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Globally, the rise in the environmental awareness on the reduction of greenhouse gas emissions has spurred the development of carbon capture and utilization (CCU) technologies, including membrane separation. Among the membrane separation technologies, dual-phase carbonate membrane is feasible for post-combustion carbon capture given its high thermal and chemical stabilities at high temperatures. The integration of carbon capture and dry reforming of methane (DRM) in a catalytic dual-phase carbonate membrane reactor to function as a single device for syngas production is an emerging area of research. This paper aims to provide a comprehensive review on the progress of the dual-phase carbonate membranes and membrane reactors in carbon capture and syngas production. The working mechanism and performance of three types of carbonate membranes in CO2 separation from various aspects (i.e., material selection, membrane configuration, modifications on the materials, and operating conditions) are thoroughly examined. Additionally, an overview of the reactions involved (i.e., DRM, steam reforming of methane (SRM), and partial oxidation of methane (POM)) and catalyst design (i.e., nickel-based supported with metal oxides and zeolites) is provided. A detailed comparison of the performance of the catalytic dual-phase ceramic-carbonate membrane reactor using different types of catalysts for syngas production is presented. Finally, the review is concluded with a discussion of the challenges, recommendations, and future insights on the development of dual-phase carbonate membranes and membrane reactors.

Methane (CH4) serves as a primary constituent of natural gas and a potent greenhouse gas. Catalytic conversion of CH4 into H2 presents a promising avenue for mitigating CO2 emissions from direct CH4 combustion, while also facilitating the transition towards cleaner energy sources. Substantial efforts have been dedicated to enhancing the efficiency of methane conversion and the selectivity for hydrogen in catalyst design. Among these endeavors, core-shell structured Ni-based catalysts have emerged as highly advantageous catalysts for CH4 conversion, with a multitude of benefits including high catalytic activity, coking resistance, and longtime stability. In this review, we provide an overview of Ni-based core-shell catalysts. Furthermore, the synthesis methods of core-shell Ni-based catalysts are explored. We then delve into the myriad advantages these core-shell structured catalysts confer upon methane conversion, specifically emphasizing their remarkable stability and resistance to sintering, and CO2 activation capacity in dry reforming of methane. Moreover, this review comprehensively outlines the versatile applications of Ni-based core-shell structured catalysts in processes such as steam reforming of methane (SRM), dry reforming of methane (DRM), partial oxidation of methane (POM), and catalytic methane decomposition (CMD) for H2 production. Additionally, we delve into the recent advancements in the field of computational chemistry, with a particular focus on density functional theory (DFT) and machine learning (ML). These techniques play pivotal roles in screening Ni-based catalysts and offer insights into the intricate reaction mechanisms underlying methane conversion. Finally, we summarize the key findings of this review and provide forward-looking perspectives. This comprehensive review serves as a valuable reference in the realm of hydrogen production from methane on core-shell structured catalysts, fostering a deeper understanding of this promising area.

Abstract Feedstock properties play a crucial role in thermal conversion processes, where understanding the influence of these properties on treatment performance is essential for optimizing both feedstock selection and the overall process. In this study, a series of van Krevelen diagrams were generated to illustrate the impact of H/C and O/C ratios of feedstock on the products obtained from six commonly used thermal conversion techniques: torrefaction, hydrothermal carbonization, hydrothermal liquefaction, hydrothermal gasification, pyrolysis, and gasification. Machine learning methods were employed, utilizing data, methods, and results from corresponding studies in this field. Furthermore, the reliability of the constructed van Krevelen diagrams was analyzed to assess their dependability. The van Krevelen diagrams developed in this work systematically provide visual representations of the relationships between feedstock and products in thermal conversion processes, thereby aiding in optimizing the selection of feedstock and the choice of thermal conversion technique.

ABSTRACTNanoparticles composed of metallic cores encapsulated in oxide shells emerged in the last decade as an attractive class of nanocomposite materials due to their high stability and unique properties provided by the high contact area between the metal and oxide components. Diverse metal-oxide interactions in metal@oxide core@shell nanoparticles enable tuning their electronic structure, spectroscopic properties, and surface reactivity for applications in sensing, electrochemistry, batteries as well as thermal and photocatalysis. Herein, we review the recent literature on the synthesis, characterization, simulations, and applications of metal@oxide nanocomposites. In particular, we discuss how the properties of metal@oxide nanoparticles can be tuned for a given application by changing the size of the metal core, the thickness and porosity of the oxide shell, as well as their composition, e.g. by alloying the core or doping the shell. Understanding of structure-property relations in metal@oxide systems provides vast opportunities for the rational design of advanced metal@oxide nanocomposites, making this class of materials promising for a wide range of applications.

Anaerobic digestion presents a viable approach for managing biodegradable waste. However, the process generates a significant amount of digestate, which, if not appropriately managed, can contribute to eutrophication and salinization. This research explores the integration of hydrothermal carbonization (HTC) and pyrolysis as a potential solution for digestate management, emphasizing volume reduction and energy recovery. The study specifically focuses on the production of biochar from agricultural waste digestate (AWD) in an energy-efficient manner. Utilizing HTC as a pretreatment was found to enhance the heating value of both the AWD and the subsequent pyrolytic char, and it also improved the carbonization degree of the resulting char. Energy balance analysis revealed that the pyrolysis of AWD shifted from an endothermic to an exothermic reaction upon HTC pretreatment. This transition decreased the reaction's energy absorption from 41.1 to 1557.6 MJ to an energy release of 685.1 to 960.6 MJ per ton of digestate, thereby optimizing energy consumption in digestate management. Additionally, it was noted that using acetone as a solvent in gas chromatography for biooil samples with high ammonia content led to the formation of diacetonamine, an outcome that is deemed undesirable.

Abstract In the past decades, machine learning (ML) has impacted the field of electrocatalysis. Modern researchers have begun to take advantage of ML‐based data‐driven techniques to overcome the computational and experimental limitations to accelerate rational catalyst design. Hence, significant efforts have been made to perform ML to accelerate calculation and aid electrocatalyst design for CO2 reduction. This review discusses recent applications of ML to discover, design, and optimize novel electrocatalysts. First, insights into ML aided in accelerating calculation are presented. Then, ML aided in the rational design of the electrocatalyst is introduced, including establishing a data set/data source selection and validation of descriptor selection of ML algorithms validation and predictions of the model. Finally, the opportunities and future challenges are summarized for the future design of electrocatalyst for CO2 reduction with the assistance of ML.

In this study, nodular cast iron parts, grinding balls, and NaHCO3 powder were placed together in a ball milling cylinder to perform the coordinated pretreatment of ball-milling and pre-oxidation. And then the cast iron parts were hot-dipped galvanized to study the synergy of ball-milling and pre-oxidation on the microstructure and corrosion resistance of the coating. The results showed that after pre-oxidation at 300 °C, Si on the surface of nodular cast iron is oxidized to form SiO2, Fe is not oxidized, and the substrate surface is selectively oxidized. After the non-oxidization sample is pickled, its surface Si content is 2.88 wt. %. After the pre-oxidized sample is pickled, its surface Si content is 2.07 wt. %. After the synergy of ball-milling and pre-oxidation, the surface Si content on the cast iron is 1.52 wt. %. Compared with the sample without pre-oxidation, the surface Si content on the cast iron after pre-oxidation decreases by 28%, and the surface Si content on the cast iron with the synergy of ball-milling and pre-oxidation decreases by 47%. In the hot-dip galvanized coating, as the surface Si content on the cast iron decreases, the ζ grains are refined, and the thickness of the Fe–Zn alloy layer decreases. The sample with the synergy of ball-milling and pre-oxidation has the finest ζ grains and the thinnest alloy layer thickness. In electrochemical corrosion, as the Si content on the cast iron surface decreases, the corrosion potential of the ζ layers are consistent, the corrosion current density decreases, the thickness of the passivation film increases, and the polarization resistance increases. The corrosion resistance of the ζ layers obtained under different pretreatment conditions is in order non-oxidization and pickling sample

Summary: Zeolite-based catalytic membrane reactors have been successfully applied in overcoming the thermodynamic limitations of CO2 hydrogenations and dry reforming of methane (DRM) reactions. This review summarizes the zeolites as membrane reactor components regarding the permeance, permselectivity, durability, conversion, selectivity, and stability by referring to the synergy of catalyst and membrane. Also, five operation parameters (temperature, pressure, feed ratio, sweeping gas flow rate, and gas hourly space velocity) are introduced regarding their impacts on the performance of membrane reactor. Besides, synthesis methods and conditions for zeolite membranes are critically illustrated in the category. Moreover, representative surface and structure properties of zeolite membranes are discussed by relating to the synthesis-structure-performance relationships. Finally, conclusive remarks are demonstrated and possible solutions to existing challenges are proposed. So far, this is the first time to discuss the applications of zeolite membrane reactors in the CO2 adsorption, separation, activation, and conversion in reforming and hydrogenation processes.

Effective capture of CO2 benefits the environmental protection and energy utilization. Zeolite membranes are featured with their ordered pore structures, CO2 affinity and chemical stability. This comprehensive review is mainly focused on the state-of-art designs and synthesis of zeolite membranes for CO2 capture, including the transport mechanisms (Knudsen, surface and gas translation diffusion), structural and surface properties (orientations, defects, thickness, hydrophobicity), synthesis methods (organic structure-directing agent (OSDA)-assisted processes, mild removal of template, gel/OSDA-free approaches), synthesis conditions (temperatures, synthesis time, pH values, seeding, chemical ratios), operation parameters (temperatures, pressures, flow rates, feed compositions, humidity, impurities) and modification strategies (composite zeolite structures, inorganic additives, supports). The synthesis‒structure‒operation‒performance relationships are discussed critically and in depth. Finally, conclusive remarks and future predictions are also provided.

Partial oxidation of methane (POM) is a prominent pathway for syngas production, wherein the hydrogen in syngas product can be recovered directly from the reaction system using a hydrogen (H2)-permeable membrane. Enhancing the efficiency of this H2 separation process is a current major challenge. In this study, Ce0.8Y0.2O2-δ-BaCe0.8Y0.2O3-δ (YDC-BCY) hollow fiber (HF) membranes were developed and characterized for their H2 permeation fluxes. Firstly, YDC and BCY ceramic powders were synthesized using the sol-gel method, followed by the fabrication of YDC-BCY dual-phase ceramic HF membranes using a combined phase inversion–sintering process. Characterization using SEM, powder XRD, EDS, and electrical conductivity tests confirmed the phases of the prepared powders and HF membranes. Well-structured YDC and BCY powders with uniform particle sizes were obtained after calcination at 900 °C. With the addition of 1 wt.% Co2O3 as a sintering aid, the YDC-BCY dual-phase HF membrane achieved densification after sintering at 1500 °C. Subsequently, the influences of sweep gas composition and temperature on the hydrogen permeation of the YDC-BCY HF membranes with YDC/BCY molar ratios of 2:1, 3:1, and 4:1 were investigated. At 1000 °C and a sweep-gas flow rate of 120 mL·min−1, the YDC-BCY HF membrane with a YDC/BCY molar ratio of 4:1 exhibited a peak hydrogen flux of 0.30 mL·min−1 cm−2. There is significant potential for improving the hydrogen permeation of dual-phase ceramic membranes, with future efforts aimed at reducing dense layer thickness and enhancing the membrane material’s electronic and proton conductivities.

Highly dispersed Mn metallic nanoparticles (15.87 nm on average) on a nitrogen-doped porous carbon matrix were prepared by thermal treatment of MnO2-x/polyaniline (PANI), which was derived from the in situ polymerization of aniline monomers initiated by γ-MnO2 nanosheets. Owing to the large surface area (1287 m2/g), abundant active sites, nitrogen dopants and highly dispersed Mn sites on graphitic carbon, an impressive specific capacity of 1319.4 mAh g−1 with an admirable rate performance was delivered in a Li-S battery. After 220 cycles at 1 C, 80.6% of the original capacity was retained, exhibiting a good cycling stability.

Powered by electricity from renewable energies, electrochemical reduction of CO2 could not only efficiently alleviate the excess emission of CO2, but also produce many kinds of valuable chemical feedstocks. Among various catalysts, single atom catalysts (SACs) have attracted much attention due to their high atom utilization efficiency and expressive catalytic performances. Additionally, SACs serve as an ideal platform for the investigation of complex reaction pathways and mechanisms thanks to their explicit active sites. In this review, the possible reaction pathways for the generation of various products (mainly C1 products for SACs) were firstly summarized. Then, recent progress of SACs for electrochemical reduction of CO2 was discussed in aspect of different central metal sites. As the most popular and efficient coordination modulation strategy, introducing heteroatom was then reviewed. Moreover, as an extension of SACs, the development of dual atom catalysts was also briefly discussed. At last, some issues and challenges regarding the SACs for CO2 reduction reaction (CO2RR) were listed, followed by corresponding suggestions.

Greenhouse effects and global warming mainly result from the CO2 generation by rapid industrialization and economic development. Exploitation of highly efficient and robust carbon-based adsorbents benefits the reduction of CO2. In this review, several representative carbonaceous materials (e.g., activated carbons, coal-derived carbons, polymer-derived carbons, metal-organic frameworks-derived carbons, carbon nanotubes, graphene oxides and carbon aerogels) as CO2 adsorbents are discussed comprehensively, including the carbonization (e.g., pyrolysis, hydrothermal treatment), activation (e.g., physical and chemical treatment) and modification (e.g., doping and heterostructure) process. The synthesis-structure-performance relationships are elucidated in depth. Finally, the conclusive remarks and future works are also proposed.

Dry reforming of methane (DRM) reaction has drawn much interest due to the reduction of greenhouse gases and production of syngas. Coking and sintering have hindered the large-scale operations of Ni-based catalysts in DRM reactions at high temperatures. Smart designs of Ni-based catalysts are comprehensively summarized in fourth aspects: surface regulation, oxygen defects, interfacial engineering, and structural optimization. In each part, details of the designs and anti-deactivation mechanisms are elucidated, followed by a summary of the main points and the recommended strategies to improve the catalytic performance, energy efficiency, and utilization rate.

Novel polymers applied in economic membrane technologies are a perennial hot topic in the fields of natural gas purification and O2 enrichment. Herein, novel hypercrosslinked polymers (HCPs) incorporating 6FDA-based polyimide (PI) MMMs were prepared via a casting method for enhancing transport of different gases (CO2, CH4, O2, and N2). Intact HCPs/PI MMMs could be obtained due to good compatibility between the HCPs and PI. Pure gas permeation experiments showed that compared with pure PI film, the addition of HCPs effectively promotes gas transport, increases gas permeability, and maintains ideal selectivity. The permeabilities of HCPs/PI MMMs toward CO2 and O2 were as high as 105.85 Barrer and 24.03 Barrer, respectively, and the ideal selectivities of CO2/CH4 and O2/N2 were 15.67 and 3.00, respectively. Molecular simulations further verified that adding HCPs was beneficial to gas transport. Thus, HCPs have potential utility in fabrication of MMMs for facilitating gas transport in the fields of natural gas purification and O2 enrichment.

Abstract Photocatalytic overall water splitting is a promising strategy to store abundant solar energy as clean fuel, but recombination of photogenerated carriers is the key factor that reduces the efficiency. Herein, we report multi‐interfacial ternary CoP@ZnIn2S4@Co3O4 photocatalyst with coordinated structural and electronic band coupling to concurrently fulfill spatially decoupled redox centers and modulated electric field. For one, the realization of 3D open framework consists of 2D ZnIn2S4 nanosheets on 1D CoP co‐catalyst maximizes exposures apart from circumvents aggregation and shielding issues. Another is the spatially defined and selective redox reactions where CoP is designated for proton reduction and Co3O4 for water oxidation. And finally, constructed type II band structure and p‐n junction facilitates directional charge separation, thereby prohibiting the recombination of charge carrier and also increase the local charge density. Besides, small band gap CoP and Co3O4 exhibit photothermal effect to further enhance photocatalytic hydrogen production. As a result, the photocatalysts could achieve the respective half reaction and pure water hydrogen evolution rate of 4254 and 145 μmol g−1 h−1 under visible light illumination and further enhance to 10 740 and 308 μmol g−1 h−1 when subjected to full spectrum photoheating. This work presents a promising strategy in designing surface and interfacial dominated photocatalytic system to achieve efficient solar energy to chemical conversion.

Hydrogen appears as an unavoidable energy vector and an almost miracle solution to global warming for many people [...]