Patent GB-702018-A (GB)
Title: Regeneration of nickel-sulfide-alumina type catalysts
IPC: C10G49/02
Filed: 1951-11-29
Abstract: In the catalytic reduction of an aromatic nitro-compound with hydrogen in the presence of a catalyst comprising nickel sulphide associated with activated or amorphous alumina, the catalyst is regenerated by treatment with a free oxygen-containing gas at 300-700 DEG  C. to remove carbonaceous deposits, followed, without any intervening sulphiding step by treatment with a hydrogen-containing gas at 200-700 DEG C.  The alumina, which may act as a carrier as well as a promoter may comprise 10 to 90 per cent. by weight of the catalyst.  In the hydrogenation of a nitrobenzene to aniline, 1 1/2 to 5 times the theoretical quantity of hydrogen is employed, corresponding to 4 1/2 to 15 mols. of hydrogen per mol. of nitrobenzene.  Temperatures of 250 to 350 DEG  C. and flow rates of 25 and 31 grams nitrobenzene per 100 c.c. of catalyst are referred to.  The catalyst, which may be employed as a fixed or fluidized bed, may be regenerated in situ. Specifications 144,614, [Class 2 (iii)], and 589,915 are referred to.ALSO:Nickel sulphide associated with activated or amorphous alumina employed as a fixed bed or fluidized catalyst in the hydrogenation of aromatic nitro-compounds with hydrogen to the corresponding amines, is regenerated by treatment with a free oxygen-containing gas at 300 to 700 DEG C. to remove carbonaceous deposits and without any intervening sulphiding step, followed by treatment with a hydrogen containing gas at 200-700 DEG C.  The alumina may function as a carrier as well as a promoter and may comprise 10 to 90 per cent. by weight of the catalyst.  According to examples (1) a catalyst prepared by impregnating activated alumina with fused crystalline nickel nitrate heating in air at 450 DEG C. and sulphiding at 450 DEG C. with hydrogen sulphide, is employed in the hydrogenation of nitrobenzene to aniline at 300 DEG C. for 540 hours, a mixture of air and steam is then passed through the bed at 300 DEG C., a temperature peak travelling through the bed in the direction of flow.  The air feed is gradually increased until the deposits are removed, when the air feed is discontinued and the catalyst purged with carbon dioxide.  Thereafter steam and hydrogen, followed by pure hydrogen, is fed at 400 DEG C., the catalyst is cooled to 400 DEG C. and production recommenced.  (2) a catalyst is prepared by coprecipitation of nickel and aluminium hydroxides and/or carbonates from a solution of the nitrates by the addition of ammonium carbonate solution.  The precipitate, optionally after heating to 90-100 DEG C. in the presence of water to form hydrated nickel aluminate, is sulphided with hydrogen sulphide and employed in the hydrogenation of nitrobenzene.  Regeneration is effected as in (1) above, the treatment with oxygen and hydrogen in each case taking 1/2 to 24 hours at 300 to 500 DEG C.  Other methods of catalyst preparation referred to are, separate precipitation instead of coprecipitation as in (2) above or co-ignition of nickel and aluminium salts to yield a mixture of oxides which is then sulphided. The coprecipitated type of nickel sulphide/amorphous alumina catalyst may also contain small amounts of copper sulphide.  Specifications 144,614, [Class 1 (i)], and 589,915 are referred to.