CC3 porous organic cage crystals and membranes for the non-thermal plasma catalytic ammonia synthesis

Binary Heterogroup-Templated Scaffolds of Polyoxopalladates as Precatalysts for Plasma-Assisted Ammonia Synthesis

In addition to improving the synthetic efficiency, the template method can do a lot more in the chemistry of polyoxopalladates (POPs), such as the establishment of novel metal-oxo scaffolds. In this endeavor, a binary system comprising heterogroups of nonmetallic {As/SiO4} and metallic {VO4/5} successfully fulfills the templated growth of two POPs with unprecedented seesaw- and spindle-like prototypes. Of these, self-aggregation of heterogroups beacons an effective route to break the highly symmetrical PdII-oxo matrix and to force the arrangement of addenda in a nonconventional manner. Aside from the interest in their structural features, the as-made POPs are available for immobilization on the mesoporous SBA-15 as precatalysts for ammonia synthesis. The outer cover of heterogroups in the POP precursors contributes to the ultrafine size and uniform distribution of derived Pd0 nanoparticles (PdNPs). With the help of plasma activation on H2 and N2, such PdNPs-SBA15 catalysts significantly improve the production performance of NH3, showcasing the maximum synthesis rate of 64.42 μmol/(min·gcat) with the corresponding energy yield as high as 4.38 g-NH3/kWh.

Dielectric barrier discharge plasma catalysis as an alternative approach for the synthesis of ammonia: a review

Numerous researchers have attempted to provide mild reactions and environmentally-friendly methods for NH3 synthesis. Research on non-thermal plasma-assisted ammonia synthesis, notably the atmospheric-pressure nonthermal plasma synthesis of ammonia over catalysts, has recently gained attention in the academic literature. Since non-thermal plasma technology circumvents the existing crises and harsh conditions of the Haber-Bosch process, it can be considered as a promising alternative for clean synthesis of ammonia. Non-thermal dielectric barrier discharge (DBD) plasma has been extensively employed in the synthesis of ammonia due to its particular advantages such as the simple construction of DBD reactors, atmospheric operation at ambient temperature, and low cost. The combination of this plasma and catalytic materials can remarkably affect ammonia formation, energy efficiency, and the generation of by-products. The present article reviews plasma-catalysis ammonia synthesis in a dielectric barrier discharge reactor and the parameters affecting this synthesis system. The proposed mechanisms of ammonia production by this plasma catalysis system are discussed as well.

Technical Challenges and Prospects in Sustainable Plasma Catalytic Ammonia Production from Methane and Nitrogen

Ammonia is crucial for human life as an important ingredient for fertilizer, industrial and household chemicals, and is considered as a future fuel alternative and hydrogen storage molecule. There remain no viable alternatives to the energy-and capital-intensive Haber-Bosch (H-B) process. Efforts in the development of novel catalytic processes operated at milder conditions (low temperatures and ambient pressure), prominently electrochemistry and non-thermal plasma (NTP), and utilization of lower-cost H sources for ammonia formation than the ultrapure H₂ have been witnessed in the last few years. Yet, limited progress from these routes has been made to date given unresolved low ammonia yield and technical challenges. Several rare works attempted to activate methane (CH₄ ) and nitrogen (N₂ ) by non-thermal plasma to produce ammonia and valued-added hydrocarbons have proven to be a promising research direction, rivalling the reaction between N₂ and ultrapure H₂ or water. The direct conversion of CH₄ and N₂ to ammonia is still at the beginning level, and it remains unclear that what extent these technologies must be improved to develop a commercial process. Toward this goal, this Perspective critiques current steps and miss-steps of sustainable plasma catalytic ammonia production from CH₄ and N₂ in terms of technology, plasma-catalyst synergy, mechanistic insights, and experimental protocols. We discuss mechanistic understandings of catalyst-promoted ammonia production and translate such discussions as well as key metrics achieved in the field into recommendations of feasible processes for ammonia and value-added hydrocarbons formation from CH₄ and N₂ .