Pressurized fluidization reactors have been widely applied in industry. Thermal CFD-DEM simulations were performed to investigate the effects of operating pressure and superficial velocity on wall-to-bed heat-transfer coefficient (h(w)), with emphasis on the link between heat-transfer performance and hydrodynamic mechanism. The simulations were validated by comparing numerical results and empirical correlations. It was found that hw increased with decreasing particle size and increasing operating pressure, in good agreement with empirical predictions, with a maximum relative error of <23 %. Specifically, as the operating pressure increased from 1 to 80 bar, hw increased by 142 % for coarse particles with a diameter of 300 mu m, and by 77 % for fine particles with a diameter of 100 mu m. Analysis of gas-bubble behavior revealed that increasing pressure generally reduced gasbubble size and improved fluidization quality, yet had minimal impact on gas-bubble rising velocity. However, these changes alone could not fully explain the observed enhancement in heat transfer. Instead, a clear and direct link was identified between improved heat-transfer performance and enhanced particle dispersion in pressurized beds, highlighting the role of particle-scale motion in thermal enhancement. As the pressure increased from 1 to 80 bar, the particle dispersion coefficient increased by 5.9 times for coarse particles and 2.5 times for fine particles. In addition, the particle temperature uniformity was improved with increasing gas velocity. The volcano-shaped hw curve was thereof attributed to the competitive effects between particle dispersion ability and the number of effective heat-transfer particles.

The twisted-tape based vortex tube is recognized as a promising reactor for the highly energy-intensive steam cracking process. This study develops a short-length twisted tape, hereinafter termed the diameter-transformed vortex generator (DTVG), to reorganize decaying swirling flow through the coupling of bulk rotating flow and longitudinal vortices. Computational fluid dynamics with the RNG k–ε turbulence model was used to investigate macroscopic transport behavior, vortex structure evolution, sectional thermal–hydraulic performance and entropy generation. Based on vortex evolution, the DTVG vortex tube can be divided into induction, twin vortex and single vortex decay sections. This sectional swirling flow reorganization transforms the induction section into a vortex regulation region rather than a strong mixing region, while shifting the main heat transfer benefit to the twin vortex decay section. There, robust helical longitudinal vortex pairs promote wall-to-core transport, and near-wall shear renews the thermal boundary layer, yielding the highest Nusselt number and performance evaluation criterion values of 306.753 and 1.163, respectively. Entropy generation analysis further provides thermodynamic evidence for this functional transformation: compared with hollow twisted tape and conventional twisted tape, global entropy generation in the DTVG induction section is reduced by 21.7% and 21.3%, and frictional entropy generation by 42.3% and 43.4%, indicating suppressed premature mechanical energy dissipation during vortex initiation.

The development of highly efficient nanozymes faces challenges of insufficient catalytic activity and low atom utilization. Atomically dispersed metal nanozymes have received widespread attention due to their high atomic utilization efficiency and exceptional catalytic activity. Bimetallic catalysts demonstrated enhanced catalytic performance owing to synergistic geometric and electronic effects arising from heterometallic interactions. Herein, we report an atomically dispersed palladium-iron bimetallic cluster nanozyme, in which fully exposed Pd clusters bonded to adjacent Fe atomic clusters are anchored onto defect-rich nanodiamond-graphene supports (PdFe/ND@G). The Pd-Fe interfacial sites fabricated in atomically dispersed bimetallic clusters deliver abundant oxygen activation sites for high-efficiency catalytic reactions and exhibit enhanced oxidase-like catalytic activity, demonstrating superior enzymatic activity and antibacterial performance compared to monometallic Pd and Fe clusters, while surpassing those of previously reported nanozymes. DFT calculations reveal that, compared to monometallic Pd clusters, atomically dispersed Pd-Fe clusters synergistically catalyze O2 cleavage into OO* intermediates via PdFe interfacial sites while exhibiting lower energy barriers, which is the critical factor for their enhanced enzyme-like activity. This study provides novel insights into constructing highly efficient atomically dispersed bimetallic cluster nanozymes. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

This study investigates the selective oxidation behavior of 35Cr45NiNb alloy, a critical high-temperature material widely used in ethylene cracking furnace tubes and other petrochemical heating equipment due to its superior creep resistance and carburization resistance at temperatures above 900 degrees C, in a H2-H2O atmosphere at 950 degrees C. The morphological evolution and compositional changes of the oxide scale were systematically analyzed using multi-scale characterization techniques. The oxide scale exhibits a triple-layer structure from outer to inner: MnCr2O4, Cr2O3, and amorphous SiO2. The distribution of amorphous SiO2plays a critical role in the growth of the oxide scale. During the initial oxidation stage (before 2 h), a locally continuous SiO2 film forms on the austenite matrix surface, inhibiting further oxidation of the alloy substrate. However, the secondary M7C3 phase in the alloy contains no Si, preventing the formation of a continuous SiO2 oxide film on its surface. Consequently, Cr and Mn elements continue to oxidize, forming oxide nodules. As the surface matrix elements deplete due to oxidation, the austenite matrix gradually transforms into ferrite. The critically annealed ferrite retained during subsequent cooling undergoes epitaxial growth. This epitaxial ferrite penetrates the amorphous SiO2oxide film, and upon exposure to the oxidizing atmosphere, forms new oxide nodules. During the simulated coking process, these mechanisms expose Fe and Ni elements in the alloy to the coking atmosphere, leading to catalytic coking. For sandblasted samples with increased specific surface area, the formation of a continuous amorphous SiO2 film is delayed in the short term, providing additional pathways for the oxidation of Mn and Cr elements. The anti-coking performance of the oxide scales on both types of samples was compared. Experimental results confirm that the oxide scale on sandblasted samples more effectively blocks the catalytic coking reactions between transition metal elements (such as Fe and Ni) and the cracking atmosphere, providing valuable insights for optimizing surface pretreatment processes to extend the service life of cracking furnace tubes in industrial applications.

Toward carbon neutrality, low-carbon synthesis routes for valuable chemicals are critically important. C4 hydrocarbons, which are key to the petrochemical industry, are currently produced through energy-intensive processes. Photocatalytic ethane coupling offers a green route from ethane to C4 hydrocarbons, but selectively activating inert C-H bonds (415 kJ/mol) over weaker C-C bonds (347 kJ/mol) by photocatalysis remains challenging. This work reports an effective strategy of Auδ+-Au relay-promoted charge transfer and the synergy of light irradiation (photons) and heating (mainly phonons) for inert C-H bond activation toward butane synthesis. Furthermore, femtosecond-nanosecond time-resolved spectroscopy analysis shows that Auδ+-Au relay remarkably accelerates hole transfer by 1000 times (from ∼nanosecond to ∼picosecond time scale), thus dramatically facilitating charge carrier separation. Together, the synergy of light irradiation (photons) and heating (mainly phonons), even with a gas hourly space velocity of 2,400,000 mL h-1 g-1 and a butane yield of 166.5 mmol/g/h (1665 μmol/h), has been achieved, which is 8.2-fold higher than that of Au/CeO2. A remarkable turnover number (410,000) with respect to Auδ+-Au clusters and a high selectivity (85%) for butane have also been obtained. Such an Au-Auδ+/CeO2 catalyst is also rather stable (≥100 h). Fundamentally, it is found that heating can remarkably enhance the coupling process, boosting butane production by 3.3 times. Overall, Auδ+-Au relay-promoted synergy of light irradiation and heating enables the highly selective activation of inert C-H bonds under mild conditions.

The selective hydrogenation of acetylene to ethylene is a critical industrial process for purifying ethylene feedstocks. Palladium single-atom catalysts (Pd SACs) exhibit exceptional ethylene selectivity in this hydrogenation reaction. However, their isolated active sites show limited ability to capture and adsorb trace acetylene molecules from ethylene-rich streams, resulting in relatively low hydrogenation activity. To overcome this limitation, we designed Pd single-atom catalyst on the SiO 2 surface modified with amino nests (Pd 1 /SiO 2 -NH 2 ). In this architecture, Pd single atoms are embedded within amino nests on the surface of SiO 2 -NH 2 support. Combined experimental and density functional theory (DFT) calculations reveal that amino nests selectively capture and adsorb acetylene molecules from ethylene-rich streams, facilitating the key acetylene adsorption step. The Pd─N bonds formed between the amino nest and the Pd atom promote hydrogen activation. At 190 °C, the Pd 1 /SiO 2 -NH 2 catalyst achieves complete acetylene conversion with the ethylene selectivity of 92%. Remarkably, it delivers a specific activity of 1900.36 mol C2H2 −1 mol Pd −1 min −1 , surpassing all previously reported SACs. This work establishes an amino nest-assisted design paradigm for single-atom catalysts, enabling efficient, selective semi-hydrogenation of acetylene.

In this Activity article, Prof. Lichen Liu (associate professor at Tsinghua University) and Prof. Guoqing Wang (chief research fellow of the SINOPEC group at the SINOPEC [Beijing] Research Institute of Chemical Industry) exchange views from industrial and academic perspectives on the trends in ethylene production in the chemical industry and the current challenges in developing advanced oxide- and zeolite-based catalysts for ethylene production through catalytic cracking. Furthermore, they give perspectives on the alternative processes for ethylene production and the promising directions in catalyst design and process engineering.

In this Activity article, Prof. Guoqing Wang (chief research fellow of the SINOPEC group at the SINOPEC [Beisity) exchange views from industrial and academic perspectives on the current status of the ethylene value chain and discuss the emerging trends in the downstream markets. Furthermore, they give perspectives on the opportunities and challenges in designing efficient catalysts for the downstream processes for converting ethylene into value-added chemicals and materials.

The catalytic activity and deactivation characteristic of spherically shaped Mo/H-ZSM-5 particles in the non-oxidative dehydroaromatization of methane was evaluated in a fluidized bed reactor under different cyclic reaction-regeneration operation modes. The aim is to verify the superiority of the H2 regeneration approach over that oxidative approach in restoring the catalytic performance of coke-deactivated Mo/H-ZSM-5 catalyst. Compared with the fresh catalyst, the catalyst samples oxidatively regenerated at 973 and 1073K exhibited at 1073K a largely reduced initial activity and an obviously accelerated deactivation rate. By contrast, the catalyst sample regenerated in a H2 stream at 1073K maintained basically the initial activity level and deactivation characteristic of the fresh catalyst over cycles. Oxidatively regenerated at a lower temperature of 773K, the catalyst sample was allowed to maintain the initial high activity of the fresh catalyst but its deactivation rate estimated over a 20min reaction period showed an obvious tendency to increase with increasing the number of regeneration cycles. Characterization of all spent catalyst samples using TG, XRD and NMR techniques revealed that a significant loss of active Mo sites via sublimation and/or formation of inactive Al2(MoO4)3 and local collapse of zeolite framework occurred to the two samples once oxidatively regenerated at 973 and 1073K, while neither Mo loss nor framework breakdown was detected with the H2-regenerated sample. Additionally, the formation of disordered non-framework Al was found to occur to the two samples once oxidatively regenerated at 773 and 873K. All these suggest that applying the H2 approach to regenerate coke-deactivated Mo/H-ZSM-5 enables the catalyst to avoid losing any of its active Mo sites in its cyclic regeneration process and therefore must be helpful for maintenance of its catalytic performance over the reaction-regeneration cycles.

Three series of 2-8 % Mo/HZSM-5 catalysts were prepared using zeolites with different crystal sizes and Si/Al ratios. These catalysts were characterized by XRD, SEM, BET, and NH3-TPD techniques and tested for methane dehydro-aromatization at 1073 K. Characterization results indicated that, with an identical Mo loading, two nanozeolites retain more Mo species on their external surface and fewer Mo species within their channels than the microsized zeolite. Catalytic performance tests showed that the optimal Mo loadings for the two nanozeolitebased catalysts differ. While one loading is identical to that for the microzeolite-based catalyst, the other is two percentage points higher. However, at their respective optimal loadings, the nanozeolite-based catalysts exhibited lower benzene formation activities and selectivities than the microzeolite-based catalyst. TG measurements of spent catalysts and catalytic pyrolysis of benzene over the three Mo/HZSM-5 catalysts revealed that the nanozeolite-based catalysts exhibit a higher activity for pyrolysis of benzene to external coke than that of the microzeolite-based one. These findings suggest that the zeolite external surface area significantly influences Mo distribution, optimal Mo loading, external coke capacity, and the aromatic selectivity and catalytic stability of the catalysts.

Hydrogenation of CO2, an abundant C1 resource, into formate, is one of the most charming utilization routes of CO2. Herein, a series of single Ru-P site catalysts coupling N sites (denoted as Ru/P&N-POPs) were designed and applied in the highly effective hydrogenation of CO2 to formate. The Ru (II) ions were firmly anchored and finely regulated by P sites in the polymeric skeleton, while the original N species surrounding single Ru-P active sites enriched and activated CO2. Besides, C-13{1H} R-type RF irradiation and two-dimensional separated local field (2D R-SLF) experiments proved the good flexibility of P&N-POPs frameworks, which were beneficial for optimizing the orientation of functional sites and the synergy of abundant Ru-P active species and N species. As a result, a ca. 2000 h(-1) TOF of CO2 and at least 5 recycles were achieved in the formate synthesis under 393 K and 6.0 MPa (CO2/H-2 = 1:1). Multiple characterization methods including mass nuclear magnetic resonance, extended X-ray absorption fine structure, scanning transmission electron microscopy, in situ Fourier transform infrared, etc. were employed to reveal the mechanism for the catalytic performance of Ru/P&N-POPs.

Semihydrogenation of acetylene to ethylene is a key process for ethylene purification in the chemical industry. The pursuit of an effective non-noble metal acetylene selective hydrogenation catalyst with low cost, high efficiency, and ultrastability is extremely urgent, especially for industrial applications. However, achieving high ethylene selectivity at full conversion under a low reaction temperature remains challenging due to the imbalance of the H-2 splitting ability and intermediate (ethylene) hydrogenation. Herein, we designed atomically dispersed and fully exposed Ni clusters on a nanodiamond@graphene support. H-2-D-2 exchange experiments and density functional theory calculations reveal that acetylene and hydrogen can be efficiently activated on fully exposed Ni cluster sites due to the enhanced catalytic hydrogenation catalytic ability. Furthermore, the desorption of ethylene on fully exposed Ni cluster sites is much more favored compared to further dissociation of H-2, leading to the high selectivity of ethylene. Thereby, the fully exposed Ni cluster catalyst delivered an ethylene selectivity of 85% at full conversion for semihydrogenation of acetylene at 190 degree celsius with a specific activity of 667 mL(C2H2)g(Ni)(-1)min(-1), exceeding the catalytic efficiency of most supported Ni catalysts. The implementation of the fully exposed Ni cluster catalyst provides an effective strategy for improving the catalytic efficiency of non-noble metal acetylene selective hydrogenation catalysts while obtaining high ethylene selectivity. The precise regulation of metal active sites at the subnanometer scale has a significant effect on the rational design of high catalytic performance atomically dispersed non-noble metal catalysts.

目前应用管式裂解炉热裂解烃类制乙烯是世界上广泛应用的乙烯生产方法,生产的乙烯占全球乙烯产量的九成多.但是,用管式裂解炉裂解生产乙烯的方法具有一定的限制.介绍了用于蒸汽裂解制乙烯各种技术的进展与存在的问题,重点阐述了其中的激波裂解技术原理、发展与现状,包括激波反应器发展历程、技术思路、技术现状与未来趋势,分析了目前有一定代表性的以激波压缩机为原型的新型激波反应器的原理、结构及裂解性能,并对其产品收率优势和存在问题进行了分析;还利用所建立的一维模型进行数值模拟,从产率和运行周期两方面对激波反应器与管式炉进行对比.

1,6-己二腈/1,6-己二胺合成技术为我国关键技术.综述了国内外合成1,6-己二腈/1,6-己二胺的技术进展,比较了1,4-丁二烯氢氰化法、丙烯腈电解二聚法、1,6-己二酸氨化脱水法和 1,6-己二醇氨化法四种合成技术路线,分析了国内外工业现状.国内很多企业布局了 1,6-己二腈/1,6-己二胺产业化,多条技术路线研发和产业化齐头并进,但产业水平仍需提高.

Anti-coking oxide films were prepared on a 25Cr35Ni and 35Cr45Ni alloy surface under the low oxygen partial pressure atmosphere of a H2-H2O mixture.The composition and phase structure of the oxide films were analyzed by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The anti-coking performance of a mini tube made of a HP40(25Cr35Ni)alloy was evaluated on a bench scale pyrolysis and coking test unit.The results showed that the surface Fe and Ni content decreased after the oxidation of the two alloys in a low oxygen partial pressure atmosphere.The oxide films were mainly composed of MnCr2O4 and Cr2O3.The average mass of coke in the mini tube with oxide film decreased by 87％relative to that of a tube without an oxide film when the cracking temperature was 900℃.The ethylene,propylene,and butadiene yields in the pyrolysis tests were almost the same for the mini tubes with and without an oxide film.The oxide film on the alloy surface effectively inhibited catalytic filamentous coke formation.An industrial test showed that the run length of the cracking furnace with the in-situ coating technology was significantly extended.

纳米金刚石具有弯曲、富缺陷的sp2/sp3 界面结构,在烃类转化反应中展现出传统金属/金属氧化物所不具备的优异性能,无论是作为催化剂,还是作为催化剂载体,均表现出明显的优势.简要介绍了纳米金刚石的制备方法、表面性质和调控手段,重点介绍了该材料及其衍生物作为催化剂或催化剂载体在丙烷、丁烷、乙苯直接脱氢和氧化脱氢及炔烃选择加氢等重要烃类转化反应中的应用情况,简要阐述了纳米金刚石材料用于催化领域存在的不足,并展望了它的应用前景.

石墨烯及衍生材料凭借独特的结构和卓越的电学、光学和力学性质,已成为国内外催化领域研究的热点.综述了石墨烯及衍生材料的合成方法,并探讨了它在催化领域中的应用,包括氧化石墨烯、还原氧化石墨烯、掺杂石墨烯以及其他石墨化碳材料作为活性组分载体或直接作为非金属催化剂用于催化反应的研究进展,讨论了它们应用于催化反应研究中存在的问题.最后展望了石墨烯在催化领域中的研究方向.

The atomically dispersed metal catalyst or single-atom catalyst (SAC) with the utmost metal utilization efficiency shows excellent selectivity toward ethylene compared to the metal nanoparticles catalyst in the acetylene semi-hydrogenation reaction. However, these catalysts normally work at relatively high temperatures. Achieving low-temperature reactivity while preserving high selectivity remains a challenge. To improve the intrinsic reactivity of SACs, rationally tailoring the coordination environments of the first metal atom by coordinating it with a second neighboring metal atom affords an opportunity. Here, we report the fabrication of a dual-atom catalyst (DAC) that features a bonded Pd1-Cu1 atomic pair anchoring on nanodiamond graphene (ND@G). Compared to the single-atom Pd or Cu catalyst, it exhibits increased reactivity at a lower temperature, with 100% acetylene conversion and 92% ethylene selectivity at 110 °C. This work provides a strategy for designing DACs for low-temperature hydrogenation by manipulating the coordination environment of catalytic sites at the atomic level.

介绍了聚四氟乙烯微孔膜的制备工艺和造孔方法,并对其在医疗卫生领域的相关研究成果及应用情况进行了总结和综述,对聚四氟乙烯微孔膜行业未来的发展方向和机遇进行了探讨.