G.H. PATEL COLLEGE OF ENGG. AND TECHNOLOGY

• SUB. NAME:- ORGANIC CHEMISTRY AND UNIT PROCESS

• SUB. CODE:- 2130501

• TOPIC NAME:- PETROLEUM REFINING,CRACKING AND SYNTHETIC PETROL

• PREPARED BY:- VYOM PATODIYA(150110105033) KRISHNA PESHIVADIYA(150110105034)

HARDIK PIPALIYA(150110105035) BHAVIN POSHIYA(150110105036)

OVERVIEW:

• INTRODUCTION• REFINING• CRACKING• TYPES OF CRACKING• SYNTHETIC PETROL• METHODS OF PRODUCING SYNTHETIC PETROL

•The primary uses of crude oil in the production of fuel. A single barrel of crude oil can produces the following components, which are listed by % of the barrel they constitute:42% Gasoline22% Diesel9% Jet Fuel5% Fuel oil4% Liquefied Petroleum gas18% other products

Introduction:

REFINING:-Petroleum refining refers to the process of converting crude oil into useful products. Crude oil is composed of hundreds of different hydrocarbon molecules, which are separated through the process of refining. The process is divided into three basic steps:•Separation•Conversion •Treatment

Distilation Column :-

CRACKING:- •Cracking is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits. This is achieved by using high pressure and temperature without a catalyst, or lower temperature and pressure in the presence of a catalyst. •The source of the large hydrocarbon molecules is often the naphtha fraction or the gas oil fraction from the fraction distillation of crude oil. These fractions are obtained from the distillation process as liquids, but are re-vaporised before cracking.

Cracking (cont…)

•There isn’t any single unique reaction happening in the cracker. The hydrocarbon molecules are broken up in a fairly random way to produce mixture of smaller hydrocarbons, some of which have carbon-carbon double bonds. One possible reaction involving the hydrocarbon C15

H32 might be: C15 H32 = 2C2H4 + C3H6 + C8H18

TYPE 0F CRACKING:-

1.)Catalytic Cracking

2.)Thermal Cracking

Catalytic Cracking:-

• Modern cracking uses Zeolites as the catalyst. These are complex aluminosilicates, and are large lattices of aluminium, silicon and oxygen atoms carrying a negative charge. They are, of course, associated with positive ions such as sodium ions. You may have come across a zeolite if you know about ion exchange resins used in water softeners.•The alkane is brought into contact with the catalyst at a temperature of about 500 C and moderately low pressures.

• The zeolites used in catalytic cracking are chosen to give high percentages of hydrocarbons with between 5 and 10 carbon atoms- particularly useful for petrol. It also produces high proportions of branched alkanes and aromatic hydrocarbons like benzene.

• The zeolite catalyst has sites which can remove a hydrogen from an alkane together with the two electrons which bound it to the carbon. That leaves the carbon atom with a positive charge. Ions like this are called carbonium ions. Reorganisation of these leads to various products of the reaction.

Thermal Cracking:- •In thermal cracking high temperatures and pressures are used to break the large hydrocarbons into smaller ones. Thermal cracking gives mixtures of products containing high proportions of hydrocarbons with double bonds- alkenes.

•Thermal cracking doesn’t go via ionic intermediates like catalytic cracking. Instead, carbon-carbon bonds are broken so that each carbon atom ends up with a single electron. In other words, free radicals are formed.

SYNTHETIC PETROL:- Introduction:- •Synthetic fuel or Synfuel is a liquid fuel obtained from coal, natural gas, oil shale, or biomass. •It may also refer to fuels to fuels derived from other solids such as plastic or rubber waste. It may also refer to gaseous fuels produced in a similar way. •Common use of the term synthetic fuel is to describe fuels manufactured via Fischer Tropsch conversion, methanol to gasoline conversion or direct coal liquefaction.

Method of producing Synthetic Petrol:-1. Polymerisation2. Fischer- Tropsch method3. Bergius process

Polymerisation:- •In these method, smaller molecules of hydrocarbons are combined to form heavier molecule resembling gasoline. It is of two type:1. Thermal Polymerisation2. Catalytic Polymerisation 

Thermal Polymerisation:- •Thermal polymerisation is carried out at temperature about 500-600 C and pressure about 70-350 kg/cm2

 

Catalytic Polymerisation:- •It is carried out at a lower temperature of 150-200 C, in a low pressure and in presence of catalyst like phosphoric acid. The rate of reaction is increased. The gasoline obtained is of improved quality and posses high antiknock properties than the gasoline obtained from thermal polymerisation process. 

Fischer- Tropsch Process:- •The Fischer-Tropsch process is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. The process, a key component of gas to liquids technology, produces a synthetic lubrication oil and synthetic fuel, typically from coal, natural gas or biomass. The F-T process has received intermittent attention as a source of low sulphur diesel fuel and to address the supply or cost of petroleum derived hydrocarbon• The water gas is varied with hydrogen and the combination is purified by transitory from side to side Fe2O3 and then into a mixture of Fe2O3+Na2CO3. The cleanse gas is dense to 5 to 25 atm and then led from side to side a converter, which is preserve at a temperature of 200-300 C.  

The converter is provided with a catalyst bed consisting of a mixture of 1000 parts cobalt, 5 parts thoria, 8 parts magnesia and 200 parts keiselghur earth. nCO + 2nH2 = CnH2n+ nH2O nCO +(2n+1)H2 = CnH2n+2 + nH2O The outcoming gaseous mixture is led to a condenser, where the liquid crude oil is obtained, The crude oil is fractionated to yield gasoline and heavy oil. The heavy oil is used for cracking to get more gasoline.

Fisher-Tropsch Process Diagram :-

Bergius Process:- •In these process, the finely powdered coal is competed keen on a paste through heavy oil and a catalyst powder is mixed with it. The paste is pumped along with hydrogen gas into the converter, where the synthetic paste is heated to 400-450 C under a pressure of 200-250 atm.• During this process hydrogen combined with coal to form saturated higher hydrocarbons, which experience additional decay at superior temperature to acquiesce combination of lesser hydrocarbons. The mix is led to a condenser, where the crude oil is attained. The crude oil is then fractionated to yield:Gasoline Middle oilHeavy oil