Propylene

Done by:Esra’a Hajjeyah Faten TaqiEman Khajah Fatma Al-TurkaitAnwar Al-Fadhli Dalal Al-Dughaishem

Capture Utilization

Outline

Introduction. Sources, uses and utilization of Carbon Dioxide. Greenhouse gases and their effect. Amounts of CO2 in Kuwait. Capture and regeneration of CO2. Comparison of capture options. Capture from ambient air. Production of propylene.

Introduction

Carbon dioxide with chemical formula CO2 was one of the first gases to be described as a substance distinct from air.

average concentration in the atmosphere: 300 ppm, 0.03 vol. %.

It is a gas at standard conditions. Physical Properties: slightly toxic, odorless,

colorless gas and slightly acidic. It is approximately 1.5 times as heavy as air.

Chemical Properties: non flammable gas and not chemically reactive, although aqueous solutions of CO2 are acidic and many reactions occur readily.

Carbon dioxide gas is easily liquefied by compression, because its critical temperature is relatively high, when this liquid is flashed to a low pressure with consequent cooling, CO2 will be reduced to a solid which is called dry ice.

Sources of Carbon Dioxide

1. Natural sources: CO2 is produced in essentially all human activities, Including the basic life process, respiration.

2. Industrial sources: Fossil-fueled power plants. Cement manufacturing. Refineries. Industrial boilers.

Uses of Carbon Dioxide

Carbon Dioxide Utilization

Refrigeration and cooling. Storage of carbon power. Fire extinguishers. Rubber and plastics industry. Raw material in the chemical process industry,

such as methanol and urea production. Carbonate soft drinks, beers, wine and soda

water.

Greenhouse Gases

Greenhouse gases are components of the atmosphere that contribute to the greenhouse effect.

Some greenhouse gases occur naturally in the atmosphere, while others result from human activities

Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

Greenhouse Gases Effect The concentration of several greenhouse

gases has increased over time because of human activities which causes global warming.

Global warming refers to the increase in the average temperature of the Earth’s near surface air and oceans.

This change would have serious effects on climate, ocean levels, and agriculture.

The increase of carbon dioxide in the air over the past few centuries

Amounts of CO2 in Kuwait from point sources Refineries (Hydrogen plants & combustion units)

9,245,400 ton/yr

Power Plants 37,840,468 ton/yr

EQUATE 620855 ton/yr

KOC Plant 7,000,000 ton/yr

Kuwait Cement Company

1,050,000 ton/yr

Total 55,756,723 ton/yr

Capture and Regeneration of CO2

The main application of CO2 capture is likely to be at large point sources such as fossil fuel power plants and refineries (mainly from hydrogen units).

The technologies available to capture CO2:1. Capture from industrial process streams: current

examples of CO2 capture from process streams are purification of natural gas and production of hydrogen containing synthetic liquid fuels.

2. Post-combustion capture: Fuel is burned with air and CO2 is captured after production of energy. Flue gas is passed through equipment which separates most of the CO2.

3. Oxy-fuel combustion capture:

In oxy-fuel combustion, nearly pure oxygen is used for combustion instead of air, resulting in a flue gas that is mainly CO2 and H2O.

The aim of oxy-fuel combustion is to increase significantly the concentration of CO2 in the flue gases to at least 90%.

The oxy-fuel combustion capture is an option still under development.

4. Pre-combustion capture:

Involves reacting a fuel with water to produce carbon monoxide and hydrogen.

The carbon monoxide is reacted with steam in a catalytic reactor, to give CO2 and more hydrogen.

CO2 is then separated, usually by a physical or chemical absorption process.

Advantages: First CO2 is not yet diluted by the combustion air. Second the CO2 containing stream is usually at elevated pressure.

Absorption

Removal of one or more selected components from a mixture of gas is carried out by contacting the gas with a suitable solvent.

Carbon dioxide separation by absorption can be achieved by physical, chemical and hybrid methods.

Physical Absorption

CO2 is absorbed in a solvent according to Henry’s law.

It is more suitable for higher partial pressure.

The most widely used process is flour process, purisol process, rectisol, selexol and sulfinol process.

Chemical Absorption CO2 reacts with the absorbent, creating

weakly bonded compounds, called carbamates.

The process can be used effectively at low CO2 partial pressure.

Chemical absorption has capture efficiency higher than 90% and produces CO2 with a purity of 99%.

The most common chemical absorption processes are:

1. Amine process: The most common types of amine solvents are: MEA, DEA, DIPA, MDEA.

2. Hot potassium carbonate process: It is particularly attractive process at higher CO2 contents.

32232 2KHCOOHCOCOK

3. Sodium carbonate process: This process of recovering pure carbon dioxide from gas , is based on the reversibility of the following reaction:

4. Caustic soda: Caustic soda is the usual commercial name for sodium hydroxide NaOH. It is used to remove CO2 from small volumes of air.

32232 2NaHCOCOOHCONa

Hybrid absorption

Hybrid solvents combine the best characteristics of both the chemical and physical absorption and they are usually composed of a mixture of components.

Adsorption Adsorption is the process where a molecule becomes

selectively attached (adsorbed) onto a surface of another phase using special solids (called adsorbents).

The most common application example is in refineries and petrochemical plants.

There are two principal mechanisms of adsorption of molecules on surface: physical adsorption and chemical adsorption.

Activated carbon and zeolits molecular sieves are used in CO2 separation.

Two methods are used to release the adsorbed CO2 from an adsorbent:

1. Temperature Swing Adsorption (TSA).2. Pressure Swing Adsorption (PSA).

Cryogenic Separation Cryogenic separation is used for the liquefaction and

purification of CO2. It is a distillation process that takes place at very low

temperature where the components of the feed gas start to liquefy.

The liquefied gas is purified in a cycle of evaporation-condensation steps.

The process requires the compression and cooling for the feed gas.

Disadvantages: high capital cost, high-energy requirements for the cooling process, and the demand for removing compounds from the feed gas that are expected to freeze before the CO2.

Membranes

Membranes separate the desired gas component without requiring phase changes or chemical or physical sorption.

There are a number of different types of gas separation membranes such as metallic membranes, ceramic membranes, zeolitic molecular sieves and polymeric membranes.

Comparison of the Capture Options

Chemical absorption is considered as the best option for capturing CO2 from the flue gas of electricity generation coal and natural gas power plants.

Physical absorption is may be considered as a good solution for capturing CO2 in hydrogen production unit, as well as in power plants.

Pressure swing adsorption offers significant advantages over temperature swing adsorption. Adsorption is widely used for the purification of hydrogen.

Cryogenic separation is unlikely to be utilized for carbon sequestration.

In the long term, membranes are accepted to play a very important role, replacing chemical absorption.

The applicability of each capture technology

depends on:

1. The feed gas conditions.

2. The concentration of CO2.

3. The degree of required CO2 removal from the feed gas.

4. The gas temperature and pressure.

Capture of CO2 from ambient air

capture of CO2 directly from the air by chemical processes require good chemical sorbents.

An ideal sorbent which absorbs CO2 from the atmosphere at large scale capture is sodium hydroxide (NaOH).

22

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3232

2322

)()4

)3

2)()2

2)1

OHCaOHCaO

COCaOCaCO

CaCONaOHOHCaCONa

OHCONaCONaOH

Propylene An organic compound having the chemical

formula C3H6, also known as propene. Properties: colorless and highly flammable gas. Used in the production of wide petrochemical

products such as polypropylene, cumene, propylene oxide.

Other uses of propylene within a refinery include alkylation, catalytic polymerization, and the production of high-octane gasoline blends.

Sources of propylene are ethylene steam cracker plants, refinery fluid catalytic cracking (FCC), propane dehydrogenation.

Production of Propylene The catalytic reduction of CO2 with the

dehydrogenation of propane on the silica supported chromium oxide catalyst (Cr2O3/SiO2) was tested by a pulse reaction technique in which CO and H2 came in to prominence.

∆H= heat of reaction=166.4 KJ/mol

∆G= free energy change=32.3 KJ/mol @1073K

The promoting effects of carbon dioxide over a Cr2O3/SiO2 catalyst were to enhance the yield of C3H6 and to suppress the catalyst deactivation.

OHHCCOHCCO 263832

The dehydrogenation of C3H8 was conducted under atmospheric pressure of C3H8+CO2 at 823 K by using a fixed bed flow reactor.

Silica-supported chromium oxide was industrially used for the productions of lower alkenes such as propene through the dehydrogenation of the propane.

the selectivity of propene was higher than 90% with a yield of 30%, and the presence of carbon dioxide enhanced propane conversion.

Suggested block flow diagram for propylene production

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