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Sulfur and zinc substituted Co(OH)2 is synthesized by a simple co-precipitation one-step method followed by solvothermal treatment for oxygen evolution reaction. The high-resolution X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) demonstrates that the Zn and S substitution significantly stabilizes the layered structure and causes an increase in the electron density around the Co center. The role of both cation and anion substitution is evaluated to enhance the oxygen evolution reactions. This enhanced activity is due to the in-situ oxidation of divalent Co into trivalent Co, and partially due to the stabilization of the layered structure, as highlighted by PXRD and TEM analysis, the gap between the layers is slightly reduced from 7.8 A to 7.5 A, for S–Zn–Co(OH)2. The in-situ conversion of Co2+ to Co3+ during electrocatalysis improved the OER electrocatalysis. The structural and physical characterizations are performed via XRD, EDX, SEM, TEM, XPS, AFM and BET.

In the scope of the rapid technological advancements, nanoparticles (NPs) have gained prominence due to their excellent and tunable biological, and physicochemical properties. Nowadays, different methods are used for their synthesis. In particular, the green synthesis of metal precursors for the synthesis of NPs, represents a cost-effective, environmentally friendly, and hazardous chemical-free method for developing a large variety of NPs. By exploiting plant extracts, the production rate of NPs is relatively faster. Due to fossil reserves and high fuel consumption, renewable and clean energy materials are urgently needed to improve environmental sustainability. With outstanding electrochemical and physicochemical characteristics, molybdenum-based NPs (Mo-NPs) are gaining increasing attention in the fields of energy conversion and storage. Considering the significance of Mo-NPs synthesized from greener routes and their energy applications, it is necessary to review recent trends and developments in this field. This review summarizes important research studies and future research guidelines for the preparation of Mo-NPs through green routes and their applications to meet global energy and environmental demands. Moreover, future research directions are also highlighted to achieve sustainable greener precursors and Mo-NPs based energy storage devices.

The process parameters for dry reforming of methane (DRM) over Ni–W/Al2O3–MgO catalyst are optimized using response surface methodology (RSM). The Ni–W bimetallic catalyst is synthesized by co-precipitation method followed by impregnation. The catalysts are characterized by BET, XRD, FESEM, EDX and TEM; to study physicochemical properties, morphology, composition, crystallite size and deposited carbon. The effect of process parameters, i.e., reaction temperature (600oC–800 °C) and feed gas ratio (0.5–1.5) on the CH4, CO2 conversions and syngas ratio are studied. A temperature of 777.29 °C with CH4: CO2 of 1.11 at GHSV of 36,000 cm3gm.cat−1h−1, delivered the CH4 and CO2 conversions of 87.6% and 93.3%, respectively along with H2:CO of 1. The predicted process parameters were verified through actual experimental analysis at the optimized conditions, and results agreed with CCD of the RSM model with insignificant error. The MWCNT formed during DRM avoided catalyst deactivation and delivered stable performance over 12 h of reaction test at the optimized conditions.

During the last few decades, the global energy requirement is soaring significantly due to the rise of global population and economic development. This resulted in colossal release of CO2 and CH4, emissions into the atmosphere referred as greenhouse gases (GHGs), which poses a detrimental effects for the environment. One of the sustainable solutions to curb emissions of GHGs into the atmosphere is efficient utilization of syngas in order to produce useful chemicals and fuels. A comprehensive review is presented to highlight the capability of Ni-based catalysts in methane reforming through the application of both steam and dry routes referred to as bi-reforming of methane (BRM). Ni-based catalysts were found to support favorable reaction activity as they are cheaper than many exorbitant catalysts. The metal used for catalyst support exhibits higher stability and thermal resistance with improved resistance to coke formation. This review entails recent progresses in the development of Ni-based catalysts along with physical and kinetic aspects of the BRM process.

DMR is a promising technique to utilize the rising greenhouse gases and produce an alternative energy source. The main hurdle in the commercialization of DMR is the catalyst deactivation. Presently, the effect of Tungsten (W) addition on Ni-based catalysts supported on mixed oxide (Al2O3–MgO) support is tested for DMR. The Ni–W bimetallic catalysts are synthesized via co-precipitation followed by the impregnation technique. An equimolar stream of feed (CH4:CO2) is used for DMR at 800 °C. The Ni–W catalyst with 4 wt% of W showed steady performance with elevated conversions of CH4 and CO2, even after 24 h of DMR. The freshly and spent catalysts are characterized by BET, XRD, FESEM, EDX, elemental mapping, TPR-H2, TPD-CO2, and XPS to confirm the elemental composition and the type of carbon formed on the catalysts. The activity of Ni catalyst declined due to formation of amorphous carbon-nanosheets, whereas Ni–W catalyst remained active due to formation of MWCNT.

Running dry reforming of methane (DRM) reaction at low-temperature is highly regarded to increase thermal efficiency. However, the process requires a robust catalyst that has a strong ability to activate both CH4 and CO2 as well as strong resistance against deactivation at the reaction conditions. Thus, this paper examines the prospect of DRM reaction at low temperature (400–600 °C) over CeO2–MgO supported Nickel (Ni/CeO2–MgO) catalysts. The catalysts were synthesized and characterized by XRD, N2 adsorption/desorption, FE-SEM, H2-TPR, and TPD-CO2 methods. The results revealed that Ni/CeO2–MgO catalysts possess suitable BET specific surface, pore volume, reducibility and basic sites, typical of heterogeneous catalysts required for DRM reaction. Remarkably, the activity of the catalysts at lower temperature reaction indicates the workability of the catalysts to activate both CH4 and CO2 at 400 °C. Increasing Ni loading and reaction temperature has gradually increased CH4 conversion. 20 wt% Ni/CeO2–MgO catalyst, CH4 conversion reached 17% at 400 °C while at 900 °C it was 97.6% with considerable stability during the time on stream. Whereas, CO2 conversions were 18.4% and 98.9% at 400 °C and 900 °C, respectively. Additionally, a higher CO2 conversion was obtained over the catalysts with 15 wt% Ni content when the temperature was higher than 600 °C. This is because of the balance between a high number of Ni active sites and high basicity. The characterization of the used catalyst by TGA, FE-SEM and Raman Spectroscopy confirmed the presence of amorphous carbon at lower temperature reaction and carbon nanotubes at higher temperature.

This study is an effort to comprehend the description of the vapour-liquid flows associated with the transformation of the phase, which may assist in determining mass, momentum and energy transfer within the interfacial region containing the steam and water. This study describes the development of a void fraction measurement sensory system, which is based on AC based electrodes, referred scientifically as Electrical Resistance Tomography (ERT) system. ERT sensors based system was applied to emphasize the phenomenon involving supersonic steam injection into a column of water. Data acquisition system supporting the ERT technique was applied for the given time interval and the acquired data was processed by using a free code known as EIDORS. Images thus obtained by use of EIDORS provided a planar picture of supersonic steam jet surrounding by the water in a vessel. Images represent the broadly visible boundaries among steam and water phases, and the turbulent interface between them. It has been found that with rising temperature 30–60°C, the area under the effect of the steam jet has been increased from 46.51–65.40% at 3.0 bar of steam’s inlet pressure.

Natural gas (NG) requires treatment to eliminate sulphur compounds and acid gases, including carbon dioxide (CO2) and hydrogen sulphide (H2S), to ensure that it meets the sale and transportation specifications. Depending on the region the gas is obtained from, the concentrations of acid gases could reach up to 90%. Different technologies are available to capture CO2 and H2S from NG and absorb them with chemical or physical solvents; occasionally, a mixture of physical and chemical solvents is employed to achieve the desired results. Nonetheless, chemical absorption is the most reliable and utilised technology worldwide. Unfortunately, the high energy demand for solvent regeneration in stripping columns presents an obstacle. Consequently, the present study proposes a novel, ternary-hybrid mixture of N-methyl diethanolamine (MDEA), amino ethyl ethanol amine (AEEA), and N-methyl 2-pyrrolidone (NMP) to overcome the issue and reduce the reboiler duty. The study employed high levels of CO2 (45%) and H2S (1%) as the base case, while the simulation was performed with the Aspen HYSYS® V12.1 software to evaluate different parameters that affect the reboiler duty in the acid gas removal unit (AGRU). The simulation was first validated, and the parameters recorded errors below 5%. As the temperature increased from 35 °C to 70 °C, the molar flow of the CO2 and H2S in sweet gas also rose. Nevertheless, the pressure demonstrated an opposite trend, where elevating the pressure from 1000 kPa to 8000 kPa diminished the molar flow of acid gases in the sweet gas. Furthermore, a lower flow rate was required to achieve the desired specification of sweet gas using a ternary-hybrid blend, due to the presence of a higher physical solvent concentration in the hybrid solvent, thus necessitating 64.2% and 76.8%, respectively, less reboiler energy than the MDEA and MDEA + AEEA.

The injection of steam into the water or saline involve intermittent wave structures that can affect the mass and heat transfer within fluid domain. It may be analogous to the processes prevailed i...

Bi-reforming of methane (BRM) is gaining an increase interest due to the critical requirements to mitigate global warming and provide alternative energy resources. However, there has been a serious challenge to the scale-up of the process to commercial production due to the catalyst deactivation. In the present study, the influence of ZrO2 modifications on the activity and stability of MgO-supported Ni catalyst in the BRM reaction was investigated. The ZrO2-MgO mixed oxide support was prepared by co-precipitation method with variation in the ZrO2 composition and subsequently impregnated with Ni. The characterization of the freshly prepared Ni/MgO and Ni/MgO-ZrO2 catalysts using N2 physisorption analysis, X-Ray Diffraction (XRD), FESEM, XPS, H2-TPR, and CO2-TPD techniques revealed suitable physicochemical properties for the BRM reaction. The Ni/MgO-ZrO2 catalysts showed an improved performance in the BRM reaction in terms of activity and stability compared to the Ni/MgO at 800°C and CH4, H2O, CO2 ratio of 3:2:1, respectively. The best performance was obtained using the Ni/15%ZrO2-MgO for the BRM with CO2 and CH4 conversion of 81.5% and 82.5%, respectively. The characterization of the spent Ni/MgO catalyst using Raman spectroscopy, FESEM, and High Resolution Transmission Electron Microscopy (HRTEM) analysis revealed the formation of amorphous carbon that could be responsible for its fast deactivation.

Methane reforming with the application of combined H2O and CO2 is appropriately known as bi-reforming of methane (BRM). The method is promising because it has potential to deliver an alternative energy source and is effective in mitigating greenhouse gases (GHGs). In this study, Ni-based catalyst with 5 wt% supported Al2O3 and various Ca (2–4 wt%) loadings were prepared by following the wetness impregnation method. Characterization techniques, including Brunauer-Emmett-Teller (BET) and X-ray diffraction (XRD), were applied to observe prepared catalysts' structural morphology and physicochemical properties. Based on XRD analysis, the CaO-4wt% catalyst exhibited higher crystallinity than the CaO-2wt% catalyst, enabling it to withstand greater forces and take longer to deteriorate. To improve the catalyst activity, CaO was added as a promoter that altered the contact between Ni and Al2O3 and modified the properties of the catalysts for an excellent activity. A fixed-bed continuous reactor with a feed ratio CH4: CO2: H2O of 3:1:2 at 1073 K was used to observe the catalysts performance. BRM catalytic reaction at 800 °C having Ni-4CaO/Al2O3 catalyst, proved greatly in converting CH4 and CO2 with 79.6% and 87.2% respectively during the 6 h reaction.

The emission of greenhouse gases (GHGs), e.g. CO2 and CH4 into the atmosphere leads to an undesirable effect on climate change. One viable solution is to convert these two GHGs into valuable syngas via catalytic dry reforming of methane (DRM). Due to low-cost, feasibility, good catalytic activity, Ni-based catalysts have been used and tested extensively for DRM. However, the main limitation is the catalyst deactivation which occurs due to carbon formation and sintering of catalyst at high temperatures. This review aimed to provide up-to-date summary on the DRM process, including aspects of composite (bimetallic and trimetallic) catalysts and also the influence of doping metal on the catalysts. Furthermore, the metal support studies with the reaction mechanisms and kinetic studies, the latest catalyst configuration and their preparation methods have been highlighted. Therefore, the impending research focuses on composite catalysts and its density functional theory modelling for DRM to design an ideal catalyst.

The rise in the global population has ultimately steered to increase in global energy consumptions. This masqueraded several challenges worldwide. The most troublesome being the accumulation of greenhouse gases (GHGs) that induced a global climatic change. The utilization of fossil fuels like petroleum, coal and natural gas on the copious scale has led to the elevated levels of carbon dioxide (CO2) and methane (CH4) in the global environment. Dry reforming of methane (DRM) is a highly favorable technique as it utilizes two of the prominent GHGs, CH4 and CO2 to generate a useful and valuable product viz. syngas. However, the deactivation, coking and sintering of catalysts are still the main hurdles in the commercialization of the process. The compound metal catalysts have shown enhanced activity and prolonged durability when compared with monometallic catalysts due to enhanced morphology, improved and stable catalytic structure, i.e., both coke and sintering resistant at high temperatures. This brief review spotlights the recent developments in DRM by emphasizing parameters such as the effects of catalyst support, bimetallic catalyst, promoters and strong metal-support interaction (SMSI) in the last decade.

Dry reforming of methane (DRM) is emerging as an enticing research area due to the crucial requirement to mitigate global environmental issues and offers as an alternative energy resource. However, the DRM commercialized prospect and industrial utilization are curbed due to the weak prospect of sustained activity of the catalysts. The objective of this research is to find out the effects of the addition of CeO2 and La2O3 as promoters on the performance of the catalyst. In this work, catalysts such as Ni/Al2O3, Ni/Al2O3-CeO2, Ni/Al2O3-La2O3 were prepared by sol-gel method. The prepared catalysts have been characterized by XRD, BET analysis, and temperature-programmed reduction (TPR). BET results revealed that the addition of CeO2 and La2O3 slightly decreased the BET surface area of the synthesized catalyst because of the deposition on the porous structure of the support and filling its pores. The performance of the catalysts in DRM at 800°C shows that catalyst with CeO2 have the highest and stable conversion, while La2O3 has a significant role towards the stability of the reaction during the 8 h reaction on stream.

Bubble flow reactors (BFR) are commonly used for various industrial processes in the field of oil and gas production, pharmaceutical industries, biochemical and environmental engineering etc. The operation and performance of these reactors rely heavily on a range of hydrodynamic parameters; prominent among them are geometric configurations including gas injection geometry, operating conditions, mass transfer etc. A huge body of literature is available to describe the optimum design and performance of bubbly flow reactors with conventional bubble injection. Attempts were made to modify gas injection for improved efficiency of BFR’s. However, here instead of modifying the geometry of the gas injection, an attempt has been made to generate swirl bubbles for gaining larger mass transfer between gas and liquid. Here an exceptionally well thought strategies have been used in our numerical simulations towards the design of swirl injection mechanism, whose paramount aspect is to inhibit the rotary liquid motion but facilitates the swirl movement for bubbles in nearly stationary liquid. Our comprehension here is that the swirl motion can strongly affect the performance of bubbly reactor by identifying the changes in hydrodynamic parameters as compared to the conventional bubbly flows. In order to achieve this bubbly flow, an experimental setup has been designed as well as computational fluid dynamic (CFD) code was used with to highlight a provision of swirl bubble injection by rotating the sparger plate.