A multifaceted role of a mobile bismuth promoter in alcohol amination over cobalt catalysts

Article abstract of DOI:10.1039/d0gc00937g

Promotion with small amounts of different elements is an efficient strategy for the enhancement of the performance of many heterogeneous catalysts. Supported cobalt catalysts exhibit significant activity in the synthesis of primary amines via alcohol amination with ammonia, which is an economically efficient and environmentally friendly process. Insufficient selectivity to primary amines, low activity and fast cobalt catalyst deactivation remain serious issues restricting the application of alcohol amination in the industry. In this work, we have discovered the multifaceted role of the bismuth promoter, which is highly mobile under reaction conditions, in 1-octanol amination over supported cobalt catalysts. First, the overall reaction rate was enhanced more than twice on promotion with bismuth. Second, the selectivity to primary amines increased 6 times in the presence of Bi at high alcohol conversion. Finally, the bismuth promotion resulted in extremely high stability of the cobalt catalyst. Characterization by XRD, temperature programmed reduction, STEM, CO chemisorption, BET, TGA and FTIR has showed that the enhancement of the catalytic performance on promotion with bismuth is due to better cobalt reducibility, easy removal of strongly adsorbed intermediates and products by the mobile promoter and suppression of amine coupling reactions resulting in secondary and tertiary amines.

Full text of DOI:10.1039/d0gc00937g

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DOI: 10.1039/D0GC00937G
Multifaceted Role of Mobile Bismuth Promoter in Alcohol
Amination over Cobalt Catalysts
Feng Niua,b, Mounib Bahric, Ovidiu Ersenc, Zhen Yanb, Bright T. Kusemab, Andrei Y.
Khodakova* and Vitaly V. Ordomskya,b*
a Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité
de Catalyse et Chimie du Solide, F-59000 Lille, France
b E2P2L, UMI 3464 CNRS-Solvay, 3966 Jin Du Rd., 201108 Shanghai, China
c Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS)-UMR 7504
CNRS, Université de Strasbourg, 23 rue du Loess, BP 43-67034 Strasbourg Cedex 2,
France
*Corresponding authors: Andrei Khodakov E-mail:andrei.khodakov@univ-lille.fr;
Vitaly Ordormsky E-mail:vitaly.ordomsky-ext@solvay.com
1

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DOI: 10.1039/D0GC00937G
Abstract
Promotion with small amounts of different elements is an efficient strategy for the
enhancement of the performance of many heterogeneous catalysts. Supported cobalt
catalysts exhibit significant activity in the synthesis of primary amines via alcohol
amination with ammonia, which is an economically efficient and environmentally
friendly process. Insufficient selectivity to primary amines, low activity and fast cobalt
catalyst deactivation remain serious issues restricting application of alcohol amination
in the industry.
In this work, we have discovered the multifaceted role of the bismuth promoter,
which is highly mobile under the reaction conditions, in 1-octanol amination over
supported cobalt catalysts. First, the overall reaction rate was enhanced more than twice
on the promotion with bismuth. Second, the selectivity to primary amine increased 6
times in the presence of Bi at high alcohol conversion. Finally, the bismuth promotion
resulted in the extremely high stability of the cobalt catalyst. Characterization by XRD,
temperature programmed reduction, STEM, CO chemisorption, BET, TGA and FTIR
has showed that the enhancement of the catalytic performance on the promotion with
bismuth is due to better cobalt reducibility, easy removal of strongly adsorbed
intermediates and products by the mobile promoter and steric hindrances for amine
coupling reactions resulting in secondary and tertiary amines.
2

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DOI: 10.1039/D0GC00937G
Introduction
Amines are important materials in chemical industry and life science [1]. Most aliphatic
amines and their derivatives are essential intermediates for organic synthesis, which are
widely used in the production of agrochemicals, pharmaceuticals, organic dyes,
detergents, fabric softeners, surfactants, corrosion inhibitors, lubricants, polymers and
so on [2,3].
A number of routes for amines synthesis have been developed like Hofmann
alkylation, Buchwald-Hartwig and Ullmann reactions, hydroamination, reduction of
nitriles, and reductive amination [4,5,6,7,8,9,10,11]. Most of currently available amine
synthesis routes involve generation of by-side products harmful for environment and
human health. Direct one-pot amination of alcohols with ammonia is a safe method of
amine synthesis with the environmentally benign byproduct such as water. This route
of amination corresponds to the most part of the principles of Green Chemistry like
prevention, atom economy, safer chemicals, no solvents, catalysis, reduce derivatives
etc.
The alcohol amination on different supported metallic catalysts, such as Ru [12],
Ni [13] and Co [14], under hydrogen can be achieved via so called hydrogen borrowing
or hydrogen auto transfer methodology [15,16,17,18], which consists of
dehydrogenation and hydrogenation processes. The one-pot alcohol amination
generally consists of three consecutive steps: (i) dehydrogenation of an alcohol to a
reactive aldehyde (or ketone); (ii) imine formation by coupling of a carbonyl compound
with ammonia; (iii) amine formation by hydrogenation of the imine over the catalyst.
3