Production of Acrylonitrile by Ammoxidation of Propylene

PRODUCTION OF  A CRYLONITRILE  AMMOXIDATION OF

PROPYLENE

BY

GROUP MEMBERS 

Waheed Ahmed (2k11-ChE-09)

 Adnan Rafi



(2k11-ChE-16)  Ahmed Haroon



(2k11-ChE-23) 

Shahzad Ali Zahid (2k11-ChE-49)

CONTENTS Introduction Process Description Site Selection Hazop study and EIA  

Introduction

Waheed Ahmad (2k11-Che-09)

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

PHYSICAL PROPERTIES 

colorless liquid and faint characteristic odor.



Other trade names.

 Acrylonitrile polymerizes explosively.



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



Reactions of the Double Bond



Diels-Alder Reactions



Hydrogenation



Halogenations



Hydrodimerization.

 

Reactions of Both Functional Groups Cyanoethylation Reactions (Michael-Type  Additions) CH2=CHCN + RH

RCH 2CH2CN

USES A ND A PPLICATION  Acrylic Fibers.

 

Copolymer Resin ("Plastics'').



Nitrile Rubbers and Resins.

 Shahzad Ali Zahid (2k11-Che-49)

M ANUFACTURING PROCESSES Early Processes a.

Passage through ethylene cyanohydrin

The following reactions are involved: CH2-CH2 + HCN

CH2OH-CH2-CN

O CH2OH-CH2-CN Temperature 200°C  Yield 90%

CH2=CH-CN+H2O

b. Addition of hydrogen cyanide to acetylene HC ≡ CH +HCN

CH2=CH-CN  ΔH0298 ≈ -175 kJ / mol



catalyst consisting of cuprous chloride and

ammonium 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

CH3CHOH-CN (10-20) °C CH2-CH-CN + H2O

 Yield 90 percent D.

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 is

CH2=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.

 A BSORBER 

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

C ATALYST 

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

H AZOP 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

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.

STEPS OF H AZOP STUDY  1.

Specify the purpose

2.

Select the HAZOP study team

3.

Collect data

HAZOP GUIDE W ORDS MEANINGS

AND

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