Karakterisasi karbon aktif dari Green Coke dengan perlakuan kimia (Na OH).

Green coke adalah hasil sainping dari destruksi minyak meritah, yang pemanfaatannya sebagiari besar sebagai bahan bakar. Untuk menambah riilai ekonomisnya maka perlu dilakukan pengembangan potensi lain dari green coke yaitu sebagai karbon aktif. Telah dibuat karbon aktif dari green coke dengan perlakuan kimia t'TaOH ,sienganyariasi00,1 H, 0,5 N, 1,0 N dengan temperatur 350 C, 450 C, 550 C, 650c, C. Karbcn aktif hasil percobaan untuk yang terbaik diperoieh pada NaOH sebesar 1,0 N dengan temperatur 650 C dengan kadar air 4,465 %; zat volatile matter 9,295 %; kadar abu 2,927 %; kadar karbon murni 83,085 %; daya scrap terhadap metileri Flue 8,25 ml/gram clan luas permukaan sebesar 51,1349 m is gram. Green coke is the residue of the destructive of crude oil , the mayor uses of green •coke is the burning material, to increase the economic value , it mustbe to developed to use of active carbon. Activated carbon have been made from green coke with NaOH chemical treatment with variety 400,1 N, N and temperature variety is 350°C, 450 C, 550°C, 650°C. C. Characterization for yield activated carbons could be obtained the best for KA 1,0 N NaOH - 650,C with _Moisture 4,645 %, Volatile Matter 9,295 %, Ash Content 2,975 %, Fixed' Carbon 83,085 % , Adsorption getilen of Blue 8,25 ml / gram and Surface area 51,1349 m/ gram

Deactivation of the catalyst during the MTO process from a molecular modeling perspective

Currently, the industrially important conversion process of methanol to olefins (MTO) forms a key process for the production of higher valued products that can easily be transported, such as ethylene and propylene. Methanol can be made from natural gas or coal via synthesis gas. Unraveling the underlying reaction mechanism of the complex MTO process has already shown to be very challenging. Recent ab initio calculations, in combination with experimental data, are in strong support of the “hydrocarbon pool model” as opposed to a direct (C-C coupling) route [1, 2]. The hydrocarbon pool has been described as a catalytic scaffold inside the zeolite building, consisting of polymethylbenzenes and their cationic derivatives. The continued growth of these initially active carbonaceous species within acidic zeolites, such as H-ZSM-5 and H-SAPO-34, is an undesired side effect resulting from secondary reactions for which at present no computational data exist whatsoever. The presence of these large species – coke precursors - inside or at the external cups of the periodic structure leads to blockage of the pores or channels and ultimately to the deactivation of the catalyst. An improved in-depth understanding of the underlying reaction mechanisms of coke formation is therefore desperately needed. A main problem is the generally poor characterization of coke, despite the great number of techniques (gas chromatography, mass spectroscopy) that can be used for locating and identifying the deposits [3, 4]. Because of this, it is not clear whether benzenoid species consisting of 3 rings can already be regarded as coke as opposed to large aromatic species present in the hydrocarbon pool that still allow an active route. Within this contribution possible reaction routes leading to the formation of naphthalene- and/or phenanthrene-like species are studied from theoretical viewpoint within various industrially relevant zeolite topologies. For each of these elementary steps reaction rates are evaluated based on energies and frequencies originating from reliable ab initio data. The latter were obtained by taking into account a large portion of the zeolites, as to be representative for the actual topology

Naphthalene derivatives in the MTO process from a molecular modeling perspective: reactive species or coke?

Currently, basic chemicals in polymer industry are mainly produced by thermal cracking of petroleum, but a promising alternative has been found: methanol-to-olefins (MTO). Methanol can be made from natural gas via syngas, but also from biomass. Molecular modeling of the MTO process has been a challenging topic, yet the reaction mechanism of the active route is starting to get unraveled based on the ‘hydrocarbon pool’ hypothesis [1], where aromatic species play a fundamental role as co-catalytic species within the zeolite pores and cages. All catalysts face the problem of deactivation due to coke formation [2]. This is a major threat for the application of the process and the need for a reliable kinetic model of the coke deposition to optimize the reaction conditions is, therefore, high. Experimentally, it is found that the deactivation is a result of the presence of voluminous polyaromatic compounds in the cages of the catalyst. For SAPO-34, which has a chabasite topology, this are phenantrene- and pyrene-like species, which show no activity towards olefin production. The topology of the catalyst is a crucial aspect regarding the coking issue: ZSM-5 only shows a blocking of the channels in the external cups, while a chabasite topology is subject to internal coking [3]. As of yet, the boundary region between active hydrocarbon pool species and deactivating coke remains uncharacterized. In this contribution, this question will be answered for naphtalenic compounds by remodeling the active route for ethylene and propylene production and comparing the activities with the original side-chain mechanism [1]. An other topic of examination is the influence of the formation of such compounds on the propene/ethene selectivity ratio [4]. And finally, the chemical composition of the catalyst, which clearly has an influence on the activity and coking rate of the catalyst [5] will be investigated by comparing the behavior of naphtalenic molecules in SSZ-13 chabasite and SAPO-34

Density functional theory (DFT) study on the reaction mechanism of in-situ no reduction in hydrogen rich blast furnace

Based on density functional theory and classical transition state theory, the reaction mechanism of NO reduction by H2 catalyzed by coke in hydrogen rich blast furnace was investigated. The results showed that the presence of active sites on the coke surface promoted the NO reduction reaction. Reactive oxygen species remaining on the coke edge inhibited the NO reaction after NO reduction. Both coke and H2 can release edge sites by reducing reactive oxygen species, but reactive oxygen species reduction by H2 requires a high barrier value of 634,3 kJ/mol, which is higher than that by coke

Methanol dehydration on carbon-based acid catalysts

Methanol dehydration to produce dimethyl ether (DME) is an interesting process for the chemical industry since DME is an important intermediate and a promising clean alternative fuel for diesel engines. Pure or modified γ-aluminas (γ-Al2O3) and zeolites are often used as catalysts for this reaction. However, these materials usually yield non desirable hydrocarbons and undergo fast deactivation. In this work, we study the catalytic conversion of methanol over an acid carbon catalyst obtained by chemical activation of olive stone with H3PO4. A significant amount of phosphorus remains over the catalyst surface after the activation process, mostly in form of C-O-PO3 and C-PO3 groups, which provide the carbon a relatively high surface acidity and oxidation resistance. Methanol decomposition on this catalyst yields selectivities to DME higher than 82% at 623K and methanol conversion of 34%, under the operating conditions studied. The activated carbon catalytic activity and stability, under inert and oxidant atmospheres, as well as different regeneration procedures, were studied. In the absence of oxygen, the catalyst suffers a progressive deactivation by coke deposition on the active acid sites (Fig. 1). The presence of oxygen modifies the carbon surface chemistry, probably through oxygen spillover on the catalyst surface, where the availability of labile oxygen avoids catalyst deactivation. A reaction mechanism has been proposed where methanol dehydration seems to proceed through an Eley-Rideal mechanism, which assumes the adsorption of water and oxygen spillover on the acid active sites, avoiding coke deposition

ENERGETIC ESTIMATION OF HEAT-RECOVERY COKE OVEN

Worldwide, steel production insistently seeks energy strength, pointing out the precision of application of all energy from the raw material with the objective of increasing production with quality and economically viable. In this sense, the energy assessment is the basis adopted to decide on the manufacture of coke in the industry. With this argument, this paper presents an energy analysis of Heat Recovery furnaces through calorific value, a method specified by the Energy Research Company of Brazil and the Brazilian Association of Metals and Materials for application in calculations in a productive environment. The data of the basic raw materials for the production of coke, the technological analysis and the energy estimation in the manufacture of coke in Coke Ovens Heat Recovery can be found in the proposed method. The present work presents result that demonstrate that the active and efficient use of the calorific value of metallurgical coal produces an energy quality coke for the manufacture of pig iron in the blast furnace.

Study of Combustion Properties for Cokes with Various Grain Size Composition

As of today, cupola-type units have rather wide range of use both for iron production or metal scrap remelting and for mineral melt production. The major fuel type for such units is solid fuel – cupola coke. Raw material market offers quite a wide range of such fuels to the factories. Their metallurgical properties based on certificate data may vary within a broad band. To determine the impact of coke grain size composition on its properties, 11 coke types from various manufacturers were selected. An actual property variation range of certain solid fuel types was identified to describe the nature of solid fuel impact on cupola shaft furnace performance. When studying the combustion properties of coal coke in conditions close to the cupola shaft furnace, operation data of total curve of differential scanning calorimetry (DSC) was used. Temperature ranges were specified for intensive heat evolution from the beginning of coke sample active oxidation to the completion of the burnup period, as well as apparent heat capacity and heat effect of coke combustion. Keywords: foundry coke, combustion parameters, burnout interval, granulometric composition, thermal effect, thermogravimetry, apparent heat capacit

Fe-MOF Materials as Precursors for the Catalytic Dehydrogenation of Isobutane.

We investigate the use of a series of iron-based metal-organic frameworks as precursors for the manufacturing of isobutane dehydrogenation catalysts. Both the as-prepared and spent catalysts were characterized by PXRD, XPS, PDF, ICP-OES, and CHNS+O to determine the physicochemical properties of the materials and the active phases responsible for the catalytic activity. In contrast to the previous literature, our results indicate that (i) the formation of metallic Fe under reaction conditions results in secondary cracking and coke formation; (ii) the formation of iron carbide only contributes to coke formation; and (iii) the stabilization of the Fe2+ species is paramount to achieve stable and selective catalysts. In this sense, promotion with potassium and incorporation of titanium improve the catalytic performance. While potassium is well known to improve the selectivity in iron-catalyzed dehydrogenation reactions, the unprecedented effect of titanium in the stabilization of a nanometric titanomaghemite phase, even under reductive reaction conditions, results in a moderately active and highly selective catalyst for several hours on stream with a remarkable resistance to coke formation

Catalytic steam reforming of volatiles released via pyrolysis of wood sawdust for hydrogen-rich gas production on Fe–Zn/Al2O3 nanocatalysts

Thermo-chemical processing of biomass is a promising alternative to produce renewable hydrogen as a clean fuel or renewable syngas for a sustainable chemical industry. However, the fast deactivation of catalysts due to coke formation and sintering limits the application of catalytic thermo-chemical processing in the emerging bio-refining industry. In this research, Fe-Zn/Al2O3 nanocatalysts have been prepared for the production of hydrogen through pyrolysis catalytic reforming of wood sawdust. Through characterization, it was found that Fe and Zn were well distributed on the surface with a narrow particle size. During the reactions, the yield of hydrogen increased with the increase of Zn content, as Zn is an efficient metal promoter for enhancing the performance of the Fe active site in the reaction. The 20% Fe/Al2O3 catalyst with Zn/Al ratio of 1:1 showed the best performance in the process in relation to the hydrogen production and resistance to coke formation on the surface of the reacted catalyst. All the catalysts showed ultra-high stability during the process and nearly no sintering were observed on the used catalysts. Therefore, the nanocatalysts prepared from natural-abundant and low-cost metals in this work have promising catalytic properties (high metal dispersion and stability) to produce H2-rich syngas with optimal H2/CO ratio from the thermo-chemical process of biomass

Study on Continuous Catalyst Reformer and Catalyst Regeneration Process

Regeneration of coked catalyst in a naphtha reformer is studied based on the effectiveness of rate coke bum off. Catalyst is temporarily deactivated by the coke deposits which are burnt in the regeneration for the catalyst reactivation. Catalyst gets deactivated by coke deposition blocking the active sites and reduces the selectivity of catalyst and the products yields. For predicting the behavior subject to catalyst deactivation, coking rate equation and the kinetic model is obtained. All reformers are moving bed and radial flow reactors. The coked catalyst are moved continuously and slowly from the reactors, withdrawn from the last reactor regenerated in a regeneration section and returned to first reactor as fresh catalyst. Coke content on the catalyst increases with residence time of catalyst. Catalyst deactivation is directly proportional to the amount of coke deposits on the catalyst. To understand and contribute to this problem, a modeling of the regeneration of coked catalyst particles (Pt-Al203) are used as model catalyst to (I) determine of the intrinsic and effective kinetics of coke bum-off (2) characterization of the catalyst's on influence of the temperature on the pore effectiveness factor, rate of mass transfer, and reactivity of coked catalyst (3) Influence ofcarbonload on porosity and tortuosity of the catalyst. With this information, modeling of the coked catalyst regeneration is produced