MXPA01013138A - Procedure for obtaining perovskite structure materials, for sulphur oxide emulsions reduction. - Google Patents

Abstract

The present invention relates with the procedure for obtaining perovskite structure materials, for the emulsions reduction of sulphur oxides SOx in the catalytic disintegration units, FCC and/or fixed sources. These solids consist in Ti, Sr, Co, Mn Ce oxides with perovskite-type structure gathered in two series as follows: Ti0.6Sr0.4Co1-XMnX and Ce0.6Sr0.4Co1-XMnX, containing different concentrations of each one of these elements varying from X = 0 up to 1, which are obtained after mixing the aqueous solutions of metallic nitrates and ammonium hydroxides with a PH between 1-4, to obtain a suspension, giving it an average size particle of between 1 -50°.m. The obtained precipitates are homogenized by means of continuous agitation, between 5000-1 0000 r.p.m., during 0.5-10.0 hour. Finally, the materials are filtrated, dryed and calcinated between 600-1200°C in air flow between 2.0-8.0 lt/hour, during 2-20 hours, forming mesh particles of bewteen 80-300 °m, apropriated for the fluidized bed.

Description

PROCEDURE FOR THE OBTAINING OF PEROVSKITA STRUCTURE MATERIALS TO REDUCE THE EMISSIONS OF SULFUR OXIDE.

DESCRIPTION TECHNICAL FIELD OF THE INVENTION The present invention relates to the process for obtaining mixed oxides of perovskite structure which function as sulfur oxides SOx emission reducing materials in the catalytic disintegration units, FCC and / or fixed sources.

These solids consist of oxides of Ti, Sr, Co, Mn, Ce, with structure pcrovskita type grouped in two series as follows: Ce06Sr04Co, .xMnx and Ti () (, Sr (HCo, .sn containing different concentrations of each of these elements varying from X = 0 to 1, which are obtained after mixing the aqueous solutions of metal nitrates with a pH between 1 - 4 and ammonium hydroxide at a pH between 8 - 12, to obtain a suspension , giving it an average particle size between l-50μm The obtained precipitates are homogenized by continuous agitation, between 5000-10000 rpm, during 0.5-10.0 hours Finally the materials are filtered, dried and calcined between 600-1200 ° C in flow of air between 2.0-8.0 lt / hour, during 2-20 hours, forming particles of mesh between 80-300 μm, appropriate for the fluidized bed.

BACKGROUND OF THE INVENTION This invention relates to a process for obtaining materials of perovskite structure applied to the reduction of emissions to the atmosphere of sulfur oxides, in refining and petrochemical processes and in fixed sources. In a specific appreciation, the invention is used in the process for catalytic cracking of the hydrocarbon feed containing sulfides so that a reduction in the amount of sulfur oxides emitted from the regenerator zone of a catalytic cracking unit is effected. hydrocarbons and the catalyst composition of such a process.

The process of the present invention is characterized by including elements of oxidation and rapid reduction in the components which increases its efficiency in the process.

The material obtained is used as an additive and / or catalyst for the removal or reduction of SOx sulfur oxides emissions in the FCC catalytic disintegration units, thus contributing to abate the contamination by sulfur compounds produced in these units.

Typically, the catalytic cracking of hydrocarbons takes place in the reduction zone under hydrocarbon cracking conditions, producing less hydrocarbon products and causing carbonaceous material (coke) to be deposited in the catalyst. Additionally, some sulfur compounds are present in the hydrocarbon feed and are also deposited as coke components in the catalyst. It has been reported that approximately 50% of the sulfur fed is converted to H2S in the FCC reactor, 40% remains in the liquid product and about 10% is deposited in the catalyst. This quantity varies with the feeding time, the hydrocarbon recycling speed, the speed of the evicted steam, the type of catalyst, reactor temperatures, etc.

The sulfur content deposited in the coke usually deactivates the catalyst. The cracking catalyst is continuously regenerated, by combustion with oxygen in the regeneration zone, at low levels of coke, typically below 0.4% by weight, operating satisfactorily when it is recycled to the reactor. In the regenerator zone, in smaller • proportion of sulfur, together with carbon and hydrogen, which is deposited in the catalyst, is oxidized and eliminated in the form of sulfuric oxide, for example SO2, S03 and from the same mixture together with considerable amounts of CO, CO, and H2O. 15 Recent research has focused on the reduction of sulfur oxide emissions from the regeneration zone of catalytic cracking units for hydrocarbons. One is the technique of the circulating mixture of more metal oxides capable of associating with sulfur oxides with the existence of cracking catalysts in the regeneration zone. When the content of particles associated with sulfur oxide are then circulated to the atmosphere When the cracked zone is reduced, the associated sulfur compounds are released as sulfurized gaseous material, such as hydrogen sulfide, which is released with the products from the cracking zone in a form that can be easily handled, for example in the plant ( Claus) of sulfur recovery from the Refining system.

The metal oxide is regenerated to an active form and is associated with more compounds with sulfur oxides during the regeneration cycle.

The US patent. No. 4,472,267 presents a summary of the first published work with reduction of sulfur oxides emissions from catalytic cracking units.

The SOx reduction mechanism of fluid-type catalytic cracking units (FCCU) is produced with a metal oxide or metal oxide types that can react with SOx to form the corresponding sulfate. In the regenerator, the sulfur carrier coke is burned giving SO2, CO, CO2 and water. A part of the SO2, in the presence of excess oxygen, burns even more to form SO3 SO3 may exist in the flue gas or react with the catalyst or with a metal oxide to form the metal sulfate. The reaction to metal sulfate can be considered as the "capture reaction" of the SOx, when moving to the reactor, the metal sulphate will react with the hydrogen to form either metal sulfide and water or metal oxide, H2S and water. In the depojadora, the metallic sulphide reacts with the water vapor to form metal oxide and H2S. Finally, the sulfur leaves the system in the form of H2S in the product stream instead of SOx in the flue gas. Therefore, the control of SOx emissions is of great importance for refineries.

Both the absolute sulfur level of the charge and the types of sulfur compounds in it will affect SOx emissions. As the percentage (by weight) of sulfur in the cargo increases, so will the potential SOx emissions. Another important parameter of the load that affects SOx capture is the type of sulfur present in the load. The sulfur associated with the paraffins tends to disintegrate to form H2S thus leaving the system with the products of the reactor. However, the sulfur associated with the aromatic chains tends to be deposited as coke; the burning of coke, carrying sulfur in the regenerator, tends to increase SOx emissions. Therefore, to determine the effect of the higher sulfur content in the charge, it is necessary to know the types of sulfur compounds present. The problem gets worse every time when the process loads add more and more heavy crude (vacuum residue, raw Mayan type) The following reaction that takes place in the regenerator: SO2 + Vi O2 = S03, is produced with an excess of oxygen, the oxygen in excess of the stoichiometric amount necessary to form SO3 will cause the indicated reaction to move to the right forming S03, which will react with the metal oxide, in the following way: SrO + SO3 = SrSO4, This reaction is called "capture". The greater the number of strontium or other metal sites available to capture SOx, the greater the reduction in SOx emissions.

The oxidation promoters of CO also promote the oxidation of the SO, to SO3 increasing the content of CO promoters SOx emissions are reduced.

A matrix rich in large surface metal oxides improves the SOx capture reaction. The SO3 captured in the regenerator is released into the reactor as H, S. The net result of these characteristics of the additive is a high level of reduction of sulfur emissions.

According to the above, what is obtained is a material that contains high density of metal sites that react with SOx, oxidize SO2 to SO3, to form the metal sulfate and also promote the total combustion of CO to CO2.

In the removal of SOx from the emissions of the catalytic cracking process, magnesium spinels with cerium and vanadium have been commonly used as described .1. S. Yoo and Bhattacharyya, in Applied. Catalysis B: Environmental 1, 169 (1992) and I & EC Res., 30, 1444 (1991).

The SOx absorption occurs by the formation of the metal sulphate with SO, by oxidation of SO, in O2, published by M. Y. Sultanov in Kinet. KataL, 28 (1), 236 (1987) Another type of mixed oxides such as perovskites have been used for the removal of SOx, as mentioned by .1. S. Yoo, C. A. Radlowski and J. A. Karch. ACS, Division o f fuel chemistry, Preprints V 39 No. 1, 238 (1994), for its structural analogy and its physicochemical properties, especially in the stabilization of unusual oxidation states and in particular the mobility of oxygen ions.

Perovskites have been discovered as cracking catalysts. The US Patent 4,055,513, mentions that the ideal crystalline perovskite structure is defined by the empirical formula of ABO3, in which A and B are cations of different metals and that cation A is coordinating at 20 oxygen atoms, while cation B occupies sites octahedral and is coordinated by 6 oxygen atoms. For example, the LaMnO compound has the ideal perovskite structure, while other materials such as La0 7Sr03MnO3 have a variety of other structures, however they are classified as perovskite type components.

The mineral perovskite (CaTiO,) has a crystalline structure at elevated temperatures. An extensive discussion of perovskite oxides related to oxide-reduction catalysts has been presented by R.J.H. Voorhoeve in chapter 5 of "Advances Materials in Catalysts", J.J. Buraton and R.L. Garten, Academic press (1977). In addition, the properties of perovskite type catalysts have been reported by Nakamura et al. In "Bulletin of •" Chemical Society of Japan "vol 55 (1982) on pages 394-399, and in the" Journal of Catalysis ", 10 vol 83 (1983) on pages 151-159, and by Happel et al. "Ind. Eng. Chem. Product Research Development ", vol 14 (1975) on pages 164-168 The preparation of the catalysts has been discussed by Johnson et al in" ceramic Bulletin ", vol 56 (1977) on pages 785 -788, and in US Patent No. 4,055,513, Nakamura et al., Investigated the oxidation-reduction properties of cobalt lanthanum, replacing it with a lower proportion of strontium, in the oxidation of carbon monoxide and the reduction of nitrogen oxides. , as exhaust gases of the automobile, and extending its studies including the oxidation of methanol and propane Happle et al., use lanthanum titanium for the reduction of SO ,, to elemental sulfur, with carbon monoxide Johnson et al. manganese, both substituted with strontium or lead, impregnated in ceramic supports by homogeneous distribution and elevated activity for oxidation of CO. In US Patent No. 4,055,513 the supported perovskites that were prepared on the sopo rte comprised a metal oxide, such as alumina having a surface layer of a spinel.

Cobalt perovskite has been suggested as a substitute for noble metals in electroreactions and as catalysts for use in the oxidation of CO in automobile exhaust gases, as well as for NOx reduction. Such catalysts have found little use in automotive systems because of their deactivation by sulfur oxides.

It is of great importance to use materials to reduce atmospheric emissions of sulfur oxides, in particular hydrocarbon conversion operations.

DETAILED DESCRIPTION OF THE INVENTION The process of the preparation of the solids and determination of the sulfur oxides uptake capacity, with the materials object of the present invention, for obtaining an additive reducing emissions of SOx and NOx type, using mixed oxides of perovskite structure , in FCC catalytic disintegration units and / or fixed sources, carried out in accordance with the following steps, which do not limit the scope of the invention.

Several very efficient techniques have been used in the preparation of fine oxide particles, in order to obtain uniformly dispersed mixed oxides. In the present invention, the coprecipitation method was used to prepare the systems of CeSrCo, .xMn, and T¡SrCo, _NlVf ?? x, where X = 0.0, 0.1, 0.3, 0.5, 0.7 and 1.0.

The catalysts were precipitated from aqueous nitrate solutions of Ce, Sr, Co, La and Mn and an ethanolic solution of titanium ethoxide. The pH in the mixture of the metal solutions in each of the systems ranges from 1 to 4. A solution of ammonium hydroxide was adhered to the mixture of the stirring metal solutions, to obtain a precipitate after 2 hours. A color change and an exothermicity was observed; as well as the pH change between 8 and 12 in all systems. The obtained precipitates are homogenized by continuous agitation, between 5000-10000 rpm, during 0.5-10.0 hours and finally the materials are filtered dried and calcined between 600-1000 ° C in air flow between 2.0-8.0 1 / hours, for 2- 20 hours., Forming mesh particles between 100-300 μm, suitable for the fluidized bed.

The phases present in the solids were analyzed by X-ray diffraction; The morphology and a semiquantitative elemental analysis was carried out by dispersive energy analysis. Sc dctemiino its textural properties by adsorption of N2 to 77K.

The SO adsorption in the catalyst is measured with a gravimetric thermal analyzer (TGA), equipped with a manual set of valves to have a process of oxidation-reduction, adsorption and cleaning of the system. The test was carried out with the following procedure: 1) 10 to 100 mg of catalyst were placed in a platinum basket on the TGA scale. 2) the sample is cleaned and stabilized, heating at 20 ° C / min. up to 650 ° C in air atmosphere, which flows at 20 cc / min. 3) the adsorption of SO begins, with a mixture of SO gases, (1%) in O, / N, (20/75), a mixture that is introduced at 20 cc / min. 4) Weight gain occurs until a maximum adsorption is reached, which may take, depending on the sample, between 30 and 120 min. It is then assumed that the weight gained is due to the SO3 adsorbed by the metals to form the respective metal sulfate, thus the percentage of sulfur trapped by the catalyst can be calculated. 5) After the SO adsorption cycle, the reduction of the resulting sulphate is carried out between lOO and 800 ° C. Said reduction is carried out with H ,, applying a flow of 20 cc / min, until the adsorbed SOx is completely removed (above 95%), this process lasts approximately from 10 to 200 min.

The catalyst is reactivated and a second SOx adsorption cycle can be carried out under the same conditions, as well as the reduction, thus forming a sequence of adsorption-reduction cycles. In this way the stability of the catalyst is determined by repeating the adsorption-reduction-oxidation cycles. • l l EXAMPLES Some practical examples related to the described procedure are described below, without thereby limiting the scope of the present invention.

EXAMPLE 1 To 14.52 grams of cerium nitrate in solution with 100 ml of water were mixed with 4.75 grams of strontium nitrate, also dissolved in 40 ml of water, to the mixture sc added 17.34 grams of cobalt nitrate in solution with 140 ml of water . The salts in solution were precipitated with a 0.2 molar solution of sodium hydroxide. After filtering and washing with several volumes of water, the solids were homogenized by continuous stirring, between 5000-10000 rpm, for 0.5-10.0 hours. For the formation of mixed oxides, the materials are filtered dried and calcined between 600-1000 ° C with air flow between 2.0-8.0 1 / h, for 2-20 hours, forming mesh particles between 100-300 μm, suitable for the fluid bed.

EXAMPLE 2 In the same way as explained in Example 1, the samples of the series CeSrCo, .xMnx were prepared with values of X between 0 and 1. Table 1 indicates the concentration of each of the precursor salts.

EXAMPLE 3 Similar to Example 1, the preparation of the series TiSrCo, _xMnx with X values between 0 and 1 was carried out, as indicated in Table 2.

EXAMPLE 4 According to the X-ray diffraction analysis, the solids are characterized by being composed of mixed oxides of SrCoO2 8, SrMnO, g, MnTiO ,, SrTiO, and Co, TiO4, accompanied by monometallic oxides of Mn3O4, Co3O4, CeO , and present a specific area between 6 and 140 m2 / g.

EXAMPLE 5 An analysis by scanning electron microscopy showed the arrangement and concentration of the metallic elements on the surface of the solids. Analysis by Electron Dispersion Spectroscopy (EDS) showed that the surface is composed in higher concentration of Sr, Co, and Mn in the most active samples, while in the series containing Ce, it predominates over the surface. It is assumed that a high surface metal dispersion favors the formation of the corresponding metal sulfates.

EXAMPLE 6 Table 3 presents the measure of effectiveness of the samples in Adsorption Desorption of SOx • 5 of the series Ce06Sr04C? | .xMn.

This table shows the maximum of total adsorption, being this between 0.3 and 0.7 of the value of X, observing a maximum of adsorption speed in 0.5. 10 The materials present SOx adsorption above 50%, similar to an industrial reference catalyst, used in the reduction of SOx in FCC units, but with an increase of around 30% in the speed of adsorption. 15 EXAMPLE 7 The importance of the application of these compounds is their ability to be reduced in the presence of a reducing agent and at relatively low temperatures. Calculated the speed of • Reduction in the initial 10 minutes of the start of the reduction to 550 ° C, this is higher than that of the reference industrial catalyst. As in adsorption, Table 4 shows a maximum reduction in the value of X = 0.3, with a factor of 2.3 being times more than the commercial reference. 25 EXAMPLE 8 Similar to Example 6, the total adsorption and adsorption rate were measured with the series Ti0 6Sr04Co1.xMnx finding a maximum total adsorption of 0.5, as well as the adsorption rate, as shown in Table 5. An increase is presented close to 100% in the adsorption speed with respect to the commercial additive EXAMPLE 9 In a manner similar to that of Example 7, the increase in the reduction speed is 2.8 times greater with respect to the reference solid. as seen in table 6.

Table 1. Quantity in grams of each of the salts in the catalysts. Catalyst CcHNO ^ óHjO Sr (N03) 2 Co (N01) 2 »6H20 Mn (N03) 2-6H, 0 NaOH Ceo.6Sro.4Co 1.0 14.52 4.75 17.34 0.00 11.90 Ceo.6Sro.4Coo.9Mn.] 14.52 4.75 15.61 1.65 11.90 Ceo.6Sro.4Coo.7Mn .3 14.52 4.75 12.14 4.94 11.90 Ceo.6Sro.4Coo.5Mno.5 14.52 4.75 8.67 8.23 11.90 Ceo Sro.4Coo.3Mno.7 14.52 4.75 5.20 11.52 11.90 Ceo.6Sro.4MiM.o 14.52 4.75 0.00 16.45 11.90 Table 2. Quantity in grams of each of the salts in the system. System Ti (OC2H5) 4 Sr (N03) 2 Co (N? 3) 2 »6H2? Mp (N03) 2 »H20 NaOH t'0.6Sro.4co? .o 8.22 5.15 15.85 0.00 11.04 Ti? .6Sr0.4Coo.9Mn.? 8.22 5.15 14.27 1.53 11.04 Ti? .6Sro.4Coo.7Mno.3 8.22 5.15 11.09 4.59 11.04 ti0.6 o.4coo.5Mn? .5 8.22 5.15 7.93 7.66 11.04 t'0.6Sro.4Coo.3Mno.7 8.22 545 4.76 10.72 11.04 Tio.6Sro.4Mn 1.0 8.22 5.15 0.00 15.31 11.04 Table 3 Adsorption of SOx (% weight) in the series Ce06Sr04Col.Mnx Ad: total sorption of SOx Adsorption, at Speed of 6Sr04Co, _Mnx SOx, 30 min. initiation adsorption X% Weight% Weight% l / min. 0. 0 35.8 20 EYE 0. 3 55.1 30 1.00 0. 5 50.0 31 1.03 0. 7 55.0 24 0.80 1. 0 54.2 28 0.94 Cl * 57.2 22 074 * Industrial catalyst Table 4. Reduction speed (l / min.) Of the series Ce06Sr04Co1.Mn e06.br04C? | .Mn Reduction at 550 ° C, at 10 Speed min. initial reduction X% Weight% 1 / m? n. 0.0 24 2.4 0.3 28 2.8 0.5 27 2.1 0.7 25 2.5 1.0 10 1.0 Cl * 12 1.2 * Industrial catalyst Table 5. Adsorption of SOx (% weight) with the series Ti06Sr04Co, .xMn Ti0 6Sr04Co, - nx Total adsorption SOx adsorption, at SOx speed, 30 min. initial adsorption X% Weight% Weight% l / min. 0. 0 56 25 0.90 0.3 56 36 1 .2 1 0.5 59 43 1 .50 0.7 44 29 1 .00 1.0 44 20 EYE Cl * 57 22 0.74 * Industrial catalyst Table 6. Reduction speed (1 / min.) Of the series Ti06Sr04Co, Mn.

Ti06Sr04Co, .xMn Reduction at 550 ° C, at Reduction speed 10 min. initials X% Weight% l / min 00 32 32 0.3 28 2.8 0.5 34 3.4 0.7 19 1 .9 LO 13 L3 Cl * 12 1.2 * Industrial catalyst

Claims (1)

NOVELTY OF THE INVENTION Having described the invention, it is considered as a novelty and, therefore, what is contained in the following clauses is claimed as property.

1. A procedure for obtaining perovskite structure materials for the reduction of sulfur oxides emissions, in the catalytic disintegration units FCC and / or fixed sources; characterized in that it comprises mixed oxides of Ti, Sr, Co, Mn and Ce, Sr, Co, Mn, with perovskite structure grouped in two series: those that contain different concentrations of each of the elements ranging from X = 0 to 1, which are obtained by mixing the metallic nitrate solutions such as Ce, Sr, Co, Mn and an ethanolic solution of titanium ethoxide, to the mixture of the metallic solutions is added a solution of ammonium hydroxide and with stirring, of 2 or more hours, with a pH between 8 and 12 in the precipitates , then homogenized by continuous stirring between 5,000 - 10,000 rpm for 0.5 - 10 hours and finally the materials are filtered, dried and calcined between 600 and 1000 ° C in air flow between 2.0 - 8.0 liters / hour for 2-20 hours and forming mesh particles between 100 and 300 μm, suitable for the fluidized bed. A procedure for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clause 1, characterized in that the co-citation method is used to obtain the systems Ce, Sr, Co, .x Mn and Ti, Sr, Co (, x), Mnx where X is from 0.0 to 1.0. A procedure for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clauses 1 and 2, characterized in that the material obtained contains high density of metal sites that react easily with SOx, from any source gaseous, with a higher adsorption speed compared with a similar industrial reference catalyst. A procedure for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clauses 1 to 3, characterized in that they promote the total combustion of CO to CO ,. A procedure for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clauses 1 to 4 because they have a specific area between 6 and 140 pr / g A procedure for obtaining materials of perovskite structure for the reduction of emissions of sulfur oxides, in accordance with clauses 1 to 5, characterized in that they present an adsorption above 50%, in the reduction of SOx in FCC units, increasing 30 - 100% in the adsorption speed. A process for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clauses 1 to 6, characterized in that it has the facility to be reduced in the presence of a reducing agent and at temperatures of 550 ° C. A process for obtaining perovskite structure materials for the reduction of emissions of sulfur oxides, in accordance with clauses 1 to 7, characterized in that the adsorption speed is 2.3 to 2.8 times higher than the reference catalyst.