Catalytic reforming is a process which is born out the the necessity for high octane fuels which are used in transportation such as gasoline and aviation fuel.. This process takes the low octane straight run naphtha that is rich in naphthenes into high octane and low sulfur fuel which is used heavily in gasoline. Using this process a higher yield of gasoline can be achieved. In order to do this a few chemical reactions which increase the octane number of naphtha, convert the naphthenes to aromatics, and insomerize n-paraffins to i-paraffins must be completed. The catalysts used to bring these reactions to completion are generally platinum, palladium, or bimetallic formulation of platinum with Iridium or Rhenium with alumina. The process creates a large volume of hydrogen, which is a very valuable bi-product because it is in high demand for hydro-treating and hydro-cracking processes. The catalytic reformer is fed by the heavy naphtha line from the naphtha splitter. The naphtha splitter is fed by the straight run naphtha. The most desirable chemical reactions in the catalytic reforming process is dehydrogenation of naphthenes to aromatics, dehydroisomerization of alkyl-c5-naphthenes, Dehydrocyclization of n-paraffins to aromatics, and isomerization of n-alkanes to i-alkanes. These reactions increase the Research Octane Number (RON) from 75 to 110, 83 to 100, 0 to 110, and -19 to 90 respectively. 
All of these reactions except for the isomerization of n-alkanes produces hydrogen. If sufficient hydrogen is not produced coking my begin.

The catalytic reforming process is not without its limits. The United States and Europe limits the amount of benzene and other aromatics which can be found in gasoline. Because these compounds are carcinogenic and are harmful to the environment in many cases, catalytic reforming is limited. The high demand for high octane fuels and the hydrogen by product makes the process very valuable to refineries despite the production of aromatics.

Catalytic reforming is a necessary chemical process used in the petroleum refining industry which takes in straight run naphtha or partially treated light straight run naphtha, depending on the process, as a feedstock and converts it into high octane reformate and gasoline products. The earliest catalytic conversion processes date back as far as the 1930’s, however they have been continually improved upon since then with advances in techniques, catalysts, and yields to meet governmental product requirements. There are several different processes that are designated into classifications based on how their individual catalyst regeneration systems work. Those classifications are: semi-regeneration, cyclic regeneration, and continuous regeneration. Older catalytic reforming processes are typically semi-regenerative while cyclic and continuous regeneration processes are newer more advanced strategies.

Semi-regenerative methods, while useful, can be problematic because they must be turned off on a scheduled basis for the regeneration process to take place. These scheduled outages mean that the refineries cannot generate products and are therefore losing money while the units are offline. Cyclic units sought to resolve some of these issues by introducing another reactor to a two or three reactor system so that while one is turned off for regeneration the others could continue running and producing high octane fuels. The most up-to-date practices use continuous regeneration which requires no shutdown time because catalysts are momentarily removed from the reaction process, regenerated, and then introduced back in to continue the transformation of low octane feedstocks to high octane products. Continuous processes appear to be the best way to go except that they are the most expensive and most technically involved of the three methods.

Besides the regeneration methods, catalytic reforming processes, such as alkylation, dealkylation, polymerization, isomerization, and disproportionation¹, have their own advantages and disadvantages as well. Sulfur is a major issue for catalysts because it will poison the catalysts causing them to be unable to function so hydrogenation must occur prior to any of these catalytic reforming processes taking place to remove sulfur. Dehydrogenation and dehydrocylcinization as overall processes can also be problematic because they can create aromatic compounds which are regulated by the U.S. government due to their nature as carcinogens. The procedure of alkylation has an advantage over other practices in this respect because it does not produce any aromatic compounds which is why it is favored in use over other reforming types.² Alkylation is not without its drawbacks though, while it yields no aromatics alkylation does require the use of highly concentrated acids, such as hydrofluoric or sulfuric acid¹. Acids such as these can be dangerous to human health as well as the environment ^{3 4}.

1. “CIEC Promoting Science at the University of York, York, UK.” Cracking and related refinery processes. N.p., n.d. Web. 10 July 2014. <http://www.essentialchemicalindustry.org/processes/cracking-isomerisation-and-reforming.html>.
2. Eser, Semih. “Alkylation.” FSC 432: Petroleum Processing. N.p., n.d. Web. 12 July 2014. <https://cms.psu.edu/section/content/default.asp?WCI=pgDisplay&WCU=CRSCNT&ENTRY_ID=F20C6357261A4AE2A750C141B
3. “Hydrogen Fluoride (Hydrofluoric Acid).” CDC. N.p., n.d. Web. 11 July 2014. <http://www.bt.cdc.gov/agent/hydrofluoricacid/basics/facts.asp>.
4. “Sulfuric acid .” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 18 Nov. 2010. Web. 12 July 2014. <http://www.cdc.gov/niosh/npg/npgd0577.html>.

Catalytic reforming is a conversion process present in petroleum refinery and petrochemical industries. In this reforming process, low octane naphtha is converted into a higher octane reformate products for gasoline blending and aromatic rich reformate for aromatic production.¹ To accomplish this reformation, the hydrogen molecules are re-arranged and re-structured in a naphtha feedstock, while breaking some of the molecules down into smaller ones.¹ The Naphtha feeds to the catalytic reforming are heavy straight run naphtha.¹ it transforms low octane naphtha into high-octane motor gasoline blending stock, and aromatics rich in benzene, toluene, and xylene with hydrogen and liquefied petroleum gas as a byproduct. ¹ Due to the valuable nature and demand of these products, the catalytic reforming process is one of the most important processes in petroleum and the petrochemical industry.

In United States refineries we had limits on catalytic reforming capacity. For any given refineries can and do change operations of their refineries to respond to the continual changes in crude oil and product markets, but only within physical limits defined by the performance characteristics of their refineries and the prosperities of the crude oil they process.² Currently in the US, the refinery Catalytic Reforming Capacity as of January 1^st is 2,541,250 (Barrels per stream Day).³ This production is limited due current environmental regulations set by the government for the amount of aromatics gasoline can contain.³ This is because when reformed the benzene content becomes carcinogenic, which lead to the environmental regulations limiting its use and what further processing is needed. The economics of the process all plays a key role in the capacity produced.³ Where as this process may result in a desirable product that the public wants, and producing more would lower the price in the market, the environmental impact is the limiting factor. A cheaper made product could have adverse effects on the environmental, so there needs to be limits on production and quality. This result in less production and higher costs of production and sale; however it’s a more sustainable option as a result of the added costs.

1. Lapinski, M.L., Baird L., James, “Handbook Petroleum refining”, Ed. Meyers, R.A., The McGraw Hill Companies , R. 4.32004.

2.  ICCT- AN INTRODUCTION TO PETROLEUM REFINING AND THE PRODUCTION OF ULTRA LOW SULFUR GASOLINE AND DIESEL FUEL, October 24, 2011

3. http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=8_NA_8CRL_NUS_5&f=A

Catalytic cracking has been widely used since the early 1900’s for production of a range of fuels, predominantly light distillates, gasoline. Three types of Catalytic cracking exist, Houdry Catalytic Cracking, Thermafor Catalytic Cracking, and Fluid Catalytic Cracking. Fluid Catalytic Cracking has been widely adopted because of its thermal efficiency compared to the other two processes as well as its little to no down time during running. Catalytic cracking generally uses gas oil as a feed for the cracking processes. The gas oil is run through a column where steam is introduced and uses catalysts such as a zeolite or aluminum/silica catalysts for the separation process. The catalysts tend to build coke an inherently become deactivated requiring activation by heated air and/or steam. The products that come from these processes are Gas, Gasoline, Light Cycle Oil, and Heavy Cycle Oil. For the Fluid Catalytic Cracker, a product is also Decant Oil which can be used for fuel oil or for feedstock to produce needle coke or carbon black. Light Cycle Oil can be processed to produce diesel fuel. The Fluid Catalytic Cracker is used not only for its efficiencies but also because of its use of better catalysts and reactivation of the catalysts. These processes have a downfall in handling a wide range of feedstocks, primarily the heavier factions.

Hydrocracking has begun to be used in the late 50’s because of this growing demand for middle and light distillates as well as its flexibility to handle wide range of feedstocks. The hydrocracking plants have the ability to crack aromatics to produce paraffinic compounds without losing carbon, which increases the yields of the desired distillates without producing low-grade byproducts, such as coking. This is a major issue that wasted time and energy in the catalytic cracking plants. The catalyst used were typically metals such as nickel and copper as well as silica/alumina as in catalytic cracking. Since the process is bi-functional it also required highly active noble metals such as platinum and palladium. This process sheds the unwanted heteroatoms and increasing the H/C ratio. Hydrocracking can be used to treat the products that were resistive to cracking from the Fluid Catalytic Cracking plant such as Light Cycle Oil.

Hydrocracking costs more to perform which leads to the reasoning of performing both the Fluidized Catalytic Cracking for what it can do and using the Hydrocracking for what the FCC cannot do to supply the necessary amounts of fuels in demand. Although Hydrocracking is more flexible with feed, produces less coke, and gives use to the byproduct produced hydrogen, Fluidized Catalytic Cracking still serves its purpose for a cost effective way to produce light distillates such as gasoline, as well as coke that can be used for heating in plants and other purposes.

Hydrocracking is essentially the combination of two processes: hydrogenation and cracking. Therefore, hydrocracking utilizes a bifunctional catalyst. The catalysts (highly active noble metals used for hydrogenation e.g. Pt and Pd) used in hydrocracking are very susceptible to poisoning and great care must be taken to remove sulfur from the feedstock. The process is typically accompanied by hydrotreating in order to remove heteroatom species (e.g. S, N and O). Additionally, while catalytic cracking is a carbon rejection process, hydrocracking is in a hydrogen addition process. Therefore, some complications from coking are avoided during the hydrocracking process. Several factors distinguish these two cracking processes; however, typically both processes are used in order to provide the most optimal yield of products in an economically efficient manner. The advantages of hydrocracking include its ability to handle a wide range of feedstock, as well as the selectivity of its distillates.

The primary objective of both cracking processes is to produce lighter saturated hydrocarbons with reduced molecular weights and boiling points from heavy oils. But due to the fact that aromatic rings cannot be cracked until they are fully saturated with hydrogen, the hydrocracking process allows for the processing of more aromatic feedstock, including the byproducts of catalytic cracking (e.g. light cycle oil). Furthermore, by modifying reactor configurations (e.g. fixed bed, ebullated bed, or expanded bed), catalysts, and hydrogen/carbon ratios, hydrocracking can be highly flexible, with the ability to process both relatively light feedstock as well as heavy vacuum residue into light and middle distillates.

Another difference between hydrocracking and catalytic cracking includes the change in enthalpy; while catalytic cracking is an endothermic process, hydrocracking is an exothermic process. The heat for catalytic cracking is supplied by the regeneration of catalysts. The evolution of the catalytic cracking (from Houdry to Thermafor to the modern fluid catalytic cracking) has continuously improved upon the thermal efficiencies of the process.

Although the hydrocracking process has several advantages over fluid catalytic cracking, hydrocracking is, in comparison, a more costly process. Therefore, it is not exclusively used, and refineries typically operate with both processes in order to produce the most desirable yield of products.

Following the development of a fixed- bed (Houdry process, 1936) and a moving-bed (Thermafor Catalytic Cracking, 1941) catalytic cracking process, fluid-bed catalytic cracking (FCC, 1942) became the most widely used process worldwide because of the improved thermal efficiency of the process and the high product selectivity achieved, particularly after the introduction of crystalline zeolites as catalysts in the 1960s.

Catalytic Cracking processes were developed during the Second World War and became widely used ever since because of their improved thermal efficiency and the high product selectivity to produce gasoline with a higher octane number. Also, catalysts and additives are very significant for the selectivity and flexibility of catalytic cracking; the introduction of zeolite catalysts in 1965 has had a huge impact on the industry processes.

In 1936, the first full scale industrial catalytic process was developed. It was known as the Houdry Catalytic cracking process, which used much less expensive catalysts, such as clay, natural alumina and silica particles. For this process, the gas oil feed stock must be heated to high temperatures and is fed to a fixed-bed reactor containing the catalyst particles. The product stream is sent to the separator to produce gas, gasoline, light cycle oil (LCO), and heavy cycle (HCO) products. A problem that faced this process was the deactivation of the catalyst bed because of coking. Thus, the process included swing reactors to switch between periodically to overcome this issue. After switching, the reactor is stripped with stream to remove the liquid products from the catalyst bed. The coke is then burnt off to reactivate the catalyst bed. A small percentage of the heat generated by burning off the coke could be used to supply heat for catalytic cracking, however the thermal efficiency of this reaction is considered low.

However, more efficient catalytic cracking processes have been developed. Such process include thermafor catalytic cracking and fluid catalytic cracking. Thermofor cracking utilizes a moving catalyst bed. In addition, catalyst particles used in this process are synthetic and thus have consistent and homogenous properties. This process is a slightly more thermal efficient process than the Houdry process. In comparison, the fluid catalytic cracking utilizes a fluidized catalyst bed. This catalytic cracking process is considered the most thermal efficient process. Also, this process enables the production of large quantities of light distillates known as crackate without the addition of hydrogen by burning off the coke.

Catalytic hydrocracking is relatively a recent addition to the petroleum industry. The main reasons for its development are the increasing demand for light and middle distillates, the large quantities of hydrogen as a by-product from catalytic reforming, and the limits imposed on sulfur and aromatics content in motor fuel. Hydrocracking is able to process a wide range of feedstocks. Its main process objective is to decrease the molecular weight and boiling point of the heavy oils from a mostly aromatic feedstock. Through the hydrocracking process, it is possible to convert an aromatic compound to a paraffin compound with out rejecting any carbon. The catalysts used for such reactions include platinum and palladium metals, however, care must be taken as they can be easily poisoned by sulfur.

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