CHEMICAL TECHNOLOGY 2

2. Chemical Technology

1.Styrene

  • Styrene from benzene and ethylene

Styrene is manufactured from benzene and ethylene. Styrene-butadiene the rubber used in tire manufacturing. A catalyst used is Fe(III) Oxide promoted by K2O. Tertiary dodecyl mercaptan is used as a modifier and potassium pyrophosphate is used as a buffer.

2.Paints

oils with oleic radical (one double bond) as film-forming paints for vehicles.

3.Sodium hydroxide production

  • Decomposition efficiency

Decomposition efficiency (ηD) of an electrolyte cell used for producing NaOH is defined as
ηD = Ratio of theoretical current to produce one gram equivalent to actual current to produce one gram equivalent.

  • Cauticizing method of production of sodium hydroxide

Historically NaOH was produced by treating Na2CO3 with Ca(OH)2 in a metathesis reaction. This process was called causticizing.

4. Petroleum and its products

  • Low aniline point implies high aromatic content.
  • Hydrogen from light petroleum stock is manufactured by steam
    reforming of naphtha. The catalyst used in steam reforming of methane is Ni/Al2O3. High octane gasoline from naphtha is produced by platforming.
  • The electrostatic precipitator is used for separating particles from gases when particle size less than one micron.
  • The order of feedstock to a catalytic reformer is virgin naphtha –> coking naphtha –> catalytic naphtha.
  • Terylene is produced from dimethyl terephthalate and ethylene glycol.

5Biodiesel

  • Biodiesel is made by chemically reacting lipids (vegetable oil, soyabean oil, animal fat) with an alcohol producing fatty acid ester.

6. General Polymer points

  • Propylene + 1-butene gives LLDPE
  • Terephthalic acid + ethylene glycol gives synthetic fiber
  • raw material for the manufacture of polyester.
  • In the manufacture of Portland cement, the major raw materials are limestone, clay, gypsum, and coal.
  • Calcium ammonium nitrate is an inorganic fertilizer.
  • Phthalic anhydride is made by oxidation of naphthalene
  • Ethylene oxidation is an auto-thermal reaction.
  • Cellulose derivatives, polyamides, and polyurethanes (mainly
    thermosetting) are polymers used for making fibers.
  • The preferred system for oxidation of O-xylene to Phthalic anhydride is jacketed steam heated multitubular reactor.
  • The raw material for grease is lithium stearate; Raw material for cosmetics is magnesium stearate; Aluminium sulfate is used in the manufacture of paper.

7. Sugar manufacturing

  • Calcium hydroxide is used in sugar manufacturing to maintain pH. Carbon dioxide is used to precipitate solid calcium compounds. Phosphoric acid is used to remove color. Calcium hydroxide + Phosphoric acid is used for the treatment of raw sugar to give final white sugar. Multi-effect evaporator is used in the manufacturing of paper and sugar.

8. Paper manufacturing

  • Black liquor is the by-product of paper industry (kraft process Press mud is the compressed sugar industry waste produced from the filtration of the cane juice.

9. Sulfite Process

  • In a sulfite process, digester chemical used as sulfite or bisulfite
    depending upon pH along with SO2. The cooking liquor is magnesium sulfate and magnesium bicarbonate.

10Iron and Steel

stronger through heat treating. However, it becomes less ductile.
Regardless of heat treatment, a higher carbon content reduces weldability. In carbon steel, the higher carbon content, lower melting point.

11. Radical Polymerization

  • Radical polymerization works best on carbon-carbon double bond of vinyl monomers, and carbon-oxygen double bond in aldehyde and ketones. If longer chains are desired, the initiator concentration should be kept low, otherwise, many shorter chains will result. Oxygen is a common inhibitor. The growing chain will react with molecular oxygen producing an oxygen radical, which is much less reactive. Diphenyl picrylhydrazyl (DPPH) is another effective inhibitor due to resonance stabilization of the radical.

12Types of Polymerization

Based on the method of formation

  • Bulk polymerization reaction mixture contains only monomer and initiator, no solvent. A reaction is carried out by adding a soluble initiator to pure monomer. The reaction is initiated by heating or exposing to radiation. As reaction proceeds, the mixture becomes more viscous. The reaction is exothermic and a wide range of molecular masses are produced. Bulk polymerization is carried out in the absence of any
    solvent or dispersant and is thus simplest in terms of formulation. It is used for most step-growth polymers and many types of chain growth polymers. Example – Nylon, polystyrene (by condensation polymerization), thermoplastic compounds.
  • Solution polymerization reaction mixture contains the solvent, initiator, and monomer. In this procedure, a monomer is dissolved in a nonreactive solvent that contains a catalyst. The reaction results in a polymer which is also soluble in the chosen solvent. Heat released by the reaction is absorbed by the solvent and so reaction rate is reduced. Moreover, the viscosity of the reaction mixture is reduced, not allowing auto acceleration at high monomer conversion. Once the desired conversion is reached, the excess solvent has to be removed in order to
    obtain the pure polymer. Hence, solution polymerization is mainly used for application where the presence of solvent is desired anyway, as in the case of varnish and adhesives. It is not useful for the production of dry polymers because of the difficulty of complete solvent removal.
  • Suspension polymerizationreaction mixture contains an aqueous phase, water-insoluble monomer, an initiator soluble in the monomer (both monomer and initiator are hydrophobic). It is a heterogeneous radical polymerization process. It requires mechanical agitation to mix monomers in the liquid phase such as water where monomers polymerize
    forming spheres of a polymer. It is used for formation of resins, PVC (not produced by condensation polymerization), styrene resins including polystyrene, expanded polystyrene, and high impact polystyrene, polystyrene-acrylonitrile, polymethyl methacrylate. It produces small uniform spheres.
  • Emulsion polymerizationit is similar to suspension polymerization except that the initiator is soluble in the aqueous phase rather than monomer droplets. The monomer is hydrophobic and an initiator is hydrophilic. An emulsifying agent is also needed. Emulsion polymerization is a type of radical polymerization which starts with an emulsion incorporating water, monomer, and surfactant. Advantages of emulsion polymerization include

1. High molecular weight polymers can be made at fast polymerization rates. By contrast, in bulk and solution free radical polymerization, there is a tradeoff between molecular weights and polymerization rate.
2. The continuous water phase is excellent conductor of heat, enabling fast polymerization rate without loss of temperature control.
3. Since polymer molecules are contained within the particles, the viscosity of the reaction medium remains close to that of water and is not dependent on molecular weight. Also used for manufacturing of synthetic rubber, SBR, polychloroprene (neoprene), fluoroelastomers (FKM), dispersions (acetate copolymers).

13. The catalyst for various reactions

  • A catalyst for conversion of methanol to gasoline – zeolite;
    edible oil hydrogenation – Raney nickel, Sulphur is a catalyst poison.; methanation – nickel, ruthenium, iron, cobalt;
    the catalyst for the formation of butyl acetate – ion exchange resins; A catalyst for sulphuric acid – vanadium pentaoxide (V2O5); The catalyst used in catalytic reforming (platforming): Pt + Re; A catalyst used for the formation of nitric acid is Platinum and Rhodium;

14. A preferred material of handling chemicals

  • Preferred material for
    handling dilute H2SO4 is nickel;
    for concentrated H2SO4 lead;
    for concentrated HCl is lead;
    wet chlorine is titanium;
    concentrated caustic soda is carbonate;
    for caustic soda is aluminum.

15. Dust explosion 

Coal forms an explosive mixture with air even at ambient temperatures if the particle size is very small (known as dust explosion). The possibility of dust explosion increases with the decrease in the size of particles.

16. Crusher

  • Gyratory crusher applies compression force and buhrstone mill applies a shear force to break materials.

17. Sulphuric acid

  • In converter of the contact process for the manufacture of H2SO4, the equilibrium conversion of SOx decreases with increase in temperature and increases with increase in the mole ratio of SO2 to air.
  • For the manufacture of H2SO4 from elemental Sulphur following sequence of major events is followed: Furnace –> Converter –> Absorber.
  • The catalytic converter for conversion of SO2 to SO3 by contact process should have fed with SO2 content between 7 – 10 %.