The main purpose of this technology is hydrogen production. Difference between thermal cracking and catalytic cracking. The use of thermal cracking units to convert gas oils into naphtha dates from before 1920. Making crude oil usefulfractional distillation and cracking.
Feb 27, 2011 i taught this lesson with a low ability year 10 group and it was observed by a regional consultant, borough consultant and head of department and judged to be a good lesson. This cracking continues until the oil vapors are separated from the catalyst in the reactor cyclones. Cracking hydrocarbons on a microscale resource rsc education. Coking in steam reforming reactions was studied to find the critical steam ratio above which coking does not occur as a function of temperature and pressure at the reaction equilibrium. Used to increase gasoline yield and improve octane yield which improves the antiknock properties of the fuel. Chemical processing how oil refining works howstuffworks. It is the principal industrial method for producing lighter alkenes olefins, including ethene or ethylene and propene or propylene figure 3. Cracking is the cleavage of carboncarbon bonds in high molecular weight alkanes induced by heat thermal cracking or with catalysts catalytic cracking. For example, crude oil can be processed cracked to.
Since catalyst speed upretard the rate of reaction, if cracking is carried out in the presence of catalyst the rate of desired reactions cracking of heavy hydrocarbons into gasoline range hydrocarbons can be. Cracking involves breaking up heavy molecules into lighter and more valuable hydrocarbons. The regulations cover wastewater discharges at over 140 refineries across the country. A family of hydrocarbons which all fit the same general formula. The process can include a reaction zone operating at conditions to facilitate olefin production and including at least one riser. Introduction to hydrocarbon free download as powerpoint presentation. Partial oxidation of heavier hydrocarbons is also used to a limited extent. Ppt hydrocarbons powerpoint presentation free to view. This reformer tube construction eliminates the need for a hot manifold and comprises in a coaxial tube arrangement a centrally located product tube and an outer composite wall spaced therefrom. However, safety concerns by many teachers and availability of equipment in some schools mean that this key and. Generally, the rate of cracking and the final products.
Catalytic cracking is the breakdown of large compounds into small hydrocarbons in the presence of a catalyst. In the overall steam methane reforming smr reaction, methane reacts with steam at high temperatures and moderate pressures in catalystfilled tubes to generate synthesis gas, a mixture of. Petroleum refining petroleum refining catalytic cracking. It is a highly endothermic process requiring large amounts of energy. Since catalyst speed upretard the rate of reaction, if cracking is carried out in the presence of catalyst the rate of desired reactions cracking of heavy hydrocarbons into gasoline range hydrocarbons can be accelerated and rate. A schematic presentation of the feedstock, products and. Minimal cracking minimal conversion 10% to 20% typical products suitable for further processing or final blending reforming, catalytic cracking, hydrocracking hydrocracking severe form of hydroprocessing break carbon. The hightemperature pyrolysis of hc acetylenic intermediate stage 2. Catalytic cracking breaks complex hydrocarbons into. Why do long hydrocarbons have higher boiling points. Niobium stabilized alloys in steam hydrocarbon reforming.
In the more modern fcc units, all cracking takes place in the riser. Difference between thermal cracking and catalytic cracking definition. Thermal cracking also known as steam cracking, is used for manufacture of ethylene. Refining is the processing of one complex mixture of hydrocarbons into a number of. Alkanes hydrocarbons containing only single covalent bonds ex. The simplest hydrocarbon, methane, is made up of one carbon atom and four hydrogen atoms. Cracking involves the breaking of cc bonds in alkanes converts. In alkylation, low molecular weight compounds, such as propylene and butylene, are mixed in the presence of a catalyst such as hydrofluoric acid or sulfuric acid a byproduct from removing impurities from many oil products. I did the demo of cracking but used the diagram as well. The temperatures used for this process ranges between 475530 oc. What is difference between reforming and cracking answers. Purpose of catalytic reforming process to improve the octane number of the feedstock, especially of heavy naphtha.
The class of chemicals based on carbon and hydrogen are called hydrocarbons. Feed stocks are light and heavy oils from the crude oil distillation unit which are processed primarily into gasoline as well as fuel oil and light gases. Octane numbers are very relevant in the reforming, isomerisation and alkylation. Reforming rearranges naphtha hydrocarbons into gasoline molecules. One exemplary embodiment can be a fluid catalytic cracking process. Thermal cracking is the process of breaking down large compounds into small compounds at high temperatures and high pressures. First, crack the vapour of liquid paraffin by passing it over a heated catalyst to produce and collect a mixture of gaseous shortchain hydrocarbons. Catalytic cracking catalytic cracking catalytic cracking uses heat, pressure and a catalyst to break larger hydrocarbon molecules into smaller, lighter molecules. Reforming chemistry britannica encyclopedia britannica. Steam reforming or steam methane reforming is a method for producing syngas hydrogen and carbon monoxide by reaction of hydrocarbons with water.
Catalytic cracking is the breakdown of large compounds into small hydrocarbons using an acid catalyst. Reforming, in chemistry, processing technique by which the molecular structure of a hydrocarbon is rearranged to alter its properties. The cracking and reforming of crude oil fractions presentation. A schematic presentation of the feedstock, products and process condition is shown in figure below. Reforming involves changing the chemical nature of hydrocarbons to achieve desired physical properties and also to increase the market value. Cracking hydrocarbons in liquid paraffin with a catalyst. These units produced small quantities of unstable naphthas and large amounts of byproduct coke. Steamnaphtha reforming is a continuous process for the production of hydrogen from liquid hydrocarbons and is, in fact, similar to steam. Cracking hydrocarbons on a microscale resource rsc. Catalytic uses a catalyst to speed up the cracking reaction. The resultant product stream cracked product is then charged to a fractionating column where it is separated into fractions, and some of the.
The primary distillation produces about 2% of the initial crude as a petroleum fraction 8carbon atom per chain the. Hydrocarbons hydrocarbons hydrocarbons hydrocarbons hydrocarbons iupac system of naming organic compounds iupac system of naming organic compounds naming branches as groups naming branches as groups structural isomers how many structural isomers compounds with the. C7c9 hydrocarbons a tmospheric gas oil kerosene diesel fuel heavy fractions lubricating oil residual or heavy fuel oil asphalt or resid boiling point range below 701400c 175275ec above above comments similar to natural gas. Catalytic cracking advantages of catalytic cracking over thermal cracking. Steam cracking is a petrochemical process in which saturated hydrocarbons are broken down into smaller, often unsaturated, hydrocarbons. Mar 20, 2017 catalytic reforming process octane number of hydrocarbons 9 paraffins reforming process 10. 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 gasoline. Revisiting its importance in the modern refinery uday t turaga. The interest in hydrocracking has been attributed to the increasing demand for light and middle distillates, the availability of byproduct hydrogen in large quantities from catalytic reforming, and the environmental regulations limiting sulfur and aromatic hydrocarbons in motor fuels 5. Cracking cracking is a procession which large hydrocarbon molecules are.
Main chemical reactions catalytic cracking of heavy hydrocarbons into lighter unsaturated hydrocarbons saturation of the. The hydrocarbon molecules are broken up in a fairly random way to produce mixtures of smaller hydrocarbons, some of which have carboncarbon double bonds. Cracking takes large hydrocarbons and breaks them into smaller ones. Oil refining method by which crude oil converted to petroleum. Quizlet flashcards, activities and games help you improve your grades. However, at 800 c, co 2 was consumed completely and carbon deposition formed via the cracking of the hydrocarbons. The performance of hydrocarbons as fuels is improved by the cracking and catalytic reforming reactions. The process of breaking higher hydrocarbons with high boiling points into a variety of lower hydrocarbons that are more volatile low boiling, is called cracking or pyrolysis.
The light gaseous hydrocarbons produced by catalytic cracking are highly unsaturated and are usually converted into highoctane gasoline components in polymerization or alkylation processes. Above 600 c, dry reforming reaction became increasingly favorable and resulted in a continual increase in the h 2 and co content and a reduction in the co 2, ch 4, and c 3 h 8 content. Two important processes used for this purpose are cracking and reforming. Commonly, this is done using a process called alkylation. Similarly, octane can produce other hydrocarbons involving cleavage of cc bonds as.
For example, a higher hydrocarbon c 1 0 h 2 2 splits according to the reaction. In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby. The formation of petroleum penn state college of earth. Hydrocarbons are used mainly as fuels, solvents and lubricants. Other hydrocarbons like octane and octadecane have more complicated structures. Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure. Cracking, in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts.
Reformer tube construction is described within which both the desired endothermic catalyzed chemical reaction and heat transfer from the reaction products to the incoming reactants are accomplished. The pressure used for this process is around 20 atm. Photo courtesy phillips petroleum company catalysts used in catalytic cracking or reforming. Ppt chapter 9 hydrocarbons from petroleum powerpoint. I taught this lesson with a low ability year 10 group and it was observed by a regional consultant, borough consultant and head of department and judged to be a good lesson. There isnt any single unique reaction happening in the cracker.
Oct 30, 2012 hydrocarbons organic compounds that contain only hydrogen and carbon. Difference between catalytic cracking and catalytic reforming. A microscale experiment, cracking the hydrocarbons in paraffin to form shorter alkanes and alkenes. Discussion of the reforming and cracking reactions. This paper will deal with large scale hydrogen production in stationary plants using steam reforming. Thermodynamic analysis of coking in the steam reforming of. Catalytic reforming catalytic reforming is the process of transforming c7 c10 hydrocarbons with low octane numbers to aromatics and isoparaffins which have high octane numbers.
A free powerpoint ppt presentation displayed as a flash slide show on id. Petroleum refinery activities start with receipt of. University of zagreb petroleum refining and petrochemical. Basically, the process rearranges or restructures thehydrocarbon molecules in the naphtha feedstocks as well as breaking. Catalytic cracking main incentive for catalytic cracking is the need to. Feb 11, 2011 you can find instructions for this experiment at cracking hydrocarbons liquid paraffin a mixture of. Also obtained from catalytic cracking and catalytic reforming. Hydrogen from catalytic reforming of biomassderived. In polymerization, the light olefins propylene and butylene are induced to combine, or polymerize, into molecules of two or three. Cracking breaks carboncarbon bonds to turn heavier hydrocarbons into lighter ones. More of each of these fractions can be made by cracking heavier fractions. And this results is shown to used for carbonfree deposition conditions of steam cracking process the critical steam ratio is strongly dependent on. Steam reforming for hydrogen production reforming reactions the principal process for converting hydrocarbons into hydrogen is steam reforming 6,7 which involves the following reactions. High octane starter to inject pace which is easily adapted for other lessons.
Chapter 9 hydrocarbons from petroleum chemistry gasoline and diesel fuel are highdemand crude oil fractions. Cracking is the most important process for the commercial production of gasoline and diesel fuel. Gasoline upgrading purpose increase the quality of feed stocks of the same boiling range as gasoline characteristics catalytic reforming converts naphthenesto aromatics produces hydrogen isomerization re. It also produces high proportions of branched alkanes and aromatic hydrocarbons like benzene. Here, moderate temperatures and pressures are provided for the cracking process. Also, molecules that burn better in internal combustion motors can be made by chemical processes e.
Plastics are made of molecules called polymers that are very long chains of hydrocarbons. It is the principal industrial method for producing the lighter alkenes or commonly olefins, including ethene or. Refinery modeling aaron smith, michael frow, joe quddus, donovan howell, thomas reed, clark landrum, brian clifton may 2, 2006. Increased capabilities and efficient processes, were designed in the refining process, and called thermal cracking of hydrocarbons. Thermal reforming alters the properties of lowgrade. Fluid catalytic cracking, or fcc, is the last step in the evolution of cat cracking processes also introduced in 1942, just like tcc or thermafor cat cracking, during the second world war in an effort to make highoctane number gasoline. This is the first and most basic step in the refining process, and is the precursor to cracking and reforming. Thermodynamic analysis of coking in the steam reforming of hydrocarbons ju ho lee and chul soo lee dept. Used in the oil and gas industry to refer to a variety of methods whereby a larger product is broken down into smaller byproducts. Catalytic reforming process octane number of hydrocarbons 9 paraffins polymerization and alkylation. Hydrocarbon cracking is the process whereby large and heavy hydrocarbon molecules longchain hydrocarbons are broken down up into simpler and smaller bits as light hydrocarbons shortchain hydrocarbons by the breaking a carboncarbon bonds in cracking stock. In thermal cracking the higher hydrocarbons are heated to a high temperature, whereby lower hydrocarbons are formed for example, 775k.
Steam reforming used for producing a mix of co and h2. The process is frequently applied to lowquality gasoline stocks to improve their combustion characteristics. However, safety concerns by many teachers and availability of equipment in some schools mean that this key and interesting experiment is often done as a demonstration. Model the industrial process of cracking larger hydrocarbons to produce smaller alkanes that can be converted into petrol. Catalytic reforming is a chemical process used to convert petroleum refinery naphthas distilled from crude oil typically having low octane ratings into highoctane liquid products called reformates, which are premium blending stocks for highoctane gasoline. You can find instructions for this experiment at liquid paraffin a mixture of. Catalytic reforming is the process of transforming c7 c10 hydrocarbons with low octane numbers to aromatics and. Cracking the hydrocarbons in paraffin to form shorter alkanes and alkenes can be done as a class practical. While they succeeded in providing a small increase in gasoline yields, it was the commercialization of the fluid catalytic cracking process in. Catalytic reforming catalytic reforming is a chemical process used in petroleum refineries to convert naphthas, typically having low octane ratings, into highoctane liquid products called reformateswhich are components of highoctane gasoline also known as petrol. Introduction to hydrocarbon cracking chemistry oil. These fractions are obtained from the distillation process as liquids, but are revaporized before cracking.
Modern living is built on crude oil this hub explains how crude oil is changed into the things we use everyday, from petrol to plastic. Aromatisation involves reactions of the type, dehydrogenation, cyclisation, and isomerisation. How does it work why is crude oil both important and useless. Catalytic reforming process octane number of hydrocarbons 9 paraffins reforming process 10. It also provides the chemical industry with very important compounds such as benzene, methylbenzene, the dimethylbenzenes, ethylbenzene and cyclohexane. Reforming converts the hydrocarbons in petroleum to aromatic hydrocarbons and highly branched alkanes, both of which are better automotive. This can occur thermally as occurs during the petroleum formation process beneath the earth or through the action of a catalyst. Sometimes, the structures of molecules in one fraction are rearranged to produce another. Epa promulgated the petroleum refining effluent guidelines and standards 40 cfr part 419 in 1974 and amended the regulations in 1975, 1977, 1982 and 1985. Cracking of hydrocarbons download pdf info publication number us2985695a. The reforming reaction which produces aromatic hydrocarbons and hydrogen takes place in reactor 1, followed by isomerisation reactions in reactor 2 and finally in reactor 3 cracking reactions.
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