Catalyst Attrition Resistance Research Articles

Comparative study of attrition measurements of commercial FCC catalysts by ASTM fluidized bed and jet cup test methods

Catalyst loss due to fines generation by attrition is a major problem in refinery fluid catalytic cracking (FCC) units as it impacts inventory loss. Attrition resistance of catalyst is one of the critical parameter in catalyst selection for a FCC unit. ASTM D5757 fluidized bed attrition test is the most commonly used attrition resistance test method to rank FCC catalysts and additives. In the present study, catalyst attrition tests were performed for FCC catalysts using an ASTM fluidized bed, cylindrical jet cup and conical jet cup. Performance ranking shows that attrition index obtained by these tests vary, but the order of ranking remains unchanged for ASTM fluidized bed and conical jet cup test methods as compared to cylindrical jet cup test. The investigation conducted here shows that morphology of attrited fresh FCC catalyst using conical jet cup was found to be similar to plant equilibrium catalyst and also takes less attrition time relative to ASTM fluidized bed.

Catalytic performance of spray-dried Cu/ZnO/Al2O3/ZrO2 catalysts for slurry methanol synthesis from CO2 hydrogenation

A series of Cu/ZnO/Al2O3/ZrO2 micro-spherical catalysts with different weight percentages of alumina sol from 0 to 20wt.% are prepared by spray drying method. The as-obtained catalysts are first tested in the fixed-bed reactor for CO2 hydrogenation to methanol. When the added alumina sol is below 10wt.%, the CO2 conversion is close to the equilibrium conversion of CO2 (26.5%) at 523K and 5MPa. Further increase of alumina sol content decreases the activity due to the decreased Cu surface area and weakened interaction among Cu and ZnO. When used in slurry bed, attrition resistance of catalysts plays an important role to determine the final catalytic performance. The catalyst without addition of alumina sol possesses low attrition resistance, which leads to catalyst loss and deactivation during reaction process. The introduction of suitable amount of alumina sol can enhance the attrition resistance of the catalysts markedly, and the catalytic activity can be still maintained at a high value. The spray-dried Cu/ZnO/Al2O3/ZrO2 catalyst with addition of 10wt.% alumina sol exhibits the best performance with high activity and high stability.

Attrition Studies of an Iron Fischer–Tropsch Catalyst Used in a Pilot-Scale Stirred Tank Slurry Reactor

Attrition resistance is a key design parameter for catalysts used in slurry phase Fischer–Tropsch (F–T) reactors, especially for industrial-scale reaction. It is well-known that iron F–T catalyst particles undergo physical attrition and chemical stresses caused by phase transformations. Here we report on attrition properties of a Fe–Cu–K–SiO2 catalyst used in a pilot-scale stirred tank slurry reactor (STSR) under low temperature F–T reaction conditions. The wax-free catalysts were characterized by SEM, EDS, BET surface area measurements, and a Mastersizer 2000 for particle size analysis. The results show that, after 408 h of reaction in an STSR, the particle size reduction due to erosion/abrasion and fracture was apparent. Large reductions in the Sauter mean diameter (93.45%) and the volume moment diameter (71.67%) were observed. The increase in the fractions of particles smaller than 5 and 10 μm was 18.25 and 30.11%, respectively. We concluded therefore that the catalyst underwent more severe attrition in industrial application and the attrition was mainly caused by the fracture of larger or smaller particles. Further study is needed to improve the catalyst attrition resistance.

Attrition resistant catalyst for dimethyl ether synthesis in fluidized-bed reactor

Fluidized-bed reactor is a candidate for dimethyl ether (DME) synthesis from syngas because of its excellent heat removal capability. In order to improve the attrition resistance of catalyst, an amount of silica sol as binder was added to the catalyst composed of methanol synthesis component CuO/ZnO/Al2O3 and methanol dehydration component HZSM-5, which was prepared by coprecipitation and shaped by spray drying to get spherical particles. The effect of silica sol on the catalytic activity was investigated in a fixed-bed flow microreactor. Based on the experiment results, silica sol in the range of 0∼20wt% had small effect on the catalytic activity. Generally, the CO conversion and DME yield decreased with the increase in concentration of silica sol, while the attrition resistance of catalysts increased with increasing silica sol, indicating that it was feasible to improve the attrition resistance without greatly sacrificing the activity of catalyst. In addition, the characterizations of catalysts were carried out using Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD) and temperature programmed reduction (TPR).

Attrition resistance of spray-dried iron F–T catalysts: Effect of activation conditions

The focus of the research reported herein was to investigate the effects of phase changes, as occur during Fe catalyst activation and Fischer–Tropsch synthesis, on Fe catalyst attrition resistance. Different activation conditions (CO, H 2 or syngas) were applied prior to attrition testing to a selected spray-dried Fe catalyst containing 9.1 wt.% binder SiO 2, which had been shown to have the highest attrition resistance in our early study of calcined catalysts. Although, XRD indicated that different Fe phase compositions resulted in the differently activated catalyst samples, chemical attrition was not observed for any of the samples. The BET surface areas of the activated samples were smaller than that of the calcined precursor but no significant changes in pore volume and particle size were found. The attrition resistances of the differently activated catalyst samples were found to be similar to that of the calcined catalyst for this spray-dried Fe catalyst. Attrition resistance was found previously to be governed by catalyst particle density, which has been shown earlier to relate to the SiO 2 network in catalysts. It is therefore suggested that the type and concentration of SiO 2 that is incorporated during the preparation of spray-dried Fe catalysts have a much more significant impact on catalyst attrition than Fe phase change during activation in the presence of CO, H 2 or H 2+CO.

Preparation of Attrition-Resistant Spray-Dried Fe Fischer−Tropsch Catalysts Using Precipitated SiO2

Spray-dried Fe Fischer−Tropsch (FT) catalysts can be prepared that have sufficient attrition resistance for use in slurry bubble column reactors without sacrifice of their activities and selectivities. Earlier studies from our group have shown that the type (binder or binder-and-precipitated) and concentration of silica incorporated into Fe spray-dried Fischer−Tropsch (FT) catalysts have significant impacts on catalyst attrition and that attrition resistance is strongly dependent on particle density. Although the use of a refractory oxide such as SiO2 is necessary to produce and maintain the high active surface area of a catalyst, the use of high concentrations of binder or binder-and-precipitated SiO2 results in poorer attrition resistance. This paper reports on the effect of precipitated silica by itself on the attrition resistance of Fe FT catalysts produced by spray drying. Earlier work by others suggested that the use of precipitated SiO2 alone produced less than adequate attrition-resistant Fe catalysts. However, our previous results hinted at the possibility for the preparation of attrition-resistant catalysts using smaller concentrations of precipitated SiO2. Spray-dried Fe catalysts were prepared having a composition of 100 Fe/5 Cu/4.2 K but with varying amounts of precipitated SiO2. The results show that the use of small amounts of precipitated SiO2 alone in spray-dried Fe catalysts can result in good attrition resistance. All catalysts investigated with SiO2 weight percentages ≤12 produced fines less than 10 wt % during the jet cup attrition test, making them suitable for long-term use in a slurry bubble column reactor. Thus, concentration rather than type of SiO2 incorporated into the catalyst has a more critical impact on the catalyst attrition resistance of spray-dried Fe catalysts. Lower amounts of SiO2 added to a catalyst give higher particle densities and, therefore, higher attrition resistances. To produce a suitable SBCR catalyst, however, the amount of SiO2 added has to be optimized to provide adequate surface area, particle density, and attrition resistance.

Attrition resistance of cobalt F–T catalysts for slurry bubble column reactor use

There exists much current interest in the use of supported Co catalysts and slurry bubble column reactors (SBCR) for the conversion of natural gas to higher hydrocarbons via the Fischer–Tropsch (F–T) synthesis. Catalyst attrition resistance is extremely important in the operation of slurry-phase reactor systems because of potential problems with plugging of system filters and/or contamination of the liquid products. This paper addresses the effects of different supports, promoters, and preparation methods on the attrition resistance of Co F–T catalysts for SBCR use. The calcined supports had attrition resistances (inversely related to % fines <11 μm generated during attrition testing) as follows: − Al 2 O 3> TiO 2( rutile)⪢ SiO 2 Loading of Co onto the supports improved the attrition resistances of both alumina and silica significantly. It has essentially no effect on titania. The resulting catalysts had attrition resistances in the order Co/ Al 2 O 3> Co/ SiO 2> Co/ TiO 2( rutile)>⪢ Co/ TiO 2( anatase) The addition of small amounts of metal (Ru, Cu) and oxide (La, Zr, K, Cr) promoters had mainly small effects on the attrition resistance of the supported Co catalysts. However, it would appear that the addition of Zr to Co/alumina had a negative impact on its attrition resistance. The different preparation methods used in this study (aqueous impregnation, non-aqueous impregnation, and kneading) did not appear to have a significant effect on catalyst attrition resistance.

Spray-Dried Iron Fischer−Tropsch Catalysts. 2. Effect of Carburization on Catalyst Attrition Resistance

Spray drying has been recently used by this research team in the preparation of Fe Fischer−Tropsch catalysts with higher attrition resistance for use in slurry bubble column reactors. In the first paper in this series, the effects of the type, concentration, and network structure of SiO2 on the attrition resistance of two series of spray-dried Fe catalysts in their calcined state were explored and the dependence of catalyst attrition resistance on catalyst particle density was discussed. As a continuation of our previous effort, the effect of carburization on catalyst attrition resistance was studied and is presented in this paper. After carburization, the majority component of the catalysts, hematite (Fe2O3), was converted to iron carbides, mostly χ-carbide (Fe2C5). Breakage of individual catalyst particles and fines formation, which can be considered as evidence of chemical attrition, was only observed during carburization of the catalyst with low SiO2 concentration <9 wt %. With an increase in the tota...

Spray-Dried Iron Fischer−Tropsch Catalysts. 1. Effect of Structure on the Attrition Resistance of the Catalysts in the Calcined State

The use of Fe Fischer−Tropsch (F−T) catalysts in slurry bubble column reactors (SBCRs) has been problematic in the past because of their poor attrition resistance. Recently, we have reported the preparation of spray-dried Fe F−T catalysts having attrition resistance suitable for SBCR use, but the reason for this improvement was not clear. This paper focuses on research done to better understand the reason for the high attrition resistance of some of the Fe catalysts prepared. Understanding the relationship between the catalyst attrition resistance and composition/structure is important for the preparation of attrition-resistant Fe catalysts. In the present study, two series of spray-dried Fe F−T catalysts having the composition Fe/Cu/K/SiO2 but with different amounts of precipitated and/or binder SiO2 were investigated. All of the catalysts studied were evaluated in their calcined form. This was done to minimize any possible attrition due to Fe phase change (such as can occur during activation and F−T syn...

The effect of pretreatment on the attrition resistance of spray-dried alumina

Spray-dried alumina is useful as a support for metal catalysts used in fluidized bed and slurry phase reactors. Catalyst attrition resistance, which can be affected by catalyst preparation and pretreatment, is a key characteristic determining successful use of a particular catalyst. In this study, the effects of calcination temperature and pH of an impregnating solution on the attrition resistance of spray-dried Vista-B alumina have been investigated. BET, X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size distribution (PSD) were used to characterize the pretreated and attrited alumina. The results indicate that the attrition resistance of the boehmite/γ-Al 2O 3 passes through a maximum for a calcination temperature of around 300°C. The impregnation of γ-Al 2O 3 to incipient wetness using different pH-value solutions followed by drying does not itself cause much change in the PSD. However, this treatment changes significantly the attrition resistance of the γ-Al 2O 3 that decreases with increasing pH value of the impregnation solution. The possible causes of the changes in attrition resistance are discussed.

The synthesis of attrition resistant slurry phase iron Fischer–Tropsch catalysts

We describe the evolution of catalyst microstructure as a precipitated Fe–Cu catalyst precursor is transformed into an attrition resistant Fischer–Tropsch (F–T) catalyst. The precipitated Fe–Cu catalyst, as-prepared, is weak compared to the same catalyst that was spray-dried, but without a binder. Spray-drying improves the attrition resistance of the catalyst. Ultrasonic fragmentation was used in this work to measure the attrition resistance of the slurry phase catalysts. Both catalysts, after ultrasonication, produce fine particles below 5 μm, which could cause filtration problems in slurry F–T reactors. The addition of silica as the binder improved the catalyst’s attrition resistance with negligible generation of fine particles below 5 μm. Cross-section TEM of the SiO 2-containing Fe F–T catalyst shows that the crystallized Fe particles with an average particle diameter of 80 nm are uniformly distributed within a silica binder. This study provides insight into the catalyst microstructure that leads to improved attrition resistance in Fe F–T catalysts.

Attrition assessment for slurry bubble column reactor catalysts

Significant interest in three-phase slurry bubble column reactors (SBCRs) has come about in recent years due to their excellent heat removal capabilities during reaction. However, no evaluation test for catalyst attrition resistance is available in the literature yet for SBCR catalysts, although severe attrition of catalyst particles has actually been encountered in SBCRs. In this paper, fluidized bed catalyst attrition tests (fluidized bed and jet cup) and other tests (collision and ultrasound) are evaluated for the first time for their suitability in predicting catalyst attrition in an SBCR. Based on comparisons of particle morphology and size distribution (PSD) of a silica supported cobalt catalyst before and after use in an SBCR with the results from the various attrition assessment tests, it is suggested that the fluidized bed, jet cup and ultrasound tests all provide reasonable and efficient predictions of catalyst attrition. Although the dominant attrition mechanism appeared to be fracture in both SBCR run and collision test, the latter showed too little attrition efficiency to be suitable as an attrition test. Despite the fact that abrasion occurs to a greater degree during the fluidized bed, jet cup, and ultrasound tests compared to during an SBCR run, all these three tests cause particle breakage similar to that in the SBCR, but in relatively short periods of time. Therefore, all three, especially the jet cup test, are suitable tests for predicting catalyst attrition resistance in an SBCR environment.

Butane oxidation to maleic anhydride over vanadium phosphate catalysts

Three aspects of the title reaction are considered: (1) control of catalyst morphology, (2) imparting catalyst attrition resistance, (3) advantages of separating the redox steps. We find that the best catalysts contain (VO) 2P 2O 7 which must be prepared from a (VO) 2H 2O(PO 3OH) 2 precursor. This dehydration reaction is topotactic in nature and controls the morphology of the (VO) 2P 2O 7 catalyst particles. The special feature of the predominant surface obtained in this way is presumably V-V pairs. By itself, (VO) 2P 2O 7 is mechanically too weak to be useful in fluid bed or recirculating solids reactors. We have discovered a novel method of imparting attrition resistance without loss of selectivity to maleic anhydride. The attrition resistance is provided using only small amounts (∼10wt%) of silica. Higher selectivities to maleic anhydride are observed when the two steps of the redox process are separated. The vanadium phosphate is circulated between two reactors. In one, butane is oxidized by vanadium phosphate; in the other, the vanadium phosphate is reoxidized.

Oxidation of Methanol in a Fluidized Bed. 1. Catalyst Attrition Resistance and Process Variable Study

Oxidation of Methanol in a Fluidized Bed. 1. Catalyst Attrition Resistance and Process Variable Study