An ammonia synthesis catalyst having high activity is obtained by having a two-dimensional electride compound having a lamellar crystal structure such as Ca.sub.2N support a transition metal. However, since the two-dimensional electride compound is unstable, the stability of the catalyst is low. In addition, in cases where a two-dimensional electride compound is used as a catalyst support, it is difficult to shape the catalyst depending on reactions since the two-dimensional electride compound has poor processability. A composite which includes a transition metal, a support and a metal amide compound, wherein the support is a metal oxide or a carbonaceous support; and the metal amide compound is a metal amide compound represented by general formula (1). M(NH.sub.2).sub.x . . . (1) (In general formula (1), M represents at least one metal atom selected from the group consisting of Li, Na, K, Be, Mg, Ca, Sr, Ba and Eu; and x represents the valence of M.)

A composition containing: at least 99.75% by weight of bis(fluorosulfonyl)imide lithium salt. A process for preparing the composition, including a) step of preconcentrating a composition C1 including an organic solvent OS1, water and bis(fluorosulfonyl)imide salt, to give a composition C2 including: the lithium salt of bis(fluorosulfonyl)imide in a content ranging from 35% to 50% relative to the total weight of composition C2; water in a mass content of less than or equal to 500 ppm relative to the total mass of composition C2; the preconcentration step being performed at a temperature of less than or equal to 50° C.; b) a step of concentrating composition C2; c) an optional step of crystallizing the composition obtained in step b).

The present invention relates to a process for preparing a compound having the following formula (II):

F—SO.sub.2—N.sup.−—SO.sub.2—R.sub.1NH.sub.4.sup.+  (II)

wherein R.sub.1 represents F or a linear or branched alkyl radical, substituted with at least one fluorine atom, said process comprising a step of bringing an anhydrous flow F1 comprising ammonia (NH.sub.3) into contact with a compound of formula (I):

F—SO.sub.2—NH—SO.sub.2—R.sub.1  (I)

R.sub.1 is as defined above.

The invention relates to a method for producing an alkali salt of bis(fluorosulfonyl)imide, comprising the step of reacting, within a reaction medium, an ammonium salt of bis(fluorosulfonyl)imide with an alkali agent, to produce alkali salt of bis(fluorosulfonyl)imide and ammonia; and simultaneously contacting the reaction medium with an inert gas stream to strip out ammonia.

A composition containing: at least 99.75% by weight of bis(fluorosulfonyl)imide lithium salt; and acetic acid in a content by mass greater than 0 and less than or equal to 400 ppm. A process for preparing the composition, including a) step of preconcentrating a composition C1 including an organic solvent OS1, water and bis(fluorosulfonyl)imide salt, to give a composition C2 including: the lithium salt of bis(fluorosulfonyl)imide in a content ranging from 35% to 50% relative to the total weight of composition C2; water in a mass content of less than or equal to 500 ppm relative to the total mass of composition C2; said preconcentration step being performed at a temperature of less than or equal to 50° C.; b) a step of concentrating composition C2; c) an optional step of crystallizing the composition obtained in step b).

The invention relates to particulate lithium metal formations having a substantially spherical geometry and a core composed of metallic lithium, which are enclosed with an outer passivating but ionically conductive layer containing nitrogen. The invention further relates to a method for producing lithium metal formations by reacting lithium metal with one or more passivating agent(s) containing nitrogen, selected from the groups N.sub.2, N.sub.xH.sub.y with x=1 or 2 and y=3 or 4, or a compound containing only the elements C, H, and N, and optionally Li, at temperatures in the range between 60 and 300 C., preferably between 100 and 280 C., and particularly preferably above the melting temperature of lithium of 180.5 C., in an inert organic solvent under dispersion conditions or in an atmosphere that contains a gaseous coating agent containing nitrogen.