R&D on Technology of Reducing Environmental Load Through Long-Life FCC Catalyst

Transcription

1 2001.M2.1.1 R&D on Technology of Reducing Environmental Load Through Long-Life FCC Catalyst (FCC Long-life Group) Nobuki Sekine, Hidenori Yamada, Tadashi Shibuya,Kenji Nagai, Junko Naito 1. Contents of Research Nearly all the FCC units in Japan serve in mixture processing of atmospheric residual oil and other residual oils, not just vacuum gas oil. The total percentage of residual oil processing, including RFCC unit, is about 25%. In view of the fact that demand is shifting toward light oils, the ratio of residual oil processing is forecast to steadily increase. When residual oil is processed in a FCC unit, the catalyst is deactivated because the metals contained in the residual oil, notably vanadium, destroy the structure of zeolite, the major active component. Additionally, the increasing coke formation, due to the dehydrogenation reaction over metal in the residual oil, notably nickel, and carbon residue, rises the temperature of the FCC unit regenerator, and catalyst is deactivated under sever conditions during catalyst regeneration. In order to compensate for the decline in activity due to this catalyst deactivation, the make up rate of fresh catalyst is increased, and in consequence, a large volume of spent catalyst gets extracted. The large volume of waste catalyst thus produced raises concern about the load it puts on the environment as an industrial waste. Because an increase in the ratio of residual oil processing leads to an even greater increase in spent catalyst, further reductions in waste catalyst have become imperative for reducing environmental load. In the present research, the aim is to develop a catalyst that is resistant against metal poisoning, withstands severe hydrothermal conditions is outstanding in coke selectivity, and thus to reduce the volume of waste catalyst to one-third the present level. In addition to efforts for reducing environmental load, it is hoped that refining costs (fresh catalyst purchasing costs and waste catalyst disposal costs) will be lowered through declines in the volume of waste catalyst and the make up rate of the fresh catalyst. Other benefits are anticipated, such as greater flexibility in operations during heavy oil processing, and better efficiency in recovering metals (Ni, V) from waste catalyst. FCC catalyst is comprised of zeolite, clay mineral kaolin, active alumina and other additives together with a mixture of silica binder that joins these components. It is a spherical porous particle measuring 60 microns on average. The performance of this catalyst is governed largely by the performance of zeolite, its main active species. 1

2 The HS zeolite that has been developed at the Satte No.3 Research Laboratory is superior to the conventional USY zeolite in hydrothermal stability, and it is believed that the dealumination procedure plays a important role in this performance. Moreover, HS zeolite contains non-framework aluminum that easily interacts with matrix, and it is supposed that the mutual phase thus formed is capable of capturing the metal contained in the residual oil, so that the catalyst shows excellent metal tolerance. Therefore, through optimization of the conditions of zeolite preparation, mainly on the preparation of HS zeolite, further improvements in hydrothermal stability is tried. Furthermore, through the search of the matrix components that lead to improved mutual phase functions, still more improved metal resistance is being targeted. Furthermore, in order to ease the severity of hydrothermal conditions during catalyst regeneration, caused by the increasing of coke formation due to carbon residue and the dehydrogenation reaction of metal in the residual oil, notably nickel, the formation of coke arising from the cracking reaction will be reduced through optimization of matrix pore structure and acidity in the preparation of catalyst. In order to evaluate the catalyst at the laboratory, it is absolutely essential to improve evaluation technology by such means as the development of catalyst pseudo deactivating methods that can imitate the patterns of catalyst deactivation in the commercial plant, or the development of catalyst evaluation methods using residual oil. Respecting the catalyst pseudo deactivating method, methods and facilities which can imitate the distribution of pollutant metals in the same manner as spent catalyst in commercial plant have already been developed as the original technologies. In addition, the patterns of catalyst deactivation in the commercial plant are being investigated in detail and the conditions for pseudo deactivation are being established. With respect to the evaluation of catalyst performance using residual oil, advances are being made in bolstering operational stability when residual oil is used at bench plants developed with original technologies, as well as in developing new evaluation equipment such as the MAT unit for residual oil, which will help to speed up evaluations. In the current fiscal year, the following items were subjects of R&D. 1.1 Investigation of hydrothermal stability In developing a catalyst that can withstand hydrothermal conditions of three times greater severity, arising residence time because the volume of make up rate of the fresh catalyst has been reduced to one-third, it is essential to elevate the durability of zeolite, the main active species. The HS zeolite that has been developed at the Satte No.3 Research Laboratory is outstanding in hydrothermal stability, and the conditions and procedures for dealumination are being investigated with the aim of achieving still greater hydrothermal stability. Last fiscal year, excellent performance of the HS zeolite in combination with alkali treatment was demonstrated. For optimization of the preparing conditions of alkali-treated HS zeolite, the effect of Si/Al ratio of NaY zeolite, the raw material zeolite, and the impact of unit cell size after the final dealumination process have been investigated in consideration of manufacturing costs. 2

3 1.2 Investigation of metal resistance By reducing the volume of catalyst use (waste catalyst) to one-third, the cumulative volume of vanadium deposition on the catalyst surface, which comes from residual oil and destroys the structure of zeolite, the main active species in catalyst, increases threefold. The same thing is true of nickel, which produces hydrogen and coke through the dehydrogenation reaction. To protect the zeolite from these large volumes of toxic metals and restrain the formation of hydrogen and coke, these toxic metals must be captured and made passive. With the HS zeolite that have been developed at the Satte No.3 Research Laboratory, a mutual phase is formed by matrix with non-framework Al, and it is suspected that this mutual phase captures the toxic metals, making the catalyst with HS zeolite superior in metal resistance to the catalyst containing conventional USY zeolite. In the past fiscal year, to further improve this function, methods for introducing the metal that demonstrated outstanding performance were established. In the current fiscal year, with the aim of commercial application, the methods for preparing FCC catalyst with the metal, and optimization of the amount to be added in the case of using the metal as an additive catalyst, were investigated. 1.3 Investigation for Commercial Application of Developed Catalyst In order to achieve the objectives of this R&D, improving hydrothermal stability and metal tolerance in catalysts performance is a vital theme, but another crucial concern is physical properties. Because catalyst is used with circulating in the FCC unit, the bulk density and particle size distribution is important for its fluidity. Other important factors are attrition (catalyst strength), which has a big influence on the flying out of catalyst from the FCC unit or unit erosion. In the development of catalyst, while advances are being made in catalyst performance through qualitative improvements in zeolite and the introduction of metal trap elements, physical properties must also be controlled adequately. Ultimately, it is imperative that a method of catalyst preparation that satisfies requirements in terms of both catalyst performance and physical properties must be established. In order to determine in detail the physical properties of developed catalyst, an investigation has been initiated for measuring and analyzing the physical properties of trial-produced catalysts. In the present R&D, studies have been oriented in two directions in catalyst performance: enhancing hydrothermal stability and elevating metal resistance. Zeolite destruction, one of the causes of deactivation, is due to hydrothermal destruction and vanadium poisoning. Moreover, increases in hydrogen and coke are caused by dehydrogenation reaction due to the destruction of zeolite and the deposition of nickel, thus, these factors interact each other. In the operation of the commercial plant, it is essential to clarify the degree of impact from each deactivation factor so as to accurately determine catalyst performance, since the strength of deactivation factors varies with the equipment. Thus a detailed analysis of deactivation factors was undertaken. 3

4 1.4 Development of Catalyst Evaluation Technology In evaluating the performance of FCC catalyst with MAT or bench plant, pseudo deactivation of the catalyst must be carried out in advance, in order to imitate the deactivated condition of the spent catalyst from the commercial plant. The most popular method of pseudo deactivation at present is the so-called Mitchell. As shown in Table 1-1, the deactivated catalyst obtained by this method is different in many respects from the spent catalyst of the commercial plant. In order to properly evaluate developed catalyst at the laboratory, it is essential to develop catalyst pseudo deactivation methods that can imitate the patterns of catalyst deactivation in the commercial plant. By the last fiscal year, pseudo deactivation conditions that could imitate the same distributions of poisonous metals and hydrothermal degradation as spent catalyst in the commercial plant were established by improving the methods of deposition of poisonous metals. Advances have also been made in the development of a pseudo deactivation method that imitates the much severe conditions of deactivation due to lowering the amount of catalyst use (waste catalyst). In this fiscal year, the method of the pseudo deactivation that could imitate the condition of the catalyst with one half of the make up rate of the fresh catalyst were established, and the performance of the newly developed catalyst has been determined using this method. Table 1-1 Comparison of Pseudo Deactivated Catalyst With Spent Catalyst (Mitchell method) Pseudo Deactivated Catalyst Spent Catalyst in the Commercial Plant Distribution of Ni in each particle uniform abundant on surface Distribution of V in each particle uniform uniform Effect of metal poisoning strong weak Deactivation of catalyst uniform distributed Distribution of metal abundant in deactivated uniform in catalyst particles catalyst particles 2. Results and Analysis 2.1 Investigation of Zeolite Modification Effect of Si/Al ratio of start zeolite on alkali-treated HS zeolite To improve the hydrothermal stability of the zeolite, optimization of the framework Al arrangement was attempted through the reinsertion of non-framework Al, produced by dealumination, into the framework by alkali treatment. In the preparation of HS zeolite, it was found that alkali treatment is effective as a pretreatment to HS treatment. For optimization of the preparatory conditions for alkali-treated HS zeolite, the effect of the Si/Al ratio (which is believed to affect the stability of zeolite structure) of NaY zeolite, the start zeolite, was investigated. 4

5 As shown in Figure 2.1-1, three types of NaY zeolite with varied Si/Al ratio were prepared, and from each NaY zeolite, three types of USY zeolite were prepared by regular method. Then, the conventional HS zeolite (HS-Z), which was prepared by HS treatment after non-framework Al extraction by acid treatment, and alkali-treated HS zeolite (HB-Z), which was prepared through HS treatment followed by non-framework Al reinsertion through alkaline treatment, were prepared using each USY zeolite as the raw material. Catalyst was prepared using each HS-Z or HB-Z mixed with matrix components, and cracking activity and hydrothermal stability of these catalysts were evaluated by MAT. As shown in Figure 2.1-2, it was found that the impact of the Si/Al ratio of start NaY zeolite was different between HS-Z and HB-Z. In HS-Z, the greater the Si/Al ratio of start NaY, the better was the hydrothermal stability; whereas in HB-Z, hydrothermal stability was better with the smaller Si/Al ratio. However, the differences were slight, and it was supposed that the Si/Al ratio of start zeolite has virtually no impact. The differences in impact of Si/Al ratio of start NaY zeolite on HS zeolite and alkali-treated zeolite can be ascribed to the fact that the greater the amount of Al in the framework of start zeolite, the greater is the amount of non-framework Al produced by dealumination through USY processing, and the greater is the impact of Al reinsertion by alkali treatment. NaY ion exchange low Si/Al ratio Base high Si/Al ratio NH4Y USY processing USY NFAL reinsertion BT-USY HS treatment HB-Z NFAL removal CZ-1 HS treatment HS-Z Figure Flow of Zeolite Modification (1) Superior Hydrothermal Stability Index Inferior SiO2/AI203 Ratio of NaY Figure Impact of Si/Al Ratio of start NaY zeolite on the performance of Alkali-Treated HS Zeolite 5

6 2.1.2 Investigation of alkaline treatment method and of the impact of unit cell size of alkali-treated HS zeolite In the preparation of alkali-treated HS zeolite, the non-framework Al produced by dealumination is reinserted into the zeolite framework by alkaline treatment, and dealumination takes place again by following HS treatment. For the optimization of the method of preparation, control of the amount or arrangement of aluminum in zeolite framework is a crucial issue. Accordingly, in HS treatment, the final dealumination process, the impact of unit cell size, the index of the amount of framework Al, was investigated. Moreover, in the alkaline treatment process, it is expected that reinsertion mechanism of Al is different with the type of alkali, so the effect of the type of alkali was investigated. As shown in Figure 2.1-3, various alkali-treated HS zeolites (HB-Z) were prepared as below; the alkaline treatment of USY zeolite was taken by sodium hydroxide; the sodium was removed by ion exchange after alkaline treatment, and in the subsequent HS treatment, the treatment temperature was changed so that the unit cell size (U.C.D.(A)) of alkali-treated HS zeolite became 24.40, and For the investigation of the types of alkali, sodium hydroxide and ammonium hydroxide were compared each other. Ammonium hydroxide was selected because it can allow the ion-exchange process to be omitted, and various alkali-treated HS zeolites were prepared with changing the frequencies of ion exchange after alkaline treatment. Catalyst was prepared using each obtained zeolite mixed with matrix components, and cracking activity and hydrothermal stability of these catalysts were evaluated by MAT. As shown in Figure 2.1-4, it was determined that the optimal unit cell size of HB-Z was at In comparison to HS zeolite (HS-Z), however, the index of hydrothermal stability of the optimum HB-Z does not manifest greater superiority. In past data, the HB-Z that had of unit cell size showed excellent performance. These data suggests that some other factors play a large role in the movement of zeolite framework Al. In an investigation of alkali types for Al reinsertion, the most outstanding hydrothermal stability was manifested in the case of treatment with ammonium hydroxide but no ion exchange. This method is also effective in terms of production cost. In cracking reactivity, however, the gasoline yield tends to be low and LPG yield tends to be high, albeit only slightly, so there must be further investigation. Acid/base treatment After HS treatment U.C.D.(A) PZ-26 Acid treatment PZ-27 NaOH treatment, ion exchange 2 times PZ-28 NaOH treatment, ion exchange 2 times PZ-29 NaOH treatment, ion exchange 2 times PZ-30 NH4OH treatment, ion exchange 1 time PZ-31 NH4OH treatment, ion exchange 0 times PZ-32 Ion exchange 1 time, NH4OH treatment NaY ion exchange SiO2/Al203 ratio of Start NaY = 5 NH4Y USY processing USY NFAL reinsertion BT-USY HS treatment HB-Z NFAL removal CZ-1 HS treatment HS-Z Figure Flow of Zeolite Modification (2) 6

7 Superior Hydrothermal Stability Index Inferior Figure Evaluation of Hydrothermal Stability of Various Alkali-Treated HS Zeolites 2.2 Investigation of Matrix Modification Method Metal Trap Introduction Method In order to protect zeolite, the main active species in FCC catalyst, from poisonous metals that has accumulated in large amount as a result of lowering the amount of catalyst use, and in order to give the catalyst metal tolerance so that the formation of hydrogen and coke due to the dehydrogenation over poisonous metals would be reduced, basic method of introducing elements effective for trap of the poisonous metals has already been established. For the commercial application, optimization of the method for introducing this metal trap material into catalyst was investigated. A model of the method for introducing metal trap material into catalyst is depicted in Figure In the present research, advances were made in an additive fashion in which the metal trap was introduced not into catalyst but into particles not containing zeolite. In terms of catalyst manufacturing costs, however, the single-body fashion in which metal trap is introduced directly into FCC catalyst containing zeolite is more effective, so three types of single-body catalyst were prepared using the developed metal trap, and comparisons were made with the additive type in terms of performance. In the evaluation of metal tolerance, the Mitchell method was used to impregnate metals (Ni, V), and catalyst evaluation was done by MAT comparing with the catalyst containing HS zeolite. As shown in Figure 2.2-2, it was found that in single-body catalyst, zeolite was destroyed by metal (V) and cracking activity declined the same as in the catalyst without metal trap; and in single-body catalyst the developed metal trap material exhibits no performance whatsoever. Thus there are great differences between the single-body catalyst and the additive type catalyst in metal tolerance. Clarifying the mechanism of metal trap is absolutely imperative for establishing the optimal method of introducing metal trap material. 7

8 Single-body type Additive type Metal trap Metal trap Separate particle FCC catalyst particle FCC catalyst particle Figure Introduction into catalyst particle Metal Trap Introduction Method Physical mixture by introduction of separate particles Conversion(mass%) ,000/2,000 10% blend in conventional catalyst Ni/V(ppm) 2,000/4,000 Conventional Catalyst Additive type Single-body type (1) Single-body type (2) Single-body type (3) Under standard condition of hydrothermal degradation Additive type (40% of metal trap C in additive particle) Single-body type (5% of metal trap C in catalyst particle) Figure Evaluation of Metal Tolerance of Catalyst Containing Metal Trap Investigation of Optimum Metal Trap Additive Amount As indicated above, the metal trap material developed exhibits no effect with the introduction of single-body catalyst, so an investigation of the additive type catalyst was continued, and the optimum amount of additive to catalyst was examined. Since zeolite is not included in the additive particle, it is feared that if the additive volume is increased, there will be a dilution effect and cracking activity will decline. But if the additive volume is minimized, the metal trap function will also decline. It is apparent, therefore, that there is an optimum additive value. Accordingly, metal trap additive was mixed into conventional catalyst in varied amounts, and metal tolerance was evaluated by MAT under conditions roughly equivalent to the severity of catalyst deactivation when the make up rate of fresh catalyst has been reduced to one-half (Ni/V = 3,000/6,000 ppm). As shown in Figure 2.2-3, the drop in activity due to destruction of zeolite caused by metal poisoning could be suppressed with an increase in metal trap additive. It was found that maximum benefit could be gained with an additive ratio of around 10%. With 10% additive, cracking activity is higher than the activity level of the spent catalyst of the commercial unit, which suggests that in practical applications the additive amount can be reduced somewhat. 8

9 Conversion/mass% Conventional catalyst + metal trap C additive Ni/V = 3000/6000ppm MAT cat/oil=3 The activity level of the spent catalyst of the commercial unit Additive ratio / mass% Figure Impact of Metal Trap Additive Amount 2.3 Investigation for commercial use of Developed Catalyst Physical Properties of Developed Catalyst The FCC unit is a unique unit that uses catalyst under circulating situation. In the development of catalyst, attention must be given to the physical properties that impact upon catalyst fluidization ability, catalyst flying out and unit erosion. Since no effect is demonstrated with single-body introduction, developed metal trap material would be introduced in an additive fashion, and the separate particles of metal trap must have the same physical properties as catalyst currently in use. Thus the physical properties of metal trap additives developed were measured. Measurement results are shown in Table In comparison to conventional catalyst, the metal trap C additive, which demonstrates the most outstanding performance, exhibits roughly the same values as conventional catalyst respecting apparent bulk density and average particle size, which are believed to impact upon flow property, and it was concluded that there are no problems with flow property. However, it was found that a large value is shown for attrition (particle strength), so that the particle strength of additive is weak and flying out of the fine particle from the unit due to degradation becomes a problem for commercial unit operation. In the preparation of additive, the process of particle production determined the particle strength, therefore, the conditions of particle production will be investigated from the standpoint of improving the particle strength of additive. Table Physical Properties of Metal Trap Additive Additive Apparent bulk density (ml/g) Average particle diameter (µm) Attrition Metal trap A Metal trap B Metal trap C Conventional catalyst

10 2.3.2 Analysis of Deactivation Factors The three major factors of catalyst deactivation are hydrothermal degradation, vanadium poisoning and nickel deposition. In general, of these factors, hydrothermal degradation and vanadium poisoning together cause the destruction of zeolite, the main active species in catalyst. They also bring about a decline in cracking activity and increases in the formation of hydrogen and coke. Nickel deposition causes increases in hydrogen and coke formation through a dehydrogenation reaction. The poisoning of both vanadium and nickel thus cause increases in the formation of hydrogen and coke, but the factors are different and of course there are differences in the volumes of hydrogen and coke produced by each. In order to determine the impact of vanadium poisoning and nickel deposition, vanadium and nickel were each added in varied amounts to a standard catalyst and cracking activity was evaluated by MAT. Figure A shows the change in cracking rate as opposed to the amount of metal loading. It was confirmed, as commonly suggested, that vanadium caused a decline in cracking activity, but that nickel had no impact on cracking activity. B and C of Figure 2.3-1, which show the volumes of hydrogen and coke formation, indicate that hydrogen and coke formation due to the destruction of zeolite by vanadium are greater that produced by dehydrogenation reaction via nickel..75 Conversion/mass% A (Cat/oil.=3) ,000 2,000 3,000 4,000 5,000 6,000 Metal/ppm v Ni Pseudo Deactivating Conditions: Steam 800 6h H2 Yield/mass% B (Conv.=70mass%) ,000 2,000 3,000 4,000 5,000 6,000 Metal/ppm v Ni Pseudo Deactivating Conditions: Steam 800 6h 6.0 C (Conv.=70mass%) v Coke Yield / mass% ,000 2,000 3,000 4,000 5,000 6,000 Metal/ppm Ni Pseudo Deactivating Conditions: Steam 800 6h Figure Impact of Poisonous Metals on Catalyst Performance 10

11 2.4 Development of Catalyst Evaluation Technology As a means of preparing pseudo deactivated catalyst under the same conditions as spent catalyst in commercial plant for the purpose of evaluating developed catalyst at the laboratory, a pseudo deactivating method has been investigated, based on the relationship between catalyst residence time (distribution of hydrothermal degradation) and the poisonous metal distribution in spent catalyst in commercial plant as shown in Figure Base of the pseudo deactivating method has already been established whereby pseudo deactivated catalyst that had the same activity and the same situation of metal poisoning and hydrothermal degradation as spent catalyst in commercial plant could be obtained. Further, by doubling the steam processing time and the loading amount of poisonous metals, the pseudo deactivated catalyst that imitate the spent catalyst of the commercial unit with half of the standard make up rate of fresh catalyst could be prepared. In the current fiscal year, the developed catalyst was evaluated by bench plant, with deactivating it under the severity equal to that when the fresh catalyst make up rate (the amount of waste catalyst) was reduced by half, which is an intermediate goal. For the evaluation, the additive containing metal trap C, the best metal trap material, was chosen, and the additive was tested as a 10% physical mixture in conventional catalyst. In this evaluation, hydrothermal stability of the catalyst was not modified, therefore, goal achievement was determined only with the enhancement of metal tolerance by the metal trap additive. Figure presents the results of a bench plant evaluation of conventional catalyst, and of conventional catalyst to which the additive was added, under a severity of deactivation equal to that at half the fresh catalyst make up rate. With conventional catalyst (catalyst containing HS zeolite), reduction at half of the fresh catalyst make up rate caused a sharp drop in activity and an increase in the formation of hydrogen and coke. But when additive was added, there was no drop in activity; activity exceeded the activity level of the spent catalyst of the commercial unit, and the formation of hydrogen and coke are also at the same as the spent catalyst of the commercial unit. Hence it was confirmed that the intermediate goal, reduction of catalyst make up rate (the amount of waste catalyst) at half with keeping the catalyst performance, was achieved. Furthermore, under the severe deactivation condition, the catalyst with metal trap additive showed higher LCO yield than that of the standard spent catalyst. It is supposed that the original cracking characteristic of zeolite was maintained because the zeolite was protected by metal trap function. Figure is an image of an electron probe microanalyses (EPMA) of the deactivated catalyst mixed with the metal trap additive, showing the distribution of metals among several catalyst particles. Nearly all the vanadium was captured in the additive, but the nickel was distributed also to catalyst other than the additive, indicating that nickel was not captured in the additive. The intermediate goal was thus accomplished only in the sense that vanadium was captured. From the aforementioned, it can be inferred that vanadium poisoning has a great influence as a catalyst deactivation factor; that its impact on the drop in cracking activity is half or greater of the all factors, and that its effect on increase of hydrogen and coke formation accounts for about half the total impact. Figure represents the impact of each deactivation factor on a drop in cracking activity and on an increase in hydrogen and coke formation in terms of degree of deactivation. It presents a difference in degree of deactivation between without and with the vanadium capture effect of metal trap additive when the catalyst make up rate is at standard, at 1/2, and at 1/3. 11

12 Figure Cumulative amount of metal deposition (ppm) 20,000 15,000 10,000 5, Catalyst deactivation time Catalyst Deactivation vs Metal Distribution in Spent Catalyst of the Commercial Unit Ratio of retention (%) Conversion(mass%) Ni/V=5,000/10,000ppm Severity of hydrothermal degradation x 2 Conventional catalyst Conventional catalyst + 10% additive (metal trap C) Level of the performance of spent catalyst from commercial unit (Ni/V=2,500/5,000ppm) H2 Yield(mass%) Ni/V=5,000/10,000ppm Severity of hydrothermal degradation x 2 Conventional catalyst Conventional catalyst + 10% additive (metal trap C) Level of the performance of spent catalyst from commercial unit Cat/Oil Conversion(mass%) Coke Yield(mass%) Ni/V=5,000/10,000ppm Severity of hydrothermal degradation x 2 Conventional catalyst Conventional catalyst + 10% additive (metal trap C) Level of the performance of spent catalyst from commercial unit LCO Yield(mass%) Ni/V=5,000/10,000ppm Severity of hydrothermal degradation x 2 Conventional catalyst Conventional catalyst + 10% additive (metal trap C) Level of the performance of spent catalyst from commercial unit Conversion(mass%) Conversion(mass%) Figure The Results of Bench Plant Test under the Severity Equivalent to 1/2 Fresh Catalyst Make Up Rate 12

13 Additive particle Catalyst particle V distribution Ni distribution Figure EPMA Analysis of Deactivated Catalyst with Additive Decline of activity Decline of activity Degree of deactivation Degree of deactivation Degree of deactivation Increase of hydrogen Increase of coke Zeolite destruction Dehydrogenation Hydrothermal degradation V poisoning Ni deposition Attainment of Intermediate Targets Degree of deactivation Degree of deactivation Degree of deactivation Increase of hydrogen Increase of coke Zeolite destruction Dehydrogenation Metal trap Hydrothermal degradation V poisoning Ni deposition Make up rate at 1/3 Make up rate at 1/2 Conventional make up rate of the fresh catalyst Make up rate at 1/3 Make up rate at 1/2 Conventional make up rate of the fresh catalyst Figure Deactivation Factors vs Drop in Performance by Reduced Catalyst Make Up Rate 13

14 3. Results of Research For the development of catalyst outstanding in durability, investigations were made of zeolite, the main active species, in terms of both strengthening and protection. For the strengthening of zeolite, a modification of the preparing method was investigated, focusing on that of HS zeolite discovered in past research at PEC. A new preparing method was developed by combining alkali treatment with HS treatment, and improvement in stability was confirmed. Optimization of conditions was also investigated; the impact of various factors on hydrothermal stability were confirmed and valuable information regarding types of alkali for alkali treatment were obtained. For the protection of zeolite, a metal trap material with the ability to capture metal included in residual oil was developed and a patent application was submitted (Patent application No Catalyst for fluid catalytic cracking of heavy hydrocarbon oil and fluid catalytic cracking process). At the laboratory, under the severity level of catalyst deactivation equivalent to that when make up rate of the fresh catalyst (the amount of waste catalyst) was at 1/2, the catalyst with the additive was evaluated, and it was confirmed that intermediate goals could be accomplished by the developed metal trap additive. Investigations for commercial use of the developed catalyst (additive) were begun; problems in the physical properties of the additive were identified; deactivation factors were analyzed further, and valuable information were obtained on the impact of poisonous metals. 4. Synopsis 4.1 R&D in FY2000 For the zeolite modification aimed at enhancing the hydrothermal stability of zeolite, advances were made in the optimization of conditions for preparation of alkali-treated HS zeolite. For improving the metal tolerance of catalyst, a metal trap material was developed, and the intermediate goal, the reduction of make up rate of the fresh catalyst (the amount of waste catalyst) at 1/2, was accomplished at the laboratory. 4.2 Future Issues Development of Catalyst Outstanding in Durability (1) Improvement in Hydrothermal Stability Advances should be made in the optimization of conditions for preparing alkali-treated HS zeolite, which is outstanding in hydrothermal stability as compared to USY zeolite, and the best catalyst preparation method should be established in consideration of manufacturing costs. (2) Improvement in Metal Tolerance Catalyst deactivation factors should be analyzed in detail; the mechanisms of poisonous metal passivation should be clarified, and the dehydrogenation suppression function of developed metal trap additive ought to be improved. 14

15 4.2.2 Investigation for Commercial Use of Developed Catalyst (1) Improvement of Metal Trap Additive for Commercial Use The attrition (particle strength) of developed metal trap C additive should be improved, and a new additive preparation method should be developed in consideration of manufacturing costs. (2) Analysis of Commercial Plant Operations The phenomenon of drastic declines in activity due to metal poisoning in commercial plant needs to be elucidated; the operating conditions of commercial plant should be analyzed in detail, and the way of trial application of developed catalyst should be confirmed. (3) Evaluation of Developed Catalyst for Final Targets Catalyst performance should be evaluated under the severity in catalyst deactivation equivalent to when the catalyst make up rate (the amount of waste catalyst) is set at 1/3 of standard, by combining metal trap C additive with catalyst containing alkali-treated HS zeolite. Copyright 2001 Petroleum Energy Center all rights reserved. 15