Energy & Fuels最新文献

Cellulosic ethanol is a pivotal biofuel, and its chemocatalytic production from lignocellulosic biomass is crucial for addressing global energy challenges. In this study, a series of Pt-loaded catalysts were developed by sequentially loading varying weight percentages (wt %) of Pt and W onto SiO₂ carriers using the impregnation method. The catalysts were comprehensively characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy to analyze the metal dispersion and active oxidation states on the SiO₂ support. Under hydrothermal conditions (240 °C and 4 MPa H₂), cellulose was directly converted to ethanol in the aqueous phase, achieving an ethanol yield of 37.5 C%. The catalysts demonstrated excellent stability, maintaining high activity over at least five consecutive reaction cycles. Notably, the WO₃ component played a key role in facilitating C–C bond cleavage and hydrolyzing cellulose into glucose and ethanal intermediates. These intermediates were swiftly transferred to the Pt active sites, further promoting the formation of ethylene glycol. Among the catalysts, 3%Pt-15%WO₃/SiO₂ exhibited optimal performance due to its well-balanced ratios of Pt⁰ and Pt²⁺, which enabled selective C–O bond activation and significantly enhanced ethanol production.

The selective oxidation of biomass-derived compounds is a cornerstone of sustainable chemical production, offering pathways to integrate renewable energy into industrial processes. In this work, we present the first proton exchange membrane (PEM) photoelectrochemical (PEC) flow cell for simultaneous glycerol valorization and hydrogen peroxide (H₂O₂) production. Bi₂O_2.33/TiO₂ (BO-x/TO, x = 1, 2, and 3) heterostructures were optimized as advanced photoanodes to achieve selective glycerol oxidation to dihydroxyacetone (DHA) at a low bias of 0.45 V vs. RHE. The optimized BO-2/TO photoanode demonstrated a photocurrent density of 1.2 mA cm^–2, achieving a DHA yield of 1680 mmol m^–2 h^–1 with 49% selectivity. Mechanistic insights revealed that the incorporation of BO not only selectively activates the middle hydroxyl group of glycerol but also enhances the generation of hydroxyl radicals (•OH), which are critical for promoting selective oxidation to DHA while suppressing overoxidation pathways. Simultaneously, the cathode yields H₂O₂ on-site and enhances the overall system performance. This innovative integration of PEM technology with PEC systems establishes a scalable and energy-efficient platform for biomass valorization, bridging the gap between green chemistry and renewable energy and setting a new benchmark for sustainable chemical transformation.

In this study, to explore the effective conditions and methods for SO₂ removal from flue gas, a CaCO₃ absorbent and various additives were used to investigate the pH changes and removal efficiency of SO₂ from aqueous solutions. Desulfurization performance was investigated using the CaCO₃ absorbent concentration and additive type as variables. CaCO₃ was dissolved in an appropriate pH range to produce HCO₃^– ions to provide a buffering effect for the H⁺ ions generated via its reaction with SO₂ in an aqueous solution. This process extended the absorption duration of the SO₂. With a higher CaCO₃ concentration, the alkalinity of the absorption solution remained longer and the SO₂ removal efficiency and absorption duration were higher. Organic acids, such as acetic, adipic, and citric acids, and the organic salts of sodium acetate, magnesium acetate, potassium acetate, and calcium acetate were used as additives. The removal efficiency of the additives in the SO₂ absorption reaction was as follows: citric acid < adipic acid < no addition < acetic acid < potassium acetate ≤ magnesium acetate ≤ sodium acetate ≤ calcium acetate. Organic acid additives lowered the initial pH of the absorption solution and effectively promoted CaCO₃ dissolution. The chemical buffering system using metal acetate salts exhibited a high SO₂ absorption performance with a gradual decrease in pH. Additionally, experiments were conducted using a simulated flue gas whose composition was similar to that of actual flue gas. The HCO₃^– from CO₂ increased the SO₂ removal efficiency and absorption duration owing to a buffering effect. This study demonstrates the potential of a system capable of long duration absorption of low-concentration SO₂ and confirms that the presence of calcium acetate and CO₂ enhances SO₂ removal capacity in desulfurization processes.

Usually, an aliphatic chain or an aromatic ring is used as the organic spacer (A) to form two-dimensional (2D) lead halide compounds with n ≥ 2 in the general formula A₂(MA)_n−1Pb_nI_3n+1 or A(MA)_n−1Pb_nI_3n+1. Departing from this practice to address their limitations, we use a cyclic amine, cyclohexanemethylamine (CMA), to synthesize a new homologous series of 2D hybrid lead iodides, (CMA)₂(MA)_n−1Pb_nI_3n+1, with n = 1–4. While electronic and dielectric confinements enhance both bandgap and exciton binding energies in this family of compounds compared to the 3D compounds, as also in other low-dimensional hybrid lead halide systems, the present n = 2 compound has the lowest exciton binding energy of 58 meV among all n = 2 hybrid lead halide 2D systems reported so far. Interestingly, time-resolved photoluminescence measurements reveal a longer lifetime (0.4–186 ns depending on n) in these compounds compared to those (generally in the range of 0.1–0.3 ns) for all other such 2D lead halide systems; the longer lifetime becomes increasingly more prominent with increasing n, indicating slower recombination and improved carrier transport than any other 2D system reported so far. Prompted by this observation, we use spin-coating of CMAI ligands on the active material to grow an integrated 2D surface/3D bulk structure, improving all solar photovoltaic parameters, including stability, and leading to an average PCE of 23.8% and a champion PCE of 24.3%, compared to photovoltaic solar cells made in the absence of the CMAI ligands but keeping all other fabrication parameters the same, achieving an average PCE of 22.6% and a champion cell PCE of 23.03%.

Water electrolysis using proton ceramic electrolysis cells (PCECs) is considered as an effective technique for green hydrogen production. While Ruddlesden–Popper (RP)-type oxides have drawn great interest owing to their interesting oxygen defect chemistry, their applications in PCECs have not yet been thoroughly investigated. In this work, we synthesize RP-type oxide La₂NiO_4+δ (LNO) and the well-studied PCEC electrode PrBa_0.5Sr_0.5Co_1.5Fe_0.5O_6–δ (PBSCF) as the model materials and systematically compare their oxygen defect chemistry and water electrolysis performance. Rietveld refinement of X-ray diffraction patterns and X-ray absorption spectroscopy measurements confirm that LNO loses oxygen in the form of oxygen interstitials upon thermal reduction, leading to a lattice expansion along the ab plane (the perovskite and rock salt layers) and a shrinkage along the c direction (the direction perpendicular to those layers). By contrast, PBSCF loses oxygen from lattice sites and forms oxygen vacancies, showing lattice expansion along all three directions. The electrochemical measurements indicate that the cells with LNO as oxygen electrodes exhibit outstanding water electrolysis performance, with a maximum Faradaic efficiency of 99.01%, noticeably surpassing 77.48% obtained for PBSCF. Our results highlight the potential of oxides with oxygen interstitials as a highly effective oxygen electrode material for PCECs.

To enhance floc size and accelerate floc formation during the coagulation treatment of highly emulsified oily wastewater (HEOW), a novel electro-enhanced coagulation (EEC) process was developed by integrating an external electric field with conventional coagulation. This process was optimized based on various operating parameters, including electrolysis time and coagulant dosage. The Turbiscan Stability Index (TSI) and floc size were measured throughout the process. The EEC process substantially improved floc formation compared with conventional coagulation. The TSI and floc size increased and then plateaued as the electrolysis time increased to 240 s. Under optimal conditions of 240 s electrolysis time and 50 mg/L Fe₂(SO₄)₃ dosage, the TSI reached 59.87 ± 0.47 and floc diameter expanded to 473.8 ± 34.1 μm. Additionally, continuous operation experiments achieved an oil removal efficiency of 94.9% ± 1.75%. The energy consumption of this process was 0.29 ± 0.01 kWh/m³. The ζ potential decreased as the electrolysis time increased from 180 to 300 s. This decrease was attributed to charge neutralization facilitated by an external electric field. Furthermore, the pH increased with prolonged electrolysis, promoting Fe³⁺ hydrolysis and facilitating the formation of iron hydroxide species, thereby contributing to enhanced floc formation during the demulsification process.

Amine-based carbon dioxide capture technologies are important for carbon emission reduction and carbon neutralization but are hindered by low absorption capacities and high regeneration energy requirements. This study introduces a series of Fe₂O₃-CeO₂/Hβ (FeCe-Hβ) catalysts, synthesized via an ultrasound-assisted self-assembly method, to enhance CO₂ desorption in the “PZ-n-butanol-H₂O” phase change system. The FeCe-Hβ catalysts demonstrated superior catalytic performance characterized by increased CO₂ desorption rates, enhanced desorption capacities, and reduced carbamate decomposition heat. Notably, the 30FeCe-Hβ catalyst improved CO₂ desorption capacity by 37.29% and reduced the decomposition heat of PZ-carbamate by 13.91%. Compared to a 30 wt% monoethanolamine (MEA) aqueous solution, it achieved an 80.39% increase in CO₂ desorption. Structural and physicochemical analyses revealed that the synergistic effects of acidic and basic sites, along with the mesopore surface area*Bro̷nsted acid sites (MSA*BAS) parameter, were pivotal to the catalyst’s performance. Stability tests indicated that 30FeCe-Hβ retained its activity, with only a 6.3% decrease in CO₂ desorption after five cycles. Mechanistic investigations proposed that CO₂ absorption products compete with n-butanol for water molecules, inducing a phase change. The FeCe-Hβ catalyst facilitated CO₂ desorption through acid–base site synergy, where acidic sites promoted the cleavage of PZCOO^–/PZ(COO^–)₂ and basic sites aided in PZH⁺/PZH₂²⁺ deprotonation.

The characterization of olefin compounds is crucial for elucidating the reaction network in thermal cracking processes. In this study, heavy olefins were selectively characterized by using Ag⁺ complexation electrospray ionization coupled with high-resolution Orbitrap mass spectrometry. Semiquantitative analysis of the olefin content was conducted using naphthalene-d₈ as an internal standard. In thermal cracking products, heavy olefins with carbon numbers ranging from C₁₀ to C₅₀ were detected, with a concentration peak observed in the C₂₀–C₂₅ range. Linear monoalkenes were found to be the most abundant species. The molecular composition of olefins in cracking products under various reaction conditions was investigated, and based on these findings, the thermal cracking reaction network was analyzed. Furthermore, the correlation between the olefin content and the bulk properties of the thermal cracking products was well correlated. This study provides valuable insights into the complex reaction network involved in the residual thermal cracking process, thereby providing a theoretical foundation for process optimization.

Low tension gas flooding is an innovative oil recovery technique that relies on the reduction of the oil–water interfacial tension for oil mobilization and the generation of foam for proper mobility control. When CO₂ is used as the working gas, LTG offers the dual benefit of improving oil recovery as well as geological carbon storage. This first-of-its-kind investigation aims to investigate the dynamics of LTG with CO₂ in an oil-wet carbonate rock under varying conditions of salinity, pressure, and surfactant concentration. Two series of core floods were conducted at 1400 and 2000 psi at 69 °C. The significance of CO₂ and surfactant in oil displacement at low pressure was established through a reduction in residual oil saturation from 14 to 2%. The impact of CO₂-microemulsion interaction on the LTG process was evaluated by accounting for the reduction in optimum salinity due to the in situ modification of crude oil composition with dissolved CO₂, which led to 90% oil recovery after only 3 PVs of injection, with a reduction of optimum salinity from 179,000 to 150,000 ppm. Reducing the slug concentration from 0.5 to 0.2 wt % resulted in a decrease in oil recovery and weaker foam propagation. The role of CO₂ in improving oil mobilization at high pressure was demonstrated by achieving comparable results to the low-pressure case at a lower surfactant concentration. These results offer valuable insight into designing optimal injection strategies for LTG flooding when CO₂ is used.

The chemical composition of crude oil provides clues about its origins, well dynamics, and reservoir performance. Target petroleum analysis using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS) has been widely used for individual identification and group-type analysis. However, untargeted analysis is sometimes faster and more effective, especially with large, complex GC×GC-TOFMS data sets. The pixel-based preprocessing approach to treating GC×GC-TOFMS data facilitates fast, easy exploration of regions or compounds in two-dimensional chromatograms, which are important for comparing complex matrices using chemometric tools. In this context, to help reservoir geochemistry researchers mitigate exploration and development risks, we investigated subtle differences in the light hydrocarbon compositions of crude oil. Fifty Brazilian crude oil samples from the Búzios presalt reservoir in the Santos Basin were evaluated. Total ion chromatograms were used to construct concatenated matrices, which were aligned, normalized, and subjected to multivariate statistical analysis. Unsupervised principal component analysis indicated minor differences between the samples, which may correspond to differences in the presalt geological formations. Supervised orthogonal partial least-squares discriminant analysis determined whether each sample came from the Barra Velha or Itapema formation; the Barra Velha formation contains lighter hydrocarbons than the Itapema formation. Additional exploratory analyses indicated slight differences among the oil samples, demonstrating that light hydrocarbons can be investigated at the molecular level using GC×GC-TOFMS high-throughput data. Pixel-based chemometrics thus proves to be a rapid, innovative approach to assisting fluid distribution in a petroleum reservoir and a faster alternative to current methodologies for processing and analyzing GC×GC-TOFMS data.