Preparation of 1,6-hexanediamine by hydrogenation of adiponitrile over a nickel catalyst under flow conditions

Recent advances in the sustainable production of α,ω-C6 bifunctional compounds enabled by chemo-/biocatalysts

“…6,7 To address these problems, unswerving efforts have been devoted in both academic and industrial area. Specifically, for the chemical transformations, several approaches have been employed: (a) different reactors including fixed bed, rotating autoclave, trickle bed reactor, three phase stirred slurry reactor and moving bed reactor 8,9 and different feeding methods comprising one-time, batch, semi-batch and continuous feeding; 10 (b) optimization of catalysts to avoid strongly alkaline or acidic solution in system: from different metals to alloy, Al 2 O 3 or active carbon supported metallic catalysts, sponge nickel catalysts, nanoparticles, hollow titanium silicalite (HTS) zeolites, dealuminated HBEA zeolite (DHBEA) and so on; [11][12][13][14][15][16][17] (c) renewable feedstock like biomass or food waste was used as substrates. [18][19][20][21] On the other hand, for the biological transformations, plenty of microbial fermentation processes and enzymes from various sources were discovered, and the whole-cell or enzyme catalyzed reactions were constructed to produce α,ω-C6 bifunctional compounds.…”

“…HMD was reported to be chemically synthesized from ADN, HDO and adipaldehyde. 9,132,135 The hydrogenation of ADN to form HMD is exothermic, and the reaction conditions and HMD yield strongly depend on the catalysts, which were normally based on the Co, Ni, Fe and noble metals (Ru, Rh, Pt 4.…”

“…and Pd). 8,9,[139][140][141][142] Among them, Ni or Co was the best choice of catalysts for primary amines production, while Rh was suggested for high selectivity to secondary amines. 8,139 Recent studies have been carried out in the liquid/liquid or gas/solid phase or in flow conditions using supported catalysts with the aim of reducing the operating pressure and operating without organic/hazards solvents.…”

“…8 The currently common route in industrial production of HMD is the catalytic hydrogenation of adiponitrile (ADN) (Scheme 18), but this process is energy-intensive and significantly leads to the emission of pollutants such as nitrous oxide and cyanide. 9,30,127,128 To overcome these problems, various catalysts, autoclave and reaction conditions have been tested for ADN conversion, 8,9,[129][130][131] while biological synthesis of HMD from AA and sugar/glycerol are also explored. 4,40 Furthermore, an integrated catalytic conversion method of HDO to HMD is also reviewed herein.…”

“…130 Other than static conditions, hydrogenation of ADN over RANEY®-Ni under a flow condition was also reported. 9 In details, the moist catalyst grains were introduced into the reactor as a continuous spray, while H 2 and dinitrile-ammonia mixture were passed into the reactor. Aluminum and RANEY®-Ni were used as catalysts and the hydrogenation products were fractionally distilled in a stream of N 2.…”