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Week-1 1st IME 2019.pptx

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  1. 1. Chemical processes Unit operation and Unit processes Week-1 1st IME
  2. 2. Chemical Processes • Interrelated elementary processes – Transfer of reactants to the reaction zone – Chemical reactions involving various unit processes – Separation of products from reaction zone via various unit operation
  3. 3. Chemical Processes cont….. Homogeneous Chemical Processes: Reactants in same phase (solid/liquid/gas) Heterogeneous Chemical Processes: Reactants in two or more phases (gas-liq, gas-sol, gas-gas, liq-liq, liq-sol etc)
  4. 4. Chemical Processes • Reversible and irreversible • Products cannot revert back to reactants • Products react with other products to give reactants • Endothermic and Exothermic • Heat absorbed (surrounding temp decrease and system temp increase) • Heat released (surrounding temp increase and system temp decrease)
  5. 5. Chemical Processes • Catalytic and non catalytic • Rate of reaction affected by catalyst • Rate of reaction unaffected by catalyst • Isothermal or Adiabatic • Temperature constant • No heat and mass transfer
  6. 6. Chemical Processes • Other variables affecting Chemical processes: – Temperature – Pressure – Composition – Catalyst activity, selectivity, stability and life – Rate of heat and mass transfer
  7. 7. Chemical Processes • Batch process • Semi-batch process • Continuous process
  8. 8. Chemical Processes • Material and energy balance, raw material and energy consumption, energy changes • 􏰀 Batch vs Continuous, process flow diagram • 􏰀 Chemical process selection: design and operation, pilot plant data, Equipment required, material of construction • 􏰀 Chemical Process Control and Instrumentation
  9. 9. Chemical Processes • Chemical Process Economics: Competing processes, Material and, Energy cost, Labour, • Overall Cost of production • 􏰀 Market evaluation: Purity of product and uniformity of product for further processing
  10. 10. Chemical Processes • Plant Location • 􏰀 Environment, Health, Safety and Hazard • 􏰀 Construction, Erection and Commissioning • 􏰀 Management for Productivity and creativity 􏰀 • Research, Development and patent • 􏰀 Process Intensification
  11. 11. Unit Operations • Physical separation of the products obtained during various processes. • Classification in 1910 by W. H. Walkers and A. D. Little
  12. 12. Unit Operations Unit Operations in Chemical Process Industries • Absorption and stripping • Membrane Process: Reverse osmosis, Electrodialysis, Adsorption and desorption, Chromatography • Crushing Grinding and Screening • Distillation: Batch distillation Flash distillation, Azeotropic distillation, Extractive distillation Reactive distillation • Solid liquid extraction • Evaporation • Fluidisation • Sublimation • Crystallisation • Solvent extraction • Liquid- Liquid extraction
  13. 13. Unit Operations • DISTILLATION • Distillation has been the king of all the separation processes and most widely used separation technology. • Distillation is used in petroleum refining and petrochemical manufacture.
  14. 14. Unit Operations • MEMBRANE PROCESSES one of the major separation processes during the recent years. used in desalination, wastewater treatment and gas separation and product purification. Membrane process classified based on driving force.
  15. 15. Unit Operations Driving force Reverse osmosis Pressure difference Ultrafiltration Pressure difference Micro and Nano filtration Pressure difference Gas permeation Concentration difference Electrodialysis Electrical potential Thermo-osmosis Temperature difference
  16. 16. Unit Operations • Absorption Separation technique for gas cleaning
  17. 17. Unit Operations • Adsorption separation and purification of gas and liquid mixture
  18. 18. Unit Processes • Unit process involves principle chemical conversions leading to synthesis of various useful product. • Provide basic information regarding the reaction temperature and pressure, extent of chemical conversions and yield of product of reaction, nature of reaction (endothermic or exothermic), type of catalyst used.
  19. 19. Unit Processes NITRATION Introduction of one/more nitro groups into reacting molecules various nitrating agents like: fuming nitric acid concentrated nitric acid aqueous nitric acid mixture of nitric acid and sulphuric acid Batch or continuous process.
  20. 20. Unit Processes Applicable in chemical industry as: solvent dyestuff pharmaceuticals explosive chemical intermediates Typical products: TNT Nitrobenzene Nitronaphthalene Nitroparaffins
  21. 21. Unit Processes Preparation of TNT (trinitrotoluene) A three-step process: 1. Toluene is nitrated with a mixture of sulfuric acid and nitric acid to produce mono-nitrotoluene or MNT. 2. MNT is separated and then renitrated to dinitrotoluene or DNT. 3. DNT is nitrated to trinitrotoluene or TNT using an anhydrous mixture of nitric acid and oleum.
  22. 22. Unit Processes HALOGENATION Introduction of one/more halogen groups into a organic compound making various chlorine, bromine, iodine, fluorine organic derivatives Various chlorinating agents are: chlorine, HCl, phosgene sulfuric chloride, hypochlorite, Various brominating agents are: bromine, hydrobromic acid, bromide, bromated, alkaline hypobromites. Various iodinating agents are: iodine, hydroiodic acid and alkali hypoiodites
  23. 23. Unit Processes Examples Ethylene dichloride Chlorinated methanes Chloroform Carbon tetra chloride Chloro propane Chloro butanes, chloroparaffins Alkyl halhides, Chlorobenzene Ethylene diiodide, Chloroflurocarbon (CFCs)
  24. 24. Unit Processes Preparation of chloroform and chloroflurocarbon (CFCs)
  25. 25. Unit Processes SULPHONATION AND SULPHATION Sulphonation: Introduction of sulphonic acid group or corresponding salt like sulphonyl halide into a organic compound Sulphation: Introduction of -OSO2OH or -SO4-. Sulphonating agents: sulphur trioxide and compounds, sulphurdixide, sulphoalkylating agents Sulphaming agents are sulphamic acid
  26. 26. Unit Processes Preparation of Saccharin Reaction of hydrogen chloride with a solution of sulfur trioxide in sulfuric acid. Sulfonation by chlorosulfonic acid gives the ortho and para substituted chlorosulfones. The ortho isomer is separated and converted to the sulfonamide with ammonia. Oxidation of the methyl substituent gives the carboxylic acid, which cyclicizes to give saccharin. • HCl + SO3 → ClSO3H
  27. 27. Unit Processes Applications: Production of lingo sulphonates linear alkyl benzene sulphonate Toluene sulphonates Phenolic sulphonates Chlorosulphonic acid Sulphamates for production of herbicide, sweetening agent (sidiumcyclohexysulphamate) Oil soluble sulphonate saccharin
  28. 28. Unit Processes OXIDATION Oxidation using oxygen: 1. oxidation via dehydrogenation using oxygen, 2. dehydrogenation and the introduction of oxygen and destruction of carbon 3. partial oxidation 4. peroxidation 5. oxidation in presence of strong oxidizing agent like KMnO4, chlorate, dichromate, peroxides H2O2, PbO2, MnO2; nitric acid and nitrogen tertra oxide, oleum, ozone
  29. 29. Unit Processes Product of oxidation: Aldehyde Ketone Benzyl alcohol Phthalic anhydride Ethylene oxide Vanillin Benzaldehyde Acetic acid Cumene Propylene oxide Benzoic acid Maleic acid Oxidation maybe carried out either in liquid phase or vapour phase.
  30. 30. Unit Processes Preparation of synthetic gas from hydrocarbon Fischer–Tropsch process, or Fischer–Tropsch synthesis (a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons) H2O + CH4 CO + 3 H2 H2O + CO H2O + CO synthetic gas
  31. 31. Unit Processes HYDROGENATION The reaction of a substance with hydrogen in the presence of a catalyst. Other reaction involving hydrogen are, hydrodesulphurisation hydrcracking hydro formylation oxosynthesis hydroammonylsis synthesis of ammonia.
  32. 32. Unit Processes Preparation of aldehyde (Hydro-formylation): H2 + CO + CH3 CH=CH2 HCo(CO)PBu3 CH3 CH2 CH2 CHO
  33. 33. Unit Processes ESTERIFICATION Esterification is an important unit process in the manufacture of: polyethylene terephathalate methyl metha acrylate cellulose ester in viscose rayon manufacture (xanthation of alkali cellulose with carbon disulphide) Nitroglycerine
  34. 34. Unit Processes HYDROLYSIS Used both in inorganic and organic chemical industry: oil and fats industry during soap manufacture (hydrolysis of fats are carried out to obtain fatty acid and glycerol followed by addition of sodium hydroxide to form soap) Manufacture of amyl alcohols. Some of the major product using hydrogen is ethylene from acetylene, methanol, propanol, butanol, production of alcohol from olefins (eg. Ethanol from ethylene). Pure hydrolysis, hydrolysis with aqueous acid or alkali, dilute or concentrated, alkali fusion, hydrolysis with enzyme and catalyst.
  35. 35. Unit Processes Preparation of ethanol from ethylene: CH2 = CH2(g) + H2O(g) catalyst CH3CH2OH(g) H = - 45 kJ mol -1
  36. 36. Unit Processes ALKYLATION Introduction of an alkyl radical into an organic compound by substitution or reduction Applications: detergent, lubricants, high octane gasoline, photographic chemicals, plasticizers, synthetic rubber, chemicals etc. Alkylating agents: olefins, alcohols, alkyl halides.
  37. 37. Unit Processes Catalysts: sulphuric acid and phosphoric acid however due to the corrosive nature of these acid now solid acid catalyst is finding wide application in new alkylation processes. Preparation of toluene Alkylation is the transfer of an alkyl group from one molecule to another. Benzene CH3Cl Toluene AlCl3 catalyst, reflux anhydrous conditions
  38. 38. Unit Processes POLYMERIZATION Applicable in manufacture of: polymer synthetic fibre synthetic rubber polyurethane paint and petroleum industry for high octane gasoline. Single monomer or with comonomer Addition or condensation reaction Bulk/ emulsion/solution/ suspension.
  39. 39. Unit Processes Important product: Polyethyelene PVC Poly styrene Nylon Polyester Acryicfibre Poly butadiene Poly styrene Phenylic Urea Melamine Alkyd resins Epoxy resin Silicon polymers Poly vinyl alcohol
  40. 40. Unit Processes Preparation of Polyethylene or polythene Most common plastic: n CH2 = CH2 -(CH2-CH2 )- n