iii. Separation of the biodiesel from the glycerol is much easier.
Homogeneous catalysts are very effective catalysts but the major problem with the use of these type of catalysts is their removal from the methyl ester requiring excessive washing. Therefore, water, a lot of energy, and time are consumed. And these catalysts cannot be reused. Due to this heterogeneous (solid) base catalysts being insoluble. They are separated simply by filtration and can be reused many times. A lot of research has also been done in this direction. Commonly used solid base catalysts are alkaline earth metal oxides, zeolites, KNO3 loaded on Al2O3, BaO, KNO3/Al2O3, CaO, SrO, and MgO. Alkaline earth metals such as Mg, Ca, Ba, Sr and Ra, their oxides and derivatives
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The most common transition metals and their oxides used for biodiesel production are viz. ZnO, TiO, TiO2/SO422 and ZrO2/SO422, ZnO and ZrO as base heterogeneous catalysts. The activity of zirconium oxide functionalized with tungsten oxide and sodium molybdate (Na2MoO4) was also studied. There are also reports of usage of mixed metal oxides with their derivatives. Zeolite-based catalysts. Zeolites as catalysts have the characteristics of acidic sites. Zeolites are different in pore structure, and inner electric fields from their crystal and surface properties contribute to their varying catalytic properties. Zeolites can accommodate a wide variety of cations such as Na+,K +, Ca 2+, Mg 2+ and many others. Due to this they are basic nature. Zeolites as potential heterogeneous catalysts for the preparation of biodiesel have been …show more content…
Base catalysts are highly sensitive to water content due to soap formation which makes separation difficult. Acid catalyst are used when the acid values of the non-edible oils are higher than the performance range of base catalysts. The acid value represents the number of acidic functional groups and is measured in terms of the quantity of potassium hydroxide required to neutralize the acidic characteristics of the sample. The protonation of the carbonyl group of the ester promotes the formation of a carbocation, which after nucleophilic attack of the alcohol produces a tetrahedral intermediate. This intermediate will eliminate glycerol to form a new ester and to reform the catalyst. Acid-catalyzed transesterification are carried out in the absence of water. The problems with the use of these catalysts are: the requirement for more alcohol; slower reaction rates; higher reaction temperatures and pressures; reactor corrosion and environmental issues. Both homogeneous and heterogonous acid catalysts can be used for transesterification. The acid catalysts more commonly used include, sulfuric acid, hydrochloric acid, phosphoric acid, and sulfonated organic acids. Due to the fact that the FFA content of neat edible oils is normally low but these oils are costly and conversion of too much edible oil into biodiesel may cause food crises, use
The experimental Fischer esterification of 8.92g of acetic acid with 5.0g of isopentyl alcohol using concentrated sulfuric acid as a catalyst yielded 4.83g (65.3% yield) of isopentyl acetate. The product being isopentyl acetate was confirmed when the boiling point during distillation had similar characteristics to that of the literature boiling points2. Physical characteristics like color and smell also concluded a match of our product with what was intended. 1H-NMR spectroscopy analysis supported this claim due to the fact that the integration values and chemical shifts were comparable to isopentyl acetate. Lastly, infrared spectroscopy (IR) showed similar key characteristics of our product’s wavelengths to that of pure isopentyl acetate5.
The most classic and standard procedure for producing esters is the Fisher-esterification reaction. Discovered in 1895 by German chemists Emil Fischer and Arthur Speier 4, this reaction involves refluxing a carboxylic acid and an alcohol in the presence of an acid catalyst. In order to drive the equilibrium towards the products, the water from the dehydration process must be removed and there must be an excess amount of alcohol. A vast range of carboxylic acids may be used for this reaction however the type of alcohols are limited. Primary and secondary alcohols are most frequently used in esterification reactions, tertiary alcohols are steric ally hindered usually resulting in poor yields5 and tend to undergo elimination reactions instead. In this rea...
MTBE, or methyl tertiary butyl ether, is an oxygenate commonly used in gasoline in America, Europe, and other countries throughout the world. It is a compound created by the chemical reaction of methanol and isobutylene that is added to gasoline because of its high octane level, allowing gasoline to reach the required octane levels and still include a gasoline component. In addition, because it is an oxygenate, MTBE helps gasoline more fully combust, which increases performance and reduces the amount of harmful pollutants such as CO, VOCs, NOx, and particulates released into the atmosphere from automobile exhaust [EFOA]. However, opposition has recently arisen against the use of MTBE in gasoline.
The Effect of Changing the Concentration of the Enzyme Catalyst on the Rate of Reaction on Hydrogen Peroxide
Non-complicated acidic conditions can be utilized if acid-sensitive functional groups are not an issue; sulfuric acid can be used or even softer acids - for longer reaction tomes. There will be less environmental effect in terms of harmfulness and product wastes of the reagents used because these are straightforward. As per Wikipedia, alkyl halides are greenhouse gasses or ozone depletors, therefore will possibly poison to the atmosphere. Another point was made is that acid anhydrides are more reactive than ester because carboxylate anion is better leaving group than an alkoxide anion because the negative charge is more
Weight loss is a goal only a few have the knack and the ability to achieve, either via an efficient workout regimen or dieting, or both. Mostly, a combination of both works best and offers tremendous and desirable results. What about the rest? You don’t have to be left out of the fold anymore, because you can now use one or a combination of the many dietary supplements available today. However, as of now, our scrutiny is directed towards two; advocare catalyst vs thermoplus.
In order to gain strong insight into the surface chemistry of silica we have perform a thorough literature search. Our goal is to identify the pioneer research performed on silica and silica supported catalyst. Particular interest lies in silica-water-cobalt and silica-alcohol-cobalt systems. This study is both on macro and micro level so that a complete theoretical base can be established. From this theoretical knowledge, key areas to look upon will be identified and a design of experiments will be established. The goal is to develop a both efficient and effective product (catalyst) using a novel methodology developed from past research.
The Advantages and Disadvantages of Using Enzymes in Medicine and Industry What is an enzyme? = == ==
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
Abstract: Enzymes are catalysts therefore we can state that they work to start a reaction or speed it up. The chemical transformed due to the enzyme (catalase) is known as the substrate. In this lab the chemical used was hydrogen peroxide because it can be broken down by catalase. The substrate in this lab would be hydrogen peroxide and the enzymes used will be catalase which is found in both potatoes and liver. This substrate will fill the active sites on the enzyme and the reaction will vary based on the concentration of both and the different factors in the experiment. Students placed either liver or potatoes in test tubes with the substrate and observed them at different temperatures as well as with different concentrations of the substrate. Upon reviewing observations, it can be concluded that liver contains the greater amount of catalase as its rates of reaction were greater than that of the potato.
Effect of different size beads on the activity of immobilised catalyse Aim: To find out how varying the size of beads containing yeast varies the rate of activity of catalase in a fermentation reaction of hydrogen peroxide with immobilised enzymes. A catalyst is a substance that speeds up the rate of a chemical reaction, without itself being used up in the process however it maybe affected physically i.e. degradation of the surface of the catalyst. Catalysts work by reducing the activation energy needed for a particular reaction by offering a different path for the reaction to take place. Activation energy is the energy, which needs to be supplied before a reaction can occur, basically the amount of energy needed to overcome the bonds between the molecules and atoms. [IMAGE] Catalysts are usually specific to one reaction, that is, different reactions need different catalysts.
The human body goes through many different reactions and processes that are necessary for humans to live. Chemical reactions by the human body are never seen with the human eye, but it is so vital that these processes are understood. Without this understanding, diseases and disorders can never be resolved or controlled. These processes may be small in size, but have a great deal of impact on the function of the human body.
This project is about to develop the power converter with improved performance with low voltage and high current dc output.One of the application of low voltage,high current dc output is supercapacitor charger(12V,20A).This paper describes the high frequency(hf) transformer and resonant inverter intended to obtain better efficiency by maintaining the constant low voltage.
Fuel systems contrast extraordinarily from aircraft to aircraft because of the relative size and many-sided quality of the aircraft in which they are installed. In the most essential structure. A fuel system will comprise of a single, gravity feed fuel tank with the related fuel line interfacing it to the aircraft engine. In a current, multi-engine passenger or cargo aircraft, the fuel system is prone to comprise of different fuel tanks which may be situated in the wing or the fuselage (or both) and, sometimes, the empange. Every tank will potentially be equipped with inner fuel pumps and have the related valves and pipes to sustain the engines , take into account refueling and defueling, seclude the individual tanks and, in a few applications, consider fuel dumping or for enhancement of aircraft center of gravity.
The animal fats and vegetable oils are esters of the alcohol, propane-1,2,3-triol (glycerol) CH2OHCHOHCH2OH and long chain carboxylic acids (often known as fatty acids) RCO2H, where the alkyl groups contain between 7 and 21 carbon atoms.”2 Saponification is the chemical reaction between fat and sodium hydroxide or potassium hydroxide. Saponification comes from the Latin word, “sapo,” which means soap. The fats and oils come from animal or plant sources and is made up of distinctive mixture of several triglycerides. The fatty acids of a triglyceride are weak acids composed of a carboxyl acid group with one hydrogen atom, two oxygen atoms, and one carbon atom plus a hydrocarbon chain. The hydroxide is an alkali metal such as sodium or potassium. They are chemically a base that reacts or neutralizes an acid. During the saponification process, a triglyceride reacts with aqueous hydroxide ion to form a mixture of glycerol and fatty acid salts, or soap. This process is called alkaline hydrolysis of esters. Triglyceride plus sodium hydroxide equals glycerol plus three soap molecules. An exothermic reaction occurs when fats or oils come into contact with a strong base. Soap uses carboxylic acid such as sodium stearate which contains eighteen carbon atoms.