, and its Properties

Increase in unconventional resources of calcium (Ca+2) for fowls, aquaculture and native animals was improved. This work was planned to define the most polymorph of calcium carbonate (CaCO3) that take place in the two types of chicken eggshells (local and imported type). In this research, the comparative analysis of calcium carbonate (CaCO3) content was approved for nominated eggshells of native strain and imported chicken via Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), Fourier-Transform Infrared Spectroscopy (FTIR) and Powder X-Ray Diffraction (PXRD) analysis. The results demonstrate that native and imported chicken eggshells comprise calcite morph that had shape between rhombohedral and spherical with distinguished pores distribution in the surface and crystallization size (31) nanometer for local chicken eggshells and (32) nanometer for import chicken eggshells respectively. The authors brief their results that local and import chicken eggshells had the top resources of calcium carbonate (CaCO3).

The diverse terminology of reptile eggshell microstructure and its effect on phylogenetic comparative analyses.

Reptile eggshell ensures water and gas exchange during incubation and plays a key role in reproductive success. The diversity of reptilian incubation and life history strategies has led to many clade-specific structural adaptations of their eggshell, which have been studied in extant taxa (i.e. birds, crocodilians, turtles, and lepidosaurs). Most studies on non-avian eggshells were performed over 30 years ago and categorized reptile eggshells into two main types: "hard" and "soft" - sometimes with a third intermediate category, "semi-rigid." In recent years, however, debate over the evolution of eggshell structure of major reptile clades has revealed how definitions of hard and soft eggshells influence inferred deep-time evolutionary patterns. Here, we review the diversity of extant and fossil eggshell with a focus on major reptile clades, and the criteria that have been used to define hard, soft, and semi-rigid eggshells. We show that all scoring approaches that retain these categories discretize continuous quantitative traits (e.g. eggshell thickness) and do not consider independent variation of other functionally important microstructural traits (e.g. degree of calcification, shell unit inner structure). We demonstrate the effect of three published approaches to discretizing eggshell type into hard, semi-rigid, and soft on ancestral state reconstructions using 200+ species representing all major extant and extinct reptile clades. These approaches result in different ancestral states for all major clades including Archosauria and Dinosauria, despite a difference in scoring for only 1-4% of the sample. Proposed scenarios of reptile eggshell evolution are highly conditioned by sampling, tree calibration, and lack of congruence between definitions of eggshell type. We conclude that the traditional "soft/hard/semi-rigid" classification of reptilian eggshells should be abandoned and provide guidelines for future descriptions focusing on specific functionally relevant characteristics (e.g. inner structures of shell units, pores, and membrane elements), analyses of these traits in a phylogenetic context, and sampling of previously undescribed taxa, including fossil eggs.

Assessment of Heavy Metals and Trace Elements in Eggs and Eggshells of Gallus gallus domesticus, Coturnix coturnix and Anas platyrhynchos from Bangladesh

Background: Despite playing an essential role as micronutrients, when exposed to an excess level, heavy metals can augment the risk of potential health diseases among humans and animals. Due to environmental degradation and food adulteration, many people are becoming the victims of those diseases by ingesting heavy metals from those food sources. Eggs are one of the principal sources of proteinaceous food and eggshells are also a good source of calcium, therefore, it is necessary to estimate the frequency of heavy metals as the poultry feeds, nowadays, are contaminated with heavy metals. Materials and Methods: Five types of egg samples were collected from the Jahangirnagar University area including indigenous, white and brown layer chicken eggs, duck eggs, and quail eggs. The concentration of Pb, Cd, Cr, Cu, Fe, and Zn was estimated both for egg contents and eggshells (10 samples) by atomic absorption spectrophotometry compared with the standard curve. Estimated daily intake (EDI), Target hazard quotient (THQ), and Hazard Index (HI) were also calculated to observe whether egg intake possesses any health hazards or not. Results: Among all the trace elements estimated, the highest concentration was 35.36±0.4 (Zn) in white layer chicken eggs, and for eggshells, the highest concentration was 0.69875±0.082 mg/kg (Fe) in Quail eggshell. Except for Fe, Pb was relatively higher compared to other elements in eggs, the amount of Pb was the highest in Quail eggs (0.486±0.09 mg/kg). All the six elements were also within the acceptable range in eggshells where the amount of Pb was the highest in Brown layer eggshells, and Cu and Zn were the highest in indigenous eggshells. Cd and Cr were below the detection limit for all types of eggshells. Estimated daily intake (EDI), Target hazard quotient (THQ) and Hazard Index (HI) values indicated that intake of eggs does not possess any health risk. Conclusion: Interestingly, the heavy metal concentration of our samples belongs within the PTDI and USEPA limit. Therefore, based on our study, all egg samples were safe considering the average egg ingestion in our country. If the average egg consumption rises, people might be at risk for higher Pb consumption through egg intake.

ECOFRIENDLY ADSORBENT FROM FOOD WASTE FOR WATER PURIFICATION

Egg shell, which is a waste material emerging out in large quantities from poultries, homes and restaurants, may be used as a good adsorbent for heavy metals. Different types of eggshells were used in this study for the adsorption of a major pollutant such as iron from surface water. Effect of CaCO3 content in the egg shell, particle size, contact time, temperature and shaking on adsorption were also studied. The adsorption isotherms fitted by the Langmuir model revealed that the adsorption of iron by eggshell samples was monolayer adsorption.

The effect of extraction time on the physicochemical characteristics of nanocalcium powder from chicken and duck eggshells

Calcium deficiency is associated with the risks of bone fracture and osteoporosis. This type of malnutrition has been a concern of governments and the World Health Organization for decades, and extensive efforts have been made to address it. There are several solutions to increase calcium intake. One is to take calcium in the form of nanocalcium. The objective of the present research was to determine the effect of extraction time on the physicochemical characteristics of nanocalcium powder extracted from chicken and duck eggshells through precipitation. This research was conducted by using a completely randomized factorial design with two factors, and each treatment analysis was repeated three times. The first factor was the type of eggshell (chicken and duck), and the second was the extraction time (1, 1.5, and 2 hours). The observed parameters were physical (yield and color) and chemical characteristics (moisture, ash, calcium content, and crystalline structure). The results showed that the type of eggshell had a significant effect (p <0.05) on yield, color (lightness), and moisture content and that extraction time had a significant effect (p <0.05) on yield, color (chroma and hue), moisture, and ash content. The highest content of the crystalline structure of nanocalcium formation (100%) was nanocalcium powder from chicken and duck eggshells, with 1 hour of extraction time. The particle size of the crystalline structure of nanocalcium from chicken and duck eggshells were 41.54 nm and 24.90 nm, respectively.

EVALUATION OF CALCIUM CARBONATE CONTENT IN EGGSHELLS OF AVIAN, TURTLE, SNAIL, AND OSTRICH USING CHEMICAL ANALYSIS AND SCANNING ELECTRON MICROSCOPY

In the present study, different eggs were collected and analyzed from five various animal species: European pond turtle (Emys orbicularis (Linnaeus, 1758)), giant African land snail (Achatina fulica (Bowdich, 1822)), common ostrich (Struthio camelus (Linnaeus, 1758)), white, light-brown, and dark-brown laying hen (Gallus gallus domesticus (Linnaeus, 1758) and European quail (Coturnix coturnix (Linnaeus, 1758). The typical mineral shell mainly composed of the calcite polymorph of CaCO3 but the eggshell consists of membranes, that composed mainly of proteins. The shell quality also could be assigned by several external and internal factors such as oviposition time, animal genotype and age, housing system (for poultry), and mineral nutrition complex. The CaCO3 content was determined by the standard titration method, coz the titration could provide a reliable method for evaluation of CaCO3 content in different types of eggshells. The structural surface characterization of eggshells was performed by scanning electron microscopy (SEM) with a field emission gun. In terms of chemical composition, ostrich eggshells generally did not differ much from those of laying hen, turtles, giant snails, or quail eggs, but the concentration of calcium carbonate was the highest. The average calcium carbonate content of various eggshells is between 84 and 98%. The thickness of the eggshell ranges from 0.08 to 1.89 mm, and it is not the same over the entire surface of the egg. At the sharp end of the egg, the shell is slightly thicker than at the blunt end. The purpose of this study was to study the quantitative content of calcium carbonate in various eggshells of different animals to draw further conclusions in which animals the eggshell contains the maximum amount of biological calcium carbonate.

Eggshell as a biomaterial can have a sorption capability on its surface: A spectroscopic research.

In this study, eggshell as a biomaterial was used as an adsorbent. This natural waste material is easy to access and cost-free. The surface of the eggshell with its porous structure showed affinity to adsorb damaging chemicals. In particular insecticides cause serious environmental pollution in agriculture, and this is a general problem all over the world. The aim was to remove insecticides from the environment and monitor the pesticides on the surface of eggshells by atomic force microscopy (AFM) images, Fourier transform infrared (FTIR) and UV/Vis spectroscopic techniques. Five types of eggshells, Denizli Hen, Coturnix Coturnix Japonica, Light Brahma Chicken, Alectoris Chukar and ISA Tinted -White, were used. Since they are commonly used, Cypermethrin, Deltamethrin and Indoxacarb were chosen as insecticide samples. The interaction effect of insecticides on the surface of eggshells was determined by AFM images; it was seen that the semispherical surface structures of the eggshells were flattened after adsorption. FTIR spectroscopy was used both to detect structural analysis and to determine the adsorption influence. In addition, UV-Vis spectroscopy was performed to evaluate the adsorption and desorption process. Porous media of different types of eggshells with an aqueous solution of insecticides had an electronegativity attractive surface which makes it an ideal adsorbent via hydroxyl groups.

Phylogeny and evolutionary history of the amniote egg.

We review morphological features of the amniote egg and embryos in a comparative phylogenetic framework, including all major clades of extant vertebrates. We discuss 40 characters that are relevant for an analysis of the evolutionary history of the vertebrate egg. Special attention is given to the morphology of the cellular yolk sac, the eggshell, and extraembryonic membranes. Many features that are typically assigned to amniotes, such as a large yolk sac, delayed egg deposition, and terrestrial reproduction have evolved independently and convergently in numerous clades of vertebrates. We use phylogenetic character mapping and ancestral character state reconstruction as tools to recognize sequence, order, and patterns of morphological evolution and deduce a hypothesis of the evolutionary history of the amniote egg. Besides amnion and chorioallantois, amniotes ancestrally possess copulatory organs (secondarily reduced in most birds), internal fertilization, and delayed deposition of eggs that contain an embryo in the primitive streak or early somite stage. Except for the amnion, chorioallantois, and amniote type of eggshell, these features evolved convergently in almost all major clades of aquatic vertebrates possibly in response to selective factors such as egg predation, hostile environmental conditions for egg development, or to adjust hatching of young to favorable season. A functionally important feature of the amnion membrane is its myogenic contractility that moves the (early) embryo and prevents adhering of the growing embryo to extraembryonic materials. This function of the amnion membrane and the liquid-filled amnion cavity may have evolved under the requirements of delayed deposition of eggs that contain developing embryos. The chorioallantois is a temporary embryonic exchange organ that supports embryonic development. A possible evolutionary scenario is that the amniote egg presents an exaptation that paved the evolutionary pathway for reproduction on land. As shown by numerous examples from anamniotes, reproduction on land has occurred multiple times among vertebrates-the amniote egg presenting one "solution" that enabled the conquest of land for reproduction.

Tiny, ornamented eggs and eggshell from the Upper Cretaceous of Utah represent a new ootaxon with theropod affinities

A new Cretaceous ootaxon (eggshell type) from the Kaiparowits Formation of Grand Staircase-Escalante National Monument is among a growing number of very small eggs described from the Mesozoic. Analyses of two partial eggs (~ 17.7 mm in diameter) and 29 eggshell fragments reveal that this new ootaxon exhibits nodose ornamentation with distinctive branching pore canals that open atop the nodes. Its two-layered microstructure consists of a mammillary layer and a continuous layer with rugged grain boundaries between calcite grains. Although the exact identity of the egg producer is unknown, the eggshell microstructure and small size is consistent with a small-bodied avian or non-avian theropod. The specific combination of small egg size, branching pores, two-layered microstructure, and dispersituberculate ornamentation preserved in this new ootaxon is unique among theropod eggs. This underscores that both eggshell and skeletal fossils of Cretaceous theropods can display a mosaic of transitional morphological and behavioural features characteristic of both avian and non-avian taxa. As such, this new ootaxon increases the diversity of Cretaceous eggs and informs our understanding of the evolution of theropod eggshell microstructure and morphology.

Fossil eggshells of amniotes as a paleothermometry tool

Raman spectroscopic analyses of thermally altered organic materials can be used to assess the paleothermometry of the sedimentary deposits. Although this technique has been widely applied to diverse microfossils, macroscopic vertebrate fossils have been neglected. In this paper, we show that fossil eggshells can be used for this purpose by demonstrating the paleothermometric potential of diverse amniotic eggshells from the Wido Volcanics (Upper Cretaceous, South Korea) that contain thermally altered organic material. We estimate the maximum paleotemperature recorded in the eggshells using Raman spectroscopic data and the spectrum deconvolution technique, which was invented and developed by organic geochemists. The results show that the same type of eggshells record different paleotemperature gradients depending on their spatial distribution in the fossil locality, whereas different types of eggshells from similar locations show similar paleotemperature gradients (except for one specimen with a peculiar microstructure). These findings are further supported by Fourier transform infrared spectroscopic results, which focus on thermally altered organic materials, and electron backscatter diffraction data, which focus on calcite twinning. This study suggests that fossil eggshells are useful and reliable materials for paleothermometry because thermally altered organic materials and calcites of eggshells provide independent opportunities to assess paleothermometry. We propose that fossil eggshells may be useful for evaluating the thermal evolution of sedimentary basins.

Investigation of coke deposition inside catalyst with heterogeneous active component distribution

Coke deposition over catalytic particles is not only associated with pore structure and pore distribution, but also depends on the active component distribution. A particle-resolved model is employed to explore the coke deposition process inside catalyst particles with heterogeneous active component distribution. The spatial and instantaneous distribution of coke deposition and its influence on catalytic performance in a single particle and a packed bed are evaluated. The results show that there is a weaker internal resistance of mass and heat transfer inside the egg-shell type catalyst so as to lead to a faster coke accumulation and catalyst deactivation, compared to the egg-yolk type catalyst. Meanwhile, the wall effect on coke accumulation is more significant for egg-yolk type catalysts.

Removal of copper (II) ions by eco-friendly raw eggshells and nano-sized eggshells: a comparative study

This work evaluates the potential of using eggshells as biosorbents for the removal of copper (II) ions from aqueous solutions. Two types of eggshells were investigated; untreated raw eggshells (ES) and eggshells that were mechanically ball-milled into the nano-size (NES). TEM imaging confirmed the nano-size of NES which lies in the range of 12–14.8 nm, while BET analysis showed that both types of eggshells are mesoporous and that the surface area of NES is 1.6 times higher than its ES counterpart. FTIR spectra, XRD patterns, and SEM-EDX measurements indicated that there are no structural differences between ES and NES. Optimum adsorption took place at pH 5 and initial Cu (II) concentration of 20 mg/L for both ES and NES where removal efficiencies of 91.36% and 97.21% were achieved, respectively. Although both biosorbents exhibited comparable adsorption capacities, yet the rate of adsorption of Cu (II) onto NES was 17 times higher than its counterpart onto ES probably due to the larger surface area of NES. It could be hypothesized that the mechanism of interaction took place via electrostatic outer-sphere complexation between the positively-charged Cu ions and the negatively-charged ES or NES as zeta potential measurements indicated. Additionally, ES and NES were regenerated for four cycles. From this study, it can thus be deduced that both ES and NES could be potentially utilized as eco-friendly adsorbents for the removal of copper ions from contaminated water. However, NES provides an additional advantage over ES since it offers much rapid removal of Cu (II) while possessing the same adsorption capacity of ES.

Searching for a Clue to Characterize a Crystalline Dinosaur's Eggshell of Baja California, Mexico.

This work presents a detailed structural and morphological analysis of different dinosaur eggshells such as Spheroolithus (sample 1, 2), lambeosaurinae, Prismatoolithus, and one unidentified ootaxon performed by high-resolution scanning electron microscopy (HRSEM). These ancient eggshells of Late Cretaceous dinosaurs were collected in the coastal area of El Rosario, Baja California in Mexico. Additionally, a thorough study was performed on the elements present in the samples by different techniques such as energy-dispersive spectroscopy (EDS), X-ray fluorescence (XRF), and X-ray photoelectron spectroscopy (XPS). The XPS technique was performed to make an accurate identification of the compounds of two different types of eggshells (Spheroolithus sample 1 and Prismatoolithus). This contribution compares the surface of five different dinosaur eggshells of 74 Ma and their inner section to determine the morphology, distribution of the chemical elements present, as well as their relationship. The observed morphology of the ornithopod eggshells of the herbivorous species shows that the mammillary cones are in the form of columns with microaggregates and irregular pores. In contrast, in the theropod eggshells, the mammillary cones are observed in different forms with wider pores. Finally, the chemical components present in the structures of each of the samples were estimated using the information obtained from SEM-EDS, evidencing the presence of calcite, quartz, and albite in each of the samples. The composition reveals that eggshells contain Si, P, S, K, Ca, Mn, Fe, and Sr and trace elements such as Cr, Cu, and Zn. The presence of heavy metals may be an indication that the eggshells presented diagenetic alterations.

Can bi-functional nickel modified 13X and 5A zeolite catalysts for CO2 methanation be improved by introducing ruthenium?

Zeolites 13X and 5A were modified with nickel and/or ruthenium for CO2 methanation. The catalysts were prepared by evaporation impregnation and XRD, SEM-EDX, TEM, STEM-EDX, nitrogen physisorption, H2-TPR and NH3-TPD were used to characterize the physico-chemical properties of the catalysts. The physico-chemical characterization results show that the zeolites structure did not change after the Ni, Ru modification, however. Ni was able to enter the pores of 13X, in the other case, 5A, an egg shell type structure was formed. Methanation experiments were performed in a lab scale fixed bed reactor system, the results showed that the mono-metallic catalysts out-performed the bi-metallic ones with Ni being the more active. One of the factors influencing the performance of the bi-metallic catalysts was the difficulty to obtain good dispersion when both metals were used. Also the morphology of the catalyst significantly influenced the selectivity. The catalysts with lower weak acidity benefit for getting a higher activity. The single metal catalysts 2.5 %Ru13X and 5%Ni13X showed good catalytic stability with around 97 % CH4 selectivity at 360 °C, with no catalyst deactivation during the 200 h catalyst stability test.

The first dinosaur egg was soft.

Calcified eggshells protect developing embryos against environmental stress and contribute to reproductive success1. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite, and an outermost waxy cuticle2-7. The calcitic eggshell consists of one or more ultrastructural layers that differ markedly among the three major dinosaur clades, as do the configurations of respiratory pores. So far, only hadrosaurid, a few sauropodomorph and tetanuran eggshells have been discovered; the paucity of the fossil record and the lack of intermediate eggshell types challenge efforts to homologize eggshell structures across all dinosaurs8-18. Here we present mineralogical, organochemical and ultrastructural evidence for an originally non-biomineralized, soft-shelled nature of exceptionally preserved ornithischian Protoceratops and basal sauropodomorph Mussaurus eggs. Statistical evaluation of in situ Raman spectra obtained for a representative set of hard- and soft-shelled, fossil and extant diapsid eggshells clusters the originally organic but secondarily phosphatized Protoceratops and the organic Mussaurus eggshells with soft, non-biomineralized eggshells. Histology corroborates the organic composition of these soft-shelled dinosaur eggs, revealing a stratified arrangement resembling turtle soft eggshell. Through an ancestral-state reconstruction of composition and ultrastructure, we compare eggshells from Protoceratops and Mussaurus with those from other diapsids, revealing that the first dinosaur egg was soft-shelled. The calcified, hard-shelled dinosaur egg evolved independently at least three times throughout the Mesozoic era, explaining the bias towards eggshells of derived dinosaurs in the fossil record.

Pigmentation of White, Brown, and Green Chicken Eggshells Analyzed by Reflectance, Transmittance, and Fluorescence Spectroscopy.

We report on the reflectance, transmittance and fluorescence spectra (λ=200–1200 nm) of four types of chicken eggshells (white, brown, light green, dark green) measured in situ without pretreatment and after ablation of 20–100 μm of the outer shell regions. The color pigment protoporphyrin IX (PPIX) is embedded in the protein phase of all four shell types as highly fluorescent monomers, in the white and light green shells additionally as non‐fluorescent dimers, and in the brown and dark green shells mainly as non‐fluorescent poly‐aggregates. The green shell colors are formed from an approximately equimolar mixture of PPIX and biliverdin. The axial distribution of protein and colorpigments were evaluated from the combined reflectances of both the outer and inner shell surfaces, as well as from the transmittances. For the data generation we used the radiative transfer model in the random walk and Kubelka‐Munk approaches.

Application of a catalytic membrane reactor to the selective hydrogenation of 1-Butyne

A catalytic membrane reactor (CMR) was applied in order to enhance the selectivity in the hydrogenation of 1-butyne in the presence of 1-butene. The performance of the CMR was studied in batch-wise operation for the hydrocarbon liquid mixture, while hydrogen was continuously fed to keep a constant partial pressure. The reaction was carried out at 44 °C and partial pressures of hydrogen in the range of 1 to 5 bar. The CMR was prepared by impregnating a commercial alumina membrane disk with Pd. Experimental results were compared with those obtained in a conventional fixed bed reactor (FBR), using a commercial catalyst of egg-shell type in its original size, and in a microreactor (MR) with the same commercial catalyst milled to a size of around 40 μm. The CMR presents high activity and selectivity, comparable to the values of the milled commercial catalyst, but significantly higher than for the commercial catalyst in its original size. Kinetic parameters for the hydrogenation of 1-butyne were obtained from the regression of the experimental data. Also, a simulation of a continuous operation of both, CMR and FBR with the commercial catalyst, was carried out to show the advantage in selectivity of the CMR.

Pore diffusion effects on catalyst effectiveness and selectivity of cobalt based Fischer-Tropsch catalyst

Abstract In this study we investigate performance characteristics (catalyst effectiveness, CH4 selectivity, and hydrocarbon product distribution) of with a highly active Co/Re/Al2O3 catalyst particle for Fischer-Tropsch synthesis. In numerical simulations we utilize kinetic parameters for CO consumption rate, CH4 formation rate and hydrocarbon formation rates (C2+ hydrocarbons) determined from experiments with this catalyst to study effects of catalyst activity, catalyst particle shape (sphere, slab, solid and hollow cylinder), size (i.e. diffusion length), catalyst distribution (uniform vs. eggshell type distribution for a spherical particle) and process conditions (temperature, pressure, syngas composition and conversion level) on the catalyst performance. With increase in Thiele modulus (i.e. particle size at a fixed set of process conditions) we observe increasing H2/CO ratio profile towards the center of the particle resulting in increase of local and average CH4 selectivity. The goal is to find conditions which allow one to use sufficiently large particles to reduce pressure drop, while avoiding negative influence of diffusional limitations on selectivity and activity. For each catalyst particle shape we determined values of Thiele modulus, i.e. characteristic length of diffusion, corresponding to the upper limit of the kinetic region, and investigated how it changes with operating conditions. We found that simultaneous increase of pressure and the use of syngas with H2/CO feed ratio of 1.4–1.7 is the best strategy for mitigating the negative impact of intraparticle diffusional limitations on CH4 selectivity. For a spherical particle of 1 mm in diameter, one can achieve CH4 selectivity of 5.6% with catalyst effectiveness factor of 1.07 at the reactor inlet by operating at 50 bar, 473 K and H2/CO = 1.4.