Ammonia (NH3) is a compelling carbon-free hydrogen carrier. Its catalytic decomposition to produce a hydrogen/nitrogen (H2/N2) gas stream is central to the “NH3-H2” clean energy cycle, provided that residual NH3 is removed to fuel-cell-grade purity downstream. This review integrates advances from the past five years across four major catalytic NH3 decomposition pathways, encompassing conventional thermocatalysis, plasma-catalytic, photo(thermal), and electrically driven catalysis, within a unified mechanistic and practical framework, distinguishing it from existing single-pathway reviews. Noble metal catalysts, particularly Ru-based systems, achieve superior low-temperature activity through support engineering, promoter effects, and active-site construction. However, our analysis reveals that non-noble metal (Fe, Co, Ni) catalysts and their alloys, nitrides, and carbides have made substantial progress, with certain Co-based and bimetallic systems approaching Ru-level performance via interfacial oxygen vacancy engineering and electronic structure modulation. Emerging non-thermal routes effectively overcome thermodynamic barriers, enabling operation at temperatures 200–300 °C below conventional thermal requirements, though each faces distinct challenges in energy efficiency, stability, and scalability. Key challenges remaining across all pathways to practical implementation, including residual NH3 removal and H2 purification, catalyst deactivation and stability, heat management and energy efficiency, start-up/shut-down dynamics, as well as system integration and economics, are critically assessed. This review provides theoretical guidance and practical recommendations for developing scalable, low-temperature NH3 decomposition technologies.
Heterogeneous catalytic CO2 hydrogenation has emerged as a versatile route for converting captured CO2 and renewable H2 into fuels and chemicals, with relevance to carbon circularity, energy storage, and the progressive defossilisation of chemical manufacturing. This review describes CO2 hydrogenation as a complex network capable of delivering CO, methanol, methane, formates, dimethyl ether, and a broad range of C2+ products. We examine how catalyst composition and structure, including metal nuclearity, metal-oxide interfaces, oxygen vacancies, acid-base properties, and pore confinement, govern pathway competition and product selectivity, and we discuss the growing importance of tandem and multifunctional catalytic platforms. Particular attention is given to the dynamic evolution of active phases under reaction conditions, and to the role of in situ and operando characterisation, together with theoretical and kinetic analysis, in establishing meaningful structure-performance relationships. We further consider the emerging contribution of data-driven methods to catalyst screening, descriptor discovery, and optimisation. Beyond catalyst-level advances, this review addresses reactor and process constraints, including transport effects, scale-up, separation, feed variability, and system integration, and examines how life-cycle assessment, techno-economic analysis, and pilot-scale validation are needed to distinguish laboratory performance from deployable value. Taken together, this review provides an integrated framework for evaluating the scientific basis and practical prospects of CO2 hydrogenation in a net-zero context.
Chengsheng Yang, Doudou Hu, Xiyue Yang et al.· Chemical Society Reviews· 0 citations
As a pivotal nitrogen fertilizer and versatile industrial feedstock, urea (CO(NH2)2) is predominantly synthesized via the Bosch-Meiser process, which is a high-temperature, high-pressure catalytic route, accompanied by substantial energy consumption and considerable CO2 emissions. In light of global imperatives for carbon neutrality and sustainable development, electrocatalytic urea synthesis from N2 and CO2 under ambient conditions using renewable electricity has emerged as a promising green alternative. This review critically examines the fundamental scientific challenges and strategic significance of electrocatalytic N2/CO2 coupling for urea production. We systematically analyze the surface activation mechanisms of both N2 and CO2 on heterogeneous catalysts, elucidate the energetically demanding C-N bond-forming steps, and comprehensively survey recent advances in rational catalyst design and optimization strategies. Furthermore, we assess emerging innovations in electrochemical reactor configurations and process integration, identify persistent bottlenecks, and outline actionable pathways to mitigate them. By synthesizing current advances and projecting future research trajectories, this work aims to establish a coherent conceptual and methodological framework to accelerate the translational development of electrocatalytic urea synthesis toward practical implementation.
Jinhua Lai, Jinyou Zheng· Chemical Communications· 0 citations
Plasma-assisted ammonia synthesis (PAAS) enables the production of ammonia at ambient temperature and pressure by utilizing high-energy free electrons to break N≡N and H-H bonds. This process leverages green electricity and hydrogen, offering an efficient and distributed alternative for renewable energy storage. However, conventional catalysts used in PAAS (Al2O3, metal-organic frameworks, molecular sieves, etc.) suffer from low efficiency, poor cycling performance, and high cost. Herein, we design and develop novel cascade porous biochar-based catalysts (Co-PB) derived from waste heavy bio-oil through catalytic pyrolysis by using cobalt nitrate as a pyrolysis catalyst, giving rise to a highly porous structure with uniformly distributed Co in Co-PB. The good mobility of heavy bio-oil ensures homogeneous C-Co bonds, which further enhances the transfer kinetics of the interfacial electron and the radical. As a result, Co-PB achieves a high PAAS rate of 1.605 mmol/g·h and exhibits excellent stability and cyclability under harsh electric fields. Economic and environmental assessments highlight the significant potential of PAAS for sustainable hydrogen and electricity storage.
Feng Gong, Juntao Bao, Yuhang Jing et al.· The Innovation Energy· 0 citations
The development of efficient, ruthenium-free catalysts for low-temperature ammonia decomposition is crucial for using ammonia as a hydrogen carrier. Conventional catalysts are typically limited by inefficient ammonia adsorption and strong hydrogen inhibition, which restrict their overall activity. Herein, we report a spatially decoupled catalytic system that integrates an oxynitride shell and a metallic cobalt core (Co@BaAl2O4–xNδ). In this system, anion vacancies in the oxynitride shell function as “nitrogen traps” for highly efficient ammonia adsorption and N–H bond activation, while the metallic cobalt core acts as a “hydrogen pump” facilitating rapid hydrogen recombination and desorption. This deliberate separation of reaction steps breaks the scaling relations inherent to single-site catalysts. To the best of our knowledge, the optimized Co@BaAl2O4–xNδ achieves the highest ammonia conversion (∼94.5%) at 475 °C among non-ruthenium-based catalysts, with stability over 200 h of continuous operation. Evidence from kinetic studies, isotopic labeling, and in situ spectroscopy confirms this concurrent synergistic mechanism. This work highlights the potential of spatial decoupling in catalyst design and establishes a paradigm for creating high-performance catalysts.
The imperative to mitigate climate change has accelerated the development of Carbon Capture, Utilization, and Storage (CCUS) technologies, particularly CO2 hydrogenation into high-value chemicals and alternative fuels. This work evaluates the fundamental thermodynamic limitations and the primary directions of CO2 conversion, with a primary focus on methanation, alongside related pathways such as methanol synthesis and the reverse water-gas shift (RWGS) reaction. To overcome the high kinetic barriers of CO2 activation, various catalytic systems are analyzed. While noble metal catalysts exhibit high catalytic performance, nickel-based catalysts serve as a viable and cost-effective alternative. To overcome nickel’s susceptibility to thermal sintering and coking, advanced bimetallic and multimetallic formulations are being developed to enhance structural stability and selectivity. These advancements are crucial for producing Synthetic Natural Gas (SNG) and sustainable aviation fuels (SAF). Ultimately, the objective of this comprehensive review is to systematically summarize recent advancements in catalyst design, critically analyze the advantages and fundamental bottlenecks of distinct catalytic systems, and outline prospective paths for the efficient industrial-scale production of sustainable alternative fuels.
Kornelia Nejranowska, Agnieszka Szymaszek-Wawryca, M. Motak· Materials· 0 citations
Dry reforming of methane (DRM) converts two major greenhouse gases, CH4 and CO2, into syngas. The products (CO and H2) can be directly utilized as feedstock for chemical processes such as Fischer–Tropsch synthesis and methanol production. Transition metal-based catalysts stand as the most commonly employed for DRM on account of their low cost and excellent intrinsic activity. Nevertheless, the harsh high-temperature conditions readily trigger the sintering of metals and carbon deposition, resulting in rapid catalyst deactivation. This critical drawback severely restricts the large-scale industrial rollout of DRM. Relying on the synergistic effect of spatial confinement and interfacial electronic modulation, confined catalysts can efficiently suppress metal sintering and side reactions. In comparison, some confined catalysts achieve a CH4 conversion of over 90% at a lower temperature, and some catalysts nearly form no graphitic carbon during a long-term durability test of 120 h. In contrast, unconfined catalysts suffer from continuous activity deterioration. This review systematically summarizes recent research progress on confined catalysts for DRM. It thoroughly analyzes anti-coking mechanisms, design criteria and optimization strategies, and clarifies the intrinsic coupling rules among geometric confinement, interfacial electronic effects and multi-dimensional synergistic confinement mechanisms. A horizontal comparison is also conducted to evaluate the advantages and limitations of four categories of confined structures: carbon-based, zeolite-based, MOF-derived, and composite support catalysts. Forward-looking optimization directions are proposed by integrating advanced techniques. The conclusions obtained from this review can provide theoretical foundations and practical references for the rational development of high-performance confined catalysts and the industrial advancement of DRM.
Unknown authors· Industrial & Engineering...· 0 citations
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