Caprolactam

Tinge, Johan Thomas; Groothaert, Marijke H.; Veld, Hans op het; Ritz, Josef; Fuchs, Hugo; Kieczka, Heinz; Moran, William C.

doi:10.1002/14356007.a05_031.pub3

Cited by 27 publications

(25 citation statements)

References 37 publications

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“…The parameters are determined using the nonlinear leastsquares solver integrated in Matlab ® Optimization Toolbox TM . The results obtained are coherent with the laws that can be extrapolated from viscosity data of the molten monomer at temperatures lower than 403 K [6,7,8].…”

Section: Temperature Dependence Of the Reactive MIXsupporting

confidence: 85%

“…In the Navier-Stokes equations, the diffusion term uses central differencing while the convection term uses the "limitedLinearV" scheme native to OpenFOAM® adapted for vector fields and blends central differencing and upwinding method in a way that satisfies TVD (Total Variation Diminishing) conditions for stability and convergence [13]. The time step Δ is chosen adaptively, according to the maximum local Courant number (8) in an element with Δ being its characteristic length. The maximum Courant number is chosen at 0.1 in order to ensure accuracy.…”

Section: Methodsmentioning

confidence: 99%

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Modeling the reactive PA6 flow for LCM processes

Han¹,

Govignon²,

Cantarel³

et al. 2021

Esaform 2021

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Fiber reinforced thermoplastic composites have shown to be attractive for industry as they can be reused, reshaped, welded and repaired, while keeping mechanical properties on par with thermoset composites. Since thermoplastics usually have high melt viscosities unsuitable for liquid composite molding processes, in-situ synthesis of PA6 from ε-caprolactam is considered. Its reactive mix has low viscosity which allows impregnation. However, the coupled crystallization and polymerization affects the resin viscosity and its flow is altered by the dual-scale permeability of the fiber preform. Thus, to predict the local differences in the thermoplastics properties, a coupled polymerization crystallization model needs to be integrated in the LCM processing simulation at representative scales. This study aims to propose a reliable simulation of the resin flow through a fibrous preform. Hence, viscosity measurements on the reactive mix are achieved using a rheometer with parallel-plate geometry, aiming to associate a viscosity model with the Hillier coupled polymerization-crystallization model previously determined by Vicard. The full chemorheological model will then be integrated into a simulation of LCM process in OpenFOAM®, an open source CFD software in order to follow the extent of the synthesis in the resin flow during the process. As a future work, simulations including microscale tow information extracted from a real textile specimen will permit to investigate the effect of permeability and double scale porosity in fibrous preforms on the final polymerization rate and crystallinity.

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Section: Temperature Dependence Of the Reactive MIXsupporting

confidence: 85%

Section: Methodsmentioning

confidence: 99%

Modeling the reactive PA6 flow for LCM processes

Han¹,

Govignon²,

Cantarel³

et al. 2021

Esaform 2021

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“…More than 98% of the CPL is produced using cyclohexanone (ONE) as an intermediate. ONE is obtained either by hydrogenation of phenol or by catalytic and noncatalytic oxidation of cyclohexane with air or by hydration of cyclohexene to cyclohexanol followed by dehydrogenation. , The most common ONE production process is promoted by oxidation of cyclohexane in the presence of catalytic metal salts to obtain a reaction mixture known as KA-oil, which contains ONE, cyclohexanol, and other impurities. − …”

Section: Introductionmentioning

confidence: 99%

“…ONE, after being purified from KA-oil, reacts with hydroxylamine (HA) (usually added as hydroxylamine sulfate (HAS)) to produce cyclohexanone oxime. ,, In this reaction, the sulfuric acid formed is neutralized using ammonia, and ammonium sulfate is obtained as a byproduct. ,,− To avoid the formation of ammonium sulfate (AS), the ammoximation of cyclohexanone has been recently proposed. In the ammoximation of cyclohexanone, aqueous H 2 O 2 and ammonia react with ONE by means of solid titanosilicate as a catalyst (known as TS-1). ,,− …”

Section: Introductionmentioning

confidence: 99%

Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Lorenzo

Salvador

Del-Arco

et al. 2019

Ind. Eng. Chem. Res.

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Caprolactam obtained after oximation and Beckman Rearrangement of cyclohexanone is the monomer of nylon-6. As the quality of the nylon-6 fibers is affected by the impurities present in ε-caprolactam, the type and amount of impurities in the cyclohexanone production process should be studied. Characterization of the purity of ε-caprolactam is accomplished using different parameters. Among them, volatile bases evaluate the presence of linear amides as impurities. They act like chain terminations and have a strong impact on average molecular weight and the size of nylon fibers. In ε-caprolactam from cyclohexane oxidation, these linear amides are frequently found, and N-pentylacetamide is one of the most abundant. In this work, it has been proposed and proven that ketones or aldehydes, such as n-heptanones, n-octanones, and hexanal present in cyclohexanone from cyclohexane oxidation, are the precursors of the most linear amides found in CPL. Special attention has been paid to the reactivity of 2-heptanone and 3heptanone in the oximation and Beckmann rearrangement steps since they have a boiling point similar to that of cyclohexanone and are difficult to remove by distillation. To do this, oximation (T = 80 °C and pH = 5) and further rearrangement (in sulfuric media at 100 C) of the aforementioned ketones or aldehydes has been carried out. Oximes and amides produced have been identified by using NMR and/or GC/MSD techniques. The kinetic model for oximation of 2-heptanone and 3-heptanone has been obtained at two temperatures (80 and 85 °C) within the pH range 3.5−6, simulating industrial conditions. In addition, the relative rearrangement rates of the linear oximes have been analyzed, showing the reaction rate to N-pentylacetamide for the production of the linear amides.

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“…[1] The polymer is made by polymerisation of e-caprolactam, which is produced by several routes,all starting from benzene. [2] In the 1990s,B ASF,D SM, and DuPont all worked on synthetic strategies towards e-caprolactam starting from methyl 3pentenoate (M3P) obtained by palladium-catalysed methoxycarbonylation of the less expensive butadiene (Scheme 1). [3] Since M3P has only five carbon atoms in the chain, asixth one had to be added by hydroformylation.…”

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confidence: 99%

Nylon Intermediates from Bio‐Based Levulinic Acid

et al. 2019

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Use of ZrO 2 /SiO 2 as asolid acid catalyst in the ringopening of biobased g-valerolactone with methanol in the gas phase leads to mixtures of methyl 2-, 3-, and 4-pentenoate (MP) in over 95 %selectivity,containing asurprising 81 %of M4P.This process allows the application of aselective hydroformylation to this mixture to convert M4P into methyl 5formyl-valerate (M5FV) with 90 %s electivity.T he other isomers remain unreacted. Reductive amination of M5FV and ring-closure to e-caprolactam in excellent yield had been reported before.T he remaining mixture of 2-and 3-MP was subjected to an isomerising methoxycarbonylation to dimethyl adipate in 91 %yield. Scheme 1. Routes to e-caprolactam from butadiene.

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Caprolactam

Cited by 27 publications

References 37 publications

Modeling the reactive PA6 flow for LCM processes

Modeling the reactive PA6 flow for LCM processes

Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Nylon Intermediates from Bio‐Based Levulinic Acid

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