ArchiveLignin-derived oxygenated aromatics, particularly phenols and aromatic ethers obtained through depolymerization, represent promising feedstocks for synthesizing high-density and high-heat-sink aviation fuels via alkylation-hydrogenation processes. This study systematically evaluates the catalytic performance of various zeolites (Hβ, HZSM-5, MCM-41 and HUSY) in the alkylation reaction of phenol with cyclohexanol. Characterization results demonstrate that HUSY zeolite showed superior catalytic activity compared to other zeolites, attributable to its favorable pore architecture and well-balanced acid site distribution that synergistically facilitate molecular diffusion and catalytic transformations. To further enhance the catalytic properties, HUSY zeolite was modified with citric acid at various concentrations and compared with those treated with NaOH and oxalic acid. The results revealed that citric acid treatment preserved the crystallinity of the zeolite while modulating its acid distribution and pore structure. All modified zeolites enhanced phenol alkylation activity. Notably, the HUSY-0.5M catalyst, which exhibited the highest medium-strong acid to total acid ratio, achieved superior catalytic performance, 80.4% conversion of phenol and 99.6% selectivity for alkylation products. The catalyst also exhibited high activity in the alkylation of various lignin-derived compounds, demonstrating its broad applicability. This work provides a new strategy for the valorization of lignin-derived phenols into high-value fuel precursors through alkylation.
Ammonia borane (AB) is an excellent hydrogen storage material with low molecular weight and high hydrogen content. To fully unleash its value, the development of low-cost and highly active catalysts for AB hydrolysis hydrogen production is precisely the core path to promote the industrialization of AB hydrolysis hydrogen production technology. This paper used anhydrous copper chloride as raw material, and prepared copper oxide nanosheets (CuO NS) precursor by solvothermal method under alkaline conditions. Through low-temperature phosphating method, CuO NS was converted into Cu3P@CuO nanosheets (Cu3P@CuO NS). The microstructure and structural composition of Cu3P@CuO NS were characterized by SEM, TEM, AFM, XRD and XPS. The effects of as-prepared Cu3P@CuO NS for hydrogen evolution reaction (HER) from AB hydrolysis were investigated. Additionally, the hydrogen evolution rate and turnover frequency (TOF value) of Cu3P@CuO NS catalyzed AB hydrolysis were explored under different reaction conditions. The results showed that when the phosphating ratio was adjusted to m (CuO NS)/m (NaH2PO2)=1 (m (CuO NS)=m (NaH2PO2)=0.1 g), Cu3P@CuO NS exhibited the optimal catalytic activity for AB hydrolysis. Cu3P@CuO NS exhibited a high turnover frequency (TOF), with a TOF value as high as 57.23 min−1 and an apparent activation energy of 44.31 kJ/mol. The hydrolysis of AB followed pseudo-first-order kinetics with respect to the catalyst dosage, while it exhibited pseudo-zero-order kinetics with respect to the AB dosage. The excellent performance exhibited by Cu3P@CuO NS could be attributed to the abundant active sites exposed by their nanosheet structure. Given the remarkably low cost of this catalyst, the Cu3P@CuO NS catalyst is highly anticipated to serve as a viable substitute for noble metal catalysts. It is poised to emerge as an ideal catalytic material for the hydrogen evolution reaction from AB, leveraging its cost-effectiveness and catalytic efficiency to address the challenges associated with high-cost noble metal-based systems.
To achieve the efficient utilization and development of red mud as a resource, this study used red mud as the raw material and starch as the carbon source. By employing sol-gel technology and carbon thermal reduction processes, FexOy/TiO2/C composite microwave absorption materials were successfully prepared. By adjusting the calcination temperature and raw material ratios, the minimum reflection loss value (RLmin) and effective absorption bandwidth (EAB) of the FexOy/TiO2/C composite material. Experimental results indicate that RmCT-5.4-700 exhibits the best microwave absorption performance, with RLmin reaching −30.2 dB and EAB reaching 5.3 GHz when the coating thickness is 2.0 mm. The excellent absorption performance of the FexOy/TiO2/C composite material stems from the synergistic effects of multiple loss mechanisms. Defects generated by carbon consumption during the carbon thermal reduction process provide dipole sites, thereby inducing dipole polarization phenomena, effectively dissipating electromagnetic wave energy and enhancing absorption performance. Graphitized carbon, Fe3O4, and Fe particles collectively form a conductive network, with electrons migrating and hopping within the network, thereby generating conductive loss. Additionally, Fe3O4, Fe and TiO2 particles are uniformly distributed on the red mud matrix, forming numerous heterogeneous interfaces, thereby inducing interface polarization. The magnetic loss characteristics of Fe3O4 and Fe particles effectively improve the impedance matching properties, enabling more electromagnetic energy to enter the composite material and be efficiently absorbed. The research approach in this work not only opens up new avenues for the resource utilization of red mud but also promotes the high-value utilization of solid waste.
In this paper, the Ni/Al2O3 monolithic catalyst with 15% Ni content was prepared using cordierite as a matrix, and the catalyst was modified with 10% NaOH to study the methanation performance of biomass gasification simulated gas based on alkali-modified Ni/Al2O3 monolithic catalyst. BET, TEM, H2-TPR, XRD, CO2-TPD and TG were used to characterize the physicochemical properties of the catalyst before and after modification. The results indicated that the CO conversion rate trends of unmodified and modified Ni/Al2O3 monolithic catalysts over 2 h were fundamentally consistent. However, the Ni/Al2O3 catalysts modified for 2 h demonstrated significantly enhanced performance compared to those modified for 1 h. Regarding CH4 selectivity, the modified Ni/Al2O3 catalyst exhibited markedly better performance than the unmodified Ni/Al2O3 catalyst, confirming the enhanced methane performance of the alkali-modified Ni/Al2O3 monolithic catalyst. Under optimized conditions (H2/CO volume ratio of 3∶1, space velocity of 10000 mL/(g·h), and temperature of 400 °C), the methanation performance of the Ni/Al2O3 monolithic catalyst modified for 2 h reached its peak, achieving a CO conversion rate of 97% with 100% CH4 selectivity.
CO2 capture and utilization (CCU) technologies have been recognized as crucial strategies for mitigating global warming, reducing carbon emission, and promoting resource circularity. As such, the design and development of related materials have attracted considerable research attention. Carbon-based materials, characterized by tunable pore structures, abundant active sites, high specific surface area, and excellent chemical stability, demonstrate significant potential for applications in CO2 capture and utilization. This review systematically analyzes the adsorption behaviors and performance variations of typical carbon materials, including activated carbon, porous carbon, graphene, and carbon nanotubes during CO2 capture processes. Concerning CO2 utilization, emphasis is placed on recent advances in the catalytic applications of carbon-based materials in key reactions such as methanation, reverse water-gas shift, dry reforming of methane, and alcohol synthesis. Moreover, the benefits and drawbacks of carbon materials in terms of CO2 adsorption capacity, catalytic activity, and stability are thoroughly evaluated, and their potential applications in integrated CO2 capture and utilization technologies are discussed. Finally, key strategies for enhancing the performance of carbonaceous materials through structural modulation and surface modification are elucidated. This review aims to provide theoretical guidance for the future development and large-scale implementation of carbon-based materials in CCU technologies.
The service life of refractory brick in the slag tapping hole of gasifiers is a significant concern for long-term and stable operation. This study examined the damage mechanism of high chromia refractory of four commercial coal-water slurry gasifiers with their corresponding gasification coal samples and the corroded refractory bricks in the slag tapping hole of the gasifier. The slag characteristic, including crystallization and viscosity-temperature of four gasification coal samples were analyzed. The results revealed that the low viscosity slag could lead to more severe damage to refractory bricks. Given the risk of slag crystallization, it is recommended to establish a safe slag tapping temperature range should be set as tICT (initial crystallization temperature) − t2.5 when tICT is higher than t25. Upon examining interior morphology of these corroded refractory bricks, some cracks were observed within them. The chemical composition of molten slag was analyzed using SEM-EDS. However, XRD results found no spinel containing zirconium in these cracks. This suggests that the emergence of these cracks are mainly attributed to the molten slag penetration and the subsequent reaction with the refractory material. The difference in thermal expansion between the newly formed substances and refractory material is critical in forming these cracks. Furthermore, SEM-EDS analysis was also conducted on the slag-aggregate and the slag-matrix interface. The results reveal that the reduction in Cr2O3 content is the earliest characteristic of damage in high chromia refractories. A proposed damage mechanism of refractory brick suggests that the matrix and aggregate of high chromia refractory are initially compromised because of the reduced Cr2O3 content. Subsequently, the molten slag penetrates the interior of the refractory brick, forming new substances, leading to damage caused by the difference in thermal expansion between the new substances and the refractory brick. Understanding and preventing the reduction of Cr2O3 content is vital to prolonging the service life of refractory brick in the slag tapping hole of the gasifier based on this damage mechanism.
In this study, melamine and cyanuric acid were used as precursors to form supramolecular crystals via hydrogen-bond-assisted self-assembly followed by hydrothermal treatment. Subsequent high-temperature calcination yielded a novel brush-like three-dimensional carbon nitride. The brush-like 3D architecture was found to expose more accessible active sites, markedly accelerate electron transfer, and suppress the recombination of photogenerated charge carriers. The resulting superoxide (
Endogenous alkali and alkaline earth metals (AAEMs) in biomass ash and pyrolysis temperature have a significant impact on the properties of pyrolysis polygeneration products. In this study, alkali metal (potassium) and alkaline earth metal (calcium) were selected as representative metals of AAEMs. Potassium ions (K+) and calcium ions (Ca2+) at different concentrations (2%, 5%, 7%) were added to corn stover via the impregnation method, and fixed-bed pyrolysis experiments were conducted at 400, 500 and 600 ℃ to systematically investigate the yields and compositions of pyrolysis gas, liquid, and solid products. The results showed that in terms of the effect of concentration, with the increase of metal ion concentration, the biochar yield increased significantly—when the concentration of Ca2+ was 7%, the biochar yield reached 24.96%—while the bio-oil yield generally decreased. Due to its strong Lewis acidity, Ca2+ significantly promoted the formation of H2 (accounting for 32.49% in the gas phase at 7% concentration) and facilitated the enrichment of furan compounds to 65.88%. For K+, low concentrations were conducive to the formation of phenolic substances, while high concentrations promoted the generation of ketone compounds and intensified bio-oil cracking. In terms of the effect of temperature, as the pyrolysis temperature increased from 400 to 600 ℃, the biochar yield decreased, while the gas yield increased continuously. In addition, high temperatures promoted the secondary cracking and reforming reactions of volatiles, significantly increasing the yields of H2 and CH4 while inhibiting the formation of oxygen-containing components. Specifically, at 600 ℃, catalysis by K+ increased the content of acidic substances to 39.41%, whereas catalysis by Ca2+ increased the content of furan compounds to 65.89%. This study realized the directional regulation of high-value components in bio-oil and high-energy gases by adjusting the concentration of metal ions and pyrolysis temperature, providing a theoretical basis for the optimized utilization of biomass pyrolysis products.
The successful development and application of CO2 hydrogenation to light olefins can not only alleviate the environmental issues caused by the massive emission of greenhouse gases, but also open up a new way for the preparation of important high-value chemicals. Due to the chemical inertness of CO2 molecules, selectively activation and conversion of CO2 into target light olefins remain highly challenging. In this work, we review the current research progress in the hydrogenation of CO2 to light olefins, with a focus on analyzing the advantages and disadvantages of the Fischer-Tropsch synthesis (CO2-FTO) route and the methanol intermediate (CO2-MTO) route. The key factors, such as the type of additives, the structure of the carrier and the concentration of surface defect sites, affecting the activation of CO2 and the formation of light olefins are discussed in detail. Meanwhile, essential role of the pore structure and acidity of zeolites in conversion of methanol intermediates to olefins is analyzed.
This study aims to investigate the influence of the thermochemical conversion behavior of microalgae pellet in molten hydroxide salts (80% NaOH-20% Na2CO3) on hydrogen production. By comparing the temperature evolution, gas release characteristics, and structure evolution of pellet with and without molten salt, and combining with char alkalization experiments, the regulatory mechanism of molten salt on the reaction pathways and hydrogen production behavior of microalgae pellet was systematically analyzed. The results indicate that the molten salt significantly enhances the internal heat transfer efficiency of the pellet, with a central heating rate reaching 177 ℃/s, effectively alleviating thermal hysteresis. Meanwhile, the molten salt promoted pellet pore development through penetration, erosion, and catalytic effects, resulting in a porosity increase of 53.2%–104.3% after 10 s of reaction. It also significantly enhanced the conversion efficiency, with the dominant reaction pathway shifting to char gasification after only 70 s. Furthermore, when the heating rate was increased above 600 ℃, the hydrogen yield from char alkalization improved more markedly, primarily attributed to the synergistic promotion effect of the molten salt’s catalytic effect and the rapid heating process on the volatiles reforming. This study provides a theoretical foundation for a deeper understanding of the mechanisms behind efficient hydrogen production from biomass in molten hydroxide salts.
This study systematically conducted preparation optimization and performance investigations on Co-modified Ce/TiO2 catalysts, with a focus on examining how preparation methods and Co loading regulate the catalyst’s low-temperature denitrification activity. After identifying optimal preparation parameters via condition screening, multiple characterization techniques-including BET, XRD, XPS, H2-TPR and in situ DRIFTS-were employed to deeply analyze the catalyst’s physicochemical properties and reaction mechanism. Results demonstrated that compared to the impregnation and co-precipitation methods, the Ce-Co0.025/TiO2-SG catalyst (prepared by the sol-gel method with a Co/Ti mass ratio of 0.025) exhibited significantly superior denitrification activity: NO conversion remained stably above 95% in the 225−350 °C temperature range, and it displayed high N2 selectivity. Characterization analysis revealed that abundant surface oxygen vacancies, a high proportion of Ce3+ species, and prominent acidic sites collectively contributed to enhancing its low-temperature denitrification performance. This work provides reference value for the development of highly efficient low-temperature denitrification catalysts.
Pyrolysis is an important approach for achieving graded conversion of low-rank coal. However, the volatiles generated during this process are rich in oxygenated compounds and heavy components, which lead to low efficiency in direct utilization. Selecting appropriate catalysts for catalytic reforming of large molecules in volatiles can facilitate the upgrading of tar into lighter fractions, thereby simplifying the tar processing flow. This study proposes a tandem catalytic system combining metal oxides and zeolites. Through synergistic catalysis between the two catalysts, the pyrolysis volatiles of lignite are efficiently and selectively converted into light aromatics (such as benzene, toluene, ethylbenzene, xylene, naphthalene, methylnaphthalene, etc.). Simultaneously, pre-cracking effectively removes oxygenated components, reducing carbon deposition on the zeolite and extending the catalyst’s lifespan. Research demonstrates that MgO, a metal oxide with strong alkalinity, significantly enhances the cracking and deoxygenation of volatiles; compared to using ZSM-5 alone, the addition of MgO in the upper layer significantly increases the yield of light aromatics while maintaining the original proportion of liquid products. The total yield of light aromatics rose by approximately 20%, reaching 21.5 mg/g. Furthermore, the incorporation of metal oxides effectively reduces carbon deposition on the zeolite, prolonging the catalyst's lifespan.
The global energy landscape is undergoing a profound transformation, with wind energy, especially wind power, gaining increasing prominence due to its clean, renewable nature. However, as the installed capacity of wind power continues to expand, the disposal of waste wind turbine blades (WWTB) has emerged as a significant challenge. These blades are predominantly composed of epoxy resin (EP) polymers, carbon fibers (CFs), and glass fibers (GFs). Improper disposal not only exacerbates environmental concerns but also leads to the loss of valuable resources, particularly carbon-based materials. Pyrolysis technology, a versatile and environmentally sustainable method for resource recovery, has garnered considerable attention in the context of WWTB disposal. This work presents a comprehensive review of the pyrolytic recycling of WWTB, focusing on the principles and classifications of pyrolysis technology, key factors influencing the pyrolysis process, as well as the pyrolysis methods, equipment, products, and their applications. Through an in-depth analysis of the current research on the pyrolytic recycling of WWTB, this review identifies critical unresolved issues in the field and provides a forward-looking perspective on emerging research trends.
Electrocatalytic CO2 reduction reaction (CO2RR) is regarded as an effective approach to reduce CO2 emissions and produce various high-value compounds. In this study, a Cu-Sn alloy catalyst with a wheat-ear-like dendritic structure was prepared via a simple one-step electrodeposition method and used for the selective electro-reducing CO2 to formate. Experimental results demonstrate that, compared to Cu and Sn electrodes, the Cu-Sn alloy catalyst exhibits higher catalytic activity and selectivity toward formate due to its unique wheat-ear-like structure, which could provide abundant active sites for the reaction process. The Faradaic efficiency for formate reaches up to 80%, and remains above 70% within the potential range from −1.7− −2.0 V. Combined electrochemical data and XPS analysis revealed that Cu and Sn atoms collectively modulate the adsorption of the CO2*− intermediate during the electroreduction process. Therefore, this simple preparation method offers a new pathway for the design of bimetallic catalysts for CO2RR.
As a key component of shale oil, petroleum fractions, and chemical products, the oxidative pyrolysis behavior of paraffin directly influences energy conversion efficiency and the direction of process optimization. A deep understanding of its oxidative pyrolysis mechanism is crucial for addressing wax deposition in oil and gas extraction, enhancing product selectivity in cracking processes, and advancing novel clean fuel technologies. Traditional experimental methods face challenges in capturing transient free-radical reaction pathways at high temperatures, whereas molecular dynamics simulations offer a powerful approach to bridge the research gap in elucidating atomic-scale dynamic mechanisms. This database is constructed based on high-precision molecular dynamics simulations, comprising oxidative pyrolysis trajectory data for three paraffin models featuring different straight-chain hydrocarbon distributions within the temperature range of 2100–2500 K. The COMPASS force field was employed to optimize the initial structures, and the ReaxFF reactive force field was used to simulate the oxidative pyrolysis process. The database includes atomic trajectories, species evolution information, and reaction network analysis results for both heating and isothermal cracking processes, with a total data volume of approximately 141 GB (including 150000 atomic configuration frames). The data is stored in a hierarchical directory structure, supporting multi-scale oxidative pyrolysis mechanism studies and providing atomic-scale dynamic evidence for revealing carbon chain length effects and temperature sensitivity.
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