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• The electrochemical and photochemical NRR mechanism is illustrated deeply and comprehensively. • The research progress of metal-based and nonmetallic NRR catalysts are extensively reviewed. • Interaction and synergistic effects of components in NRR heterojunction catalysts are demonstrated. • Advanced improvement methods of NRR catalysts are summarized. As zero-carbon artificial ammonia synthesis technologies for nitrogen fixation, eNRR (electrocatalytic nitrogen reduction reaction) and pNRR (photocatalytic nitrogen reduction reaction) are receiving more and more attention, in which NRR catalysts play a crucial role with significant potential. Herein, The NRR mechanism including nitrogen adsorption, activation, electron migration, and hydrogenation, eNRR & pNRR experiment system, and the basic properties, structure-performance relationship and advanced improvement design of NRR catalysts are reviewed. Metal-based catalysts including Fe, Mo, Bi, Ti, Ru, Au, Ag, Ce, Zn, Sn and so on, have an advantage in nitrogen adsorption, nitrogen activation and ammonia selectivity. In addition to being catalyst support, non-metallic materials can also have certain NRR activity, such as g-C 3 N 4 and graphene, especially with vacancy design and modification. Besides, the photoelectric and catalytic performance can be further improved by synthesize composite catalysts to produce heterojunction structure. This review aims to assist academia to understand the research progress of NRR technology and catalyst and provide ideas for innovating more promising and high-performance NRR catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The main N 2 O removal methods and their catalysts are elucidated. • The previous mechanism studies using DFT are revealed. • The characteristics and improvement strategies of various catalysts are summarized. • The future development of more efficient N 2 O removal catalyst is proposed. • It furnishes theoretical basis and data support for exploring N 2 O removal catalysts. With the increasing global warming, the control of nitrous oxide (N 2 O) emissions in various fields has become urgent. Direct catalytic decomposition is currently the most widely used technology to reduce N 2 O emissions from the nitric acid industry. Selective catalytic reduction (SCR), which can utilize unburned NH 3 from engine exhaust as a reductant, is the most promising technology for reducing N 2 O emissions from ammonia-fueled engines. Increasing demands on the operating temperature window, O 2 /H 2 O/NO resistance, and hydrothermal stability of catalysts have stimulated the development of novel catalytic N 2 O removal catalysts. This review first summarizes the N 2 O generation mechanism, comprehensive N 2 O catalytic removal reaction mechanism and O 2 /H 2 O/NO inhibition mechanism, and then provides a comprehensive overview of the related catalysts, including Ru- and Rh-based precious metal catalysts, Cu- and Co-based non-precious metal catalysts, and Fe- and Cu-based molecular sieve catalysts, focusing on direct catalytic decomposition of N 2 O and N 2 O-SCR. Effective strategies for various catalysts to improve the acidity, redox cycling, and toxicity resistance of the catalysts through modification, creation of novel nanostructures, and exposure of specific crystalline surfaces are summarized, and the challenges and opportunities they face are presented. In addition, this paper summarizes some other methods for catalytic removal of N 2 O and develops a detailed description for the synergistic removal of N 2 O and NO x. Finally, this review provides some suggestions for future research directions. It is hoped that this review will provide a theoretical basis for the optimal preparation of catalysts to bridge the gap between catalyst performance and practical needs, and help to realize the commercial application of efficient catalysts in the near future. [ABSTRACT FROM AUTHOR]

• The SCR properties of molecular sieve catalysts are discussed according to the active elements. • The preparation, structure, hydrothermal aging properties and effects of poisoning of molecular sieve catalysts are described in depth. • A detailed description of the NH 3 -SCR reaction mechanism of molecular sieve catalysts is presented. • Provides an outlook on the development of molecular sieve catalysts. NH 3 -SCR technology is a highly efficient denitrification technology that is widely used in the purification of diesel exhaust and coal-fired flue gas from thermal power plants. Molecular sieve catalysts have been extensively investigated for their high activity and selectivity. In this review, the preparation, structure, active sites and some resistances of Cu-based molecular sieve catalysts, Fe-based molecular sieve catalysts and composite metal molecular sieve catalysts are systematically investigated for relevant elaboration. In addition, the NH 3 -SCR reaction mechanism over the catalysts is also explained. With the increasingly stringent requirements of NO x emission, we need to develop more efficient catalysts. This paper provides a summary of the hydrothermal aging stability and the inorganic element (S / P / Alkali and alkaline earth metal) poisoning mechanisms as well as the influence of the preparation process in the molecular sieve catalysts, and we hope this review contributes to the development of molecular sieve catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

SCR (Selective Catalytic Reduction) catalysts are used in a variety of industrial applications to reduce nitrogen oxide (NOx) emissions from exhaust gases. SCR catalysts can be poisoned by contaminants in the exhaust gas, such as sulfur, phosphorus, and alkali metals. These poisoning leads to deactivation of catalysts and thus need to be avoided. The objective of this review is to provide a comprehensive and systematic overview of the mechanisms of poisoning and the research on resistance of various metal oxide catalysts, including vanadium-based, cerium-based, copper-based, manganese-based, and iron-based catalysts, as well as various zeolite catalysts. The discussion will cover the catalysts' resistance against hydrothermal aging, sulfur poisoning, phosphorus poisoning, alkali metal poisoning, alkaline earth metal poisoning, and heavy metal poisoning. Furthermore, potential approaches and strategies for enhancing catalyst resistance in the future will also be examined. The article serves as a valuable resource for researchers and practitioners working on SCR technology and emissions control, providing insights into the mechanisms of catalyst poisoning and strategies for improving catalyst resistance. [Display omitted] [ABSTRACT FROM AUTHOR]