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Green Chemistry: Bio-Diesel and Bio-Petrol


Published on Dec 13, 2018

Abstract

The Objective of this project is to study GREEN CHEMISTRY- Bio diesel and Bio petrol also study extraction process of Bio diesel.

Green chemistry is the branch of chemistry concerned with developing processes and products to reduce or eliminate hazardous substances. One of the goals of green chemistry is to prevent pollution at its source, as opposed to dealing with pollution after it has occurred.

Introduction

Bio-diesel is an eco-friendly, alternative diesel fuel prepared from domestic renewable resources i.e. vegetable oils (edible or non- edible oil) and animal fats. These natural oils and fats are made up mainly of triglycerides. These triglycerides when rea w striking similarity to petroleum derived diesel and are called “Bio-diesel”. As India is deficient in edible oils, non-edible oil may be material of choice for producing bio diesel . For this purpose Jatropha curcas considered as most potential source for it. Bio diesel is produced by transesterification of oil obtains from the plant.

Jatropha Curcas has been identified for India as the most suitable Tree Borne Oilseed (TBO) for production of bio-diesel both in view of the non-edible oil available from it and its presence throughout the country. The capacity of Jatropha Curcas to rehabilitate degraded or dry lands, from which the poor mostly derive their sustenance, by improving land’s water retention capacity, makes it additionally suitable for up-gradation of land resources. Presently, in some Indian villages, farmers are extracting oil from Jatropha and after settling and decanting it they are mixing the filtered oil with diesel fuel.

Although, so far the farmers have not observed any damage to their machinery, yet this remains to be tested and PCRA is working on it. The fact remains that this oil needs to be converted to bio-diesel through a chemical reaction – trans-esterification. This reaction is relatively simple and does not require any exotic material. IOC (R&D) has been using a laboratory scale plant of 100 kg/day capacity for trans-esterification; designing of larger capacity plants is in the offing. These large plants are useful for centralized production of bio-diesel. Production of bio-diesel in smaller plants of capacity e.g. 5 to 20 kg/day may also be started at decentralized level.

Activity 1: Making Biodiesel

Biodiesel is a mixture of methyl esters of fatty acids (long chain carboxylic acids). It has similar properties to the diesel fuel made from crude oil that is used to fuel many vehicles. It can be made easily from vegetable cooking oil that contains compounds of fatty acids. Enough fuel can be produced in this activity to burn in a later activity, although it is not pure enough to actually be used as fuel in a car or lorry. The synthesis is a simple chemical reaction that produces biodiesel and propane-1,2,3-triol (glycerol). Cooking oil is mixed with methanol and potassium hydroxide is added as a catalyst. The products separate into two layers, with the biodiesel on the top. The biodiesel is separated and washed, and is then ready for further experimentation.

What you will need

• Eye protection

• Access to a top pan balance

• One 250 cm3 conical flask

• Two 100 cm3 beakers

• One 100 cm3 measuring cylinder

• Five plastic teat pipettes

• Distilled or deionised water

• 100 cm3 vegetable-based cooking oil

• 15 cm3 methanol (highly flammable, toxic by inhalation, if swallowed, and by skin absorption)

• 1 cm3 potassium hydroxide solution 50% (corrosive).

Procedure:

1. Measure 100 cm3 of vegetable oil into the 250 cm3 flask. Weigh the flask before and after to determine the mass of oil you used.

2. Carefully add 15 cm3 of methanol.

3. Slowly add 1 cm3 of 50% potassium hydroxide.

4. Stir or swirl the mixture for 10 minutes.

5. Allow the mixture to stand until it separates into two layers.

6. Carefully remove the top layer (this is impure biodiesel) using a teat pipette.

7. Wash the product by shaking it with 10 cm3 of distilled or deionised water.

8. Allow the mixture to stand until it separates into two layers.

9. Carefully remove the top layer of biodiesel using a teat pipette.

10. Weigh the amount of biodiesel you have collected and compare it to the amount of vegetable oil you started with.

Apparatus for Testing Biodiesel

Activity 2: Testing biodiesel

How does biodiesel compare to other fuels? Just because we can produce a fuel from an alternative source, does that mean it is a good idea? There are many factors that go into the decision to use alternative fuels. Ideally the physical properties of an alternative fuel should equal or exceed those of the traditional product. But how are fuels evaluated in the first place. In this activity, biodiesel and some other fuels are tested and compared for sootiness and acidity.

What you will need

• Eye protection

• Small glass funnel (approximately 7 cm diameter)

• One 250 cm3 flask

• Two boiling tubes

• One two-hole stopper to fit the boiling tubes

• Filter pump

• A piece of wide bore glass tubing approximately 10 cm long with two one-hole stoppers to fit

• A piece of vacuum tubing approximately 35 cm long

• Two short pieces of glass tubing to fit the one-hole stoppers

• 5 cm glass bend to fit the two-hole stopper

• 90o glass bend to fit the two-hole stopper (one leg to extend to bottom of flask)

• Two stands and clamps

• Two small metal sample dishes

• A little sodium hydroxide solution 0.1 mol dm-3 (irritant)

• Universal indicator solution

• A little mineral wool.

Procedure:

1. Pour 125 cm3 of distilled water into the 250 cm3 flask and add 10 cm3 of universal indicator. Add one drop of 0.1 mol dm-3 sodium hydroxide solution and gently swirl the flask so that the colour of the solution is violet or at the most basic end of the universal indicator colour range.

2. Place 10 cm3 of this solution into the boiling tube.

3. Assemble the apparatus illustrated in Figure 1, attaching it to the filter pump with the vacuum tubing.

4. Place 2 cm3 of biodiesel onto a wad of mineral wool in the metal sample cup.

5. Turn on the water tap so the filter pump pulls air through the flask and ignite the biodiesel. Position the funnel directly over the burning fuel, so as to capture the fumes from the burning fuel. Mark or note the position of the tap handle so you can run the pump at the same flow rate later in the experiment.

6. Allow the experiment to run until the universal indicator turns yellow and time how long this takes.

7. Record what happens in the funnel and in the glass tube containing the second piece of mineral wool.

8. Clean the apparatus, and repeat the experiment using 2 cm3 of kerosene (this is very similar to diesel fuel).

Activity 3: Potential for Biofuels

1. Technical Feasibility

• Can be blended in any ratio with petro-diesel

• Existing storage facilities and infrastructure for petro-diesel can be used with minor alteration.

• From environment and emissions point of view it is superior to petro-diesel.

• It can provide energy security to remote and rural areas.

• It has good potential for employment generation

2. Sources of Bio-diesel

All Tree Bearing Oil (TBO) seeds – edible and non edible

Edible: Soya-bean, Sun-flower, Mustard Oil etc.

Non-edible: Jatropha Curcas, Pongemia Pinnata, Neem etc.

• Edible seeds can’t be used for bio-diesel production in our country, as its indigenous production does not meet our current demand.

• Among non-edible TBO, Jatropha Curcas has been identified as the most suitable seed for India.

3. Advantages of Jatropha

• Jatropha Curcas is a widely occurring variety of TBO

• It grows practically all over India under a variety of agro climatic conditions.

• Can be grown in arid zones (20 cm rainfall) as well as in higher rainfall zones and even on the land with thin soil cover.

• Its plantation can be taken up as a quick yielding plant even in adverse land situations viz. degraded and barren lands under forest and non-forest use, dry and drought prone areas, marginal lands, even on alkaline soils and as agro-forestry crops.

• It grows as a tree up to the height of 3 – 5 mt.

• It is a good plantation for Eco-restoration in all types wasteland.

Trans-desertification Process

• It is the displacement of alcohol from an ester by another alcohol in a similar process to hydrolysis.

• Vegetable Oil i.e. the triglyceride can be easily trans-esterified in the presence of alkaline catalyst at atmospheric pressure and at temperature of approximately 60 to 70oC with an excess of methanol.

• If 100 gm of vegetable oil is taken, 1 gm of the alkaline catalyst (Potassium Hydroxide), and 12 gm of Methanol would be required

• As a first step, the alkaline catalyst is mixed with methanol and the mixture is stirred for half an hour for its homogenization.

• This mixture is mixed with vegetable oil and the resultant mixture is made to pass through reflux condensation at 65oC.

• The mixture at the end is allowed to settle.

• The lower layer will be of glycerin and it is drain off.

• The upper layer of bio-diesel (a methyl ester) is washed to remove entrained glycerin.

• The excess methanol recycled by distillation.

• This reaction works well with high quality oil. If the oil contains 1% Free Fatty Acid (FFA), then difficulty arises because of soap formation. If FFA content is more than 2% the reaction becomes unworkable.

• Methanol is inflammable and Potassium Hydroxide is caustic, hence proper and safe handling of these chemicals are must.

References:

1. www.google.co.in

2. www.chemistry.org

3. www.ott.doe.gov/biofuels/environment.html

4. www.pcra.org





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