Structure of catalytically active Rh–In bimetallic phase for amination of alcohols

Abstract

The structure of Rh-In bimetallic catalysts supported on carbon for amination of alcohols was determined by XRD, TEM-EDX, XPS, CO adsorption and EXAFS. At low In/Rh ratio (In/Rh # 0.2), Rh metal particles with sizes of <3 nm were observed, and the particles were partially covered with indium oxide species. With addition of more In, a tetragonal RhIn alloy with a particle size of $20 nm was formed. This tetragonal alloy has a structure with a ¼ 0.315 nm and c ¼ 0.328 nm where metal atoms are located at (0, 0, 0) and (0.5, 0.5, 0.5). The catalytic activity of the tetragonal RhIn alloy is much higher than that of Rh metal particles with or without indium oxide species. With an excess amount of In (In/Rh > 1) on the high Rh loading (20 wt%) catalyst, the cubic RhIn phase with a CsCl structure was observed instead of the tetragonal RhIn phase, and the catalytic activity was much decreased.

Substitution of alcohols by N-nucleophiles via transition metal-catalyzed dehydrogenation

“…The osmium hydride complex 106 mediated the reaction of ethanol with ammonia at 200 1C to form diethylamine (32%) and triethylamine (25%), exhibiting a potential application in the preparation of shortchain aliphatic primary amines (eqn (34)). 92 The Rh-In bimetallic catalysts supported on carbon were applied for the amination of alcohols with ammonia in an aqueous phase, 111 and the reaction of 1,2-propanediol with NH 3 was conducted at 180 1C for 24 h under 5 MPa hydrogen atmosphere, affording a mixture of 1-amino-2-propanol, 2-amino-1-propanol, and dimethylpiperazines (Scheme 28). 111,112 (34) 2.2.4 Using ammonium salts.…”

“…92 The Rh-In bimetallic catalysts supported on carbon were applied for the amination of alcohols with ammonia in an aqueous phase, 111 and the reaction of 1,2-propanediol with NH 3 was conducted at 180 1C for 24 h under 5 MPa hydrogen atmosphere, affording a mixture of 1-amino-2-propanol, 2-amino-1-propanol, and dimethylpiperazines (Scheme 28). 111,112 (34) 2.2.4 Using ammonium salts. The surrogates of ammonia, that is, ammonium salts, were also used as the nitrogen source for the synthesis of higher-order amines with alcohols as the alkylating agents.…”

Selectivity Control in Catalytic Reductive Amination of Furfural to Furfurylamine on Supported Catalysts

“…For a similar chemistry, Tomishige et al. achieved roughly 20 % conversion with slightly over 80 % selectivity to amino alcohols from 1,2‐propanediol over a high metal loading Rh/In/C catalyst . Nickel catalysts have been used extensively for the amination of aliphatic alcohols.…”

“…[17] For a similar chemistry, Tomishige et al achieved roughly 20 % conversion with slightly over 80 % selectivity to amino alcohols from 1,2-propanediol over a high metal loading Rh/In/C catalyst. [18] Nickel catalysts have been used extensively for the amination of aliphatic alcohols. Tomer et al produced n-octylamine with 60-90 % conversion and 80-90 % selectivity using nickel on alumina [19] and 80 % conversion and 78 % selectivity to n-octylamine over nickel on aluminaceria.…”

Synthesis and characterization of TiO2 nanotube supported Rh-nanoparticle catalysts for regioselective hydroformylation of vinyl acetate

“…Nanoscale Rh particles have been holding people's interests 14 for their novel electronic, magnetic, optical and catalytic properties. [15][16][17][18][19][20] Their enhanced performances, especially for size-dependent catalytic properties, result from their size or shape and high surface-to-volume ratio. 21 However, pristine Rh nanoparticles are thermally unstable and tend to agglomerate in solution when heated.…”