Sustainable Energy & Fuels最新文献

Chemical looping technology is an emerging method for hydrogen production and storage, characterized by its environmentally friendly and safe inherent gas separation processes. However, the development of this technology requires consideration of oxygen carrier selection, reactor design, and process optimization, trial-and-error experimental methods are labor-intensive and costly. Herein, we propose the integration of machine learning into the chemical looping hydrogen production system to achieve accurate prediction and evaluation during the development process. Based on a dataset of 315 data sets, the ANN and Extra Tree models demonstrated the highest generalization ability among six models, with prediction accuracies for hydrogen yield and purity reaching R² = 0.96 and R² = 0.94, respectively. The interpretability algorithm analyzed the impact of different input parameters on hydrogen yield and purity, revealing that reaction temperature and fuel gas had the most significant influence. We predicted the hydrogen production performance of four new-input natural oxygen carriers using the trained ANN and Extra Tree models. The results indicated that the predictions were generally consistent with experimental results, with the best oxygen carrier maintaining a hydrogen yield of ∼3.12 mmol g⁻¹ and a hydrogen purity of 99.65% after 10 cycles. In summary, machine learning can serve as an alternative to traditional trial-and-error methods, accelerating the development process of chemical looping hydrogen production technology.

This work reported the design and fabrication of a ternary heterostructure for efficient photocatalytic and electrocatalytic hydrogen production. Here, the C-SnO₂–g-C₃N₄–MoS₂ heterostructure with unique electronic and optical properties is developed using a simple two-step synthesis strategy, in which first a C-doped SnO₂ nanostructure (C-SnO₂) was prepared by thermal decomposition and then a hybrid ternary heterostructure of C-SnO₂ with layered 2D materials g-C₃N₄ and MoS₂ was developed by using a simple solution chemistry approach. The reported C-SnO₂–g-C₃N₄–MoS₂ hybrid heterostructure exhibited an enhanced photocatalytic activity of 11.85 mmol g⁻¹ hydrogen production and 17.21% apparent quantum efficiency (AQE) due to improved catalytically active sites, boosted charge transfer efficiency at the interface, suppression of charge carrier recombination, and synergistic interaction between the components. Moreover, the C-SnO₂–g-C₃N₄–MoS₂ heterostructure material showed outstanding electrocatalytic activity for hydrogen production (HER), requiring an overpotential of −0.18 V vs. RHE to accomplish a current density of 10 mA cm⁻². The superior HER performance of the heterostructure is ascribed to its more electrochemically active surface sites, combined with the synergistic interaction among its components.

This study explores the influence of varied stacking configurations in microbial fuel cells (MFCs) to channel acidogenic metabolism for enhanced bioelectricity generation, value-added chemical synthesis, and wastewater treatment. Five MFC units were operated in series and hybrid configurations, evaluated over nine operational conditions in a gravity-fed, up-flow system with domestic wastewater as the feedstock, spanning a 78 day period. The hybrid stacking configuration promoted an acidogenic metabolic shift, favouring the production of short-chain carboxylic acids, specifically acetic acid (0.23 g L⁻¹) and propionic acid (0.13 g L⁻¹), with efficiencies of 23% and 10.4%, respectively. In contrast, the series stacking configuration proved more effective for bioelectrogenesis with enhanced energy output, achieving four times the power density of the hybrid setup (series: 1.2 W m⁻², 1.27 W h kg⁻¹ COD vs. hybrid: 0.3 W m⁻², 0.35 W h kg⁻¹ COD). Series stacking also delivered a higher coulombic efficiency of 15.6% and a 6% improvement in treatment efficiency compared to that of the hybrid stacking. The open circuit current (OCC) was relatively higher in the series configuration (1.55 mA vs. 0.2 mA in hybrid), indicating improved biocompatibility. Additionally, a power management system (PMS) facilitated temporary energy storage, enabling the illumination of a 1.7 V LED through a supercapacitor without amplifiers. This study demonstrates an approach to sustainable synthesis of value-added products and bioenergy generation by varying the stacking configuration of MFCs.

Fast pyrolysis of woody materials is a technology pathway for producing renewable fuels and chemicals. This is a presentation of isolating needles, bark, and stemwood from a single tree as well as isolating stemwood and whole tree samples from the same species of tree with different ages and pyrolyzing each individually as well as in mixtures. This gives insight into the role of tree anatomical fractions on the resulting intermediate oil product as well as into interactions between these components. The highest carbon content oil (45.1 wt% as received) was produced from a one-to-one mixture of stemwood and needles, followed by the pure stemwood (43.4–43.8 wt% as received), while the lowest oil carbon content was from a one-to-one blend of bark and needles (26.7 wt% as received). The pyrolysis oil yield (combining oil and aqueous where separation occurred) varied from 54 wt% as received (needles) to 72.3 wt% as received (stemwood). When comparing trees of different ages, we find the change in the ratio of the anatomical fractions is a dominant factor in the product composition and yields, while the product composition and yields vary slightly with tree age when only the stemwood is pyrolyzed. Here we present the bench-scale pyrolysis, yields, and product characterization of loblolly pine feedstocks (13- vs. 23 year-old, residues, air-classified residues, whole tree, needles, bark, and stemwood).

A Mg₉₃Ni_3.5Y_3.5 hydrogen storage alloy was prepared using a composition design approach with a protective covering agent method. A self-synthesized 1 wt% nano (Ni–TiO₂)@C catalyst was added by ball milling. The in situ formation of the endogenous long-period stacking ordered (LPSO) phase facilitated the catalytic decomposition of products after hydrogenation. The synergistic effect of the external and in situ endogenous catalysts enhanced the hydrogen absorption and desorption capacities, increased the reaction rate and lowered the temperature corresponding to the maximum hydrogen storage capacity. The composite material absorbed up to 6.39 wt% of hydrogen at 300 °C and 30 bar. Even at 100 °C, it absorbed 3.87 wt% of hydrogen within 2 hours. The enthalpies of formation for the materials Mg₉₃Ni_3.5Y_3.5 and Mg₉₃Ni_3.5Y_3.5 + (Ni–TiO₂)@C (with the added catalyst) were −53.96 and −55.04 kJ mol⁻¹ H₂, respectively. The corresponding hydrogen absorption activation energies were −34.14 and −39.51 kJ mol⁻¹ H₂. In addition, the material displayed excellent cycling stability after 100 cycles with the addition of the catalyst.

NiO-Co₃O₄/TiO₂ showed the best catalytic performance for one-step synthesis of 2-cycloamylcyclopentanone from cyclopentanone, which enhanced the competitiveness of cyclopentanone self-condensation. Both intermittent and segmented hydrogenation methods led to increased selectivity for 2-cyclopentenylcyclopentanone. Both acidic and basic substances were added to the reaction integration system, which resulted in a decrease of catalyst activity. The addition of acetic acid could promote the hydrogenation of the CO bond, while the addition of ammonia water reduced the competitiveness of cyclopentanone direct hydrogenation. The by-products in the reaction system were determined, and the reaction network was proposed. Combined with the curve of cyclopentanone conversion-product yield-time, the reaction pathway was speculated. The cyclopentanone self-condensation reaction was catalyzed by NiO-Co₃O₄/TiO₂ at the initial stage of the reaction. Hydrogenation products appeared at a reaction time of 20–30 min, and the yield of 2-cyclopentenylcyclopentanone increased first and then decreased. Combined with XRD and XPS analyses, the valence states of metals were determined.

Methanol, as a promising liquid hydrogen carrier, has attracted considerable interest in sustainable energy applications due to its renewability and ease of storage and transportation. Although methanol steam reforming for hydrogen production has been extensively studied, it faces several challenges, including high energy consumption at elevated temperatures, low hydrogen purity, and substantial CO₂ emission. We propose a four-step H₂ absorption-enhanced methanol steam reforming method that includes reforming/absorption, vapor purge, vacuum desorption, and pressurization steps. A two-dimensional, axisymmetric transient numerical model is developed, accounting for flow, heat transfer, mass transfer, chemical reactions, and hydrogen absorption/desorption. All components of the established model, including methanol steam reforming and H₂ absorption/desorption, are separately validated through experimental data, confirming the reliability of the model. Results indicate that under baseline conditions of 463 K and 3 bar, the reforming/absorption step achieves a methanol conversion of 98.88% and a hydrogen production rate of 0.87 mmol g⁻¹ min⁻¹, representing an improvement of 17.43 percentage points and 0.17 mmol g⁻¹ min⁻¹ compared with conventional methanol steam reforming, respectively. Additionally, a CO₂ stream with a concentration of 98.87% is obtained from the reactor outlet, which is comparable to the concentrations achieved by specialized CO₂ capture technologies and can be directly sequestered or reused. In the four-step cycle, incorporating the vapor purge enhances hydrogen purity, achieving levels exceeding 99.9%, compared with only 96.89% purity in the direct vacuum desorption method. Moreover, the four-step method obtains a hydrogen recovery rate of 98.92%. The proposed method provides a clean, straightforward, and highly integrated approach to sustainable hydrogen production and presents a novel option for accelerating the decarbonization of fossil fuel-dominated energy systems.

As one of the most successful inorganic materials, MFI zeolite has been widely used in petrochemical and fine chemical industries. However, the presence of only micropores in MFI zeolite creates diffusion barriers and thus precludes its usage in processes involving large substrates. It is highly desirable to mitigate the diffusion pathways in MFI zeolites. One of the efficient methods is the morphology control strategy, which has become a hot topic in the past few decades. In this review, we summarize the progress of MFI zeolite morphology control using specific organic additives as morphology modifiers to enhance the catalytic and separation performance. Organic additives, including urea, amino acids, small organic molecules, and polymers, were categorized based on the MFI zeolites induced by them. The morphologies generated can be classified as nanocrystals, aggregated nanoparticles, nanosheets, intergrown nanosheets, plates, intergrown plates, needles, and bulky prismatic crystals, depending on the specific additives. The formation mechanisms of different morphological MFI zeolites and their properties are also discussed. This review is of great importance for the controllable synthesis of zeolites and rational design of zeolite catalysts.

Covalent organic frameworks (COFs) enable highly effective photocatalysis due to their crystallinity, tunable pores and channels, and expansive light absorption. The performance of COFs in photocatalysis is underpinned by the intrinsic tendency of charge separation and transfer, thereby depending on the molecular building blocks. Benzobisthiazole (BBT), with an electron-withdrawing effect, shows superior potential in various optoelectronic materials. Therefore, with tetrabutylammonium hydroxide as a catalyst, a fully conjugated COF, BBT-sp²c-COF, is synthesized from 2,2′-(benzo[1,2-d:4,5-d′]bis(thiazole)-2,6-diyl)diacetonitrile and 1,3,6,8-tetrakis(4-formylphenyl)pyrene. As such, a series of characterizations demonstrate the structural and optical properties of BBT-sp²c-COF. The fully conjugated COF, BBT-sp²c-COF, possesses enhanced charge separation, electron transfer, and recycling stability. As expected, BBT-sp²c-COF photocatalysis achieves effective selective oxidation of benzyl amines with oxygen under blue light irradiation. Superoxide is identified as the crucial reactive oxygen species during the formation of imines. The full conjugation of organic building blocks into COFs can achieve highly effective photocatalysis.

Refused derived fuel (RDF) is finding suitable applications in thermochemical conversion methods, including plasma gasification, to generate clean syngas. This addresses both the challenges of sustainable energy and waste management. In this study, RDF waste is utilized in a plasma gasification unit integrated with combined cycle, molten carbonate fuel cell (IPGCC-MCFC) and chemical looping reforming (IPGCC-CLR) systems for the co-generation of hydrogen and electricity. The simulations of the proposed plants are conducted using Aspen Plus software, and subsequently, the techno-economic assessment and life cycle analysis are performed. The results indicated that the highest net overall energy efficiency of 66.05%, lowest cost of electricity of 74.90 $ per MW h and levelized cost of hydrogen of 1.02 $ per kg, can be obtained for the IPGCC-CLR system. This improved the energy return on investment to 2.89 MW/MW as compared to 1.69 MW/MW for the IPGCC-MCFC plant. The life cycle analysis estimated the total fossil fuel consumption of 5.06–6.16 MJ s⁻¹ and CO₂ emissions of 285.14–335.61 g_CO2eq. s⁻¹ throughout the project duration. The plants reduce fossil fuel consumption by 1.5 times and CO₂ emissions by 3 times as compared to the reported literature. Moreover, the analyses of other factors of environmental impact types of acidification potential, eutrophication potential, human toxicity potential, etc., show that the RDF processing stage contributes the largest pollution, followed by hydrogen compression and the transportation stage. The emissions can be minimized by replacing fossil fuels with hydrogen-based products at every stage.