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The role of methane (CH4) in the 21st century presents a critical dilemma. Its abundance and clean-burning nature make it a promising energy source, while its potent greenhouse effect threatens climate stability. Despite its potent greenhouse gas (GHG) nature, CH4 remains a crucial energy resource. However, advancements in CH4 capture, utilization, and emissions mitigation are rapidly evolving, necessitating a critical assessment of the advances, their potential, and challenges. This study aims to comprehensively evaluate the current state of the art in these advancements, particularly focusing on the emissions trends, with corresponding global warming potentials of projected CH4 emissions, and a discussion on the advances that have been made towards reducing the impacts of CH4 emissions. The areas of these advances include measurement, computational, numerical modeling, and simulation studies for CH4, emerging technologies for CH4 production, management and control, the nexus of CH4 –X, and case study applications in countries. This study reports on these advances, which involves a technical review of studies, mainly from the last decade, discussing the technical feasibility, economic viability, and environmental impact of these advancements. Our trend analysis reveals that even though the share of CH4 in the GHG mix has been around 19% compared with carbon dioxide (CO2), still, CH4 reduction would need to be highly subsidized because of the high global warming potential it has, compared with CO2. We conclude that while significant progress has been made, further research and development are essential to optimize the performance, scalability, and affordability of these advancements. Additionally, robust policy frameworks and international collaborations are crucial to ensure widespread adoption and maximize the potential that comes with the advancements in the mitigation of the impact of CH4 emission. This study contributes to the ongoing dialogue on balancing the potentials of CH4 with its environmental footprint, paving the way for a future where this versatile resource can be utilized sustainably. [ABSTRACT FROM AUTHOR]

In recent times, solar energy has become one of the largest available sources of renewable energy at our disposal. However, the design of highly efficient solar cells is increasingly becoming crucial as there has been a surge for economically viable alternative energy sources with the lowest cost. Significant advances have been made through different routes to make photovoltaic (PV)/solar technologies economically viable, eco-friendly and consequently scalable. As a result, cellulose nanomaterials have become one of the emerging technologies in this regard because of the advantages of high-value bio-based nanostructured materials, such as their abundance and sustainability. Nanocellulose-based photoactive nanocomposite materials can be made by integrating conducting photoactive and electroconductive materials with hydrophilic biocompatible cellulose. Inorganic nanoparticles, such as graphene/reduced graphene oxide cadmium sulphide quantum dots, amongst others, can be introduced into the nanocellulose matrix and can be applied either as charge transporters or photoactive materials in different types of solar cells. Thus, in this review, we highlight the optoelectronic properties of different photoactive materials, particularly nanocellulose-based graphene nanocomposites; their efficiencies and drawbacks were X-rayed. The effect of doping each PV material on the PV performance is also discussed. It is anticipated that the novel material would result in a reduction in the cost of solar cells, jointly enhancing their efficacy in generating environmentally friendly electricity. Since the fabrication techniques and equipment play a crucial role in the development of solar cells, the fabrication techniques of bulk-heterojunction (BHJ) cells containing a nanocellulose-based graphene composite and case studies of already fabricated BHJ PV cells with nanocellulose-based graphene composite are discussed. [ABSTRACT FROM AUTHOR]

Recently, CO2 methanation has become a technique that aims to reduce anthropogenic CO2 emissions by converting CO2 captured from stationary and mobile sources and H2 produced from renewable sources into CH4. Due to their excellent performance‐to‐cost ratio, Ni‐based catalysts were frequently used in such conversions. The main drawbacks, however, are that Ni has the propensity to aggregate and deposit carbon during the high‐temperature reaction. These issues can be partially resolved by including a support (e.g., MOF, zeolite, activated carbon, etc.) and a second transition metal (e.g., Mo, Co, or Fe) in Ni‐based catalysts. Therefore, the activity of Ni‐based catalysts at low temperatures needs to be improved. In this study, a series of mesoporous activated carbon (AC) supported bimetallic Ni–Mo catalysts (Ni–xMo/AC, Ni = 13 wt.%, x = 5, 7, 9, 11 wt.%) were synthesized using the incipient wetness impregnation method. The effect of Mo content on the catalyst's activity was examined in a fixed‐bed reactor. At 250–650°C, 1‐atmosphere pressure, gas hourly space velocity (GHSV): 1200 mL h−1 g−1, and H2/CO2 ratio: 4:1, the catalytic efficiency of these catalysts was examined. The catalysts were analyzed using transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), X‐ray powder diffraction (XRD), N2‐physisorption, and scanning electron microscopy/energy dispersive X‐ray spectroscopy (SEM‐EDX). Ni–7%Mo/AC catalyst showed the lowest carbon deposition rate, superior stability, and the best activity. The addition of Mo can improve the heat resistance of the Ni/AC catalyst and the interaction between the metal nickel and the support, which prevents the sintering of the catalyst. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The aim of this study was to apply the central composite design technique to study the interaction of the amount of formic acid (6-12 mL), amount of hydrogen peroxide (6-10 mL), temperature (54-58°C) and reaction time (40-60 min) during the oxidative desulphurisation (ODS) of tyre-derived oil (TDO). The TDO was oxidised at various parametric interactions before being subjected to solvent extraction using acetonitrile. The acetonitrile to oil ratios used during the extraction were 1:1 and 1:2. The content of sulphur before and after desulphurisation was analysed using ICP-AES. The maximum sulphur removal achieved using a 1:1 acetonitrile to oxidised oil ratio was 86.05%, and this was achieved at formic acid amount, hydrogen peroxide amount, temperature and a reaction time of 9 mL, 8 mL, 54°C and 50 min respectively. Analysis of variance (ANOVA) indicated that the reduced cubic model could best predict the sulphur removal for the ODS process. Coefficient of determination (R2 = 0.9776), adjusted R2 = 0.9254, predicted R2 = 0.8356 all indicated that the model was significant. In addition, the p-value of lack of fit (LOF) was 0.8926, an indication of its insignificance relative to pure error.

The hydrocracking of waste vegetable (cooking) oil was studied over two different catalysts as an alternative way to produce jet fuel range alkanes (C9 - C15). Experiments were carried out in a packed bed reactor at temperatures of 400, 425 and 450°C and with a hydrogen pressure of 120 bar. Two types of fresh and regenerated catalyst were used: ruthenium/alumina (Ru-Γ- Al2O3) and nickel oxide/alumina (NiO-Γ- Al2O3), both subject to a sulphidation pre-treatment prior to the experimental run. At the conditions studied, the hydrocracking on fresh NiO-Γ- Al2O3 catalyst at the highest temperature gave the highest concentration on a mass basis (7.14 wt. %) of C9-C15 hydrocarbons in the liquid product. The liquid product yield ranged from 29.83 to 92.06 wt. %. The higher yields were obtained at the higher reaction temperatures using fresh catalyst. Within the liquid product, the higher percentages of C9 - C15 alkanes were achieved at the higher temperatures using fresh catalyst, indicating that an increase in reaction temperature favours hydrocracking. Furthermore, fresh catalyst proved to have a greater effect on the degree of hydrocracking when compared to its regenerated counterpart. Fresh untreated catalyst proved less effective than regenerated treated catalyst indicating the importance of the pre-treating stage in order to activate the catalyst for hydrocracking of triglycerides. The balance of the product was made up of gas and a waxy residue. This waxy residue was found to contain a small portion of similar alkanes to those in the liquid product but would require further processing to separate out the target compounds from the high molecular weight hydrocarbons. [ABSTRACT FROM AUTHOR]