PRODUCTION OF ACRYLONITRILE BY AMMOXIDATION OF PROPYLENE

GROUP MEMBERS

Waheed Ahmed (2k11-ChE-09) Adnan Rafi (2k11-ChE-16) Ahmed Haroon (2k11-ChE-23) Shahzad Ali Zahid (2k11-ChE-49)

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CONTENTSIntroductionProcess DescriptionSite SelectionHazop study and EIA

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Introduction

Waheed Ahmad (2k11-Che-09)

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INTRODUCTION

 It was first prepared in 1893 by the French chemist Charles

Chemical Formula C3H3N. This pungent-smelling colorless liquid It is  monomer for the manufacture of  plastics. It produce toxic combustion products

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PHYSICAL PROPERTIES

colorless liquid and faint characteristic odor. Other trade names. Acrylonitrile polymerizes explosively.

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Property Value

Molecular weight 53.06

Boiling point, 0C 77.3 At 103.3 kPa

Critical temperature,0C

246.0

Density, g/L 806.0 At 20"C

Explosive limit at 250C, vol%

3.05-17.0

Flash point 0C -5

Freezing point, 0C -83.55

Heat of polymerization, kJ/mol

-72.4

Ignition temperature, °C 481.0

Viscosity at 25°C, cP 0.34

Heat capacity, 2.094

CHEMICAL PROPERTIES

Reactions of the Nitrile Group

Hydration and Hydrolysis Alcoholysis

NH-HX

CH2=CHCN + ROH + HX XCH2CH2—C—OR

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Reactions of the Double Bond Diels-Alder Reactions Hydrogenation Halogenations Hydrodimerization.

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Reactions of Both Functional Groups Cyanoethylation Reactions (Michael-Type

Additions)

CH2=CHCN + RH RCH2CH2CN

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USES AND APPLICATION

Acrylic Fibers. Copolymer Resin ("Plastics''). Nitrile Rubbers and Resins.

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Shahzad ali zahid

(2k11-Che-49)

MANUFACTURING PROCESSES

Early Processesa. Passage through ethylene cyanohydrin

The following reactions are involved: CH2-CH2 + HCN CH2OH-CH2-CN

O CH2OH-CH2-CN CH2=CH-CN+H2O

Temperature 200°CYield 90%

b. Addition of hydrogen cyanide to acetylene

HC ≡ CH +HCN CH2=CH-CN

ΔH0298 ≈ -175 kJ / mol

catalyst consisting of cuprous chloride andammonium chloride in solution in hydrochloric acid temperature of 80 to 90°C molar yield is up to 90 per cent by-products are acetaldehyde, vinyl acetylene,divinyl

acetylene, vinyl chloride, cyano butene, lacto nitrile,methyl vinyl ketone

C. Passage through lactonitrile

CH3-CHO + HCN CH3CHOH-CN (10-20) °C

CH3CHOH-CN CH2-CH-CN + H2O

Yield 90 percentD. Nitric oxide with propylene

4CH2=CH-CH3+6NO 4CH2=CH-CN + 6H2O + N2

E. From Propionitrile.

CH3CH2CN CH2 = CHCN + H2

F. From Propionaldehyde.

CH3CH2CHO + NH3 CH2 = CHCN + H20 + 2H2

G. Acrylonitrile Manufacture by ammoxidation of propylene (Sohio Process)

CH2=CH-CH3+NH3+3/2O2 CH2=CH-CN+3H2O

ΔH0298 ≈ -515kJ/mol

Better quality product Economical Its conversion in a single pass is high Energy efficient process

PROCESS DESCRIPTION

Raw Material

Ammonia (NH3) Air Propylene(C3H6)

FEED RATIO= PROPENE/AMMONIA/AIR=1/1.2/9.5

the oxygen (air) is introduced below mixed propylene and ammonia through

“spiders” positioned above the grid The operating pressure should be low to prevent

the by-ptoducts The residence time in the reactor is between

2 and 20 s The main reaction isCH2=CH-CH3+NH3+3/2O2 CH2=CH-CN+3H2O

ΔH0298 ≈ -515kJ/mol

It now appears clear that this overall result can be explained by the production of Acrolein as the main intermediate

CH2 = CH – CH3 + O2 CH2 = CH – CHO + H2O

CH2 = CH – CHO + NH3 CH2 = CH – CH = NH + H2O

CH2 = CH – CH = NH + 1/202 CH2 = CH – CN + H2O

EFFECT OF DIFFERENT VARIABLES ON CONVERSATION

Effect of residence time Effect of reaction temperature Effect of reaction pressure Effect of Catalyst

REACTION MECHANISM

PROCESS FLOW DIAGRAM

QUENCHER It is used to remove ammonia from the reactor

effluent and low down its temperature using sulphuric acid. It produces ammonium sulphate salt ((NH4)2SO4) at bottom which is used as a fertilizer and the top effluent is sent to absorber.

No. of Stages : 10 Sulphuric acid: 30% concentrated H2SO4 Bottom stream coming out of quencher mainly consists

of ammonium sulphate. This stream is further passed into Crystallizer where crystals of ammonium sulphate are produced which is used as fertilizer.

ABSORBER Function of Absorber is to remove the residual gases,

containing unconverted propylene, CO2 and other VOC. Random Packing: 5 segments of Raschig rings made up of

ceramic, diameter=0.375in Height of each packing segment=10ft Column Diameter=5ft

RECOVERY UNIT

Idea is to recover the useful components from the aqueous solution like ACN, AN etc.

No. of stages: 10 Random Packing: Saddles made up of ceramic,

diameter=0.5in Total tower height=40ft Column diameter=5ft

CATALYST

Sohio, who initially employed bismuth phosphomolybdate in 1967 by a mixture based on oxides of antimony and

uranium In 1972, Sohio then returned to an iron and bismuth

phosphomolybdate doped by additions of cobalt, nickel and potassium

The catalysts used in the process are mostly based on mixed metal oxides such as bismuth-molybdenum oxide, iron-antimony oxide, uranium-antimony oxide, tellurium - molybdenum oxide etc.

Adnan Rafi

2k11-Che-15

HAZOP STUDY

A HAZOP survey is one of the most common and widely accepted methods of systematic qualitative hazard analysis.

It is used for both new or existing facilities and can be applied to a whole plant, a production unit, or a piece of equipment

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OBJECTIVES OF A HAZOP STUDY To identify areas of the design. To identify and study features of the design. To familiarize the study team. To ensure a systematic study. To identify pertinent design information. To provide a mechanism for feedback.

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STEPS OF HAZOP STUDY

1. Specify the purpose2. Select the HAZOP study team3. Collect data

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HAZOP GUIDE WORDS AND MEANINGS

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Guide Words Meanings

No Negation of design Intent

Less Quantitative decrease

More Quantitative increase

Part of Qualitative decrease

As well as Qualitative increase

Reverse Logical opposite of

Other than Complete substitution

4. Conduct the study5. Write the report HAZOP Study of Storage Tank for Propylene