Search

In the current study, the biogas production was carried out by using a semi-continuous stirring tank reactor (CSTR). Consequently, the producer biogas was scrubbed/enriched by the combination of three steps of scrubbing (H2S scrubber, packed column water scrubber (PCWS), and activated charcoal scrubber (CS)). In PCWS, the static water scrubbing (SWS) and flowing water scrubbing (FWS) techniques were employed. In SWS, the biogas was scrubbed at a defined water level for a defined time while in FWS, the biogas was scrubbed at different water/gas (w/g) flow rates. In case of SWS, removal of was up to 95% H2S removal, removal of was up to 89% CO2 removal and 97% methane refinement was achieved. While for FWS, 97% removal of H2S, 90% removal of CO2 and 97% methane refinement was achieved. Both processes proved remarkable impacts on methane refinement but FWS was found more practical because CO2 was found more soluble in flowing water as compared with static water scrubbing.

In this study, Ce0.85-xLa0.15CaxO2-δ was synthesized using sol-gel combustion method and appliedfor partial oxidation of methane (POM). The physicochemical properties of catalyst were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). Material shows a pure cubical structure and is highly stable up to 850 °C. The performance testing indicated the conversion of CH4 is 65% and selectivity of H2 and CO are 28% and 8%, respectively. The performance indicated the catalyst has a potential to be used for partial oxidation of methane on a larger scale. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

In this study, metallic copper (Cu) nanowires are synthesized by reducing thermally synthesized CuO nanowires under an indigenously developed hydrogen plasma system. The X-ray diffraction (XRD) results of the plasma-synthesized nanowires indicate the presence of metallic copper [(111) and (200)] and the field emission scanning electron microscopy (FESEM) further affirms the findings by presenting a stark difference in contrast of the nanowires before and after plasma treatment with diameters of 50 and 100 nm, respectively. The nanowires are studied for hydrogen evolution reaction in a neutral medium and they show excellent performance than the previously reported studies on bulk copper, with an overpotential of 210 mV at a current density of 10 mA/cm2 and an exchange current density of 60 exp-5 A/cm2 which is an order of magnitude larger than the reported values on bulk copper. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy indicates that the surface of the nanowires is highly rich in metallic copper resulting in better electrochemical performance of the metallic Cu nanowires in a neutral environment.

The catalyst has a significant role in gas processing applications such as reforming technologies for H2 and syngas production. The stable catalyst is requisite for any industrial catalysis application to make it commercially viable. Several methods are employed to synthesize the catalysts. However, there is still a challenge to achieve a controlled morphology and pure catalyst which majorly influences the catalytic activity in reforming applications. The conventional methods are expansive, and the removal of the impurities are major challenges. Nevertheless, it is not straightforward to achieve the desired structure and stability. Therefore, significant interest has been developed on the advanced techniques to take control of the physicochemical properties of the catalyst through non-thermal plasma (NTP) techniques. In this review, the systematic evolution of the catalyst synthesis using NTP technique is elucidated. The emerging DBD plasma to synthesized and effective surface treatment is reviewed. DBD plasma synthesized catalyst performance in reforming application for H2 and syngas production is summarised. Furthermore, the status of DBD plasma for catalyst synthesis and proposed future avenues to design environmentally suitable and cost-effective synthesis techniques are discussed.

The excess emission of greenhouse gases (GHGs) such as CO2 and CH4 is posing an acute threat to the environment, and efficient ways are being sought to utilize GHGs to produce syngas (H2, CO) and lighter hydrocarbons (HCs). In this study, the dry reforming of methane (DRM) has been carried out at 700 °C using La2O3 co-supported Ni/MgAl2O4 nano-catalyst in a fixed bed thermal reactor. The catalyst is characterized using various techniques such as XRD, FESEM, EDX-mapping, CO2-TPD, H2-TPR and TGA. The modified MgAl2O4 shows the flake type structure after the addition of La2O3. The TPR and TPD analysis shows the highly dispersed metal and strong basic nature of the catalyst consequently enhances the conversion of CO2 and CH4. The highest conversion for CH4 is 87.3% while CO2 conversion is nearly 89.5% in 20 h of operation time. The selectivity of H2 and CO approached 50% making the H2/CO ratio above unity. In the longer time-on-stream (TOS) test, the catalyst shows elevated potential for longer runs showcasing better catalytic activity. The stability of the catalyst is indicated via a proposed reaction mechanism for DRM in operating conditions. Moreover, TGA indicates the lower weight loss of spent catalyst which ascribed the lower formation of carbon during TOS 20 h.

This chapter discusses charge transfer and transportation in energy materials and devices, especially focusing on single layer or electrolyte-free fuel cells (EFFCs). Here, charge means electrons a ...

Nondestructive characterization of solid oxide fuel cell (SOFC) materials has drawn attention owing to the advances in instrumentation that enable in situ characterization during high-temperature cell operation. X-ray photoelectron spectroscopy (XPS) is widely used to investigate the surface of SOFC cathode materials because of its excellent chemical specificity and surface sensitivity. The XPS can be used to analyze the elemental composition and oxidation state of cathode layers from the surface to a depth of approximately 5–10 nm. Any change in the chemical state of the SOFC cathode at the surface affects the migration of oxygen ions to the cathode/electrolyte interface via the cathode layer and causes performance degradation. The objective of this article is to provide a comprehensive review of the adoption of XPS for the characterization of SOFC cathode materials to understand its degradation mechanism in absolute terms. The use of XPS to confirm the chemical stability at the interface and the enrichment of cations on the surface is reviewed. Finally, the strategies adopted to improve the structural stability and electrochemical performance of the LSCF cathode are also discussed.

An evaluation of pollution level has been done for drinking water which is used in Kirkuk city by heavy metals ( As,Cd,Cu,Fe,Mn,Ni,Zn,Cr,Pb) samples were collected during wet and dry of 2016-2017 from Kirkuk unified water supplied project (WTP) which is supply the city with drinking water, as well as from water of tanks type (GST2), and also from (tap water) (Zone3). The results showed the concentration of the (As,Cd,Cu,Fe,Mn,Ni,Zn,Cr,Pb)inppbfor (WTP)are (0.5,0.6,6.45,38,4.6,2.5,6537,0.58,1.4) (0.6,0.8,6.76,46,5.5,3.5,6675,1,2.4) for (GST) (0.5,0.63,6.46,52.3,4.4,3.6,6550,0.6,2.5) (0.60,0.7,6.78,63.7,6.7,3.7,6680,1.1,2.6) and for tap water are (0.53,0.65,7.00,60.2,4.4,3.65,7200,0.8,2.7) (0.60, 0.71, 7.10, 67.6, 6.8,3.75,7320,0.9,2.75) for two seasons respectively the concentrations are within the allowed limits by WHO just Zn is exceed the allowed limits . the level of health risks were also assessed by using a number of indices (HQ)ing, (HQ) derm, (HI), (CR) ing (CR) derm for adult and children and for two seasons . (HI) value for Zn show health risks this high value of (HI) for Zn make water undrinkable.

This study mainly aimed to elucidate the effects of strontium co-doping on the structural, optical, and electrical properties of erbium-doped ceria (Ce0.8Er0.2O2-δ). Ce1-x-yErxSryO2-δ co-doped electrolytes were synthesized through sol–gel-assisted citric acid–nitrate combustion technique and sintered at 1500 °C for 6 h. X-ray diffraction results confirmed that the sintered electrolytes possessed a cubic fluorite crystal structure. However, a perovskite secondary phase (SrCeO3) was observed in Ce0.8Er0.125Sr0.075O2-δ co-doped composition due to the low solubility limit of strontium (~5 mol%) in ceria. UV–Vis spectroscopy showed that the co-doping of strontium from 0 mol% to 7.5 mol% increased the direct band gap from 3.41 eV to 3.43 eV. The relative densities and the grain size were in the range of 96.02–97.68% and 1.5–3.28 µm, respectively, with increasing the strontium content from 0 mol% to 7.5 mol%. Electrochemical impedance spectroscopy showed that the total resistance of Ce0.8Er0.2O2-δ increased as the strontium content increased. Singly doped Ce0.8Er0.2O2-δ electrolyte exhibited the highest ionic conductivity of 18.22 mS/cm at 700 °C and the lowest activation energy of 0.55 eV within 600–800 °C among all other studied electrolytes.

The effect of current collecting layer (CCL) and cathode functional layer (CFL) thicknesses on the catalytic activity of the La0.6Sr0.4Co0.2Fe0.8O3-δ-Ce0.8Sm0.2O1.9 (LSCF-SDC) composite cathode was investigated by electrochemical impedance spectroscopy at 600 °C for 100 h. Results revealed that the charge transfer process associated with the incorporation of O2− ions and the surface oxygen reduction reaction rate are dependent on CFL and CCL thicknesses, respectively. Area-specific resistance is dependent on CCL thickness in high-frequency arcs and on CFL thickness in low-frequency arcs. No significant change was observed in area-specific resistance value as the thickness of LSCF CCL decreased (25–5 μm) while the LSCF-SDC CFL thickness (5-25 μm) was gradually increased. However, the LSCF-SDC composite cathode (without CCL) showed poor catalytic activity toward the oxygen reduction reaction and had a high area-specific resistance value (3.31 Ω cm2). When LSCF CCL (5 μm) was used, the area-specific resistance value decreased by 16 times relative to the ASR of a sample without CCL. The field emission scanning electron microscopy results indicated that these cathodes exhibited a clear change in microstructure on the surface of the LSCF CCL after 100 h of thermal treatment in oxygen. The particle agglomeration and Sr surface segregation affected the surface catalytic activity toward oxygen reduction reaction at the LSCF CCL. As a result, the ASR value increased gradually in 100 h thermal treatment.

Three different series of doped ceria-based composite electrolyte consisting of M-doped ceria (M = Ce0.85Er0.15O2-δ (ErDC), Ce0.85La0.15O2-δ (LaDC) and Ce0.95Sr0.05O2-δ (SrDC)) and ternary carbonate (mixture of Li2CO3, Na2CO3 and K2CO3) were developed as functional solid electrolytes for low-temperature solid oxide fuel cells. X-ray diffraction, transmission electron microscopy and UV–visible spectroscopy were used to analyze the chemical stability, morphology, and bandgap, respectively, of the prepared composite powders. All composite electrolytes exhibited cubic fluorite structure as a primary phase and small peaks corresponding to (Li/Na/K)2CO3 as an amorphous phase. The bulk densities of the sintered composite electrolyte pellets were in the range of 3.34 g/cm3–3.45 g/cm3. The total conductivity of the composite electrolyte materials was evaluated by electrochemical impedance spectroscopy in air and hydrogen (90 vol% N2 + 10 vol% H2) in the temperature range of 350 oC–650 °C. The SrDC-ternary carbonate composite electrolyte showed the highest conductivity of 0.092 Scm−1 and lowest activation energy at 650 °C in hydrogen. The formation of hydrated phase from chemical interaction between the carbonates and hydrogen gas and the presence of Sr2+ and cerium ions is useful in enhancing the proton conduction in the SrDC-ternary carbonate system.

Pakistan appeared on the globe of the world as an independent country in 1947 after the British rule ended in India. At the time of independence, Pakistan inherited an educational system that was launched by a foreign government before hundred years ago. This system was established on economic, cultural, social, and political notions that were totally dissimilar from the ideologies of independent nations. During the colonial period, specific development in the education system has been observed. However, this development was mostly restricted to Indian areas. The areas consisted of Pakistan were surprisingly backward in all fields as well as in education. 85% of the population of Pakistan was illiterate at the time of independence. The literacy rate was much low in underdeveloped regions such as Baluchistan and the share of rural women in literacy rate was almost zero. A reviewing study of the history of educational planning and policymaking in Pakistan during the period of 1947 to 1980 was commenced which demonstrates that fixing of goals and targets, unsuccessfulness in the achievement of these goals, and fixing of new tasks with demonstrative willingness is an ongoing activity. The policymakers have been playing this game on countless public expenses from the past more than 70 years. Different forms of governments whether military or civilians, socialist or Islamic, elected or otherwise have done slight alterations in the style of playing of this game. The outcomes have been similar in all instances. The purpose of the study is to learn the salient features of educational planning and policies in Pakistan from 1947 to 1980. The analysis shows the lack of political commitment towards education or literacy. This paper recommends that the targets of educational policies can be acquired through the implementation of a proper mechanism for the execution and constant monitoring of these policies.

In this study preparation and characterization of four biomass pellets i.e. bamboo leaf, mustard straw, rice husk and wood mix were carried out with cow dung that is considered to be a potential binder to improve the physicochemical properties of pellets. Initially the samples were dried at 105°C to remove moisture content up to 15% and then pellets were prepared using biomass and cow dung in 1:1. The samples were characterized using FT-IR, compressive strength and TGA analysis during which their compositional, mechanical, thermal and physicochemical properties were analyzed. The energy density of biomass pellets was also calculated. Bamboo leaf being the promising candidate exhibited improved properties compared to other biomass pellets with maximum compressive strength of 11.6MPa and energy density of 19434.8 MJ/m3 along with enhanced structural properties. Whereas wood mix indicated the least compressive strength i.e. 3.73MPa but highest energy density i.e. 20456.5 MJ/m3 and good thermal characteristics. The lignin content present in cow dung is one of the main sources that makes it good biofuel. The experimental results revealed that cow dung is a most suitable binder as it is abundantly available and also increases the durability of biomass pellets comparative to other binders used in different studies.

The performance of solid oxide fuel cells (SOFCs) is significantly affected by the properties of its components which are electrolyte, electrodes (cathode and anode) and interconnect. Among the components, cathode is considered as the most critical component as high cathode polarization resistance (Rp) contributes to a major loss in SOFC performance. Thus, developing of good materials as cathode has been attempted to cater the problem. The development of cathode materials for SOFCs started with pure electronic conductor. This type of cathode materials provides limited electrochemical reaction sites, resulting in high Rp. Next, mixed ionic-electronic conductor (MIEC) cathode materials have been developed and followed by composite cathode materials. Both types of cathode materials are better than pure electronic conductor as they provide larger electrochemical reaction sites. However, some of them still resulting in high Rp especially at operating temperatures ranging from 400 °C to 800 °C. Then, the current researches are devoted to develop triple-conducting (H+/O2-/e-) oxide (TCO) cathode materials. This type of cathode materials is particularly useful for proton-conducting SOFC application. Therefore, this paper aims to provide a short review on the properties and performance of the TCO cathode materials along with the factors influencing its properties and performance.

Perovskite-based composite cathodes, La0.6Sr0.4Co0.2Fe0.8O3-&delta, (LSCF)&ndash, Ce0.8Sm0.2O1.9-carbonate (SDCC), were investigated as cathode materials for low-temperature solid-oxide fuel cells. The LSCF was mixed with the SDC&ndash, carbonate (SDCC) composite electrolyte at different weight percentages (i.e., 30, 40, and 50 wt %) to prepare the LSCF&ndash, SDCC composite cathode. The effect of SDCC composite electrolyte content on the diffraction pattern, microstructure, specific surface area, and electrochemical performances of the LSCF&ndash, SDCC composite cathode were evaluated. The XRD pattern revealed that the SDCC phase diffraction peaks vary according to its increasing addition to the system. The introduction of SDCCs within the composite cathode did not change the LSCF phase structure and its specific surface area. However, the electrical performance of the realized cell drastically changed with the increase of the SDCC content in the LSCF microstructure. This drastic change can be ascribed to the poor in-plane electronic conduction at the surface of the LSCF cathode layer due to the presence of the insulating phase of SDC and molten carbonate. Among the cathodes investigated, LSCF&ndash, 30SDCC showed the best cell performance, exhibiting a power density value of 60.3&ndash, 75.4 mW/cm2 at 600 &deg, C to 650 &deg, C.

This study examined the effects of samarium and erbium co-doping on the structural, optical, and electrical properties of ceria (CeO 2 ). Ceramic (Ce 0.8 Sm 0 .2- x Er x O 2- δ ; x = 0, 0.05, 0.10, 0.15, 0.20) electrolytes were synthesized via sol-gel assisted citric acid–nitrate combustion and calcined at 850 °C for 5 h. The calcined electrolytes possessed a cubic fluorite crystal structure without impure phases. The direct band gap of the calcined electrolytes increased as the erbium content increased and the lowest band gap was obtained for Ce 0.8 Sm 0.2 O 2- δ (SDC) electrolyte. The calcined electrolyte powders were subsequently pressed into cylindrical pellets by uniaxial die pressing, and the pellets were sintered at 1400 °C for 5 h. The sintered densities of the pellets were measured with Archimedes’ method. The relative density of Ce 0.8 Sm 0.1 Er 0.1 O 2- δ co-doped ceria electrolyte was higher than those of singly doped ones, and these findings were further confirmed through field emission scanning electron microscopy. Electrochemical impedance spectroscopy indicated that the conductivity of erbium-doped ceria increased as the samarium content increased. The maximum total ionic conductivity was observed in Ce 0.8 Sm 0.1 Er 0.1 O 2- δ co-doped electrolyte. However, the singly doped SDC electrolyte exhibited the highest ionic conductivity of 13.12 mS/cm and the lowest activation energy of 0.580 eV at 600 °C among all other Ce 0.8 Sm 0 .2- x Er x O 2- δ co-doped ceria electrolytes.

La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) is a mixed ionic electronic conductor with excellent surface catalytic activity for oxygen reduction. This work demonstrated that introduction of pure oxygen ion conductor to LSCF particles can significantly influence in-plane electronic conduction at the surface of LSCF-samarium-doped ceria (SDC) composite. The composite functional layer was prepared by mixing 50 wt% SDC particles with LSCF particles obtained from glycine–nitrate process. Homogeneous LSCF-SDC composite layer deposited by screen printing on an SDC substrate has been studied with and without LSCF current-collecting layer (CCL). The microstructural, optical, Raman, mechanical and electrical properties, and interfacial polarization resistance ( R p ) of the prepared powders were evaluated. Results revealed that addition of oxygen ion conductor SDC exerted negligible effect on the phase structure and specific surface area but significantly influenced the band gap, oxygen vacancies, and electrical conductivity of LSCF. SDC addition significantly increased area specific resistance (ASR) of LSCF from 0.138 Ω cm 2 to 0.481 Ω cm 2 at 800 °C, thereby blocking the conduction path among LSCF particles. R p value of LSCF-SDC composite can be improved by more than six times by enlarging the in-plane electronic conduction with thin CCL. Electrochemical measurement revealed that LSCF CCL reduced the R p value, resulting in the lowest ASR of 0.087 Ω cm 2 at 800 °C for the LSCF–SDC composite.

La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) is a perovskite-type oxide that exhibits excellent mixed ionic–electronic conducting properties and is a suitable cathode material for intermediate temperature solid oxide fuel cells. This study investigates the microstructural, optical, mechanical, and electrical properties of an LSCF–samarium-doped ceria (SDC) composite cathode. LSCF–SDC composite cathode powders were prepared by mixing 50 wt% SDC electrolyte with LSCF cathode powders obtained by the rotary evaporation technique. The band gap of the prepared powders was determined via diffuse reflectance UV–visible spectroscopy. The chemical composition, mechanical properties, and electrochemical properties of the sintered pellets were characterized using Raman spectroscopy, Vickers hardness, and impedance spectroscopy, respectively. X-ray diffraction and Rietveld analysis showed that phase purity was only 96%. Moreover, a small fraction of tetragonal phase impurity was observed on the LSCF powders. Impurities significantly affected the phase stability and microstructure of the LSCF–SDC composite cathode. The addition of the SDC electrolyte enhanced the densification of the composite cathode, thereby improving mechanical properties. However, the addition of SDC exerted different effects on the DC electrical conductivity and area-specific resistance (ASR) of the composite cathode. At 800 °C, the ASR value of the LSCF was only 2% that of the LSCF–SDC composite cathode. Overall, the electrical properties of the LSCF–SDC composite cathode are closely related to the crystal structure, purity, and microstructure of LSCF cathode powders.

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process.