Two-phase nitration of toluene. Part II

Cox, P.R.; Strachan, Alec N.

doi:10.1016/0300-9467(72)80022-4

Cited by 36 publications

(29 citation statements)

References 16 publications

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“…According to Chapman and Strachan [12] Eqs. (2) and (3), which are modifications of equations proposed by previous authors [13,3], can provide the diffusion coefficient of an aromatic compound in the mixed acid,…”

Section: Mass Transfer With Chemical Reactionmentioning

confidence: 99%

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Continuous adiabatic industrial benzene nitration with mixed acid at a pilot plant scale

Quadros

Oliveira

Baptista

2005

Chemical Engineering Journal

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A pilot plant for the continuous adiabatic nitration of benzene was constructed, reproducing the industrial operating conditions, in order to identify the reaction regime prevailing in this industrial process. Important process parameters were tested covering a wide range of operating conditions: reaction temperature (80-135• C), benzene to nitric acid molar feed ratio (0.96-1.15) and stirring speed (390-1700 rpm). The residence time and the sulphuric acid strength were fixed at 2 min and 68%, respectively. The data from a large number of experiments show a good agreement with the results of a mathematical model of the reactor.In the range of operating conditions tested, it was shown that the prevailing reaction regime is the intermediate one (0.3 < Ha < 2). The film model used to predict the mononitrobenzene production according to the intermediate regime achieved a good accuracy. The asymptotic solutions for the fast and slow reaction regimes were compared with the full solution model and it was clearly shown that the last led to improved results. Since the film model is a simple approach to describe the mass transfer with simultaneous chemical reaction, the results achieved confirmed the adequacy of this modelling approach.

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Section: Mass Transfer With Chemical Reactionmentioning

confidence: 99%

“…The sulphuric acid acts as a catalyst [1,2]. The strength of the sulphuric acid used determines the type of reaction developed, enabling operation in the kinetic or the fast reaction regimes, if the remaining parameters are kept constant [3]. Important developments have been achieved in the comprehension of these heterogeneous reactions.…”

Section: Introductionmentioning

confidence: 99%

Continuous adiabatic industrial benzene nitration with mixed acid at a pilot plant scale

Quadros

Oliveira

Baptista

2005

Chemical Engineering Journal

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“…24 Once phenol is formed, it is not possible to stop its nitration. 15 The concentration of sulfuric acid determines the reaction regime, which can range from a slow to a fast reaction 25 and is quantified by the Hatta number, Ha. 1 …”

Section: Continuous Adiabatic Benzene Nitration Processmentioning

confidence: 99%

Different Modeling Approaches for a Heterogeneous Liquid−Liquid Reaction Process

Quadros

Reis

Baptista

2005

Ind. Eng. Chem. Res.

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Multivariate linear regression (MLR) techniques were used to develop empirical models which are able to predict the formation of the main product and byproducts of the adiabatic benzene nitration process, as a function of the main operating conditions. Experiments carried out in a pilot plant enabled us to reproduce the operating conditions of the industrial process, providing experimental data in the intermediate and fast reaction regimes. The nitrobenzene (MNB) formation was modeled according to the film and Danckwerts mechanistic models, and the results were compared with a MLR model, showing that both approaches are suitable for describing this reaction. Nevertheless, the results stress an improved performance of the MLR model when compared to the mechanistic models, despite its structural simplicity. The statistical models developed for the nitrophenols (NPs), namely for the dinitrophenol and trinitrophenol (DNP and TNP, respectively), describe accurately the formation of these byproducts, overcoming the lack of data on kinetic and physical-chemical properties required by the mechanistic approach. The MLR models can be used for process optimization regarding conversion, productivity, and selectivity. By making use of these models, it was possible to estimate the operating conditions (temperature, 81°C; F B /F N ratio, 1.5; residence time, 1.9 min; nitric acid concentration, 2.6%; sulfuric acid concentration, 64%; interfacial area, 46.7 × 10 3 m 2 ‚m -3) that enable the attainment of a 99.99% MNB yield, with a total NP concentration<215 ppm.

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“…The first two parameters significantly affect the kinetics of the reaction. Kinetic studies of nitration of benzene,2 toluene,3 chlorobenzene,4 and nitrobenzene5–7 have been reported in the literature. However, only a few works have reported kinetic studies at high concentrations of sulfuric acid.…”

Section: Introductionmentioning

confidence: 99%

Nitration of nitrobenzene at high‐concentrations of sulfuric acid: Mass transfer and kinetic aspects

2009

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This article reports studies on mass transfer and kinetics of nitration of nitrobenzene at high concentrations of sulfuric acid in a batch reactor at different temperatures. The effects of concentration of sulfuric acid, speed of stirring, and temperature on mass transfer coefficient were investigated. The kinetics of nitration under homogenized conditions was studied at different sulfuric acid concentrations at these temperatures. The reaction rate constants were determined. The variation of rate constant with sulfuric acid concentration was explained by the M c function. The activation energies of the reactions were determined from the Arrhenius plots. The regimes of the reactions were determined using the values of the mass transfer coefficients and the reaction rate constants. A model was developed for simultaneous mass transfer and chemical reaction in the aqueous phase. The yields of the three isomers of dinitrobenzene were determined, and the variation of isomer distribution with sulfuric acid concentration and temperature was analyzed. This work demonstrates that more than 90% conversion of nitrobenzene is possible at high-sulfuric acid concentrations resulting in high yield of the product even at moderate temperatures and at low speeds of stirring.

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Two-phase nitration of toluene. Part II

Cited by 36 publications

References 16 publications

Continuous adiabatic industrial benzene nitration with mixed acid at a pilot plant scale

Continuous adiabatic industrial benzene nitration with mixed acid at a pilot plant scale

Different Modeling Approaches for a Heterogeneous Liquid−Liquid Reaction Process

Nitration of nitrobenzene at high‐concentrations of sulfuric acid: Mass transfer and kinetic aspects

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