Co3Mo3N is one of the most active catalysts for ammonia synthesis; however, little known about atomistic details N2 adsorption and activation. Here we examine whether can adsorb activate at nitrogen surface vacancies. We have identified favorable sites vacancy formation calculated free energies (and concentrations) taking into account configurational entropy temperature pressure conditions relevant to synthesis (380–550 °C, 100 atm) via a semiempirical approach. show that 3-fold hollow bound...

This short overview summarises some of the basic considerations which should be undertaken when Scherrer equation is applied to reflection widths in X-ray diffraction patterns heterogeneous catalysts order extract meaningful information. Frequently, little account has been taken apparent complications arising from presence microstructural strain and disorder such as that can introduced upon doping or anisotropic effects are highlighted.

In this overview, we present examples of the use high volume waste materials in catalysis or for catalyst synthesis. Waste derived from both industrial and biological sources have attracted interest is briefly summarized. The described include red mud, aluminium dross, fly ash, blast furnace slag, rice husk various kinds shell.

Dispersion-corrected periodic DFT calculations have been applied to elucidate the Langmuir–Hinshelwood (dissociative) and an Eley–Rideal/Mars–van Krevelen (associative) mechanism for ammonia synthesis over Co3Mo3N surfaces, in presence of surface defects. Comparison two distinct mechanisms clearly suggests that apart from conventional dissociative mechanism, there is another proceeds via hydrazine diazane intermediates are formed by Eley–Rideal type chemistry, where hydrogen reacts directly...

By means of selected examples taken from the zeolite and zeotype academic literature, influence binders matrix components upon performance heterogeneous catalysts is illustrated. Such effects can be significant, showing that matrices are far inert in many systems that, accordingly, their role worthy greater consideration than has hitherto been case.

The 14N/15N isotopic exchange pathways over Co3Mo3N, a material of interest as an ammonia synthesis catalyst and for the development nitrogen transfer reactions, have been investigated. Both homomolecular heterolytic processes studied, it has shown that lattice species are exchangeable. behavior was found to be strong function pretreatment with ca. 25% N atoms being exchanged after 40 min at 600 °C N2 700 compared only 6% following similar Ar pretreatment. This observation, which potential...

A systematic study was carried out to investigate the potential of manganese nitride related materials for ammonia production. A-Mn-N (A = Fe, Co, K, Li) were synthesised by nitriding their oxide counterparts at low temperature using NaNH2 as a source reactive nitrogen. The reactivity lattice nitrogen assessed synthesis model reaction. In case Mn3N2, limited observed and only 3.1% available found be towards hydrogen yield while most lost N2. However, presence co-metal played key role in...

Periodate in the mix: The first crystallographically characterized tungstatoperiodate cluster of form β*-[H3W18O56(IO6)]6−, with periodate embedded inside a {W18O54} cage, remains intact solution, and is new class [HnW18O56(XO6)]m− heteropolyoxotungstates. Mass spectrometry, electrochemical catalytic studies, verified by DFT calculations, reveal its unusual physical properties. Supporting information for this article available on WWW under...

In this article, an overview of the application selected metal nitrides as ammonia synthesis catalysts is presented. The potential development some systems into nitrogen transfer reagents also described.

Cobalt molybdenum nitride (Co3Mo3N) is one of the most active catalysts for ammonia synthesis, although atomistic details reaction mechanism are currently unknown. We present a dispersion-corrected (D3) DFT study adsorption and activation molecular nitrogen hydrogen on Co3Mo3N-(111) surfaces to identify possible sites synthesis. H2 was found adsorb both molecularly Mo3N framework dissociatively Co8 clusters or Mo3 that were exposed due N-vacancies. find there two N2 where can coadsorb. The...

Whilst the Mars-van Krevelen mechanism is well established for metal oxide catalysed oxidation reactions, it has been much less studied in case of nitrogen based reactions by nitrides. In this overview, some recent literature relation to possible operation Mars- van ammonia synthesis nitrides presented, along with relating via chemical looping approaches.

Lattice nitrogen within the catalyst Co3Mo3N is both reactive and likely highly mobile, enabling potential novel transfer pathways; evidence suggests that loss subsequent regain of lattice in system reversibly cycles through previously unknown nitride, Co6Mo6N.

The temperature-programmed reaction of Co3Mo3N under H2/Ar results in a new nitride with composition Co6Mo6N. Powder neutron diffraction (PND) studies have confirmed unequivocally that the compound possesses η-12 carbide structure, which N atoms are exclusively located at 8a crystallographic sites, as opposed to 16c sites occupied phase. On this basis, it possible rationalize observation 50% nitrogen loss occurs high-temperature reduction conditions employed. Reaction reduced phase N2/H2...

The nature of the active site in Pd-catalysed aerobic selective oxidation cinnamyl and crotyl alcohols has been directly probed by bulk surface X-ray techniques. importance high metal dispersions crucial role palladium oxide have identified.

A detailed study of the morphological changes that occur during ageing a copper zinc oxide (Cu ∶ Zn 2 1), formed by co-precipitation from nitrates is reported and discussed. Using TEM STEM-EDS, composition morphology non-calcined precursor are observed to change an initial amorphous state micro-crystalline aurichalcite rosasite, which present as needles platelets, respectively. In addition, microscopy has shown dispersion Cu-rich nanoparticles progressively precipitate ages. On calcination...