2. Introduction

Unit process involves principle chemical conversions leading to synthesis of various useful product and provide basic information regarding the reaction temperature and pressure, extent of chemical conversions and yield of product, nature of reaction whether endothermic or exothermic, and type of catalyst used.

• Oxidation

• Combustion

• Hydrogenation

• Sulfornation - a chemical reaction which introduces the sulfonic acid functional group (-\(\ce{SO3H}\)) into a molecule.

• Halogenation

• Hydrolysis

• Polymerization

Unit processes applied to various chemical industries will be discussed in detail in your course on Chemical Process Industries - IV Sem

• Combustion: Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. The fuel can be a solid, liquid, or gas, although for airplane propulsion the fuel is usually a liquid. The oxidizer, likewise, could be a solid, liquid, or gas, but is usually a gas (air).

  When a hydrogen-carbon-based fuel (like gasoline) burns, the exhaust includes water (hydrogen + oxygen) and carbon dioxide (carbon + oxygen).

• Nitration: Nitration involves the introduction of one or more nitro groups into reacting molecules using various nitrating agents like fuming, concentrated, aqueous nitric acid mixture of nitric acid and sulphuric acid in batch or continuous process.

  • Nitration products find wide application in chemical industry as solvent, dyestuff, pharmaceuticals, explosive, chemical intermediates.

  • Typical products: TNT, Nitrobenzene, m-dinitrobenzene, nitroacetanilide, alpha nitronaphthalene, nitroparaffins.

• Halogenation: Halogens involve introduction of one or more halogen groups into a organic compound for making various chlorine, bromine, iodine, fluorine organic derivatives. All though chlorine derivatives find larger application, however some of the bromine and fluorine derivatives are also important.

• Various chlorinating agents are: chlorine, HCl, phosgene sulfuric chloride, hypochlorite,

• Bromination: bromine, hydrobromic acid, bromide, bromated, alkaline hypobromites.

• Iodination: iodine, hydroiodic acid and alkali hypoiodites

• Polymerization: Polymerization is one of the very important unit processes which find application in manufacture of polymer, synthetic fibre, synthetic rubber, polyurethane, paint and petroleum industry for high octane gasoline. Polymerisation maybe carried out either with single monomer or with comonomer. Polymerisation reaction can be addition or condensation reaction.

  Typical important product from polymerization are, Polyethyelene, PVC, poly styrene, nylon, polyester, acryicfibre, poly butadiene, poly styrene, phenylic, urea, melamine and alkyd resins epoxy resin, silicon polymers, poly vinyl alcohol etc.

• Hydrogenation: The process of hydrogenation involves the use of hydrogen molecules to saturate organic compounds, in the presence of a catalyst.

  Common catalysts used during hydrogenation are metals such as nickel and platinum.

  Hydrogenated fats and oils are common ingredients found in some of the foods we purchase. They are used to extend the shelf life of a food item or keep the intended food flavor stable.