A Review Study Ability Zeolite Synthetis Combination for Catalytic Cracking

Zeolite Catalyst
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  A Review Study Ability Zeolite Synthetis Combination forCatalytic Cracking,and Adsorption Metals Ion. Boby Royan, A.Abstract .Zeolite is a chemical compound hydrated alumino-silicates which have a uniquesruktur melekular, wherein the silicon atom surrounded by four oxygen atoms to form a kindof network with a regular pattern. Aluminum Atom only has 3 + charge, while the silicon itself has a charge of 4 + . The existence of Aluminium atom as a whole will menyebababkanzeolites have a negative charge. The negative charge that causes the zeolite capable of binding cations. So zeolites are widely used both as penjerap metals and catalysts that canreduce the energy requirements of production but still be able to obtain maximum results asin the process of cracking hydrocarbons. Introduction Natural zeolite is recently reported asexcellent material to support metal in the preparation of catalyst. Naturalzeolite materials are easily found in USA, Japan, Cuba, Soviet Union, Italy,Czechoslovakia, Hungary, Bulgaria,South Africa, Yugoslavia, Mexico, Korea, andIndonesia. In Indonesia, natural zeolite reserves were discoveredmore than 205.82 milliontons. Zeolite deposits are most numerous in the Java island,i.e: Central Java (Wonosari,Klaten), West Java (Bogor, Tasikmalaya, Sukabumi), and East Java (Bayah). Hydrocrackingof plastic waste hasbeenwidely studied in literatures . However, the Indonesia’s natural zeolite especially from Sukabumi israrely applied as a catalyst for hydrocracking. haveobserved the naturalzeolite from Sukabumi. It contains the most mordenite mineral that hashigh thermal stability. Hence, this workwould study the effect of temperature condition aswell.The activation through acid treatment and modificationusing supported metals couldincrease itsacidity, pore and surface areaas well could produce the goodcatalyst forhydrocracking processes. Furthermore, the natural zeolite is very abundant and cheap, henceits use as acatalyst isvaluable to lower the cost of production.Supports provide the cracking functions, where the cracking takes place on strong acid sitesin the supports. The most important function of support is maintenance of high surface areafor the active component and acidity for hydrocracking reactions. A support material ischosen for given application on the basis of the several important characteristics including its  inertness to undesired side reactions, appropriate mechanical properties (attrition resistance,strength, etc), stabilityunder reaction conditions, a surface area and pore size distributionappropriate for the desired reaction, and its cost [6]. Zeolites are widely used as catalystsupport and play an important role in the catalysts used in hydrocracking process becausethey improve catalytic activity, selectivity, or stability byimparting shape selectivity.Zeolites are defined as crystalline aluminosilicates, have been investigated and extensivelyused in industry. Zeolites have been successful because of their crystallinity, high surfacearea, adsorption capacity, and uniform size distribution which enable shape selectivity. Theelementary building units of zeolites are SiO4and AlO4tetrahedra. Among the propertieswhich are affected by the framework aluminacontent are the density of negative framework charges, cation-exchange capacity, the density of Bronsted acid sites, their strength andthermal stability [8]. For the majority of catalytic applications, medium or large pore zeoliteswill usually be preferred. In the processes which work under hydrogen pressure, such ashydrocracking of heavy petroleum distillates, the catalytic activity stems from the Bronstedacid sites rather than the Lewis acid sites. It is well known, due to the higher electronegativityof silicon compared to alumina, the strongest Bronsted acidsites in zeolites willoccur oncompletely isolated Al/Otetrahedra. This is the reason why,upon dealumination of Yzeoliteswith typical Si/Alratioof 2.5, the catalytic activitygenerallyincrease up to Si/Alratioof 10. In this region, the gain in acidstrength overcompensatethe decrease in thedensityof Bronsted acid sites. Adsorption& Recovery Heavy Metas ion. Before any uses or applications of zeolites to the recovery of heavy metals from mining ormetallurgicaleffluents can be seriously considered it is necessary to characterize the zeoliteminerals. Characterizationmakes it possible to match the physical and chemical properties of the zeolite mineral to theenvironmentof the application in which it must operate.Characterization begins at the zeolite deposit. This means that a zeolite deposit must bethoroughlyexplored to determine its extent, continuity and quality. Both the mined andprocessed product must becarefully sampled to insure the purchaser a dependable supply of zeoliteswhich are of a consistentquality. The specifications which are used for grade orquality control must match the specificationsrequired for the intended use or application.The characterization of zeolite minerals initially requires careful screening techniques toidentify thezeolite and gangue minerals and to determine the percentage of each present inthe product. Next theelemental composition of the product should be determined. Both themineralogy and the elementalcomposition must be known before the zeolite can beconsidered for any ion exchange applications. Ifthe zeolite product contains a highpercentage of usable zeolite minerals usually chabazite, clinoptiloliteor mordenite and doesnot contain significant quantities of the minerals smectite (montmorillonite),calcite or  dolomite or the elements additional testing.The additional testing capacity, pHstability, ex metal ions. These are s application if the product introduced into effluent s composition of either th approach has seldom ever Hydrocracking Proces Oil is nowadays the mai continue in the next deca been achieved in oil refi research and innovation. of zeolites as catalysts. T been considered as one of In this tutorial review, t connection with their use refiningprocesses in whi alkylation, reforming, cra future developments in th and the coprocessing of review is intended to prov otassium, magnesium or calcium then the product ill determine other properties such as the am change selectivities, and exchange capacities for meof the properties which must be matched is to performsuccessfully.In the past zeolite pro treams and expected to performWithoutany inf effluent stream or the zeolite product. Clearlyt been.   n energy source and this prevalent position mos es. This situation is largely due to the degree of ing and petrochemistry as a consequence of the he remarkable efficiency of oil refining is largely he use of zeolites as catalysts in refining and pet the major accomplishments in the chemistry of th he introductory part describes the main features as solid acids.The main body of the review des   ch zeolites are used including light naphtha isom cking and hydrocracking. The final section contai field such as the increase in the quality of the tran increasing percentage of biofuels together with oi ide the rudiments of zeolite science applied to refini should undergo onia exchange selected heavy to the specific ucts have been rmation on the hishit or miss t probably will aturity that has large effort in ased on the use ochemistry has XXth century. of zeolites in ribes important rization, olefin s our view on sportation fuels l streams. This g catalysis.  Hydrocracking catalyst is a bi-functional catalyst and has a cracking function andhydrogenationdehydrogenation function. The former is provided by an acidic supportwhereas the latter isimparted by metals. Acid sites (Crystalline zeolite, amorphous silicaalumina, mixture ofcrystalline zeolite and amorphous oxides) provide cracking activity.Metals [Noble metal (Pd, Pt)or non noble metal sulphides (Mo, Wo or Co, Ni)] providehydrogenation dehydrogenationactivity. These metals catalyze the hydrogenation of feedstocks making them more reactive forcracking and hetero-atom removal as wellreducing the coke rateZeolite based hydrocracking catalysts have following advantages of greater acidity resulting ingreater cracking activity; better thermal/hydrothermal stability;better naphtha selectivity; betterresistance to nitrogen and sulphur compounds; low cokeforming tendency, and easyregenerability.Hydrocracking process isacatalytic cracking process which takes place in the presence of anelevated partial pressure of hydrogen and is facilitated by bio-functional catalyst havingacidicsites and metallic sites. During hydrocracking process hydrotreating reactions andhydrocrackingreactions are two major reactions which take place.A typical hydrocracking reaction is as follows. C 22 H 46 + H 2   C 16 H 34 + C 6 H 14 Various hydrotreating reactions are hydrodesulphurization, denitrogenation, hydrodeoxygenation, hydro metallization, olefin hydrogenation partial aromaticssaturation.Various hydrocracking reactions are splitting of C-C bond and or C-Crearrangement reaction(hydrisomerisation process) Hydrogenation anddehydrogenation catalyst. Conclusion Hydrocracking of saturated hydrocarbons can proceed by means of four distinctly differentmechanisms. On bifunctional catalysts comprising hydrogenation/dehydrogenation andBrønsted acid sites alkenes and carbocations occur as intermediates. The current mechanisticviews of bifunctional hydrocracking of long-chain n-alkanes are discussed in detail withemphasis on the now widely accepted concept of ideal hydrocracking. Other mechanisms arehydrogenolysis and Haag  –  Dessau hydrocracking which proceed, respectively, on


Jun 26, 2018
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