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Monitoring and simulating the events occurring on the catalysts under the real reaction conditions has significant meaning for elucidating the dynamic changes of the active sites during the reactio...

A novel low-concentration CO2 capture material (PEI/MCS) was developed by loading polyethylenimine (PEI) over mesoporous carbon spheres (MCS) with high porosity. The effects of pore structure, PEI loading, capture temperature, and promoters on CO2 capture of PEI/MCS were studied. The MCS with perfect spherical morphology was successfully synthesized by a hard-template assisted reverse emulsion method. The pore structure of MCS was adjusted by tuning the ratio of silica to carbon (Si/C) in the precursors. With increasing the Si/C from 0.8 to 1.1, the pore volume of MCS increased from 1.25 to 2.68 cm3/g. The optimal PEI loadings depending on the pore volume of MCS were 45, 62.5, and 65 wt.% for MCS-0.8, MCS-1.1, and MCS-1.5, respectively. The highest CO2 capture capacity (3.22 mmol/g) was achieved on 62.5PEI/MCS-1.1 at CO2 partial pressure of 0.05 bar (5 vol.%, a typical concentration of the tail gas from natural gas power plant and natural gas processing plant) and temperature of 75 °C, outperforming most of the solid amine sorbents reported at similar condition. However, the cycling stability of PEI/MCS is poor at the capture-regeneration temperature of 75 °C. The promoters Span 80 and 1,2-epoxybutane did not show remarkable effect on the cycling stability of PEI/MCS at 75 °C. Decreasing the capture-regeneration temperature can significantly improve the stability of PEI/MCS and there is almost no CO2 capacity loss (regeneration >99.5 %) when the temperature decreased to 50 °C. As a result of high CO2 capacity and excellent regenerability and stability, PEI /MCS will be one of the ideal candidates for CO2 capture in the future.

The biochemical parameters (i.e. chlorophyll and nitrogen content) of crops are essential to evaluate the health status and to monitor crop growth. The incorporation of near-proximal sensor data with satellite data has offered a new angle for rapid, detailed, and reliable assessment of crop biochemical parameters. This study aimed to utilize the higher spatial and spectral resolution of Sentinel-2A multi-spectral instrument (MSI) satellite data in conjunction with near-proximal sensor data to derive the chlorophyll (Chl) content and nitrogen balance index (NBI) of paddy at different growth stages during the monsoon season (2017) in Ranchi district, Jharkhand. The key findings revealed that the satellite-derived Chl content and NBI of paddy were overestimated as compared to the field-based measurements. The correlations between satellite-derived and empirical model-based Chl content and NBI of paddy revealed a R2 of 0.92–0.99 (p

This study was performed to evaluate the spatial and temporal distribution of major ions in water samples of a newly designated Ramsar site, namely Kabar Tal (KT) wetland of Bihar. Samples were collected during summer, monsoon, and winter seasons. The analytical and GIS results show that concentration of electrical conductivity, chloride, and nitrate are higher in summer than monsoon and winter. However, the concentration of major cations such as sodium, potassium, calcium, and magnesium are higher in winter than monsoon and summer. In addition, major anions like sulphate and phosphate concentration is higher during monsoon than summer and winter. Multivariate statistical tool (discriminant analysis) results suggest that temperature, pH, electrical conductivity, sulphate, and potassium are the major parameters distinguishing the water quality in different seasons. The study confirms that seasonal variations are playing a major role in the hydrochemistry of KT wetland. Overall, this work outlines the approach towards proper conservation and utilization of wetlands and to assess the quality of surface water for determining its suitability for agricultural purposes. Overall, this work highlights the approach towards estimating the seasonal dynamics of chemical species in KT wetland and its suitability for irrigation purposes. HIGHLIGHTS Spatiotemporal assessment of surface water has been characterized through hydro-chemical studies.; Temperature, pH, EC, sulphate, and potassium, influences water chemistry.; Hydrochemical facies of surface water is of Ca2+ and Cl−; Ca2+- Mg2+ -SO42− and Cl− type.; The surface water of the wetland is of good quality for irrigation.; Detailed exploration for the water chemistry has been studied through statistical methods.

The autothermal gas-phase oxidative dehydrogenation of ethane (ODHE) in a tubular reactor was analyzed by one-dimensional (1D) and two-dimensional (2D) reactor simulations coupling with a detailed ...

Cu-CHA is the state-of-the-art catalyst for the Selective Catalytic Reduction (SCR) of NOx in vehicle applications. Although extensively studied, diverse mechanistic proposals still stand in terms of the nature of active Cu-ions and reaction pathways in SCR working conditions. Herein we address the redox mechanism underlying Low-Temperature (LT) SCR on Cu-CHA by an integration of chemical-trapping techniques, transient-response methods, operando UV/Vis-NIR spectroscopy with modelling tools based on transient kinetic analysis and density functional theory calculations. We show that the rates of the Reduction Half-Cycle (RHC) of LT-SCR display a quadratic dependence on CuII , thus questioning mechanisms based on isolated CuII -ions. We propose, instead, a CuII -pair mediated LT-RHC pathway, in which NO oxidative activation to mobile nitrite-precursor intermediates accounts for CuII reduction. These results highlight the role of dinuclear Cu complexes not only in the oxidation part of LT-SCR, but also in the RHC reaction cascade.

Interpenetrating polymer networks of vinyl ester (VE) resin and polyurethane (PU) were synthesized using blend ratio of 93:7(w/w). Two sets of nanocomposites based on i) pure vinyl ester and ii)VE/PU IPN(93VE), were prepared with organically modified silica nanoparticle (OMS) as filler by 1, 2, 3 and 5% weight of the matrix resin. All the nanocomposites were characterized in terms of mechanical and thermomechanical properties.VE/silica nanocomposite with 2% filler (VES2) showed improvement in ultimate tensile strength by 83.5% and toughness by 42% compared to that of VE resin itself. The IPN based nanocomposite, 93VES2, exhibited 31.14%, 10.8% and 18%greater tensile strength, Young’s modulus and toughness respectively in comparison to that of the base 93VE IPN. IPN based nanocomposites were tougher than VE based nanocomposites. Storage modulus of nanocomposites was lower than that of 93VE and VE matrix system. Higher tanδmaxof the 93VE/OMS nanocomposites than that of the 93VE matrix was indication of more elastic nature of the later. Smaller size of dispersed domains was found in SEM micrographs for IPN based nanocomposites than that in micrographs of VE based nanocomposites of corresponding composition.

The concentration of trace metals Mn, Pb, Ni, Zn, and Cu in the core sediment from Kabar Tal wetland was analyzed to understand the level of contamination in the vertical profile. Additionally, total organic carbon (TOC) and available phosphorus (AP) were also analyzed to infer the biogeochemistry of trace metals and the correlation that exists among them. Five core sediments were collected at the end of the monsoon season from different locations in the study area, representing diverse anthropogenic and agricultural activities. The average concentration of trace metals in sediments followed the order Mn > Pb > Ni > Zn > Cu. The trace metal concentration in the surface sediments was higher and decreased with depth in the vertical profile. Contamination factor (CF), geoaccumulation index (Igeo), enrichment factor (EF), and pollution load index (PLI) were used to evaluate sediment quality and the pollution status of the lake sediments. Cu, Zn, and Ni showed minor to moderate enrichment, and Pb showed a severe level of enrichment in all the core sediment samples. However, the sediment quality guidelines’ index indicates that the sediments are moderately polluted with copper, zinc, and nickel and severely polluted with lead. There exists a strong positive correlation among Pb-Ni, Ni-AP, and AP-Pb, and a strong negative correlation among TOC-Ni, TOC-Pb, and TOC-AP for all the sediment samples. Additionally, the principal component analysis (PCA) and cluster analysis (CA) suggest that a good similarity exists among Pb, Ni, and Zn. The study indicates that trace metals in wetland sediments have originated from multiple anthropogenic sources like agricultural runoff (fertilizers), direct addition of solid wastes, discharge of untreated wastewater, and long-range transport from the oil refinery in the wetland.

Colocasia [Colocasia esculenta var. antiquorum (L.) schott.], which is also known as Taro, Arvi, Katchu and eddode belongs to the family Araceae is an important edible aroid. Africa ranks first in area and production of colocasia and in India colocasia is favourite among Gujarat, Konkan region of Maharashtra and several other parts of south India. The cormels, corms, leaves and petioles are used as a vegetable and considered as rich source of carbohydrates, proteins, minerals and vitamins. Due to increasing demand of taro, there is a need to increase its yield. Foliar application of plant growth regulators is reported to improve growth and tuber yield. Hence, the present investigation has been carried out in the the Horticulture Research unit, Department of Horticulture, Faculty of Agriculture, Birsa Agricultural University, Kanke, Ranchi during Kharif season of 2017. There were eleven treatments used namely T1- Naphthalene Acetic Acid (25 ppm), T2- Naphthalene Acetic Acid (50 ppm), T3- Indole Acetic Acid (25 ppm), T4- Indole Acetic Acid (50 ppm), T5- Maleic Hydrazide (50 ppm), T6- Maleic Hydrazide (100 ppm), T7- Gibberellic Acid (100 ppm), T8- Gibberellic Acid (200 ppm), T9- Ethrel (75 ppm), T10- Ethrel (150 ppm) and T11- Control (water spray only). To find out feasibility of increment in growth & yield of taro by means of application of plant growth regulators on the till date most accepted variety of taro, Muktakeshi by the growers in the state of Jharkhand. Among the eleven treatments used GA3 at 200 ppm was found to record maximum yield parameters in cultivation of taro.

Ooty lake, in the southern part of India, has raised huge concern about the role of metals in a lake due to increasing anthropogenic activities. Present study is aimed at understanding fate of trace metals in a lake's sediment. Sixteen sediment samples collected from bottom of the lake at various locations during March 2017 were analysed for trace metals cobalt, chromium, copper, iron, lead, manganese, nickel and zinc. Fe and Mn dominate total metal concentration followed by Ni and Cr. A high concentration of Cr, Cu, Ni and Zn in residual fraction indicates weathering as the source for these metals. A significant concentration of metals in exchangeable, reducible and oxidisable fraction indicates adsorbtion/chelation of these metals with oxides and organic matter due to change in oxic state. Geo-accumulation index for metals show unpolluted to moderate nature of sediments at all sampling locations. Moderate to significant enrichment factor of Cr, Ni and Zn indicates influence of anthropogenic sources. Co, Pb and Zn show a high amount of bioavailability for aquatic life. Other metals (Cr, Ni, Fe and Mn) show scarce to moderate bioavailability. On the other hand, a global contamination factor denotes moderate to high metal contamination of sediments in the entire lake. Statistical analysis of metals shows good inter-element correlation among metals Fe, Cr, Ni, Co, Cu and Zn indicating natural source. Influence of domestic sewage and recreational activities as the main/additional source is revealed by negative loading of Pb and Zn in principal component analysis. The present study, in essence, has identified rock weathering, as a major source of trace meals in the sediments of Ooty lake entering through stream and surface runoff from an adjacent forest area. The study has also identified high bioavailability of Pb and Zn, which is derived through the recreational activities (boating) causing permanent adverse impact.

Ethylene oxychlorination is the key technology in vinyl chloride (VCM, the monomer of PVC, polyvinyl chloride) production to close the chlorine loop by consuming the HCl released from the former cracking step. Due to the high demand for PVC, this leads to ethylene oxychlorination being one of the most important processes in the industry. This Review covers an in-depth analysis of the dynamic nature of active sites for the main and side reactions involved in ethylene oxychlorination, featuring the findings and viewpoints from the dynamic kinetics study and analysis under industrial operating conditions. A unified picture of the mechanism of the surface reactions, and the effect of supports and promoters, has been presented based on the decoupled redox-cycle experiments, which leads to a significantly better understanding of the mechanism and provides valuable guidelines for effective catalyst design. Operando techniques and kinetic tools of the rate-diagram, as well as their application to the study of the redox-cycle in ethylene oxychlorination and kinetic models on both the main product and byproduct, are also reviewed. Perspectives on challenges and new process development and future research focus for better study of the VCM production chemistry are also proposed. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.

It may be concluded from the results that the application of nitrogen and phosphorus without potassium (K) or inadequate K fertilizer application would cause greater mining of reserve soil K. Hence prior to crop production adequate K fertilizer application is needed.

Kenaf fibre-reinforced vinyl ester (VE)/polyurethane (PU) interpenetrating polymer network (IPN)-based composites were made by hand lay-up technique. The kenaf bast fibre was chemically treated with 3, 6 and 9% vinyl silane. Treated fibres were characterized in terms of crystallinity, mechanical strength, density, thermal property and morphology. In comparison with the untreated fibre, 6% silane-treated fibres showed 25.4% higher % crystallinity, 66.9% increase in modulus elasticity and 604.2% increase in tenacity. Comparison of the pure VE with VE/PU IPN showed that the IPN had 3.3% lower modulus but 26.4% higher toughness than the former. Composites based on pure VE matrix and VE/PU IPN matrix were manufactured with the variation of untreated and treated fibre loading as 15, 20, 25, 30, 35 and 40 wt%. Novelty of this work lies in the modification of both the fibre surface and the matrix system simultaneously with the aim of increasing the adhesion between the fibre surface and matrix material of the composite. Composites with untreated fibres showed poor strength compared to that with modified fibres having corresponding compositions. IPN-based composites, with 35 wt% silane-treated fibre, showed improvement in tensile modulus by 16.61% and flexural modulus by 6.35% than pure VE-based composites with corresponding fibre loading.

Research in the sustainable conversion of biomass to fuels and chemicals is a necessity for the reduction of the carbon footprint in transport energy. Herein, we demonstrate an efficient tandem catalyst to selectively convert (simulated) bio-oil to hydrocarbons with enhanced C4+ fuel yield in a fixed bed reactor of a small pilot plant. The tandem catalytic system is a multifunctional dual bed system; carbon coupling catalysts (0.2 wt % X-TiO2(X: Ru, Pd, Au) at the upper layer and hydro-deoxygenation (Ru-MoFeP/Al2O3) at the bottom layer in a single fixed bed reactor. The upper-bed catalysts facilitated the carbon coupling reaction of C2–C4 light oxygenates and significantly reduced the light gases yield (C1–C5) to ca. 40% and increased the organic (C4+) phase ca. 15%. The analysis of the organic phase suggests that among the screened upstream catalysts, 0.2 wt % Ru/TiO2||Ru-MoFeP/Al2O3 recorded the optimum activity. The coupled light oxygenates (acetone) alkylated with the phenolic compounds and sequentially hydro-deoxygenated to yield higher C4+ hydrocarbons. This versatile tandem catalytic approach has a potential application in the emerging biorefinery concept.

The impact of operating parameters on H2S capture from a syngas mixture by a Mo-promoted Mn-based high-temperature sorbent was investigated. The parameters investigated included temperature, space velocity, H2S concentration in the feed gas, and steam content. The H2S and SO2 concentrations in the gas after passing over a bed of the sorbent were analyzed and compared with thermodynamic calculations. The results confirmed that low temperature, low space velocity, low H2S concentration, and a dry feed were favorable for achieving a low residual concentration of sulfur compounds in the effluent gas. The sorbent was able to reduce the residual H2S concentration to below 1 ppm under all tested conditions. However, the unavoidable steam content in the gas phase had a significant adverse effect on sulfur removal from the gas. An empirical model, containing the three variables, i.e., temperature, space velocity, and H2S concentration in the feed, was developed and can be used to predict the effluent H2S residual concentration after treatment by the 15Mn8Mo sorbent.

By introducing Pt atoms into the surface of reduced hydrotalcite (HT)-derived nickel (Ni/HT) catalysts by redox reaction, we synthesized an enhanced active and stable Ni-based catalyst for methane dry reforming reaction. The bimetallic Pt–Ni catalysts can simultaneously enhance the catalyst activity, increase the H2/CO ratio by suppressing reverse water–gas shift reaction, and enhance the stability by increasing the resistance to the carbon deposition during the reaction. Kinetic study showed that 1.0Pt–12Ni reduces the activation energy for CH4 dissociation and enhances the catalytic activity of the catalyst and lowers the energy barrier for CO2 activation and promotes the formation of surface O* by CO2 adsorptive dissociation. It is beneficial to enhance the resistance to the carbon deposition and prolong its service life in the reaction process. In addition, density-functional theory calculations rationalized the higher coke resistance of Pt–Ni catalysts where CH is more favorable to be oxidized instead of cracking into surface carbon on the Pt–Ni surface, compared with Ni(111) and Pt(111). Even if a small amount of carbon deposited on the Pt–Ni surface, its oxidation process requires a lower activation barrier. Thus, it demonstrates that the bimetallic Pt–Ni catalyst has the best ability to resist carbon deposition compared with monometallic samples.

A detailed kinetic model describing the consumption of key components and productdistribution in the Fischer–Tropsch synthesis (FTS) over a 20%Co/0.5Re γ-Al2O3commercial catalyst is developed. The developed model incorporates the H2O-assisted CO dissociation mechanism developed by Rytter and Holmen and a novelapproach to product distribution modeling. The model parameters are optimizedagainst an experimental dataset comprising a range of process conditions: total pres-sure 2.0–2.2 MPa, temperature 210–230C, CO conversion range of 10%–75% andfeed with and without added water. The quality of the model fit measured in termsof mean absolute relative residuals (MARR) value is 23.1%, which is comparable to lit-erature reported values. The developed model can accurately describe both positiveand negative effects of water on the rate kinetics, the positive effect of water on thegrowth factor, temperature and syngas composition on the kinetics and product dis-tribution over a wide range of process conditions, which is critical for the design andoptimization of the Fisher–Tropsch reactors.

A bifunctional catalyst comprising CuCl2/Al2O3 and nitrogen‐doped carbon was developed for an efficient one‐pot ethylene oxychlorination process to produce vinyl chloride monomer (VCM) up to 76 % yield at 250 °C and under ambient pressure, which is higher than the conventional industrial two‐step process (≈50 %) in a single pass. In the second bed, active sites containing N‐functional groups on the metal‐free N‐doped carbon catalyzed both ethylene oxychlorination and ethylene dichloride (EDC) dehydrochlorination under the mild conditions. Benefitting from the bifunctionality of the N‐doped carbon, VCM formation was intensified by the surface Cl*‐looping of EDC dehydrochlorination and ethylene oxychlorination. Both reactions were enhanced by in situ consumption of surface Cl* by oxychlorination, in which Cl* was generated by EDC dehydrochlorination. This work offers a promising alternative pathway to VCM production via ethylene oxychlorination at mild conditions through a single pass reactor., Vinyl chloride monomer (VCM) is directly produced by a metal‐free nitrogen‐doped carbon catalyst in one step via the ethylene oxychlorination process at 250 °C. Ethylene oxychlorination and high‐temperature dehydrochlorination reactions are integrated into a single pass with remarkable conversion and selectivity. The efficient combination of tandem reactions produces a VCM yield as high as the current two‐step process, and under mild conditions.

A kinetic model was developed by taking into account the dynamic nature of the active sites in Mars–van Krevelen type catalytic reactions to predict the evolution of the reactant and product composition in the gas phase and the CuCl2 concentration in the solid catalyst. The kinetic model at the steady-state of ethylene oxychlorination was obtained by combining transient experiments of the two half-reactions in the redox cycle, namely CuCl2 reduced to CuCl by ethylene and CuCl oxidation by oxygen on the K-promoted CuCl2/γ-Al2O3 catalyst. The dynamic transitions between CuCl2 and CuCl of the active sites during the reactions are also modeled, and the contributions of two active sites, namely Cu coordination numbers of 4 and 3 in CuCl2 were distinguished and included in the kinetic model. The kinetic models describe well the transient response of the reduction and oxidation steps as well as the reaction at the steady-state at different reaction conditions. Moreover, by combining the reactor modeling through a steady-state approach, the spatial-time resolved CuCl2 profile and the C2H4 reaction rate can be well predicted in comparison with the experimental results. The approach of both transient and steady-state kinetic modeling and simulation is supposed to have general relevance for a better understanding of Mars–van Krevelen type reactions. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The comprehensive kinetic study for CuCl2/γ-Al2O3-based catalysts was performed to elucidate the co-promoter effect in the ethylene oxychlorination, one of the most significant industrial processes to produce vinyl chloride monomer. Kinetic analysis was performed separately by transient kinetic studies, taking account of the reduction and oxidation steps in the catalytic cycle. The promoter effects on ethylene oxychlorination were ascribed to their influence on the Cu2+ reduction or Cu+ oxidation in the catalytic cycle. The reaction rate-diagram was gained and used to predict the steady-state reaction rate and Cu oxidation state by an operando setup combing MS and UV–vis-NIR spectroscopy. The results indicated that the K-doped catalyst could greatly increase the reaction rate of the oxidation step, which gave rise to higher Cu2+ concentration on the catalyst. Mg-doped catalyst had a great effect on enhancing the reaction rate for the reduction step. K and Mg co-doped catalyst had the dual effect, both the reaction rate and Cu oxidation state were located between K and Mg mono-doped catalyst. The results of steady-state reactions indicated that the reaction rates were quite close with that predicated by the rate-diagram. Byproduct analysis during the steady-state was also performed, the results demonstrated that the co-promoted catalysts can also reduce the byproduct formation. The current study is expected to provide one way for exploring the potential benefits of co-promotion on CuCl2/γ-Al2O3-based industrial oxychlorination catalysts to improve the catalytic performance and understand the reaction further.

Alumina-supported copper chloride serves as an industrial catalyst for ethylene oxychlorination, resulting from its high activity and selectivity. A better understanding of the detailed active site structure and reaction mechanism is highly desired. The present work aims to explore the dependence of the structure of active sites and the adsorption of ethylene on differently sized (CuCl2)n (n = 1–4) clusters supported by γ-Al2O3. The effect of the support facets (i.e., (110) and (100) surfaces) on the interface structures between the active component CuCl2 and the support was also investigated. The stronger CuCl2–support interaction was found on the (110) surface compared to the (100) surface, which is attributed to the stronger Lewis acidity of Al of the (110) surface. The adsorption strength of (CuCl2)n) (n = 1–4) clusters becomes weak with the increment of cluster size on the (110) surface. The cluster size has a profound influence on the interaction between ethylene and the clusters. Ethylene binds to a copper atom on the small clusters (i.e., CuCl2 and (CuCl2)2), while it extracts two chlorine atoms to form dichloroethane from the large clusters (i.e., (CuCl2)3 and (CuCl2)4), which explains the high activity of catalysts with high loadings upon exposure to ethylene. The effects of cluster size and alumina facets on the short d-band center and the Bader charge of the active sites result in the distinct formation energy of the chlorine vacancy and the interaction energy between C2H4 and the clusters. Thus, an improved catalyst could be achieved by the modification of the surface electronic structure via fine-tuning the support or adding promoters.

Fischer-Tropsch synthesis has been investigated over a commercial type cobalt-based catalyst (20 %Co/0.5 %Re/γ-Al2O3) by varying the H2/CO ratio (2.55–1.12), CO conversion (15–75 %), reaction temperature (210 °C, 230 °C), and by adding water to the syngas. The experiments were conducted in a fixed bed reactor with the main purpose of obtaining experimental data to be used in the development and fitting of a mechanistic model. A positive effect of water on the catalyst activity was found for experiments with a H2/CO ratio higher than 1.7. Water was found to always increase the C5+ selectivity regardless of the H2/CO ratio. Increasing conversion led to increased C5+ selectivity. The selectivity to CO2 was significantly enhanced at higher conversions (high water partial pressure), particularly with the lowest H2/CO = 1.12, interpreted as the emergence of water-gas shift activity. Re-oxidation of cobalt, probably limited to small cobalt particles, is proposed as the main deactivation mechanism caused by water while a steeper deactivation curve was found for higher temperature, indicating that sintering also may play a role. © 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Utilization of sustainable biomass to produce jet fuel range hydrocarbons is imperatively needed to mitigate CO2 emissions and to liberate the over-reliance on fossil resources. Using propanal as the feedstock, an excellent jet fuel range hydrocarbon yield (81.7%), high conversion (ca. 100%), and purity (85%) were achieved over a novel dual-bed Cu/SiO2–TiO2||Ni/ZSM-5 catalyst at low temperature and pressure in only one reactor. The intrinsic active site requirement was further investigated by multitechniques including density functional theory calculation, quantitative CO2/NH3-temperature-programmed desorption/diffuse reflectance infrared Fourier-transform spectroscopy, high-resolution transmission electron microscopy, and thermogravimetric analysis–mass spectrometry. Results showed that for the upstream bed catalyst (Cu/SiO2–TiO2), the Ti–O site pair and Ti Lewis acid site were crucial for enolate formation, carbon-chain growth, and ring closure reactions, which can be altered by the calcination temperature. The synergy between the site strength and number led to a volcanic relationship between acidity/basicity and the intermediate yield. In addition, the downstream bed Ni/HZSM-5 catalyst promoted the hydrodeoxygenation reaction toward hydrocarbon formation. Copyright © 2020 American Chemical Society. This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.

Hydrogen is highly demanded in biorefinery, and hydrogen production from renewable sources is essential to produce truly green transportation fuels from biomass. The present work demonstrates experimentally the production of high pressure H2 with high purity by pressure swing sorption enhanced steam reforming (PS-SESR) of the byproducts from biorefinery. Pure hydrogen was produced by one-pot high pressure sorption enhanced reforming of a mixture of acetic acid (AA), glycolaldehyde (Gl) and hydroxyacetone (Hy), as model of the byproducts obtained from biomass fast-hydropyrolysis, which is integrated in the H2Bioil process, aimed at producing liquid transportations fuels. SESR was performed using Pd/Ni-Co derived from a hydrotalcite-like material as catalyst and dolomite as CO2 acceptor. Both thermodynamic analysis and experimental study revealed enhanced hydrogen purity but lower hydrogen yield at high pressure compared to atmospheric pressure. Moreover, a compromise between pressure and temperature is needed to get high purity and yield of hydrogen. A H2 purity as high as 99.6 vol% can be obtained at atmospheric pressure and 550 °C, while a H2 purity of 99.0 vol% can be reached at 5 bar and 600 °C. Under these conditions, the H2 yield is of 92.3% at 1 bar and 92.6% at 5 bar. These results show that the SESR of the biomass-derived compounds is an efficient method for the production of highly pure, hot and high pressure hydrogen, which is required for the overall process studied. According to the thermodynamic analysis, and given that the process is performed at high pressure, a pressure swing decarbonation process is suggested for the sorbent regeneration.

Highlights • In middle Gangetic plains, high arsenic concentration is present in water, which causes a significant health risk. • Two bacterial isolates, AK1 (KY569423) and AK9 (KY569424) were isolated and characterised for Arsenic detoxification. • aoxR, aoxB and aoxC genes were also observed in the isolated starin which help in arsenic detoxification by oxidation method., In middle Gangetic plain, high arsenic concentration is present in water, which causes a significant health risk. Total 48 morphologically distinct arsenite resistant bacteria were isolated from middle Gangetic plain. The minimum inhibitory concentration (MIC) values of arsenite varied widely in the range 1–15 mM of the isolates. On the basis of their MIC, two isolates, AK1 (KY569423) and AK9 (KY569424) were selected. The analysis of the 16S rRNA gene sequence of selected isolates revealed that they are belong to the genus Pseudomonas. The AgNO3 test based microplate method revealed that isolates, AK1 and AK9, have potential in transformation of arsenic species. Further, the presence of aoxR, aoxB and aoxC genes in the both isolated strain AK1 and AK9 was confirmed, which play an important role in arsenic bioremediation by arsenite oxidation. Isolated strains also showed heavy metal resistance against Cr(IV), Ni(II), Co(II), Pb(II), Cu(II), Hg(II), Ag(I) and Cd(II).

The performance of CuCl 2 /Al 2 O 3 with and without La and K promoters, designated as Cu, K 0 . 23 Cu 0.77 , K 0.29 Cu 0.71 , La 0.29 Cu 0.71 and K 0.21 La 0.08 Cu 0.71 was studied in the ethylene oxychlorination at 503 K and 1 atm by in-situ UV–vis-spectroscopic kinetic study through a two-step approach. The effects of the dopants on the oxychlorination reaction were firstly deconvoluted to their influence on the Cu 2+ reduction and Cu 1+ oxidation in the redox catalyst cycle by transient kinetic study. It followed kinetic study using the rate diagram as well as the steady state kinetic study to investigate the effect of dopants on the steady state reaction rate and Cu 2+ contents. All dopants increased the fraction of reducible Cu 2+ for ethylene oxychlorination. The results demonstrate that La significantly increased the reactivity of the active sites towards the reduction step, whilst K increased the rate of oxidation of Cu 1+ . The co-promoted catalyst improved the site activity by 40.6% during the reduction step compared to the single doped K catalyst. The combined effect of La and K in K 0.21 La 0.08 Cu 0.71 substantially increased the oxidation of Cu 1+ . The kinetic study by the rate diagram from the transient kinetic data predicted a higher steady state rate and Cu 2+ content on co-doped catalysts K 0.21 La 0.08 Cu 0.71 . The steady state experiments confirm the high Cu 2+ content obtained, but a slightly higher reaction rate on K 0.21 La 0.08 Cu 0.71 compared to K 0 . 23 Cu 0.77 , due to a suppressing effect by La promoted strong adsorption of HCl. The current study is expected to pave the way for exploring the potential benefits of co-promotion on CuCl 2 /Al 2 O 3 based oxychlorination catalysts in order to enhance catalyst properties and performance. The rate diagram approach is a powerful tool for obtaining mechanistic insights and for guiding the design of co-doped oxychlorination catalysts.

Obtaining the comprehensive kinetics of elementary reaction steps in catalytic redox cycles remains a challenge. We report here an operando study by combined mass and UV–vis–NIR spectrometry to obtain kinetic data for reduction and oxidation steps in the catalytic cycle of ethylene oxychlorination on potassium-promoted CuCl 2 /Al 2 O 3 catalysts and understand the catalytic consequences of potassium promotion for ethylene oxychlorination through a comprehensive kinetic analysis of the catalytic cycle. The results demonstrate that the Cu 2+ and Cu 1+ concentration, the number of active sites, and the activity of the active sites are highly dynamic, depending on the catalyst composition and the operating conditions. A pseudo-steady-state approach was applied to deconvolute the effect of promoters on the oxychlorination reaction into the effects on the individual reduction and oxidation steps, as well as their consequences in steady state in terms of the active site number and the site activity. It has been found that the rate of oxidation of Cu 1+ by oxygen is much lower than the rate of reduction of Cu 2+ by ethylene at relatively high Cu 2+ content. This resulted in CuCl dominating at the surface and thus a low rate in the steady state on the neat CuCl 2 catalyst. Potassium promotion increased the reducible Cu 2+ content from 0.61 mol/mol Cu of the neat CuCl 2 catalyst to 0.8 mol/mol Cu by reducing the interaction between Cu and the alumina support. Further increasing the potassium loading from 0.92 to 1.54 wt.% decreases the reducible Cu 2+ from about 0.8 to 0.7 mol/mol Cu . Potassium promotion significantly increased the site activity of the Cu 1+ oxidation, but decreased the site activity of the Cu 2+ reduction by ethylene. The positive effect of potassium promotion is due to the increase in the number of Cu 2+ active sites, which was more significant than the negative impact on turnover frequency (TOF); thus, potassium promotion increased the steady-state reaction rate. In addition, owing to the kinetic balance between the higher Cu 1+ oxidation rate and the lower Cu 2+ reduction rate, potassium promotion yielded an increased Cu oxidation state with Cu 2+ dominating the steady-state catalyst surface. This led to remarkably improved stability of CuCl 2 catalysts.

A comprehensive understanding of the role of bimetallic alloys in surface steam reforming (SMR) reactions and carbon formation on real catalysts at an atomic level remains a challenge due to their different material properties and pressures. We report here a density functional theory (DFT) study and an experimental study of the effects of the surface composition of a Ni/Ag alloy on methane activation and steam methane reforming compared to those of a pure Ni catalyst. The Ni/Ag bimetallic catalyst demonstrates better surface alloying compared to other bimetallic catalysts, which is confirmed by X-ray photoelectron spectroscopy (XPS) and hydrogen chemisorption. The DFT calculation shows that Ag selectively substitutes for the more active Ni sites in the order Ni(211) > Ni(100) > Ni(111), so that the substitution of Ag on the Ni surface has a profound influence on the activities of the sites near Ag. These sites surrounding the Ag atom are inactive to C–H activation in the methane molecules, and Ag serves as a blocking agent to block the more active sites on the Ni nanoparticles, as suggested by both the kinetic and DFT studies. Furthermore, the study shows that the apparent activation energy increases with increasing fraction of Ag on the catalyst surface. A better understanding of the chemistry and catalytic consequence of surface alloying in SMR reactions is achieved by combining well-controlled surface alloying, detailed kinetic assessment and the DFT study. Thus, this approach provides the key to understanding the mechanism for suppressing carbon formation and is expected to have a significant implication on the general methods of SMR bimetallic catalyst design in order to have better activity and stability.

Siderophores (Gk iron carriers) are low molecular weight secondary metabolites produced by bacteria, fungi, and plants that have strong binding affinity for iron. Owing to their iron-chelating ability, they are produced mainly when the organism faces iron scarcity. The present study empirically investigated the importance of applying hydroxamate siderophore extracted from Aspergillus nidulans to the cells of Bacillus subtilis for bioremediation of cadmium salt. This investigation deals with siderophore-mediated intracellular Cd accumulation by bacterial cells, growth estimation, biochemical assays like lipid peroxidation, total protein content, carbohydrate content, and iron content estimation. In silico docking and STRING analyses revealed specific interaction between Aspergillus siderophore and receptors present on B. subtilis. Estimation of intracellular Cd by atomic absorption spectroscopy showed more accumulation of Cd ions by B. subtilis in the presence of hydroxamate siderophore. This suggests a possibility of confiscating environmental Cd2+ by utilizing metal chelation property of siderophores and hence can lead to emerging bioremediation mechanisms for heavy metals. In silico studies support experimental investigation and suggest higher affinity of siderophore for Cd ions as compared with ferric ions.

This study was aimed to assess soil nutrient status, heavy metal content, and their impact on phosphate solubilizing bacteria (PSB) as well as to determine relationship between PSB and coliform in soils of urban area of Patna town during monsoon and winter. The eight sampling areas are included for study namely Bazar Samiti (S1), Moin-ul-Haq Stadium (S2), Agamkuan (S3), Kumhrar (S4), Beur Jail (S5), Phulwari Sharif (S6), BIT Campus (S7), and Danapur (S8). Nutrients, such as carbon, phosphorus, and potassium, varied with seasons and sites. The average concentration of heavy metals for monsoon followed the order Mn > Zn > Co > Pb > Cu > Ni > Hg, while for winter the order was Mn > Zn > Pb > Co > Cu > Ni > Hg, whereas Cd was below detection limit (0.1 ppm) in all sites. To evaluate the degree of pollution in soils of Patna region contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), and pollution load index (PLI) were calculated. An elevated concentration of Mn and Zn was reported on most of the sites; however, PLI showed that soils have become polluted with heavy metals. In addition, enumeration of bacterial cells revealed that PSB grew efficiently in winter when pH (6 to 6.8) was low, which might be due to production of organic acids, and coliform count was moderate to low. The negative correlation between PSB and coliform in winter suggests that both the species are competitor of each other.

Gaya, a prominent city of Bihar (India) with rich cultural and religious significance has been susceptible to massive urbanization, population growth and pollution which have huge impact on its surface water bodies. The study was conducted on five major ponds of Gaya namely Bisar, Dighi, Vaitarni, Ramsagar and Suryakund. This paper attempts to evaluate their drinking and irrigational water quality status, trace metal contamination in water and sediments (except Suryakund), hydrogeochemical characterization and evolutionary trends and processes involved in the water chemistry. The WQI values (>130) revealed that the ponds are facing heavy pollution load and the water is not fit for drinking purposes; however, irrigational indices indicates that the water of these ponds is suitable for irrigational purposes. The ponds' water and sediments are heavily contaminated with trace metals particularly cobalt (CF and PI >17) and lead (CF>1.4 and PI>5) in sediments. The PCA and HCA were also performed to find the relevant sources, trends and groups in trace metal contamination in their water. The hydrogeochemical profile of surface water (Piper's plot, Durov's diagram, Gibbs diagram and IBE) indicated that they are of mixed water type with most abundant facies being Na–Ca–Mg–Cl, Ca–Na–Mg–Cl and Ca–Na–Mg–Cl–HCO3. SI values showed ponds to be oversaturated with Ca–Mg based minerals and dissolution of halite, magnesite and anhydrite indicating high degree of rock water interaction and reverse cation exchange process dominating the water chemistry. However extensive mixing of pollutants and dissolution has caused the overall geochemical character of water to change. The overall study shows that urbanization may further increase the rate of anthropogenic activities overtime which could enhance trace metal accumulation in the ponds and pose a serious health risk.

The promotion effect of Mo-addition to alumina-supported Mn-based sorbents for high-temperature desulphurization was explored. A series of Mn-based sorbents with fixed Mn-loading and different Mo-loadings were prepared by the wet impregnation method and both fresh and used sorbents were characterized with respect to their physical and chemical properties. The sorbents were active for H2S removal at 600 °C and could be regenerated by oxidation in diluted air. The sorbents were subjected to 10 repeated sorption/regeneration cycles, and some loss of capacity occurred during the cycles. The results show that Mo-addition promotes the Mn-based sulfur sorbent performance both in terms of capacity and stability. Over the range investigated (0–8 wt% Mo added to a 15 wt% Mn sorbent), the improvement increased with an increasing amount of Mo added. The sample with the highest Mo-addition (15Mn8Mo) also retained the capacity best, as over 90% of the capacity remained after 10 sorption-regeneration cycles, in spite of suffering the most from sintering (observed as loss in surface area, increased pore size, and growth in Mn particle size). Characterization of the fresh and used samples using XRD and Raman spectroscopy indicates that a mixed Mn–Mo oxide suggested to be MnMoO4 plays a role in the promotion mechanism. The sorbent, 15Mn8Mo, is suggested to be promising for high-temperature desulphurization of bio-syngas. This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In this study, we have developed a method to predict the steady-state rate and Cu oxidation state during ethylene oxychlorination from a reaction rate diagram of the individual steps involved in the catalytic oxychlorination cycle. The steady state of the redox cycle is represented by a cross point of the reaction rates of the reduction and oxidation steps as a function of the Cu2+ in the rate diagram. Transient kinetics of elementary reactions and steady-state kinetics of the overall catalytic cycle were investigated in an operando study using combined mass and UV–vis-NIR spectrophotometry. The catalytic consequence of the promoters was then evaluated in terms of reduction and oxidation activity as well as number of active sites, site activity, and the catalyst oxidation state at steady state. Results revealed that the neat CuCl2 catalysts operated at low Cu2+ at the steady-state conditions with stoichiometric feed composition, as a result of relatively low oxidation rate of Cu1+. As a consequence of a h...

Rice is one of the most important crops in India, and chlorophyll (Chl) and nitrogen (N) content of leaf serve as a significant indicator for monitoring crop status and precision farming. These biochemical parameters can be obtained from remote sensing data, but can have limitation on the precision of these parameters. In this aspect, near-proximal optical sensors placed in contact with the crop and can provide a rapid assessment of Chl content and N status. So, in this study, both satellite data and proximal sensors were used to estimate Chl content and N status of paddy in Sahibganj district in the state of Jharkhand (India). The key findings showed that multiple regression (MR) based models comprising RVI, NDVI, and EVI were more competent to estimate the Chl content and crop nitrogen status (CNS) with r-value of 0.72 and 0.77, respectively. Notably, the ratio vegetation index (RVI) based model was also promising with r-value of 0.69 and 0.74 for Chl and CNS estimation, respectively. It was noticed that the empirically derived Chl content and N status of paddy were in general hyped than the satellite-based estimates as represented by the root mean square error (RMSE) and mean absolute deviation (MAD).

The draft genome sequence of a novel strain, Pseudomonas sp. MR 02, a pyomelanin-producing bacterium isolated from the Mahananda River at Siliguri, West Bengal, India, is reported here. This strain has a genome size of 5.94 Mb, with an overall G+C content of 62.6%. The draft genome reports 5,799 genes (mean gene length, 923 bp), among which 5,503 are protein-coding genes, including the genes required for the catabolism of tyrosine or phenylalanine for the characteristic production of homogentisic acid (HGA). Excess HGA, on excretion, auto-oxidizes and polymerizes to form pyomelanin.

© 2018 Elsevier B.V. Solvent-free synthesis pathway for obtaining two imidazole derivatives (2-chloro-1-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole (CLMPDI) and 1-(4-bromophenyl)-2-chloro-4,5-dimethyl-1H-imidazole (BPCLDI) has been reported in this work, followed by detailed experimental and computational spectroscopic characterization and reactivity study. Spectroscopic methods encompassed IR, FT-Raman and NMR techniques, with the mutual comparison of experimentally and computationally obtained results at DFT/B3LYP level of theory. Reactivity study based on DFT calculations encompassed molecular orbitals analysis, followed by calculations of molecular electrostatic potential (MEP) and average local ionization energy (ALIE) values, Fukui functions and bond dissociation energies (BDE). Additionally, the stability of title molecules in water has been investigated via molecular dynamics (MD) simulations, while interactivity with aspulvinonedimethylallyl transferase protein has been evaluated by molecular docking procedure. CLMPDI compound showed antimicrobial activity against all four bacterial strain in both gram positive and gram negative bacteria while, BPCLDI showed only in gram positive bacteria, Staphylococcus Aureus (MTCC1144). The first order hyperpolarizability of CLMPDI and BPCLDI are 20.15 and 6.10 times that of the standard NLO material urea.

Here we provide new mechanistic and kinetic insights into the functions of oxides on Ni catalysts in methane dry reforming combining kinetic studies with density functional theory (DFT) calculations. Hydrotalcite derived Ni catalysts with a small amount of oxide additive (CeO2, ZrO2, ZnO) as promoters are synthesized and characterized by different techniques, X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 physisorption, H2 chemisorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis combined with mass spectrometry (TGA-MS). Regarding H2/CO ratio, the CeO2-Ni shows the highest the values along all the temperatures. Moreover, the CeO2-Ni catalyst has the best stability among the four catalysts, while ZnO-Ni experiences the most severe deactivation. Kinetic studies in terms of reaction orders and activation energies are performed and compared to the DFT investigations, to assess the functions of oxide promoters. The CeO2-Ni catalyst shows the lowest apparent activation energy for CO2 activation, and it is also found that forward turnover rate is independent of CO2 partial pressure for all the samples. In DFT calculations, CO2 is more favorable to be activated on the support and the TOF obtained from G plot is in perfect agreement with our experiment value. In addition, it is also found that basicity of oxide additives and electronegativity of metal element can be well correlated to the activation of CO2 and catalyst’s deactivation. In general, both the increased basicity of oxide and the decreased electronegativity of metal element help to promote the CO2 activation and enhance the catalyst’s stability. We propose that the CeO2-Ni catalyst has best performance for CO2 activation, thus leading to a higher surface oxygen concentration to oxidize the carbon on the catalysts, which prolongs the catalyst’s life.

The nature and distribution of lipid biomarkers (n-alkanes, n-alkanols, sterols and triterpenols) were investigated in five dated sediment cores from the Pichavaram mangrove–estuarine complex in order to: 1) identify the organic matter (OM) sources and its preservation and 2) trace recent changes associated with coastal processes and anthropogenic activities. The mangrove sediment extracts have higher biomarker concentration (22.6 ± 13.3 μg/g dry weight) than the estuarine extracts (6.42 ± 4.92 μg/g dry weight). Triterpenols are dominant biomarkers in both estuarine and mangrove sediments, and constitute > 50% of the total lipid extracts. The presence of n-alkanols (n-C26,28,30) and abundance of phytosterols (stigmasterol and β-sitosterol) and triterpenols (taraxerol, β-amyrin, germanicol, and lupeol) indicate that mangrove vegetation is the primary source of sedimentary OM. The high abundance and unimodal distribution of the long-chain n-alkanes (mainly n-C25,27,29), and high values of Terrestrial Aquatic Ratio (TAR 2.4 to 41) and Carbon Preference Index (CPI > 8) indicate dominance (and better preservation) of higher plant derived immature OM in mangrove sediments. In contrast, the weak dominance of high molecular weight n-alkanes, low CPI (0.75 to 0.90) and TAR (1.9 to 5.7) values, and the presence of high C27 and C28 sterols indicate that phytoplankton/algal derived OM is more pronounced in estuarine sediments. Diagenetic changes in sedimentary OM indicate that some of the lipid fractions are reactive, and as a result, they degrade more rapidly than bulk OM. These compounds follow first order decay kinetics, and concur with the downcore diagenetic changes in coastal areas. Resistance to degradation among the different lipid classes show the trend: n-alkane > sterol > triterpenol > n-alkanol. Finally, the study indicates that less freshwater discharge from the Coleroon River is causing a gradual change in mangrove vegetation. There is less input of OM derived from mangrove vegetation into recent sediments. Biomarker trends also indicate that less salt tolerant Rhizophora spp. are gradually replaced by more salt tolerant vegetation consisting of Sueda spp. and Aviccenia spp.

Objective: Certain anthraquinone compounds are effectively used for treatment of cancer. The present study describes the inhibitory activity of lac dye, a mixture of polyhydroxy anthraquinone compounds (Laccaic acid A, B, C, D and E), produced by the Indian lac insect, Kerria lacca (Kerr). Materials and Methods: In vitro testing for anticancer activity of lac dye was done at four concentrations (10, 20, 40, 80 μg/ml) on ten human malignant cell lines including six human leukemia cell lines, U973, Raji, K562, Jurkat, MOLT 4 and HL60 using SRB assay. Results and Conclusion: Both crimson and yellow lac dye inhibits proliferation of Human leukemia cell lines, Raji, U937, K562, HL60 and Jurkat, therefore can be considered as a potential anticancer agent for leukemia.

The knowledge about genetic origin of the chemi- cal elements is important for the evaluation of hydro- geochemistry of aquatic ecosystem. In the present study, pre- and post-monsoon samples were collected to identify the role of rain and seawater in the hydro-geochemical processes. Geochemical model and multivariate statistical methods of data analysis were jointly used to define the variations and the genetic origin of chemical parameters of water in man- grove ecosystem. The geochemical model, WATEQ4F, was executed to compute the saturation indices of the minerals with respect to surface water. The interpretation of the satura- tion indices for minerals shows that the majority of samples fall inthe categoryof under saturationstate exceptfor fluorite. An increase in the concentration of various nutrients, namely, nitrate and phosphate, was observed. Suitability of water was checked on the basis of chemical categorisationby Aquachem software. Grouping of waters on the Piper diagram suggested a common composition and origins. Further results showed that pre- and post-monsoon samples mainly consist of Na-Cl and Ca-Cl water type indicating a significant contribution of cations and anions from terrestrial and marine inputs in the mangrove ecosystem.

The functional role and commercial importance of insect pigments have been studied for well over a century. They are classified into those synthesized by insects, which include anthraquinones, aphins, pterins, tetrapyrroles, ommochromes, melanins and papiliochromes, and those sequestered from their host plants, the antioxidative carotenoids and water-soluble flavonoids. They can also be categorized into those that are produced by cyclization of linear precursors, e.g. anthraquinones, aphins and tetrapyrroles and those derived from cyclic precursors such as pterins, ommochromes, melanins and anthocyanins. Anthraquinones and aphins are derived by cyclization of linear polyketides via successive condensation of simple carboxylic acid metabolites and occur in two major Superfamilies of Hemiptera, the Coccoidea and Aphidoidae, respectively. Ommochromes, tetrapyrroles and melanins are derived from different amino acid precursors, tryptophan, glycine and tyrosine, respectively. Apart from providing body colouration, ommochromes are visual pigments, melanins act as a protectant against UV and tetrapyrroles facilitate oxygen transport to cells. Papiliochromes are synthesized using both, the essential amino acids tyrosine and tryptophan. Pterins are derived from guanosine triphosphate (GTP) and are also present in ommatidia of eyes. The sequestered pigments, anthocyanins and carotenoids, are synthesized from phenylalanine and by condensation of two isoprene units, respectively, in plants. The biosyntheses of chemochromes in insects are governed by a complex set of enzymes, pathways and genetics. This review provides a comprehensive understanding of the molecules that are not only responsible for the striking colours but also provide functional benefits for insects. The commercially important pigments are also discussed.

This article describes the reactive kinetics of Ca-based synthetic sorbent composed of 25 wt.% mayenite ( Ca 12 Al 14 O 33 ) and CaO with CO 2 at temperatures of 1023 K for multiple cycles. The carbonation reaction is a gas–solid reaction system, which generally follows one out of two controlled regimes, namely the kinetic- and product layer diffusion (PLD) controlled regimes. A mathematical model based on the grain model was applied modelling the carbonation reaction. The CO 2 capture properties of Ca-based synthetic sorbent were studied in both TGA (thermogravimetric analysis) and fixed bed reactor. Experimental results show that there is considerable effect of the diffusional limitation in the fixed bed reactor in comparison to the TGA study. A large bypass in the conventional TGA could limit its application in kinetic study. Compared to TGA, a fixed bed reactor has well controlled contact between the gas–solid acceptors and being influenced by numerous of factors. Hence, it is found that the fixed bed reactor is a better tool for kinetic study of the carbonation reaction. The mass based pellet model formulated for the sorption process describes the evolution of species mole fractions, pressure, total concentration, temperature, fluxes, and convection within the voids of the porous pellet. The internal effectiveness factors of the carbonation reaction has been calculated for the sorption process. The change in pellet void-fraction due to the formation of the solid CaCO 3 , the diffusion of the gaseous phase through the product layer, and the structural changes of the spherical grains by the inclusion of a variable diffusion coefficient were considered in the pellet model. The nature of the gas–solid reaction system elucidated by the effectiveness factor graph, i.e., the gas–solid reaction system occurs in two different stages: kinetic- and product layer diffusion controlled stages. Hence, by neglecting the product layer diffusion controlled stage for the carbonation reaction might lead to false estimation of concentration profile. Therefore, both the kinetic- and product layer diffusion controlled stages should consider for modelling of the carbonation reaction system.