PPT_Petrochem 10 - SEM 1 12-13

PETROCHEMISTRYBSK3513

Dr. Mohd Hasbi Ab. Rahim

Reactions and Chemicals of BenzeneOxidation, , Hydrogenation, Alkylation, Chlorination, Nitration

Reactions and Chemicals of TolueneOxidation, Chlorination, Nitration, Carbonylation, Dealkylation, Dispropornation

Chemicals from XyleneTerepthalic acid, Phthalic Anhydride, Isophthalic Acid

AROMATIC HYDROCARBONS

•Benzene, toluene, xylenes (BTX), and ethylbenzene are the aromatic hydrocarbons with a widespread use as petrochemicals.

•They are important precursors for many commercial chemicals and polymers such as phenol, trinitrotoluene (TNT), nylons, and plastics.

•Aromatic compounds are characterized by having a stable ring structure due to the overlap of the π-orbitals (resonance).

•Accordingly, they do not easily add to reagents such as halogens and acids as do alkenes.

•Aromatic hydrocarbons are susceptible, however, to electrophilic substitution reactions in presence of a catalyst.

•Aromatic hydrocarbons are generally nonpolar. They are not soluble in water, but they dissolve in organic solvents such as hexane, diethyl ether, and carbon tetrachloride.

Catalytic reforming for aromatics production

Desired reactions in Catalytic reforming

60-90°C cut for benzene90-110°C cut for toluene110-140°C for xylenes

The reactions are:

Uses of benzene

• Benzene (C6H6) is the most important aromatic hydrocarbon.• Almost all compounds derived from benzene are converted to other chemicals and polymers.• Benzene is not easy to polymerize due to the resonance stabilization of benzene ring.

Oxidation of Benzene

+ 9/2 O2 + 2 CO2 + 2 H2O

Oxidation of benzene to maleic anhydride, 380 oC, atm. Pressure with V2O5/MO3 cat.90% Conversion with 50 – 60% selectivity.

The main route is oxidation of n-butane

Hydrogenation of Benzene (production of cyclohexane)

OH

+

O

O2

-H2

H2

HNO3

COOH

COOH+N2O

Hydrogenation which involved an addition of H2 into benzene ring to produce cyclohexane.Ni/Al, Ni/Pd cat. , 160 – 220 oC, 25 – 30 atm.The pressure of H2 play an important role in controlling the catalytic activity and selectivity.

Cyclohexane is oxidized in a liquid-phase process to a mixture of cyclohexanol and Cyclohexanone. (Cobalt acetate & orthoboric acid as cat., 95 – 120 oC, 10 atm).

With similar catalyst at lower temperature and longer residence time produces adipic acid.

Cyclohexane

Adipic acid

2.5 O2

COOHCOOH COOH

COOH O

OH

OH

OH

OHOH

(current route)

(Noyori's route)

adipic acid muconic acid

D-glucose

(Biocatalysis; Frost's route)

Enviro-friendly routes for adipic acid

O2 COOH

COOH

O2

R. Noyori, Science 281 (1998) 1646 K.M. Draths & J.W. Frost, JACS 120 (1998)10545

J. M. Thomas & R. Raja, Chem. Commun. Feature Article, 675 ( 2001)

• Alkylation is the introduction of an alkyl group into a molecule • It may involve a new C-C, O-C, N-C bond formation• Alkylation is catalyzed by acidic or basic catalysts

Acid catalysts are used mainly in aromatics alkylation at ring-C

Basic catalysts are used in alkylation at side-chain-C

CH3

+ MeOH

CH3

CH2CH3

CH3

Acid Catalyst

Basic Catalyst

(p-Xylene)

(Ethylbenzene)

Alkylation

Some important industrial alkylation reactions

Reactants Product Catalyst Process licensors

Benzene + ethylene /EtOH EB ZSM-5 Mobil-Badger /NCL etc

Benzene + propylene Cumene H-Y; H-M; H- DOW, UOP etc

Benzene + C11 – C13 olefins LAB Solid acid/ RE-Y UOP / NCL

kg

Alkylation of Benzene1. Production of ethyl benzene (EB), C6H5CH2CH3

Colorless liquid with boiling point of 136 oC.

C6H6 + CH2=CH2 C6H5CH2CH3 (AlCl3-HCl, 40-100 oC, 2 – 8 atm)

(Diethylbenzene and higher alkylated also form which later recycled and dealkylated to EB)

Main use of EB: Manufacture of styrene (C6H5CH=CH2)

Dehydrogenation of EB produce styrene

C6H5CH2CH3 C6H5CH=CH2 + H2

ReactorsTemp. (ºC)WHSV (h-1)PressureBenzene / alc. (mole)Alcohol sel. (%)EB + DEB (%)EB (%)Cycle length (days)No. of cycles

3 beds in series380 – 420 ºC5 – 10 (6)1 - 44 – 15 (5)98958545>25

+ + H2O

CH2 CH3

CH2CH3 OH

Mobil-Badger process is based on ethylene and uses ZSM-5;Other licensors are UOP, CDTECH etc; use other zeolitesCDTECH process uses reactive distillation

Mobil-Badger process

Catalyst is Encilite – pentasil (ZSM-5) type

Mobil-Badger process

Uses ethylene as the alkylating agentT = 370 - 420°C; P = 7 – 27 bars;

[Degnan et al. Appl. Catal. A 221 (2001) 283]

Kg

> 40 SPA units have been licensed (UOP

Main use of cumene: in the production of phenol

2. Production of Cumene or isopropylbenzene, C6H5CH(CH3)2

Benzene + propylene Cumene

Comparison of NCL (H-beta) and SPA catalysts

CATALYST N.C.L. S.P.A.

Mole Ratio (benz./C3) 6.0 8.0

Temperature (°C) 150 210

Pressure (bar) 30 30

WHSV (h-1) 3.5 2.5

Products (wt. %)

Aliphatics 0.003 0.67

Toluene + Ethylbenzene 0.01 0.01

Cumene 22.03 17.18

Di-isopropylbenzene 1.70 1.11

Conversion of propylene 99.99 99.90

Prop. Sel. To Cumene 92.80 89.70

Bromine index <0.1 1-2

CUMENE

NCL processes for alkylation and transalkylation are available

Benzene + propylene Cumene

Process licensors: UOP, CDTECH, Enichem, Mobil-Badger, DOW

Zeolite processes involve a transalkylation (with benzene)step to convert >10 % di i-pr-Bz into cumene

Yield of cumene in zeolite processes is more as transalkylation is not possible with SPA catalysts

CDcumene process (CDTECH)

Reaction is done in catalytic distillation reactor The catalyst is held in distillation traysA transalkylation reactor converts the di-iprBz.

Features

H3PO4/zeolite

[O]

N2O

FeZSM-5

TS1

O

OOH

OH

H2O2/

+

(Benzene) (Cumene) (Cumene hydroperoxide)

(phenol)

Phenol production

Phenol is a white crystalline material with a distinctive odor, highly soluble in water andSoluble in weakly acidic solution.Important monomer for phenolic resins, reaction with acetone produce bis-phenol A whichIs important monomer for epoxy resin and polycatbonates., Aspirin, salicyclic acid

3. Production of linear alkylbenzene (LAB), C6H5CH(CH3)

R

C6H6 + RCH=CH2 C6H5CH(CH3) R

The alkylating agents are either linear C12 – C14 mono olefins or monochloroalkanes.Alkylating with olefin is industrially preferred

Normally to produce biodegradable anionic detergents.

UOP

Evolution ofLAB processes;BecomingGREENER

Benefits in product quality - use of solid acid

Green

Catalyst

AlCl3

AlCl3

HFSolid acid

Production of LAB Alkylation of benzene with C11 – C13 olefins

Heavy alkylates

H2 rich off gas

Distillation

N-paraffin recycle

ParaffinRecovery

BenzeneRecovery

Alkylation Solid-acidCATALYST

Make up H2

PACOL

DehydrogenationPt/Al2O3

SelectiveHydrogenation

DEFINE

Fresh n-paraffin

H2 recycle Fresh benzene

Ben

zene recycle

LAB

Linear alkyl benzene (LAB) using a solid-acid catalystLinear alkyl benzene (LAB) using a solid-acid catalyst

Detal process for Linear Alkyl Benzene production

Industrial alkylation Processes

Chlorination of Benzene

Electrophilic substitution reaction in which Cl serve as electrophile.

Lewis acid i.e. FeCl3 as catalyst, 80 100 oC, atm. Pressure.

The products are a mixture of mono- and dichlorobenzenes. The ortho- and the para-Dichlorobenzene are more common than meta-

Nitration of Benzene

Electrophilic substitution reaction in which (nitronium ion) NO2 serve as electrophile.

Concentrated nitric and sulfuric acids as catalysts at 50 oC.

HNO3 + 2H2SO4 2HSO4- + H3O+ + NO2

+

C6H6 + NO2+ C6H5NO2 + H+

Nitrobenzene use to produced aniline, C6H5NH2 (hydrogenation of nitrobenzene), quinoline, benzidine and as a solvent for cellulose ethers.

Reactions and Chemicals of Toluene

Toluene (methylbenzene) is similar to benzene as mononuclear aromatic, but it is more activedue to the presence of the electron-donating methyl group.

Could produced more polysubstituted products compared to benzene.

DeAlkylation of Toluene (produce benzene)

DeAlkylation of toluene produce benzene

C6H5CH3 + H2 C6H6 + CH4

(La, Ce, Pr, Nd, Sm, Th or Ni-Cr2O3 as catalyst, 600 – 800 oC or Ni-Al2O3 catalyst at 320-630 oC)

Disproportionation of Toluene (produce benzene & xylene mixture)

Disproportionation of toluene produce benzene and xylene mixture

2C6H5CH3 + H2 C6H6 + C6H5(CH3)2

(450 – 530 oC, 20 atm, CoO-MoO3 on aluminosilicates/alumina catalyst, ZSM5)

Some important industrial alkylation reactions

Reactants Product Catalyst Process licensors

Toluene + methanol P-Xylene Modified ZSM-5 Mobil

Naphthalene + propylene 2,6-DIPN H-mordenite Chiyoda

Naphthalene + methanol 2,6-DMN Zeolite Rütgerswerke

Biphenyl + propylene 4,4’-DIPB H-mordenite DOW

Alkylation of Toluene

Oxidation of Toluene (produce benzyl alcohol, benzaldehyde, benzoic acid)

1. Production of benzoic acidC6H5CH3 + 1.5O2 C6H5COOH + H2O

(cobalt acetate, 165 oC, 10 atm)

Benzoic acid is a white crystalline solid, soluble in water and most common organic solvents.

Use to season tobacco, preserve food, make dentifrices, precursor for caprolactam, phenol,Terepthalic acid

Phenol from benzoic acid:

C6H5COOH + 1/2O2 C6H5OH + CO2

2. Production of benzaldehyde and benzyl alcohol

C6H5CH3 + 1.5O2 C6H5COH + 1.5O2 C6H5CHO + H2O

1.5O2

+ C6H5COOH Esterification

Benzyl benzoate

How to limit over oxidation?

Selective catalyst, short residence time, high toluene-to-oxygen ratio, low reaction temperature

Benzaldehyde use as a solvent for oils, resin, cellulose esters, ethers,As flavoring compound and synthetic perfumes.

O

O

Chlorination of Toluene

Free radical reaction with Cl resulting benzyl chloride, benzal chloride, benzotrichloride

Benzyl chloride can produce benzyl alcohol by hydrolysis:

C6H5CH2Cl + H2O C6H5CH2OH + HCl

Benzyl alcohol use as precursor for butylbenzyl phtalate, a vinyl chloride plasticizer,Precursor for phenylatic acid which later produced phenobarbital (sedative)

Carbonylation of Toluene (produced p-Tolualdehyde)

Carbonylation with CO in the presence of HF/BF3 catalyst

C6H5CH3 + CO C6H4(CH3)CHO

C6H4(COOH)2

P-Tolualdehyde use as intermediate in perfume synthesis, dye and in pharmaceutical.

?

Chemicals from toluene

(bp, 110 - 140°C)

Reforming(Pt-Re-Sn/Alumina)

Fraction-ation

Xylene iso-merizatrion(Pt-ZSM-5; Pt-Mord.;Pt-MAPO)

Fraction-ation

Arom. Extraction

TransalkylationPt/Mordenite

Mol. SieveSeparation

(PAREX)

Benzene

Toluene

Xylenes + EB

C9+Arom.

DisproportionationPt/Mordenite

Naphtha

o-Xylene

p-Xylene

m- + EB

Raffinate

Production of xylenes

Xylene isomerization

Catalysts are usually bifunctional typesTypical examples: Pt-ZSM-5, Pt-mordenite& Pt-(silica)-alumina

Xylene isomerizationXylene isomerization

CH3

CH3

CH3

CH3+

CH3

CH3

+

CH3

CH3

Zeolite

Catalyst: ZSM-5, Mordenite; MAPO; SiO2-Al2O3 loaded with Pt

XYLOFINING developed by NCL-ACC-IPCL in 1986

Mechanism

Production of Terephthalic Acid (HOOCC6H4COOH)

Oxidation of p-Xylene with cobalt acetate/NaBr or HBr as catalyst in an acetic acid medium,200 oC, 15 atm pressure.

p-Xylene + 3/2O2 HOOCC6H4CH3 (p-Toluic acid) + H2O

HOOCC6H4COOH

Has an annual capacity of approximately 610,000 tonnes and employs over 170 full-time employees. PTA is the key raw material for the manufacture of polyester for fabric, as well as audio and videotapes, and in making plastic drink bottles.

*With 1 tonne of PTA , can make approximately 3,500 car tyres

Production of Phtalic anhydride ( )

Oxidation of o-Xylene with metal oxides catalyst i.e. V2O5 + TiO2/Sb2O3

Vapor phase, 375 – 435 oC, 0.7 atm, yield about 85%

Liquid phase, 150 oC, Cobalt or manganese acetate in acetic acid medium as catalyst.

C6H4(CH3)2 + 3O2 + 3H2O

Use for producing plasticizer.

Production of Isopthalic Acid (HOOCC6H4COOH)

Liquid phase Oxidation of m-Xylene with ammonium sulfite

m-Xylene + 2(NH4)2SO3 HOOCC6H4COOH + 2H2S + 4NH3 + 2H2O

Main use for producing polyesters

END