Since its inception, the Haber-Bosch (HB) process for ammonia (NH3) synthesis has allowed for a significant increase in global food production as well as a simultaneous decrease in global hunger and malnutrition. The HB process is estimated to be responsible for the subsistence of 40% of the world population as approximately 85% of the over 182 metric tons of NH3 produced in 2017 was used as fertilizer for crop production. The natural gas consumed (mostly to generate H2) represents approximately 2% of the global energy budget, while the CO2 produced is about 2.5% of all global fossil CO2 emissions. Approximately 40% of food consumed is essentially natural gas transformed by the HB process into agricultural products. However global food production will need to double due to expected increase in world population to 9.6 billion by 2050 and rising demand for protein among developing nations. A novel thermochemical reaction cycle for sustainable NH3 synthesis at atmospheric pressure is explored herein. Both thermochemical and kinetic rationales are discussed regarding choice of Mn as the cycled reactant. The energetic driving force for these reactions is conceptually derived from concentrated solar energy. Mn was reacted with N2 forming Mn-nitride, corrosion of Mn-nitride with steam at 500°C formed MnO and NH3, and lastly MnO was reduced at 1150 °C in a 4 vol % CH4 - 96 vol % N2 stream to Mn-nitride closing the cycle. Optimum nitridation at 800°C and 120 min produced a Mn6N2.5-rich Mn-nitride mixture containing 8.7 ± 0.9 wt. % nitrogen. NH3 yield was limited to 0.04 after 120 min during nitride corrosion but addition of a NaOH promotor improved NH3 yield to 0.54. Mn6N2.58 yield was 0.381 ± 0.083 after MnO reduction for 30 min with CO and H2 but no CO2 detected in the product. Mn-nitridation kinetics were investigated at temperatures between 600 and 900°C for 10 and 44 [mu]m reactant powder particle sizes. That equilibrium conversion decreased with increasing temperature was confirmed. Jander's rate law, which assumes gaseous reactant diffusion through a solid product layer, described the experimental data reasonably well. The rate constants and initial rates were as much as an order of magnitude greater for the 10 [mu]m Mn reactant particle size. Additionally the activation energy was found to be 44.1 kJ mol−1 less for the 10 [mu]m reactant particle size. Reducing the particle size had a small but positive effect on Mn-nitridation kinetics. Further reducing particle size will likely have a greater impact. A review of relevant classical thermodynamics is discussed with special attention paid to open systems. Confidence issues regarding over-reliance on x-ray diffraction are considered with options suggested for mitigation. Opportunities for future work are assessed.

This book presents sustainable synthetic pathways and modern applications of ammonia. It focuses on the production of ammonia using various catalytic systems and its use in fuel cells, membrane, agriculture, and renewable energy sectors. The book highlights the history, investigation, and development of sustainable pathways for ammonia production, current challenges, and state-of-the-art reviews. While discussing industrial applications, it fills the gap between laboratory research and viable applications in large-scale production.

Ammonia is one of the most significant industrially produced chemicals for its role as fertilizer in feeding the world's growing population. The Haber-Bosch process for the reduction of atmospheric nitrogen to ammonia using fossil-derived hydrogen is also one of the most scientifically important reactions in heterogeneous catalysis, as many of the fundamental concepts in the field such as the significance of defect sites and the existence of rate-determining steps were developed by researchers studying this reaction. Despite enormous effort, two major drawbacks of the industrial process are (A) the expensive and wasteful centralized infrastructure for fertilizer production and distribution necessitated by the harsh conditions required to activate the N-N triple bond while maintaining a strong thermodynamic driving force, and (B) the environmental impact associated with the dependence on unsustainable fossil fuel resources for energy and hydrogen. The development of an alternative route to ammonia that operates in a distributed fashion under ambient conditions, based on renewable energy sources such as solar and wind, could be both economically and environmentally beneficial. In this work, we use electronic structure calculations based on density functional theory in conjunction with microkinetic modeling to develop three strategies toward sustainable ammonia synthesis: (1) designing improved catalysts for a low-temperature, low-pressure version of the thermochemical Haber-Bosch process, (2) establishing a set of guidelines for an active and selective electrochemical ammonia synthesis process, and (3) designing a hybrid approach that leverages the beneficial elements of both the thermochemical and electrochemical processes. Finally, we improve the efficiency of our computational methods by developing two machine learning approaches that reduce the number of density functional theory calculations required for the construction of surface phase diagrams and the prediction of activation barriers.

Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.

Ammonia holds great promise as a carbon-neutral liquid fuel for storing intermittent renewable energy sources and power generation due to its high energy density and hydrogen content. Photo-Electrochemical Ammonia Synthesis: Nanocatalyst Discovery, Reactor Design, and Advanced Spectroscopy covers the synthesis of novel hybrid plasmonic nanomaterials and their application in photo-electrochemical systems to convert low energy molecules to high value-added molecules and looks specifically at photo-electrochemical nitrogen reduction reaction (NRR) for ammonia synthesis as an attractive alternative to the long-lasting thermochemical process. Provides an integrated scientific framework, combining materials chemistry, photo-electrochemistry, and spectroscopy to overcome the challenges associated with renewable energy storage and transport Reviews materials chemistry for the synthesis of a range of heterogeneous (photo) electrocatalysts including plasmonic and hybrid plasmonic-semiconductor nanostructures for selective and efficient conversion of N2 to NH3 Covers novel reactor design to study the redox processes in the photo-electrochemical energy conversion system and to benchmark nanocatalysts’ selectivity and activity toward NRR Discusses the use of advanced spectroscopic techniques to probe the reaction mechanism for ammonia synthesis Offers techno-economic analysis and presents performance targets for the scale-up and commercialization of electrochemical ammonia synthesis This book is of value to researchers, advanced students, and industry professionals working in sustainable energy storage and conversion across the disciplines of Chemical Engineering, Mechanical Engineering, Materials Science and Engineering, Environmental Engineering, and related areas.

The phenomenon of catalysis is found in many homogeneous and heterogeneous systems undergoing chemical change, where it effects the rates of approach to the equilibrium state in processes as diverse as those found in the stars, the earth's mantle, living organisms, and the various chemistries utilized by industry. The economies and the living standards of both developed and developing countries depend to varying degrees upon the efficacy of their chemical industries. Con sequently, this century has seen a wide exploration and expansion of catalytic chemistry together with an intensive investigation of specific, essential processes like those contributing to life-supporting agricultures. Prime among the latter must surely be the "fixation" of atmospheric nitrogen by catalytic hydrogenation to anhydrous ammonia, still the preferred synthetic precursor of the nitrogenous components of fertilizers. In each decade contemporary concepts and techniques have been used to further the understanding, as yet incomplete, of the catalyst, the adsorbates, the surface reactions, and the technology of large-scale operation. The contributors to the present volume review the state of the art, the science, and the technology; they reveal existing lacunae, and suggest ways forward. Around the turn of the century, Sabatier's school was extending the descriptive catalytic chemistry of hydrogenation by metals to include almost all types of multiple bond. The triple bond of dinitrogen, which continued to be more resistant than the somewhat similar bonds in carbon monoxide and ethyne, defied their efforts.

"Spillover and Mobility of Species and Solid Surfaces" collects the papers which were presented at the Fifth International Conference Spillover, either as oral or poster contributions, as well as the summaries of the invited lectures. This congress and its publication in the Studies on Surface Science and Catalysis series follow the tradition of previous conferences on spillover, initiated in Lyon, 1983, and continued in Leipzig, 1989, Kyoto 1993 and Dalian, 1997. For the fifth conference, held in S.L. el Escorial (Madrid), the organising committee has attempted to compile representative contributions which illustrate the advances in understanding the spillover phenomenon since 1997. Spillover is a process taking place during the interface of gas reactant molecules (mainly hydrogen and oxygen) on solid surfaces. However, different contributions to the more general area of the chemistry at surfaces, related with the mobility and migration of species, diffusion through membranes, fuel cell catalysts, etc., have also been included. In fact the title of the present volume summarizes this attempt to extend the conference topics towards dynamics at surfaces.Among the 70 contributions received, the 56 accepted papers were selected on the basis of the reports of at least two international reviewers, according to standards comparable to those applied for other specialised journals. These papers are from 21 different countries.

Sustainable Hydrogen Production provides readers with an introduction to the processes and technologies used in major hydrogen production methods. This book serves as a unique source for information on advanced hydrogen generation systems and applications (including integrated systems, hybrid systems, and multigeneration systems with hydrogen production). Advanced and clean technologies are linked to environmental impact issues, and methods for sustainable development are thoroughly discussed. With Earth's fast-growing populations, we face the challenge of rapidly rising energy needs. To balance these we must explore more sustainable methods of energy production. Hydrogen is one key sustainable method because of its versatility. It is a constituent of a large palette of essential materials, chemicals, and fuels. It is a source of power and a source of heat. Because of this versatility, the demand for hydrogen is sure to increase as we aim to explore more sustainable methods of energy. Furthermore, Sustainable Hydrogen Production provides methodologies, models, and analysis techniques to help achieve better use of resources, efficiency, cost-effectiveness, and sustainability. The book is intellectually rich and interesting as well as practical. The fundamental methods of hydrogen production are categorized based on type of energy source: electrical, thermal, photonic, and biochemical. Where appropriate, historical context is introduced. Thermodynamic concepts, illustrative examples, and case studies are used to solve concrete power engineering problems. - Addresses the fundamentals of hydrogen production using electrical, thermal, photonic, and biochemical energies - Presents new models, methods, and parameters for performance assessment - Provides historical background where appropriate - Outlines key connections between hydrogen production methods and environmental impact/sustainable development - Provides illustrative examples, case studies, and study problems within each chapter

Ammonia Fuel Cells covers all aspects of ammonia fuel cell technologies and their applications, including their theoretical analysis, modeling studies and experimental investigations. The book analyzes the role of integrated ammonia fuel cell systems within various renewable energy resources and existing energy systems. Covers the types of ammonia fuel cells that have been developed over history Features explanations of the underlying fundamentals and principles of ammonia fuel cells, along with methods to assess the performance of different types of cell Includes case studies considering different applications of ammonia fuel cells and their significance in the future of clean energy

This book provides a review of worldwide developments in ammonia synthesis catalysts over the last 30 years. It focuses on the new generation of Fe1-xO based catalysts and ruthenium catalysts — both are major breakthroughs for fused iron catalysts. The basic theory for ammonia synthesis is systematically explained, covering topics such as the chemical components, crystal structure, preparation, reduction, performance evaluation, characterization of the catalysts, the mechanism and kinetics of ammonia synthesis reaction. Both theory and practice are combined in this presentation, with emphasis on the research methods, application and exploitation of catalysts.The comprehensive volume includes an assessment of the economic and engineering aspects of ammonia plants based on the performance of catalysts. Recent developments in photo-catalysis, electro-catalysis, biocatalysis and new uses of ammonia are also introduced in this book.The author, Professor Huazhang Liu, has been engaged in research and practice for more than 50 years in this field and was the inventor of the first Fe1-xO based catalysts in the world. He has done a lot of research on Fe3O4 based- and ruthenium based-catalysts, and has published more than 300 papers and obtained 21 patents during his career.