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Sugars and sugar alcohols are renewable raw materials which can be used for char production. Their acid-catalyzed hydro-carbonization results in the formation of carbon materials with acidic functional groups on the surface, which makes them suitable to be used as heterogeneous catalysts in esterification reactions. Hydrochars materials were prepared by low-temperature slow carbonization of glycerol, xylitol, sucrose, and glucose in the presence of different amounts of H₂SO₄ (mass ratios from 1 to 4). The hydrochars were extensively characterized and tested in the methanolysis reaction of oleic acid. All the carbon materials were amorphous with features of polyaromatic sheets with hydroxyl (–OH), carboxylic acid (–COOH), and sulfonic (−SO₃H) functional groups. The effect of the oleic acid water content on catalytic performance was studied, showing a strong inhibition effect due to the hygroscopic character of catalysts induced by sulfonic groups and other surface groups with oxygen. Under the conditions evaluated (5 % wt. of catalyst, methanol/oleic acid = 9 M ratio, methanol reflux temperature) the sucrose-derived catalyst prepared with the highest H₂SO₄ content showed the best performance, leading to methyl oleate yield > 90 % after 2 h of reaction, which is only achieved by the majority of analogous catalysts reported in the literature after 4 to 8 h of reaction. The data showed that there is a correlation between the methyl ester yield and the graphitization of the catalyst, as this makes the catalyst more hydrophobic, which is an advantage in esterification catalysts.

Estimating CO₂ storage capacities is crucial in developing carbon capture and storage projects. Material balance equation (MBE) methods, widely employed for oil and gas reserve estimation, offer a direct approach to estimating CO₂ storage capacities. However, previous MBE methods rely on an original fluid in-place volume calculated using volumetric methods to estimate CO₂ storage capacities, lacking validation for accuracy. It is essential to accurately estimate the original fluid in-place volume, representing the pore volume, as it substantially influences CO₂ storage capacity. This study presents a refined MBE method that ensures accurate estimates of CO₂ storage capacities by validating the original fluid in-place volumes in saline aquifers. The accuracy of this method was evaluated by comparing it with a commercial reservoir simulator for a synthetic aquifer example and the Sleipner L9 model. In the synthetic aquifer example, the relative error in CO₂ storage capacity estimation with the proposed MBE method was only 2.09%, even when short-term (1-year) injection data were utilized. The proposed MBE method demonstrates consistent accuracy in estimating CO₂ storage capacities under different aquifer properties, operating conditions, and MBE-related conditions. The proposed MBE method also accurately estimated the CO₂ storage capacity in the Sleipner L9 model, achieving a relative error of 3.47%.

Natural gas hydrates are not only substantial energy sources but also have significant applications in the chemical industry and other fields. Although investigating hydrate formation in sediment minerals is crucial for their development and utilization, the underlying hydrate formation mechanism remains unclear. Here, molecular simulations were conducted in systems incorporating hydrophobic and hydrophilic pores of different sizes to investigate methane hydrate formation processes. The findings suggest that, as the hydrophobic slit size increases, there is a larger number of dissolved methane after the system reaches a metastable equilibrium state. The probability of cage formation indicates that hydrate cages readily form on hydrophobic surfaces or in the solution phase near the solution/gas interface. The larger slits are preferred for hydrate nucleation, regardless of whether the surface is hydrophobic, with most initial nuclei located near the liquid/methane interface. However, the interface perturbation can lead to the movement and growth of hydrate nuclei near the solution/methane interface into the bulk solution phase. Additionally, hydrate can nucleate and grow on the hydrophobic surface, facilitated by the adsorbed methane molecules and nonstandard cages. Pores hinder methane storage capacity in the hydrate phase due to the confinement effect and the amorphous nature of the hydrate formed. These molecular-level findings enhance our understanding of hydrate formation in sedimentary environments and porous materials, benefiting the development of natural gas hydrates and the use of porous materials for gas storage and transportation.

The carbon canister is adsorbing gasoline vapors under high-speed loading conditions during vehicle refueling, and ensuring the carbon canister’s working capacity is the key to controlling refueling emissions. This study analyzed carbon canister working characteristics during refueling as well as carbon canister bleeding emission components. The activated carbon deterioration curve was obtained by 300 adsorption/desorption cycle tests, and the deterioration mechanism was further analyzed by using characterization means and molecular simulation techniques. The results show that the working capacity of carbon canister decreases approximately linearly with the increase of gasoline vapor loading speed, with the working capacity at 2700 g/h loading speed being only 58.6 % − 69.6 % of that at conventional loading speed. Carbon canister bleeding emissions consist primarily of small molecule alkanes, and refueling emissions cannot be equated with bleeding emissions. The working capacity of the activated carbon showed a tendency to decrease with the increase in the number of cycles, with the most severe deterioration in the initial cycle stage and finally stabilizing. Difficulty in desorption of adsorbates at high-energy sites is the main cause of deterioration. The residuals in the activated carbon during the initial cycle stage are predominantly C4 − C6 species, followed by a gradual replacement of most C4 − C6 species by C7 − C10 species. In terms of methods to cope with the deterioration of carbon canisters, three aspects can be considered: increasing the desorption capacity, increasing the desorption temperature, and decreasing the proportion of small micropores in activated carbon.

The high electron-hole complexation rate and wide band gap of TiO₂ are significant hindrances to photocatalytic hydrogen production. It has become a challenge to design a photocatalyst that improves the separation efficiency of photogenerated carriers. Bismuth-based hierarchical oxides with high chemical stability and good photocatalytic activity. In this study, we employed hydrothermal and physical mixing techniques to fabricate TiO₂/Bi₂O₂CO₃ (TB) type II heterojunctions, aiming to enhance the efficiency of separating photogenerated carriers in the materials. The findings from the BET analysis indicate that the incorporation of a heterojunction structure leads to a significant increase in the material’s specific surface area. This, in turn, facilitates the exposure of more reactive sites of the catalyst material. The TPR, EIS, and PL findings indicate that the TB composites exhibit superior efficiency in separating photogenerated carriers and lower resistance to charge transfer when the Bi₂O₂CO₃ (BOC) mass fraction is at 5 %, resulting in a photocurrent intensity of approximately 1.9 μA/cm². As a result, TB composites demonstrated remarkably efficient performance in producing hydrogen through photocatalysis. The hydrogen production rate of the optimal TB-5 ratio reached 3906.38 μmol g⁻¹ h⁻¹, which was 27 times higher compared to pure TiO₂. Additionally, the apparent quantum efficiency (AQY) achieved an impressive value of 5.028 %. The current study presents a new approach for developing low-cost TiO₂-based photocatalysts with high efficiency in separating photogenerated carriers and producing hydrogen through photocatalysis.

Environmental pollution and energy shortage are two major challenges facing humanity today. Photocatalytic technology, as a green and sustainable approach, is an important choice for effectively addressing these challenges. The formation of S-scheme heterojunctions and built-in electric fields can significantly improve the transfer and separation of photoinduced charge carriers, hence enhancing the efficiency of photocatalytic reactions, which is greatly significant for improving the performance of photocatalysts. In this study, a photocatalyst CdS/ZnIn₂S₄ with a built-in electric field, which is an S-scheme heterojunction photocatalyst, was prepared by a simple solvothermal method. CdS/ZnIn₂S₄ exhibited efficient visible-light-driven H₂ evolution from water, with a rate of 4.09 mmol g^-1h⁻¹, 3.60 and 2.80 times higher than that of CdS and ZnIn₂S₄, respectively, and an apparent quantum efficiency (AQE) of 2.71 %. Moreover, it also showed performance in visible-light-driven degradation of various ECs, achieving degradation rates of 82.2 %, 80.9 %, and 81.5 % for tetracycline, ciprofloxacin, and norfloxacin, respectively, within 40 min. It was confirmed that the successfully constructed S-scheme heterojunction can effectively separate photoinduced electron-hole pairs and suppress their recombination. The built-in electric field inside the composite material can effectively promote the movement of photoinduced charge carriers, thereby promoting the course of photocatalytic reactions. This study is positively significant for the development of novel efficient photocatalysts, exploration of new methods for environmental pollution control, and development of green hydrogen energy.

The release of alkali compounds during the combustion of solid biomass causes fine particle emissions and deposition formation on heat exchanger surfaces. These depositions drastically reduce the efficiency and durability of biomass-fired power plants. The main driver of fine particle emissions and deposition formation is the released potassium content of the fuel. Mineral sorbents can shift the potassium release behavior and the ash melting towards significantly higher temperatures. As a result, less potassium enters the gas phase, and fine particle and deposition formation are reduced.

This work analyzes the effect of kaolin and coal fly ash on the potassium release behavior and ash stability of miscanthus, torrefied wood, and beech wood. The ash melting behavior is analyzed and the ash composition is determined by X-ray fluorescence analysis. A novel electrothermal evaporation unit connected to an inductively coupled plasma optical emission spectrometer is used to determine the temperature-resolved potassium release from the samples. The experimental data is compared to the most common fuel indices for the prediction of the slagging and fouling tendencies of biofuels.

Conflicting fuel suitability predictions are made by the fuel indices studied. Kaolin and coal fly ash shift the potassium release of miscanthus and torrefied wood by up to 300 °C and increase their ash stability. The additives do not improve the ash characteristics of beech wood. A comparison of the different methods shows that potassium release analysis is more accurate than fuel indices and ash melting analysis in predicting ash-related problems and the effect of additives.

The Mn-based oxygen carrier (OC) owns a great oxygen carrying capacity and a high reactivity in the chemical looping gasification of biomass. However, the sintering of the Mn-based OC can cause serious defluidization or even the shut-down of the biomass chemical looping gasifier. In this study, the sintering kinetics and mechanism of Mn-based OC in the gasification of two typical biomass ash were revealed by thermomechanical and thermodynamic analysis. It revealed that the manganese silicate was converted to iwakiite (MnFe₂O₄) and liquid at high temperatures in the high-Mn OC (OC2), leading to the liquid sintering mechanism and high apparent activation energy of sintering (E_s), with a maximum shrinkage rate of 6.14 %/^oC. Conversely, the solid sintering mechanism of the low-Mn OC (OC1) was attributed to the FeMn₂O₄ crystallization, leading to a low shrinkage rate (The maximum shrinkage rate was 0.30 %/^oC). The sintering rate of Mn-based OC was closely related to the liquid content, and the biomass ash addition advantaged the liquid formation. Therefore, the E_s of OC1 was increased from 44 kJ/mol to 151 kJ/mol at the 15 wt% addition of corn straw ash, and E_s of OC2 was increased from 72 kJ/mol to 93–107 kJ/mol at 20 wt% addition of biomass ash. Element distribution analysis supported that Ca in sawdust ash improved the bonding between Mn and Si, improving the Mn-based minerals crystallization and OC expansion. However, the K in corn straw ash facilitated the melting of rhodonite(MnSiO₃), and the expansion of Mn-based OC was inhibited. This study provides valuable insights into the sintering mechanism of the Mn-based oxygen carrier and its relationship with liquid evolution behavior in the chemical looping gasification of biomass.

Designing efficient nitrogen reduction reaction (NRR) electrocatalysts for ammonia (NH₃) synthesis under mild conditions is an attracting and challenging theme in energy electrocatalysis. Herein, the catalytic activity of a series of 3d (Cr, Mn, Fe, Co, Ni), 4d (Mo, Tc, Ru, Rh, Pd) and 5d (W, Re, Os, Ir, Pt) transition-metal (TM) atoms anchored Janus MoSSe monolayers for NRR is systematically explored by means of the first-principles calculations. A four-step NRR screening strategy (ΔG(*N₂) < 0 eV, ΔG(*N₂ → *NNH) < 0.50 eV, ΔG(*NH₂ → *NH₃) < 0.50 eV and ΔG(*N₂) < ΔG(*H)) is designed and applied to 15 TM-MoSSe systems, and only the Mo-, Re- and Os-MoSSe stand out. The reaction mechanisms of NRR on Mo-, Re- and Os-MoSSe are all via the distal pathway and exhibit excellent catalytic activity (with the limiting potentials of −0.49, −0.39 and −0.49 V, respectively), especially the Re-MoSSe. The high NRR activity of the Mo-, Re- and Os-MoSSe can originate mainly from the effective activation of N₂, high built-in electrical field and superior electrical conductivity. Present findings may suggest a reliable and effective NRR screening strategy for the design of NRR electrocatalysts and promote the further exploration and development of novel NRR electrocatalysts.

Movable oil, the critical factor for shale oil enrichment and effective production, is influenced by the pore structure and shale oil occurrence state. However, the pore spaces storing movable oil, the occurrence state of shale oil, and the lower flowing pore size for shale oil remained unclear. To address this knowledge gap, we chose the lacustrine organic-rich Chang7 shale of the Ordos Basin as the research target. By combining gas adsorption techniques (nitrogen and carbon dioxide) with Soxhlet Extraction, we investigated the pore structure alteration of Chang7 shale after Soxhlet Extraction. Based on a comprehensive analysis of mineralogical composition, TOC, and shale oil components, we discussed the pore space in which shale oil exists. Then, we established a slit-shaped clay model and clarified the occurrence state of multi-component shale oil in the pore space with the help of molecular simulation. Our investigation revealed that (1) Chang7 shale can be categorized into three distinct types. Type I, characterized by a high clay mineral content, possesses the greatest SSA and PV and has the highest abundance of movable oil, partially filling the “ink-bottle”-type pores. Shale oil in Type II and III shales mainly exists within slit-type pores. (2) The pore space of Chang7 shale is primarily comprised of mesopores rather than micropores. Moreover, mesopores’ PV and SSA are predominantly governed by clay minerals rather than organic matter. (3) A threshold pore size of 10 nm significantly impacts the occurrence state of shale oil in the Chang7 shale. Beyond this threshold, free oil accounts for over 80% of the total. Chang7 shale oil within micropores (<2 nm) is predominantly asphaltene, existing in an adsorbed state. Within pores sized 2 to 10 nm, shale oil is present in both adsorbed and free states, and the proportion of free-state shale oil increases with the pore size. Free-state shale oil prevails in pores exceeding 10 nm, with a smaller fraction adsorbed onto organic matter and mineral surfaces. Thus, we recommend adopting 10 nm as the lower flowing pore size limit for Chang7 shale.