Hydrogenation Of Adiponitrile Research Articles

A novel two-step process for the synthesis of hexamethylenediamine from 6-hydroxyhexanenitrile derived from ε-caprolactone

Hexamethylenediamine (HMDA) is an important chemical product for the production of various value-added chemicals especially in the manufacture of polyamides, and its current production mainly relies on the hydrogenation of adiponitrile (ADN). However, the processes for the production of ADN are complicated and monopolized by some transnational corporations. In this work, a novel two-step synthesis of HMDA, consisting of the aerobic oxidation of 6-hydroxyhexanenitrile (6-HHN) to 5-cyanopentanal (5-CPA) and the reductive amination of 5-CPA to HMDA, has been developed. The aerobic oxidation of 6-HHN to 5-CPA was readily realized in an excellent yield of 92.2% under the catalysis of a classic catalyst system Fe(NO3)3/4-AcNH-TEMPO/NaCl under mild conditions. The reductive amination of 5-CPA to HMDA was conducted over a bimetallic Ni30Co7/SiO2, and the conversion of 5-CPA was 99.0% with a HMDA selectivity of 89.5% under optimal parameters. The characterization results show that Ni and Co are mainly present in the form of a Ni-Co alloy. The formation of the Ni-Co alloy in the catalyst Ni30Co7/SiO2 endows with a synergistic effect between Ni and Co in the reductive amination of 5-CPA to HMDA. Catalyst deactivation occurs during catalytic run. Deactivation is mainly due to the metal agglomeration, the oxidation of Ni0 to Ni2+, and the carbon deposition. Deactivated catalysts can be completely regenerated by H2 high-temperature reduction.

(Invited) Electrochemical Engineering Approaches for High-Performing Electrosynthesis of Polymer Precursors

The chemical industry accounts for ~5% of the US energy utilization and >30% of the US energy-derived industrial CO2 emissions. Amongst these processes, the production of organic chemical commodities, many of which are used as polymer precursors, account for the majority of the energy utilization (>1200 TBTU/y). The electrification of these processes via the implementation of electro-organic reactions could accelerate the decarbonization of the chemical industry, and bring additional sustainability advantages over their thermo-chemical counterparts. Currently, however, two major challenges prevent the deployment of electro-organic reactions: their low selectivity and their low production rates. To circumvent these barriers, our group deploys electrochemical reaction engineering principles to engineer electrode/electrolyte interfaces and design high-performing electro-organic processes. In this presentation, I will discuss how we implement this approach to understand and improve the performance of electro-organic reactions for the production of large-scale precursors for the production of Nylon 6,6 and polyethylene.The production of Nylon 6,6 involves the step-growth polymerization of 1,6-hexanediamine (HMDA) with adipic acid. HMDA is currently produced by the hydrogenation of adiponitrile (ADN). Here, I will present our insights into the electrohydrodimerization of acrylonitrile (AN) to adiponitrile (ADN). This is one of the largest electro-organic reaction deployed in industry and serves as a model process for the development of practical organic electrochemical processes. Our investigations on ADN uncovered relationships between the microenvironment at and near the electrical double layer (EDL) and reaction performance metrics (i.e., selectivity, efficiency, and productivity). I will discuss general guidelines for electrolyte formulation, dynamic electrochemical operation, the implementation of convective forces to mitigate transport limitations, ultimately leading in the conversion of AN to ADN at Faradaic efficiencies >80% and current densities of 100’s mA/cm2. Our learnings on ADN electrosynthesis helped us to engineer the electrocatalytic hydrogenation of ADN to HMDA, achieving the highest reported selectivity to date for this reaction (>95%). I will also show how similar electrochemical engineering approaches allowed us to elucidate factors that control performance in the electrochemical production of ADN from glutamic acid, an abundant and inexpensive bio-based feedstock, and of ethylene from bio-derived propionic acid. Through our studies, we aim to electrify and bring sustainability to chemical manufacturing, one reaction at a time.

Regulation of Ni/Al2O3 catalysts by metal deposition procedures for selective hydrogenation of adiponitrile

The chemical structure of Ni/Al2O3 was modulated by precipitators, and the balance between Ni0 and acid sites regulated the 1,6-hexanediamine yield.

Hydrogenation of Adiponitrile to Hexamethylenediamine over Raney Ni and Co Catalysts

Hexamethylenediamine (HMDA), a chemical for producing nylon, was produced on Raney Ni and Raney Co catalysts via the hydrogenation of adiponitrile (ADN). HMDA was hydrogenated from ADN via 6-aminohexanenitrile (AHN). For the two catalysts, the effects of five different reaction parameters (reaction temperature, H2 pressure, catalyst loading, and ADN/HMDA ratio in the reactant) on the hydrogenation of ADN were investigated. Similar general trends demonstrating the dependence of ADN hydrogenation on the reaction conditions for both catalysts were observed: higher temperature (60–80 °C) and H2 pressure, as well as lower ADN/catalyst and ADN/HMDA ratios, led to higher HMDA yields. A further increase in temperature from 80 to 100 °C increased the HMDA yield from 90.5 to 100% for the Raney Ni catalyst, but did not affect the HMDA yield (85~87%) for the Raney Co catalyst. A 100% HMDA yield (the highest yield reported to date) was also achieved via ADN hydrogenation over the Raney Ni catalyst, with a high HMDA content in the reactant (e.g., ADN/HMDA volumetric ratio of 0.06). No sign of metal leaching into the product solution was found, meaning that the Raney Ni and Raney Co catalysts were stable during ADN hydrogenation.

Functionalized multi-walled carbon nanotubes supported Ni-based catalysts for adiponitrile selective hydrogenation to 6-aminohexanenitrile and 1,6-hexanediamine: Switching selectivity with [Bmim]OH

Functionalized multi-walled carbon nanotubes supported nickel-based catalysts were prepared and applied in adiponitrile (ADN) hydrogenation. The characterization results show that different functional groups such as NH2, COOH, OH on MWCNTs surface can effectively act on metal ions by electrostatic attractions and chemical interactions so as to provide nucleation sites, and N species in MWCNTs can act as active sites for Ni deposition due to the strong electronic interactions between N species and Ni so as to promote ultra-small Ni nanoparticles formation, decrease NiO reduction activation energy, increase zero-valent Ni amounts as well as Ni nanoparticles dispersion. Furthermore, the doped N increases the lewis basicity, which favors the formation of primary amine of 6-aminohexanenitrile (ACN) and 1,6-hexanediamine (HDA). Moreover, the basic ionic liquid [Bmim]OH may switch the selectivity by inhibiting nucleophilic addition of the primary amine to the α-carbon of aldimine via the stabilization of NH2 groups in the amino-imine intermediates so as to impede by-products formation. In addition, the mechanism for ADN hydrogenation in [Bmim]OH was studied by density functional theory calculations. Under optimized conditions, it gives 97.80% total selectivity to ACN and HDA at 95.34% ADN conversion over Ni/N-MWCNTs-800 in the presence of [Bmim]OH.

Multi-walled carbon nanotubes supported nickel nanoparticles doped with magnesia and copper for adiponitrile hydrogenation with high activity and chemoselectivity under mild conditions

Multi-walled carbon nanotubes supported nickel nanoparticles doped with magnesia and copper catalysts were prepared by incipient wetness impregnation method and used in adiponitrile (ADN) hydrogenation to 6-aminohexanenitrile (ACN) and 1,6-hexanediamine (HMDA). The prepared catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), temperature-programmed hydrogen reduction (H2-TPR), H2 chemisorption, temperature-programmed ammonia desorption (NH3-TPD), temperature-programmed carbon dioxide desorption (CO2-TPD) and N2 adsorption-desorption. The results showed that the introduction of magnesia could lead to form NiO-MgO eutectic so as to restrain the reduction of nickel oxide, and it might increase the alkaline site which is conducive to the formation of primary amines in ADN hydrogenation so as to increase the selectivity to ACN and HMDA. Moreover, the formation of NiO-MgO eutectic can also inhibit the sintering of nickel in a certain extent, hence promote the nickel dispersion. And it was revealed that doping of copper can highly promote the catalytic activity by attributing to the strong synergetic effect between copper and nickel which can lead to better dispersion of nickel nanoparticles, larger metallic surface area, lower reduction activation energy of nickel oxide precursor and higher ratio of Ni0+ on the surface of the support. Multi-walled carbon nanotubes supported nickel nanoparticles doped with copper and magnesia presents the best catalytic performance of 96.27% conversion of ADN and 91.22% selectivity to ACN and HMDA under 2 MPa and lower temperature of 328 K.

Reductive amination of 1,6-hexanediol with Ru/Al2O3 catalyst in supercritical ammonia

Hexamethylenediamine (HMDA) is an important reagent for the synthesis of Nylon-6,6, and it is usually produced by the hydrogenation of adiponitrile using a toxic reagent of hydrocyanic acid. Herein, we developed an environmental friendly route to produce HMDA via catalytic reductive amination of 1,6-hexanediol (HDO) in the presence of hydrogen. The activities of several heterogeneous metal catalysts such as supported Ni, Co, Ru, Pt, Pd catalysts were screened for the present reaction in supercritical ammonia without any additives. Among the catalysts examined, Ru/Al2O3 presented a high catalytic activity and highest selectivity for the desired product of HMDA. The high performance of Ru/Al2O3 was discussed based on the Ru dispersion and the surface properties like the acid-basicity. In addition, the reaction parameters such as reaction temperature, time, H2 and NH3 pressure were examined, and the reaction processes were discussed in detail.

Catalytic properties of nickel/sepiolite promoted with potassium and lanthanum in adiponitrile hydrogenation under mild conditions

K–La–Ni/SEP were prepared and tested in adiponitrile (ADN) hydrogenation. Nickel/sepiolite promoted with potassium and lanthanum presents high activity and selectivity to 6-aminocapronitrile (ACN) and hexamethylenediamine (HMDA).

Kinetics of Adiponitrile Hydrogenation Over Rhodium-Alumina Catalysts

The catalytic hydrogenation of adiponitrile is generally carried out industrially at high temperature and pressure over Ni-Raney catalysts, which have the disadvantages of possessing low mechanical resistance and of being pyrophoric. In this work adiponitrile was hydrogenated in a three phase stirred slurry reactor using rhodium over alumina powder as a catalyst instead. Catalysts were prepared with a ion exchange technique by contacting 100 micron alumina powder with a solution of hydrate rhodium cloride for 36 h. The reaction runs were conducted in a 100 cc vessel at a pressure of 3 MPa and temperatures of 72 – 92 °C varying the initial concentration of adiponitrile. A variety of series-parallel reactions took place when adiponitrile was contacted with hydrogen in our reactor. Attention was concentrated on hexamethylenediamine, the final product, and on aminocapronitrile, a very interesting intermediate which could be used subsequently for caprolactam production (and from this the direct synthesis of nylon). Samples were withdrawn from the reactor at fixed interval of time and analysed with a gas-chromatograph so that time dependency of reactant conversion and product selectivity could be determined. The results showed the expected qualitative behaviour: adiponitrile conversion increased with time, as did the hexamethylenediamine selectivity, whereas aminocapronitrile selectivity showed a clear maximum and then decreased to negligible values. The “Chemical reaction engineering” approach was used and proved sufficient to describe quantitatively the observed kinetic behaviour of the reactor.

Preparation and characterisation of Rh/Al 2O 3 catalysts and their application in the adiponitrile partial hydrogenation and styrene hydroformylation

Rh/Al 2O 3 catalysts with a low metal loading were prepared using different preparation methods (ion exchange and homogeneous precipitation through urea decomposition). Catalysts with very high rhodium dispersion were obtained by properly choosing the preparation parameters. Moreover the kinetic parameters for the adsorption of the precursor on the support were determined. The catalysts were tested in two industrially important reactions: the adiponitrile hydrogenation and hydroformylation reaction of styrene. The hydrogenation of adiponitrile was carried out in mild conditions in a slurry reactor, at temperatures between 70 and 100 °C and under a hydrogen pressure of 3 MPa. The catalyst prepared with the ion exchange technique gave aminocapronitrile with a conversion of 60% and a selectivity of 99%. The catalyst was very active in the hydroformylation of styrene, but it suffered leaching problems such as many supported catalysts.

Evolution of several Ni and Ni–MgO catalysts during the hydrogenation reaction of adiponitrile

The changes of the surface properties of two bulk Ni (one commercial Raney-Ni and one prepared crystalline Ni) and two Ni–MgO catalysts were studied after the hydrogenation of adiponitrile in the gas phase at atmospheric pressure for 216 h at two different reaction conditions. Catalysts before and after the catalytic reaction were characterized by different techniques. Raney-Ni and Ni–MgO catalysts show an evolution of activity with the reaction time until reaching constant conversion and selectivity values. The metallic area decreases after reaction for all catalysts. Interestingly, this decrease is lower and the surface area slightly increases when using reaction conditions of high space velocity, which favour the desorption of condensation products and results in a certain disagglomeration of particles. The high hydrogenation ability of Raney-Ni and the basicity of Ni–MgO catalysts allow them to achieve much higher conversions than the bulk Ni catalyst prepared. The presence of defined octahedral particles, observed for the crystalline Ni and Ni–MgO catalysts by SEM, has been related to the constant high value of selectivity to 6-aminohexanenitrile (around 80%) maintained after 216 h of reaction at less hydrogenating conditions.

Gas-phase hydrogenation of adiponitrile with high selectivity to primary amine over supported Ni-B amorphous catalysts

Gas-phase hydrogenation of adiponitrile (ADN) was performed at 1 atm pressure over the Ni-B/SiO 2 amorphous catalyst, which exhibited high selectivity to 1,6-hexanediamine (HDA) at 100% ADN conversion. The selectivity to HDA could be further enhanced by MgO dopant. The product analysis revealed that the selectivity to HDA was mainly dependent on the contents of 6-aminohexanenitrile and azacycloheptane formed during the ADN hydrogenation. The 6-aminohexanenitrile was an intermediate in the reaction; it resulted from the half-hydrogenation of ADN; and its content was strongly affected by the activity of the catalyst. The azacycloheptane was a side-product (secondary amine) formed via the nucleophilic addition of the primary amine on one side of ADN chain to the aldimino carbon atom on the other side which was adsorbed by the Ni active sites. The electronic density of the Ni active sites played a key role in determining the content of azacycloheptane. The presence of the alloying B resulted in the electron-enriched Ni active sites which effectively inhibited the formation of azacycloheptane and in turn, resulted in the high selectivity to HDA.

Gas-Phase Adiponitrile Hydrogenation over Modified Ni–P/SiO2 Amorphous Catalysts

Abstract Gas-phase hydrogenation of adiponitrile were carried out in a fixed-bed reactor at 1 atm pressure, and in the absence of ammonia. In comparison with other Ni-based catalysts, the Ni–P/SiO2 amorphous catalyst exhibited higher activity and/or better selectivity to 1,6-hexanediamine, which could be further improved by W or MgO-additives.

Activity and XRD phase identification of several nickel catalysts for adiponitrile hydrogenation

Activity and XRD phase identification of several nickel catalysts for adiponitrile hydrogenation

Activity and surface characteristics of several alkali-doped iron catalysts for nttrile hydrogenation

Abstract A non-doped and several alkali (Na, K, Cs)-doped iron catalysts were prepared by reduction of the impregnated iron oxide. The surface characterization of the catalysts was accomplished by use of BET, XRD, XPS, and surface acid determination. The surface areas of the catalysts decrease with the increase of the alkali atomic volume (BET). Alkali migration towards the surface is always found (XPS). The surface acid determination shows an increase in the number of acid centres per m2 of catalyst with the atomic volume of the alkali promoter. The curves of base adsorption show the presence of acid sites of different strengths in all the reduced catalysts. The characterization results are correlated with those of catalytic activity for hydrogenation of adiponitrile at 200–250 °C. The results indicate correlations between conversion and the type and concentration of surface acid sites.

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

1. The effect of various factors on the hydrogenation of adiponitrile in a flow system under pressure was investigated. 2. It was shown that, under flow conditions with a sufficiently long layer of catalyst, adiponitrile is hydrogenated with formation of 1,6-hexanediamine In high yield (ranging to 80%). 3. The high.activity of the Raney nickel catalyst and the high ratio of the amounts of catalyst and of dinitrile undergoing hydrogenation make it possible to carry out the process under mild conditions (temperature 80°, pressure of hydrogen 50 arm). 4. Lowering of the temperature to 60° and of the pressure to 20 atm leads to a reduction in the yield of the diamine and an increase in the yield of the product of incomplete hydrogenation, 6-aminohexanenitrile, Raising the temperature and pressure favors side reactions and accelerates the deactivation of the catalyst. 5. Addition of 0.24% of sodium hydroxide to the dinitrile leads to a great reduction in the yield of diamine and to an increase in the yield of hexamethylenimine.