Intrinsic Kinetics of Three-Phase Slurry Hydrogenation of o

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Intrinsic Kinetics of three-phase slurry Hydrogenation of onitro Cardanol to o-amino Cardanol over Ra/Ni catalyst. Bhagwat Ramdas Patil, Atul Harishchandra Bari, Dipak V Pinjari, and Aniruddha Bhalchandra Pandit Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b02523 • Publication Date (Web): 08 Sep 2017 Downloaded from http://pubs.acs.org on September 11, 2017

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Industrial & Engineering Chemistry Research

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Intrinsic Kinetics of three-phase slurry Hydrogenation of o-nitro Cardanol to o-amino

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Cardanol over Ra/Ni catalyst.

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Bhagwat R. Patil, Atul H. Bari, Dipak V. Pinjari and Aniruddha B. Pandit*

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Department of Chemical Engineering, Institute of Chemical Technology,

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Mumbai-40019, India

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* Corresponding Author, Email: [email protected] Phone: +91 22 33611111

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Fax: +91 22 33611020

ACS Paragon Plus Environment


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Abstract:

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The intrinsic kinetics of the hydrogenation of o-nitro cardanol (ONC) to o-amino cardanol

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(OAC) over Ra/Ni has been investigated with methanol as a reaction medium. The catalytic

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hydrogenation was carried out in an agitated three-phase slurry reactor, operating in the

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kinetically controlled regime. The operating conditions were varied with temperatures in the

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range of (60-900C), the initial concentration of o-nitro cardanol in the range of (5.73-14.3

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mmol), hydrogen partial pressures in the range of (8-20bar), and catalyst loading in the range

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of (0.25-0.75g dm-3). Catalyst reusability was also examined. The reaction was found to

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follow first-order kinetics with respect to both hydrogen and o-nitro cardanol. LHHW

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approach was used to investigate the possible mechanistic path of the reaction. It was found

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that the reaction proceeds through dual site molecularly adsorption of reactant species with

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the surface reaction being the rate controlling step. Also, the various thermodynamic

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properties associated with various rate constants were estimated.

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Keyword: o-nitro cardanol, o-amino cardanol, Hydrogenation, Kinetic Modelling, LHHW

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Modelling, Raney nickel.

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1 Introduction:

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Aromatic amino compounds are important starting materials for the intermediates of

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dyes, drugs, polymers, pigments and pesticides. It is widely recognized that, for the

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preparation of amino derivatives, rapid and selective reduction of nitro compounds is of

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importance. Remarkable work has been done using various methods for the reduction of

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aromatic nitro compounds to amino compounds. Most of them are, meta/acid reduction [1],

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catalytic hydrogenation

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catalytic transfer hydrogenation [4] etc.

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In the perspective of the industries, hydrogenation of nitro phenol is a very important process

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for the manufacturing of amino phenol. One of such amino phenol, which finds a wide range

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of applications, is amino cardanol. Amino cardanol can be used as an anti-oxidant for the

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petroleum products such as turbine oils, hydraulic oils, motor oils, cutting oils, petroleum

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waxes and gum inhibitor in cracked gasoline.

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hydrogenation of nitro cardanol. Nitro cardanol is obtained by the nitration of saturated

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cardanol, which is the naturally occurring unsaturated phenol obtained from cashew nut shell

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liquid (CNSL) a by-product of cashew industry.

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The cashew nut industry is largely present in countries of tropical regions, such as India,

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Brazil, and Viet Nam. The global world production of cashew nut shell liquid was estimated

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around 4 million tons in 2012 (Food and Agriculture Organisation (FAO)), mainly located in

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Vietnam (1.2000.00tonnes/year) followed by Nigeria, India, etc. (Fig.1).

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, homogeneous catalytic transfer hydrogenation [3], heterogeneous

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Amino cardanol can be obtained by the



1400000

Production (Metric Tonnes)

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1200000 1000000 800000 600000 400000 200000 0 Vietnam

Nigeria

India

West Africa

Brazil

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Fig.-1. Main cashew nut shell liquid producing countries in 2012. Cardanol is yellow oil obtained after the vacuum distillation of CNSL

[6-9]

.

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Hydrogenation of unsaturated cardanol [10] and its subsequent nitration gives amino cardanol.

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Thus, amino cardanol can be derived from a renewable resource and hence it is viable to

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study the hydrogenation of nitro cardanol.

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The kinetic study of such reaction is an inevitable part of the understanding of the

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mechanism of reactions required for the designing of reactors. Several kinetic studies have

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been carried out for the hydrogenation of some of the nitro aromatic compounds. Chaudhary

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et al. have reported the detailed kinetics of Hydrogenation of o-Nitro phenol to o-

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Aminophenol on Pd/C catalysts with methanol as solvent.[11] It is believed that, among all the

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solvents, methanol is the best solvent for the hydrogenation of nitro aromatic compounds to

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amino compounds.[12] Scholnik et al. studied the catalytic reduction of nitro compounds on

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the intermediate compounds with Raney nickel as a catalyst.[13] Bawane et al. have reported

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the kinetics of hydrogenation of p-nitro phenol to metol using Raney nickel as a catalyst.[14]

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However, as per our knowledge, the detailed kinetic study on the hydrogenation of nitro

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cardanol to amino cardanol hasn’t been reported.


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The present work emphases on the kinetic aspects of the hydrogenation of o-nitro

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cardanol (ONC) to o-amino cardanol (OAC). A typical reaction scheme is shown in figure 2.

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The catalytic hydrogenation was carried out in an agitated three-phase slurry reactor with

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Ra/Ni catalyst and methanol as a reaction medium. We have investigated the detailed kinetics

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and proposed a Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism responsible

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for hydrogenation.

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2 Reaction scheme:

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Fig. 2 Hydrogenation of Ortho nitro cardanol to ortho amino cardanol

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3 Experimental:

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3.1 Materials:

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The cardanol was obtained from Gargi Huttenes Albertus Pvt. Ltd., Mumbai, India.

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Then, we have synthesized the Nitro Cardanol in our own lab y successive hydrogenation and

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nitration (Purity checked by HPLC was 99%). Hydrogen and nitrogen cylinder were

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purchased from Inox Air product, Mumbai. India, (purity was > 99.9%). The commercial

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Ra/Ni (KAlCAT-2921) catalyst was supplied by Monarch Catalyst Pvt., Ltd., Mumbai, India.

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Methanol (AR grade) was procured from S.D.Fine Chemicals., Mumbai, India.

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3.2 Experimental setup:

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The catalytic hydrogenation of o-nitro cardanol was performed in a batch reactor of the

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capacity of 250ml, made up of SS-316 (Provided by Amar equipment Pvt. Ltd., Mumbai,



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India). This reactor was equipped with a variable speed magnetic drive, pitched bladed

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turbine agitator, cooling coil and a thermowell for sensing the temperature. It was provided

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with inlet and outlet gas nozzles with valves, a liquid outlet nozzle valve and a rupture disc

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for safety. A pressure gauge was installed to monitor the total pressure in the reactor. A

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temperature sensor was provided to measure the temperature of the reactants in the reactor.

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The temperature sensor was immersed into the thermowell filled with mineral oil. An

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electrically heated jacket servo linked to thermocouple output was used along with an internal

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cooling coil to achieve and maintain the desired heating requirements.

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3.3 Experimental protocol:

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All the reactions were carried out by charging 5g of O-nitro cardanol into the reactor

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along with 100 ml of methanol (as reaction solvent) and desired quantity of the catalyst

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(Ra/Ni). Then, the reactor was sealed with quick fit assembly to ensure a leak proof system.

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After which, the reactor was purged thrice with nitrogen to flush the inside air and maintain

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the inert atmosphere. Then, the reactor was heated electrically and the temperature was

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controlled by power stat. When the reactor temperature was stabilized at the desired

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temperature, hydrogen gas was added to the reactor. Hydrogen was added till the reactor got

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pressurized to a pre-set pressure value. This time was considered as the zero time of the

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reaction. The pressure inside the reactor was maintained constant throughout the reaction by

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supplying hydrogen from a high-pressure cylinder. The temperature of the reactor was

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maintained constant at the desired value with an accuracy ±1 0C by circulating cold water

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through the internal cooling coil of the reactor. During these operations, the stirrer was kept

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running at a desired speed of agitation. Each experiment was performed minimum in

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duplicate. To ensure the reproducibility, experiments were further repeated if experimental

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observation shows 5% deviation from the mean observation. In such procedure two


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experiments with closest results (with deviation

Intrinsic Kinetics of Three-Phase Slurry Hydrogenation of o

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