PETROCHEMICALS Notes

1 6 3 PetrochemicalsOPTIONAL MODULE - 2 NotesChemistry and Industry32 PETROCHEMICALSn the first five modules of this course in chemistry you have learnt about the conceptualframework of this vast subject. In the first two modules you studied the chemistry of theelements of s,p,d and f blocks and of organic compounds respectively. In this optionalmodule you would learn about some important industrial first lesson of this module deals with PETROCHEMICALS , the chemicals derived frompetroleum. PETROCHEMICALS include a very vast range of chemicals.

2 You would learn abouttheir meaning, classification, production and application. This lesson also deals with soapsand detergents and rocket fuels. Many of them are the important byproducts obtainedfrom PETROCHEMICALS . In the next lesson you would learn about polymers another vastclass of molecules which are integral part of our day to day reading this lesson you will be able to : define PETROCHEMICALS ; explain different generations of PETROCHEMICALS with flow sheet diagram; cite various examples of PETROCHEMICALS ; list uses of various PETROCHEMICALS ; write about the status of PETROCHEMICALS in India; distinguish between soaps and detergents; explain types of detergents.

3 List advantages and disadvantages of detergents over soaps; explain cleaning action of soaps and detergents; classify rocket propellants; give examples of chemicals used in various classes of rocket propellants and write about the status of propellants with reference to Indian Space 4 ChemistryOPTIONAL MODULE - 2 NotesChemistry and What are PETROCHEMICALS ?You are aware, petroleum is a complex mixture of hydrocarbons formed by thedecomposition of fossil remains. It exists as a liquid (crude oil), gas (natural gas) or assolids (oil shales) and is found deep underground or below have also studied that petroleum is refined to several useful fractions, which are usedas fuel (LPG, petrol, diesel, etc.)

4 Or lubricants. About 10% of the petroleum is used toprepare a range of chemicals called PETROCHEMICALS , we may define, PETROCHEMICALS as agroup of chemicals produced directly or indirectly from the hydrocarbons of petroleum ornatural gaseous hydrocarbons are also obtained as a by product during petroleum hydrocarbons may contain one to five carbon atoms, for example, methane, ethane,propane, butane, iso-butane, pentane, etc. Methane (CH4) is also a major hydrocarboncomponent of natural gas, which occurs in association with one time these gaseous hydrocarbons were of almost no use and the only way todispose them was to burn them.

5 With passage of time these gaseous hydrocarbons havefound important use as starting material to produce a large variety of , the demand of PETROCHEMICALS and the materials derived from PETROCHEMICALS is sogreat that we need to deliberately convert higher hydrocarbons to smaller gaseoushydrocarbons by the process of list of PETROCHEMICALS is endless. Some important PETROCHEMICALS are methyl alcohol,ethyl alcohol, acetaldehyde, acetic acid, acetic anhydride, acetone, benzene, toluene, xylenes,phenol, vinyl chloride, etc.

6 Some of these can be used directly or as raw materials for themanufacture of other useful products. These are used to manufacture a vast variety ofuseful materials like solvents, adhesives, antifreezes, synthetic rubbers, synthetic fibers,nylon, polyester, plastics, synthetic detergents, rocket fuels, every area of human activity makes use of PETROCHEMICALS or the materials madefrom PETROCHEMICALS , our life without PETROCHEMICALS would be very different and Classification of PetrochemicalsThe nature of petrochemical industry is very complex.

7 The journey from petroleum touseful end products is long and there are many steps in the process. Let us try to understandfeed-stock, primary and intermediate PETROCHEMICALS and the end products in the contextof StockThe starting material used for the production of PETROCHEMICALS is called feed stock. Thereare two common feed stocks for the manufacture of PETROCHEMICALS ; these are :1. Natural gas2. Naphtha and reformed naphthaYou would recall that natural gas occurs in nature in association with petroleum .

8 Themajor hydrocarbon component of natural gas is methane. Naphtha is a fraction obtainedduring refining of 5 PetrochemicalsOPTIONAL MODULE - 2 NotesChemistry and IndustrySome countries or industries prefer to use natural gas while some other use naphtha as astarting material (feed stock) for the production of PETROCHEMICALS . The choice for theuse of natural gas or naphtha as feed stock by a particular country or industry dependsupon the availability of a particular feed stock or the availability of technology for themanufacture of Primary PetrochemicalsPrimary PETROCHEMICALS are the molecules obtained from the feed stock and are used tomanufacture petrochemical intermediates.

9 Since the feedstock consists of natural gas,naphtha and reformed naphtha, these give different primary PETROCHEMICALS . The primarypetrochemical obtained from these are compiled in Table : Important Primary PETROCHEMICALS from different feed gasEtheneCH2 = CH2 PropeneCH3 CH = CH2 EthyneCH = CH2 PropeneCH3 CH = CH2 ButadieneCH2 = CH CH = xyleneCH3CH3m-xyleneCH3CH3p-xyleneCH3CH3 6 6 ChemistryOPTIONAL MODULE - 2 NotesChemistry and Intermediate PETROCHEMICALS and DerivativesThe PETROCHEMICALS obtained from primary PETROCHEMICALS by chemical reaction are called(secondary) intermediate PETROCHEMICALS .

10 PETROCHEMICALS are also refered to as firstgeneration PETROCHEMICALS and second generation PETROCHEMICALS , First generationpetrochemicals are converted to second generation PETROCHEMICALS . These intermediatepetrochemicals may be put to some use or these may be further processed to get derivativesof PETROCHEMICALS by a chemical reaction or a series of reactions to get products for otherend PetrochemicalsFeed stockPetroleumSecondary PetrochemicalsUseful End ProductsFig. :Relationship between petroleum , feedstock, primary PETROCHEMICALS , secondary(intermediate) PETROCHEMICALS and useful end Down Stream PetrochemicalsThe PETROCHEMICALS obtained from a given feedstock by a series of reactions are calleddown stream PETROCHEMICALS .