BR112015010500B1 - additives for reducing sox gas emissions in hydrocarbon fluid catalytic cracking units - Google Patents

Abstract

ADDITIVES TO REDUCE SOx GAS EMISSIONS IN HYDROCARBON FLUID CATALYTIC CRACKING UNITS. The present invention provides additives for reducing SOx emissions in fluid catalytic cracking units of hydrocarbons prepared from an alumina-type support, with a high surface area, at least 150 m 2 / g, and a high porous volume, at least 0.25 cm 3 / g, incorporating: calcium, in the form of calcium oxide in a concentration of at least 5%; and an oxirreduction promoting agent, in the form of its oxide, in the concentration range between 1 and 5% me.

Description

FIELD OF THE INVENTION

[001] The present invention deals with additives for the reduction of polluting gas emissions of the SOx type in hydrocarbon fluid catalytic cracking (FCC) units, more specifically to additives prepared from calcium oxides and an oxidation promoter dispersed in a high volume pore support.

BACKGROUND OF THE INVENTION

[002] The fluidized bed catalytic cracking (FCC) process stands out in a refinery for transforming heavy fractions of oil into products with high added value, notably gasoline. The FCC catalyst, composed of zeolite Y, active matrix of alumina, synthetic matrix of silica and inert matrix of kaolin, is the compound responsible for cracking the load and the yield of the products.

[003] The main components of the FCC industrial unit are the riser, reactor where the load cracking reactions occur, generating the products, and the regenerating vessel, where the spent catalyst is burned to eliminate coke and metallic contaminants deposited in its surface. After regeneration, the catalyst is reinjected into the riser for a new reaction cycle.

[004] During the burning of the coke, contaminant sulfur, originating from the cargo, is also oxidized, releasing SO2 and SO3 gases, hereinafter called SOx gases. The emission of SOx is potentially harmful to the environment and human health as it causes acid rain and the formation of particulate matter in the atmosphere. In Brazil and in the world, environmental regulatory entities impose restrictive norms for industrial and vehicular emissions of SOx.

[005] With this, it is critical to control emissions from an FCC unit, since this unit is the largest individual SO2 emitter in a refinery, contributing approximately 17% of the total emitted from the pollutant.

[006] A technique adopted to control SOx emissions consists of the physical mixing of additives to the FCC-based catalyst in the proportion of 0.5% to 3% by weight. Additives are specific catalytic systems for capturing SOx gases during the burning of spent catalyst, reducing the atmospheric emission of the contaminant.

[007] Commercial additives for reducing SOx emissions are constituted by magnesium oxide in the form of spinel or hydrotalcite. In spinels there are mixed oxides of MgO and AI2O3 with the MgAI2O4 structure, while hydrotalcites are magnesium and aluminum hydroxycarbonates belonging to the class of compounds called anionic clays, with lamellar structure and formula [Mg6AI2 (OH) 16] (CO3) .4H2O. An oxirreduction promoter is also necessary, preferably cerium oxide - CeO2, which is an active metallic phase impregnated to the support with the function of kinetically favoring the reactions involved in the process, such as the oxidation of SO2 to SO3.

[008] The mechanism of action of the additive involves two stages. First, in the regenerator at a temperature of approximately 710 ° C and with the presence of oxygen, the additive promotes the oxidation of SO2 to SO3 and the formation of magnesium sulfate, MgSO4, according to reactions 1.1 to 1.3: Reactions in the regenerator: S (coke) + O2—> SO2 (1.1) SO2 + O2 — ► SO3 (1.2) SO3 + MgO- »MgSO4 (1.3)

[009] Then, the sulphate formed follows up to the riser together with the regenerated catalyst. The risera presents a reducing environment due to H2 molecules and light hydrocarbons from the cracking of the cargo. In this condition, the sulfate must be reduced to H2S and MgO (reaction 1.4) so that the H2S is released and, in the presence of the other FCC products, conducted to the due treatment. The additive, in turn, becomes recovered to return to the regenerator and start a new sulfur capture and desorption cycle. MgO regeneration can also occur with SO2 release (reaction 1.5). Another possible mechanism is the formation of MgS sulfide in the riser (reaction 1.6) and its subsequent conversion to MgO in the rectification step (reaction 1.7): Reactions in the riser. MgSO4 + 4H2 -> MgO + H2S + 3H2O (1.4) MgSO4 + H2 - MgO + SO2 + H2O (1.5) MgSO4 + 4H2 - MgS + 4H2O (1.6) Reaction in the rectifier: MgS + H2O -> MgO + H2S (1.7)

[010] To comply with these premises, the additive must form a sulfate that is stable in the oxidizing conditions of the regenerator, but that is unstable under the reducing conditions of the riser. Calcium oxide binds more strongly to SO3 than MgO, so that replacing MgO with CaO would increase the efficiency of the additive to store SOx. In addition, replacing magnesium with calcium can reduce the final cost of the additive, since calcium oxide is found on the market at a lower cost compared to oxide magnesium.

[011] However, the use of CaO is strongly contraindicated by the literature, under the justification that the resulting calcium sulfate, precisely because it is very stable, does not decompose in the riser, drastically limiting the useful life of the additive. Commercial additives for use in FCC units do not contain calcium in their composition.

[012] The use of calcium oxide to treat SOx recorded in the literature concerns the minerals dolomite (CaCO3.MgCO3) and limestone (CaCO3), used as sulfur absorbers in plants that burn coal for energy production. In the past decades, precisely because of the stability of the reaction products and the low cost of the raw material, the spent absorbents could simply be discarded. However, due to more restrictive environmental standards, the additive regeneration step became necessary, in which the material used and treated with a reducing gas, such as hydrogen, methane or carbon monoxide, at temperatures above 1000 ° C, a condition does not exist in the FCC unit.

[013] US patent 4,529,502 explores the use of CaO supported on alumina as an additive for UFCC. In order to circumvent the problem of deactivating the additive, the patent describes the need to install an additional reactor, between the regenerator and the riser, precisely to decompose CaSO4 at high temperatures and the presence of reducing gas. This would make the SOx removal process very expensive.

[014] The patent application MX 2009004594A claims additives based on alkaline earth metals, including magnesium and calcium and transition series metals supported on alumina. However, calcium is not the main component of the additive. Oxides such as calcium and vanadium are impregnated on alumina together with magnesium oxide, with no further advantage of these compositions compared to that using mainly magnesium.

[015] US patent application 2008/0227625 describes additives for NOx reduction comprising an alkaline or alkaline earth metal (preferably calcium and / or manganese), phosphorus, and transition metals in a support. The preferred composition of the additive comprises: CaO (3 to 6% by mass), P2O5 (3 to 5% by mass), MOx (1 to 4% by mass), where M is a transition metal and ex varies with the state of oxidation of the metal, using alumina (85% to 93% by mass).

[016] In this case, the presence of phosphorus, more specifically phosphates, would facilitate the formation and reduction of alkaline or alkaline earth metal sulphates by forming highly dispersed surface coatings or monolayers of alkaline / alkaline earth metal phosphates on the alumina support , preventing the formation of alkaline earth metal spinel. Despite promoting the stabilization of alkali / alkaline earth metal sulphates, the presence of phosphorus in the formulation of the additive leads to inhibition of the capture of SO3 by calcium oxide, as can be seen by analyzing the examples presented.

[017] Thus, a catalytic system containing calcium as the main component is still unprecedented, where there is no need to incorporate other elements, such as magnesium, or specific crystalline structures (spinel), capable of reducing pollutant gas emissions. of the SOx type in hydrocarbon fluid catalytic cracking units.

SUMMARY OF THE INVENTION

[018] In petroleum refining, the control of SOx gas emissions in fluid catalytic cracking process units - FCC can be advantageously performed by mixing additives to the circulation catalyst inventory.

[019] Such additives comprise particles of calcium oxide and an oxidation-reducing agent, where calcium oxide acts as a sulfur-storage agent, such particles being highly dispersed, in the form of small crystallites, on the high volume support. of pores.

[020] The product obtained is highly efficient in capturing sulfur during the regeneration stage of spent FCC catalysts and is susceptible to the reduction of the sulfate particles absorbed on its surface under the conditions of the riser, guaranteeing the regeneration of the additive and a greater campaign time.

[021] Thus, the present invention provides additives prepared from an alumina-type support, with a high surface area, at least 150 m2 / g, and a high porous volume, at least 0.25 cm3 / g, having incorporated : a) calcium, in the form of calcium oxide in a concentration of at least 5%. b) An oxidation-reducing agent, in the form of its oxide, in the concentration range between 1 and 5% w / w.

[022] Mixing such an additive to the circulation catalyst inventory in an FCC unit provides control of polluting SOx emissions, maintaining the conversion levels and yield of the unit's products under fluid catalytic cracking conditions.

[023] Therefore, the invention deals with the use of additives in admixture to the circulation catalyst inventory in an FCC process, being applicable to fillers containing hydrocarbons; advantageously, the concentrations of SOx emissions in the effluent gas from the regenerator are controlled, providing the reduction of atmospheric pollutants in oil refining.

BRIEF DESCRIPTION OF THE FIGURES

[024] Figure 1 illustrates diffractograms of two samples: (1a) Gamma-alumina support; (1b) CA1V additive: 10% w / w CaO and 3% vanadium incorporated in gamma-alumina.

[025] Figure 2 illustrates the Raman spectra of two samples: (3a) Analytical grade reagent anhydrous calcium sulfate - CaSO4 PA, for comparison; (3b) CA1S: 10% w / w CaO incorporated in gamma-alumina and sulfated; (3c) CAV1S: 10% w / w CaO and 3% w / w vanadium incorporated in gamma-alumina and sulfated.

[026] Figure 3 illustrates the thermal reduction curves at the programmed temperature of three samples: (4a) CAV1S: 10% w / w CaO and 3% w / w vanadium incorporated in gamma-alumina and sulfated; (4b) CA1S: 10% w / w CaO incorporated in gamma-alumina and sulfated; (4c) MF1S: Physical mixture of 10% w / w CaO PA and 90% sulfated gamma-alumina.

DETAILED DESCRIPTION OF THE INVENTION

[027] Broadly speaking, the invention deals with additives applicable to the control of SOx emissions in the flue gas effluent from the fluid catalytic cracking process unit regenerator - FCC.

[028] Such additives consist of a high surface area support, of at least 150 m2 / g, and a high porous volume, of at least 0.25 cm3 / g, incorporating: calcium, in the form of calcium oxide , with a concentration of at least 5% and preferably 10%; and a redox promoter, in the form of its oxide, in the concentration range between 1 and 5% w / w.

[029] The high pore volume of the support is necessary to enable the high degree of dispersion of the particles of calcium oxides and the promoter of redox in it. The high dispersion of calcium and the redox promoter on the support allows the SO3 present in the regenerating vessel and the reducing gases present in the riser of FCC units to have greater accessibility to the sites containing the metals, which favors the extension of the reactions involved in the process . Consequently, the high pick-up factor (PUF) is achieved, that is, the molar ratio between captured SO3 and existing CaO and the necessary reduction of CaSO4 under the conditions existing in a fluid catalytic cracking unit riser.

[030] Among the porous high volume supports useful for the present invention we can mention: (i) gamma-alumina; (ii) high volume porous alumina-type catalysts containing an inert matrix. An example is the catalyst comprising 90% low crystallinity alumina and 10% kaolin, also tested in the present invention, called VCLA-kaolin 90:10.

[031] The crystallinity of alumina is defined in terms of the size of the crystal. Aluminas containing 4.5nm crystal size are considered to have low crystallinity. Crystal sizes of 7.5 nm and 15 nm, for example, refer to medium and high crystallinity aluminas, respectively.

[032] In the case of gamma-alumina, this is prepared by calcining hydrated aluminum hydroxide (Boehmita) at 500-650 ° C, preferably at 600 ° C, for up to 5 hours, preferably one hour, in the presence of air. Alumina is obtained with a high surface area, approximately 200 m2 / g and a high porous volume, approximately 0.35 cm3 / g.

[033] The VCLA-kaolin support 90:10 is prepared from the peptization of alumina and the subsequent addition of kaolin. The matrix thus obtained has a surface area of approximately 290 m2 / g and pore volume of approximately 0.35 cm3 / g.

[034] For the preparation of additives, an active phase comprising calcium is first incorporated into the support, preferably by the pore volume impregnation method, in the form of their respective salts, such as sulfate, chloride or nitrate, preferably nitrate , followed by drying at 100 ° C for 1 to 3 hours, preferably one hour.

[035] Next, an oxidation-promoting metal, such as iron, copper, zinc, chromium, manganese and, in particular, vanadium, preferably 3% w / w vanadium, is incorporated.

[036] The transition metal incorporation is preferably carried out by the pore volume impregnation method, in the form of their respective salts, such as sulfate, chloride or nitrate, preferably nitrate.

[037] For the impregnation of vanadium, ammonium metavanadate and vanadyl oxalate are the salts preferably used. With these reagents, vanadium can be incorporated in two ways: (i) pore volume impregnation with aqueous vanadyl oxalate solution, followed by drying at 100 ° C for 1 to 3 hours, preferably one hour; (ii) wet spot impregnation with aqueous ammonium metavanadate solution conducted at 80 - 100 ° C for 1 to 5 hours, preferably 4 hours, followed by evaporation of excess solvent and drying at 100 ° C for 1 to 3 hours, preferably one hour.

[038] Then, a calcination step between 500 and 650 ° C, preferably at 500 ° C, for up to 5 hours, preferably 3 hours, in the presence of air, allows the fixation of the incorporated metals, which are homogeneously dispersed throughout the support particle.

[039] The presence of the redox promoter, notably vanadium, is justified for two reasons. First, in the regenerating vessel, the redox promoter catalyses the oxidation of SO2 to SO3 so that SO3 is captured by CaO to form CaSO4. The presence of the promoter becomes indispensable because the generation of CaSO4 necessarily passes through the SO3 reaction intermediate and, however, the thermodynamic conditions of the regenerating vessel shift the reaction equilibrium to the predominance of SO2.

[040] Secondly, in the riser, the redox promoter acts in the CaSO4 reduction step, leading to an alternative reaction mechanism that results in the reduction of the sulfate reduction temperature and, consequently, in the highest percentage of particles reduced to lower temperatures.

[041] The mechanism of action of the promoter in reducing CaSO4 is not well known. It is speculated that the promoter acts, either participating effectively in the reduction step by forming an unstable intermediary under the conditions of the riser, or inducing the formation of an alternative structure for the supported CaSO4 that is more easily reduced.

[042] Thus, the results show that the presence of vanadium enables the reduction of sulfated CaO layers at a temperature of 530 ° C. EXAMPLES The following examples were developed based on the following considerations: a) Examples 1 and 2 illustrate the chemical and textural properties of the additives object of the present invention, indicating their properties; b) Examples 3 and 4 are results of tests on a laboratory scale that prove the performance of the additives to capture and desorb sulfur according to their composition; c) Example 5 is the result of tests on a pilot scale that proves the performance of additives to capture and desorb sulfur under the conditions of application in an FCC process; d) Example 6 illustrates that the presence of the additives developed in this invention does not interfere with the performance of the final catalytic system. e) Example 7 illustrates that the additives of the present invention meet the requirements for physical properties.

EXAMPLE 1

[043] This example illustrates the characterization of additives comprising calcium and vanadium supported on Y-AI2O3. Two diffractograms are illustrated: (1a): diffractogram of the gamma-alumina support; (1b): diffractogram of the additive called CA1V, containing 10% w / w calcium oxide (CaO) and 3% w / w vanadium incorporated in gamma-alumina by the procedure previously described.

[044] The X-ray diffractogram of the CA1V additive overlaps with the diffractogram of the Y-AI2O3 support (Fig. 1), revealing the absence of referring crystalline CaO phases detectable by XRD. In this concentration, vanadium forms polymeric layers of vanadate (VOx) n, which are amorphous compared to XRD.

[045] Thus, the data obtained by X-ray diffraction confirm that the samples have a high degree of spreading of the particles of calcium and vanadium on the support.

[046] Example 1 also illustrates the RAMAN spectra of samples so named: (3a) Analytical grade reagent anhydrous calcium sulfate (CaSO4 PA), for comparison; (3b) CA1S: precursor containing 10% w / w calcium oxide incorporated in gamma-alumina and sulfated; (3c) CA1VS: additive containing 10% w / w calcium oxide and 3% w / w vanadium incorporated in gamma-alumina and sulfated. The sulfation reaction of additives and precursors in a fixed bed is described in detail in Example 2.

[047] Analysis by Raman spectroscopy (Fig. 2) reveals that the peaks of the sulfated precursor CA1S overlap perfectly with the spectrum of the analytical grade anhydrous CaSO4 reagent, which confirms the achievement of supported CaSO4 particles. The spectrum of the sulfated additive CAV1S also confirms the formation of these particles and, in addition to these peaks, the banded envelope centered at 890 cm'1 is observed, which refers to vanadium, which does not undergo sulfation.

EXAMPLE 2

[048] This example illustrates the ease of reduction of sulfated compounds formed in the additive object of the present invention.

[049] The following samples were subjected to the sulfation reaction described below: CA1 (10% w / w calcium oxide incorporated in gamma-alumina); CA1V (10% w / w calcium oxide and 3% w / w vanadium incorporated in gamma-alumina); MF1 (physical mixture containing 10% w / w reagent calcium oxide PA and 90% w / w gamma-alumina).

[050] These were sulfated in a simulated laboratory process. The sulfation process of the samples was carried out in a fixed bed quartz reactor with a quadrupolar mass spectrometer coupled to the reactor output.

[051] Initially, the temperature was raised to 725 ° C at a rate of 10 ° C / min under helium flow, at a flow rate of 60 mL / min and thus maintained for 30 minutes.

[052] In the second stage, the samples, also at 725 ° C, were subjected to a gas mixture of SO2 / O2 in helium containing 0.5% v / v SO2 and 2% v / v O2. The reaction continued until the samples were saturated by gas, which was observed by the stabilization of the SO2 signal in the mass spectrometer. The samples CA1, CA1V and MF1 after the sulfation stage were named as follows, respectively: CA1S, CA1VS and MF1S. The physical mixture was analyzed for comparison.

[053] The reduction tests at the programmed temperature (Fig. 3) of the samples CA1S, CA1VS and MF1S show that obtaining CaSO4 particles anchored in a support with a high surface area already results in a significant decrease in their reduction temperature in comparison at the temperature of the mass CaSO4 in the physical mixture, the reduction of the temperature being drastic when the presence of vanadium, as observed in CA1VS. The peak observed in MF1 at a temperature of approximately 650 ° C refers to the sulphation of gamma-alumina.

[054] From the characterization tests and reduction test, it is concluded that, in fact, the supported particles of calcium compound are in the form of highly dispersed CaO. It is also concluded that the CaSO4 formed through sulfation can be reduced at temperatures significantly lower than the mass CaSO4.

EXAMPLE 3

[055] This example illustrates the performance of the additives object of the present invention in function of analysis by thermogravimetry (TGA).

[056] The functioning of the additives will be illustrated both for the capture of SOx and for the release of absorbed SOx.

[057] In addition to samples CA1 and CA1V, data from the following samples are illustrated: CA2 (20% w / w CaO incorporated in gamma-alumina); CA2V (20% w / w CaO and 3% w / w V incorporated in gamma-alumina); CA1c (10% w / w CaO incorporated in VCLA-kaolin); CA2c (20% w / w CaO incorporated in VCLA-kaolin); CA1Vc (10% w / w CaO and 3% w / w V incorporated in VCLA-kaolin); CA2Vc (20% w / w CaO and 3% w / w V incorporated in VCLA-kaolin).

[058] In the SO3 capture and desorption test, the sample initially undergoes pre-treatment in situ, when the temperature is raised to 725 ° C in an inert atmosphere, a condition maintained for 30 minutes. Then, still at 725 ° C, the inert gas flow is exchanged for the oxidizing mixture in helium containing 0.5% v / v SO2 and 2% v / v O2, which is maintained for 45 minutes, when mass gain occurs due to the capture of SO3 and the formation of supported CaSO4 particles. Then, the sulfated sample is subjected to the reduction process, when the temperature is reduced from 725 ° C to 530 ° C and the oxidizing mixture is exchanged for the mixture of 5% v / v H2 in helium. This condition would simulate the step of reducing the riser of an FCC unit. The flow of H2 / He is maintained for 45 minutes. The loss of mass in this condition occurs due to the desorption of SO3, caused by the reduction of part of the absorbed sulfate.

[059] Then, the percentage of SO3 desorbed in relation to the mass of SO3 absorbed, which is related to the reducibility of the additive, is calculated.

[060] Vanadium redox may also cause mass gain and / or loss. The contribution of vanadium was evaluated by subjecting the additives to oxidation with the 5% v / v O2 mixture in He and then to the reduction step. Mass gain and / or loss of 0.1% or 0.2% was observed in some additives and these numbers were deducted from the respective capture and desorption values of SO3 of the additives.

[061] The corrected data of SO3 captured and desorbed by the samples are found in Table 1. TABLE 1

[062] In terms of capture, we can clearly see in Table 1 that the samples of supported calcium CA1 and CA2 have values of factor pick-up approximating the physical mixture MF1, whereas the samples according to the present invention, CA1V and CA2V , are better at absorbing SO3, resulting in a pick-up factor of approximately 0.80. A similar conclusion is reached by observing the samples prepared with the VCLA-kaolin support: the sample pairs CA1c and CA2c have pick-up factors lower than the respective samples with vanadium, CA1Vc and CA2Vc. The data prove the highest susceptibility to capture and, ultimately, the highest production of SO3 when vanadium is present. The promoter also contributes to the higher capture speed of SO3 by the additive.

[063] Table 1 also compares the additives in terms of ease of reduction, that is, ease of desorbing SO3 at 530 ° C. The ease of reducing samples to 530 ° C is not observed for precursors without vanadium, nor for the physical mixture. Vanadium samples, however, show mass losses of 7.6% to 29% in relation to the mass initially absorbed. Thus, the results show that the presence of vanadium enables the reduction of sulfated CaO layers at a temperature of 530 ° C.

EXAMPLE 4

[064] In order to demonstrate the influence of the pore volume of the support used in the additives object of the present invention, additives were prepared with the nominal concentrations of CaO and V of 20% and 3%, respectively, using, however, , as support, different equilibrium catalysts (e-cat). Equilibrium catalyst is the representative sample of the catalyst circulating in the FCC unit, composed of particles of different ages due to the frequent removal of a fraction of the spent catalyst and replacement of virgin catalyst fraction. The older the particle in the FCC unit, the higher the content of contaminating metals deposited on it and the lower its remaining catalytic activity. That is, for Example 4, a support containing low crystallinity alumina and kaolin was used in its composition, but with a low pore volume.

[065] Table 2 shows the PUF values and the percentage of CaSO4 reduction at 530 ° C, determined by thermogravimetry, of the equilibrium catalysts and samples containing calcium supported in the respective e-cats. Comparing these data with Table 1, it is clearly noted that the pick-up values are significantly lower than those obtained with high porous volume supports. The low pore volume of e-cats also provided very low values for reducing CaSO4 at 530 ° C.

[066] Although e-cats have relatively high surface areas for this preparation, the low pore volume causes the deposition of larger particles of CaO and CaSO4, which reduces the accessibility of gases to their sites and, consequently, reduces the extent of reactions involved. TABLE 2

EXAMPLE 5

[067] This example illustrates the performance of the additives object of the present invention in a DCR pilot unit - Davison Circulating Riser, licensed by W. R. GRACE & Co. In the pilot scale test, the additives CA1V and CA1Vc were evaluated with a real load, typical of Brazilian oil fields, containing 2.9% sulfur. The commercial additive used as a reference was KDSOx, sold by ALBEMARLE, containing transition metals and approximately 50% magnesium oxide. The rest of the test conditions are described below: Reaction temperature of the riser.530 ° C Load temperature: 120 ° C Regenerator temperature: 720 ° C Excess O2: 2% Approximate run time per additive: 2.5 hours

[068] At the beginning of the test, 1800g of equilibrium catalyst circulated through the unit until the level of SO2 emitted by the load stabilized. Then, a mixture was prepared containing a small amount of additive and the necessary mass of the equilibration catalyst to obtain a total of 200 grams. This mixture was then injected, totaling 2000 grams of catalyst circulating in the unit. The amount of SO2 absorbed was calculated from the area of the figure formed by the time elapsed between the time of injection of the additive and the restoration of the level of SO2 after injection. The life cycle of the additive was also determined, which corresponds to the period until the SO2 level returns to the initial value and the pick-up factor, calculated, in this test, by the relationship between the amount of SO2 absorbed with the additive dose. used in the test. In addition, due to the different levels of active metals (Mg and Ca) in the additives, the pick-up metal factor (PUF / m) was used, normalizing the absorbed SO2 value based on the mass of active metal (Mg or Ca) present in the additive dose.

As vantagens do uso dos aditivos ficam bastante evidentes: _ Os aditivos CA1V e CA1Vc possuem tempos de vida útil significativamente superiores ao KDSOx, o que se deve à reducibilidade das partículas suportadas de CaSO4. Principalmente, a presente invenção detém atividade residual para a captura de SOx, o que reduz o percentual de aditivo a ser reposto pelo refinador. _ Considerando-se o pick-up factormetálico, CA1V e CA1Vc possuem desempenhos aproximadamente três vezes superiores ao aditivo comercial. Isto significa que, mesmo tendo teor de metal (cálcio) três vezes menor que o KDSOx (magnésio), estes aditivos deverão ter desempenhos similares em uma unidade de FCC.[069] The data regarding the evaluations in a pilot unit are shown in Table 3. TABLE 3

The advantages of using the additives are quite evident: _ The CA1V and CA1Vc additives have a significantly longer service life than KDSOx, which is due to the reducibility of the supported CaSO4 particles. Mainly, the present invention has residual activity for the capture of SOx, which reduces the percentage of additive to be replaced by the refiner. _ Considering the metallic factor pickup, CA1V and CA1Vc perform approximately three times higher than the commercial additive. This means that, even though the metal (calcium) content is three times lower than KDSOx (magnesium), these additives should have similar performances in an FCC unit.

[070] In this way, the pilot scale test proves the reducibility of the CaSO4 particles when well dispersed in a support of high specific area, such as the alumina range and the VCLA-kaolin catalyst. 90:10. The viability of using the additive obtained by the present invention for SOx capture in FCC units is proven. It shows its excellent performance compared to the commercial additive.

EXAMPLE 6

[071] This example illustrates the performance of the object additives of the present invention in relation to their catalytic activity.

[072] In order to verify the possible impact of the additive of the present invention in relation to the conversion and selectivity of the load, the catalytic evaluation tests were performed in the ACE unit. CA1V and KDSOx additives were tested in the virgin state, that is, without suffering any contamination or deactivation and also previously deactivated. The deactivation was carried out in a tubular oven, with a fixed bed reactor, at a temperature of 788 ° C for 5 hours and with 100% water vapor.

[073] Each additive was mixed with the reference equilibrium catalyst, obtaining 2% w / w of the first. All samples were evaluated in duplicate keeping the catalyst / oil ratio equal to five. Diesel fuel typical of Brazilian oil fields was used and the reaction temperature was 535 ° C. The data were compared with the equilibrium catalyst without additive.

[074] It is concluded, from the data in Table 4, that the additive CA1V does not significantly impact the conversion, nor the selectivity of the load under the test conditions.

[075] Additionally, similar performance was observed with the catalytic system containing the commercial additive KDSOx. TABLE 4

EXAMPLE 7

[076] The additives CA1V and CA1Vc were subjected to the friction resistance test in FCC catalyst by air injection in a home-made unit.

[077] The control of the friction index is important to maintain the proper fluidization of the catalyst in the riser and reduce the emission of particulates. The values obtained for the additives of this invention, in addition to meeting the specification, are better for certain commercial additives. Table 5 shows the friction index values of the additives of this invention and of the commercial additives, KDSOx, LoSOx-PB and SuperSOxgetter, the latter marketed by INTERCAT. TABLE 5

Claims (12)

1. ADDITIVES FOR REDUCING SOx GAS EMISSIONS IN HYDROCARBON FLUID CATALYTIC CRACKING UNITS, characterized by comprising a support with a high surface area of at least 150 m2 / g and a high porous volume of at least 0.25 cm3 / g, having incorporated: calcium, in the form of calcium oxide, with a concentration of at least 5% by weight and preferably 10% by weight; and a redox promoter, in the form of its oxide, in the concentration range between 1 and 5% w / w. 2. ADDITIVES according to claim 1, characterized in that the concentration of calcium oxide in the additive is preferably 10% by weight. 3. ADDITIVES, according to claim 1, characterized in that the high porous volume support is chosen from: (i) gamma-alumina; (ii) high porous volume catalysts of the alumina type, containing an inert matrix. 4. ADDITIVES, according to claim 1, characterized in that the calcium is incorporated into the support by the pore volume impregnation method, in the form of a salt, chosen from a salt of: sulfate, chloride or nitrate, followed by drying 100 ° C for 1 to 3 hours. ADDITIVES according to either of Claims 1 and 4, characterized in that the drying period is preferably 1 hour. 6. ADDITIVES, according to claim 1, characterized in that the redox promoter is chosen from: iron, copper, zinc, chromium, manganese and vanadium. 7. ADDITIVES according to either of claims 1 or 6, characterized in that the vanadium oxidoreduction promoter is in a concentration of 3% w / w. 8. ADDITIVES according to either of claims 1 or 6, characterized in that the incorporation of the oxidation promoter obtained by the pore volume impregnation method, in the form of a salt, chosen from a salt of: sulfate, chloride or nitrate. 9. ADDITIVES according to either of Claims 1 or 6, characterized in that the incorporation of the vanadium oxidoreduction promoter is obtained by the method of pore volume impregnation with aqueous vanadyl oxalate solution or wet spot impregnation with aqueous solution of ammonium metavanadate. 10. ADDITIVES, according to claim 1, characterized in that after the steps involving the incorporation of calcium and an oxidation reduction promoter, a calcination step is followed at temperatures between 500 and 650 ° C, for up to 5 hours, in presence of air. 11. ADDITIVES according to either of Claims 1 and 10, characterized in that the calcination step is preferably at 500 ° C. 12. ADDITIVES according to either of Claims 1 and 10, characterized in that the calcination step lasts for 3 hours.

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