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Title: Shape-selective catalysts for Fischer-Tropsch chemistry : iron-containing particulate catalysts. Activity report : January 1, 2001 - December 31, 2004.

Abstract

Argonne National Laboratory is carrying out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (FT) chemistry--specifically, the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to needing high activity, it is desirable that the catalysts have high selectivity and stability with respect to both mechanical strength and aging properties. It is desired that selectivity be directed toward producing diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. The goal is to produce shape-selective catalysts that have the potential to limit the formation of longchain products and yet retain the active metal sites in a protected 'cage'. This cage also restricts their loss by attrition during use in slurry-bed reactors. The first stage of this program was to prepare and evaluate iron-containing particulate catalysts. This activity report centers upon this first stage of experimentation with particulate FT catalysts. (For reference, a second experimental stage is under way to prepare and evaluate active FT catalysts formed by atomic-layer deposition [ALD] of active components on supported membranes.) To date, experimentation has centered upon the evaluation of a sample of iron-based, spray-dried catalyst prepared by B.H. Davis of the Center ofmore » Applied Energy Research (CAER) and samples of his catalyst onto which inorganic 'shells' were deposited. The reference CAER catalyst contained a high level of dispersed fine particles, a portion of which was removed by differential settling. Reaction conditions have been established using a FT laboratory unit such that reasonable levels of CO conversion can be achieved, where therefore a valid catalyst comparison can be made. A wide range of catalytic activities was observed with SiO{sub 2}-coated FT catalysts. Two techniques were used for SiO{sub 2}coating. The first involved a caustic precipitation of SiO{sub 2} from an organo-silicate onto the CAER catalyst. The second was the acidic precipitation of an organo-silicate with aging to form fractal particles that were then deposited onto the CAER catalyst. Several resulting FT catalysts were as active as the coarse catalyst on which they were prepared. The most active ones were those with the least amount of coating, namely about 2.2 wt% SiO{sub 2}. In the case of the latter acid technique, the use of HCl and HNO{sub 3} was much more effective than that of H{sub 2}SO{sub 4}. Scanning electron microscopy (SEM) was used to observe and analyze as-received and treated FT catalysts. It was observed that (1) spherical particles of CAER FT catalyst were made up of agglomerates of particles that were, in turn, also agglomerates; (2) the spray drying process of CAER apparently concentrated the Si precursor at the surface during drying; (3) while SEM pointed out broad differences in the appearance of the prepared catalyst particles, there was little indication that the catalysts were being uniformly coated with a cage-like protective surface, with perhaps the exception of HNO{sub 3}-precipitated catalyst; and (4) there was only a limited penetration of carbon (i.e., CO) into the FT catalyst during the conditioning and FT reaction steps.« less

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE; NETL
OSTI Identifier:
928626
Report Number(s):
ANL-05/63
TRN: US200812%%525
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Technical Report
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; AGING; CARBON; CARBON MONOXIDE; CATALYSTS; CHEMISTRY; DEPOSITION; DRYING; FRACTALS; HYDROCARBONS; HYDROGEN; MEMBRANES; PARTICULATES; PRECIPITATION; PRECURSOR; RESEARCH PROGRAMS; SCANNING ELECTRON MICROSCOPY; SPRAY DRYING; STABILITY; WAXES

Citation Formats

Cronauer, D., and Chemical Engineering. Shape-selective catalysts for Fischer-Tropsch chemistry : iron-containing particulate catalysts. Activity report : January 1, 2001 - December 31, 2004.. United States: N. p., 2006. Web. doi:10.2172/928626.
Cronauer, D., & Chemical Engineering. Shape-selective catalysts for Fischer-Tropsch chemistry : iron-containing particulate catalysts. Activity report : January 1, 2001 - December 31, 2004.. United States. doi:10.2172/928626.
Cronauer, D., and Chemical Engineering. Fri . "Shape-selective catalysts for Fischer-Tropsch chemistry : iron-containing particulate catalysts. Activity report : January 1, 2001 - December 31, 2004.". United States. doi:10.2172/928626. https://www.osti.gov/servlets/purl/928626.
@article{osti_928626,
title = {Shape-selective catalysts for Fischer-Tropsch chemistry : iron-containing particulate catalysts. Activity report : January 1, 2001 - December 31, 2004.},
author = {Cronauer, D. and Chemical Engineering},
abstractNote = {Argonne National Laboratory is carrying out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (FT) chemistry--specifically, the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to needing high activity, it is desirable that the catalysts have high selectivity and stability with respect to both mechanical strength and aging properties. It is desired that selectivity be directed toward producing diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. The goal is to produce shape-selective catalysts that have the potential to limit the formation of longchain products and yet retain the active metal sites in a protected 'cage'. This cage also restricts their loss by attrition during use in slurry-bed reactors. The first stage of this program was to prepare and evaluate iron-containing particulate catalysts. This activity report centers upon this first stage of experimentation with particulate FT catalysts. (For reference, a second experimental stage is under way to prepare and evaluate active FT catalysts formed by atomic-layer deposition [ALD] of active components on supported membranes.) To date, experimentation has centered upon the evaluation of a sample of iron-based, spray-dried catalyst prepared by B.H. Davis of the Center of Applied Energy Research (CAER) and samples of his catalyst onto which inorganic 'shells' were deposited. The reference CAER catalyst contained a high level of dispersed fine particles, a portion of which was removed by differential settling. Reaction conditions have been established using a FT laboratory unit such that reasonable levels of CO conversion can be achieved, where therefore a valid catalyst comparison can be made. A wide range of catalytic activities was observed with SiO{sub 2}-coated FT catalysts. Two techniques were used for SiO{sub 2}coating. The first involved a caustic precipitation of SiO{sub 2} from an organo-silicate onto the CAER catalyst. The second was the acidic precipitation of an organo-silicate with aging to form fractal particles that were then deposited onto the CAER catalyst. Several resulting FT catalysts were as active as the coarse catalyst on which they were prepared. The most active ones were those with the least amount of coating, namely about 2.2 wt% SiO{sub 2}. In the case of the latter acid technique, the use of HCl and HNO{sub 3} was much more effective than that of H{sub 2}SO{sub 4}. Scanning electron microscopy (SEM) was used to observe and analyze as-received and treated FT catalysts. It was observed that (1) spherical particles of CAER FT catalyst were made up of agglomerates of particles that were, in turn, also agglomerates; (2) the spray drying process of CAER apparently concentrated the Si precursor at the surface during drying; (3) while SEM pointed out broad differences in the appearance of the prepared catalyst particles, there was little indication that the catalysts were being uniformly coated with a cage-like protective surface, with perhaps the exception of HNO{sub 3}-precipitated catalyst; and (4) there was only a limited penetration of carbon (i.e., CO) into the FT catalyst during the conditioning and FT reaction steps.},
doi = {10.2172/928626},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri May 12 00:00:00 EDT 2006},
month = {Fri May 12 00:00:00 EDT 2006}
}

Technical Report:

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  • Argonne National Laboratory carried out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (FT) chemistry-specifically, the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to needing high activity, it was desirable that the catalysts have high selectivity and stability with respect to both mechanical strength and aging properties. It was desired that selectivity be directed toward producing diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. The original goal was to produce shape-selective catalysts that had the potential to limit the formation of long-chain products and yetmore » retain the active metal sites in a protected 'cage.' This cage would also restrict their loss by attrition during use in slurry-bed reactors. The first stage of this program was to prepare and evaluate iron-containing particulate catalysts. Such catalysts were prepared with silica-containing fractal cages. The activity and strength was essentially the same as that of catalysts without the cages. Since there was no improvement, the program plan was modified as discussed below. A second experimental stage was undertaken to prepare and evaluate active FT catalysts formed by atomic-layer deposition [ALD] of active components on supported membranes and particulate supports. The concept was that of depositing active metals (i.e. ruthenium, iron or cobalt) upon membranes with well defined flow channels of small diameter and length such that the catalytic activity and product molecular weight distribution could be controlled. In order to rapidly evaluate the catalytic membranes, the ALD coating processes were performed in an 'exploratory mode' in which ALD procedures from the literature appropriate for coating flat surfaces were applied to the high surface area membranes. Consequently, the Fe and Ru loadings in the membranes were likely to be smaller than those expected for complete monolayer coverage. In addition, there was likely to be significant variation in the Fe and Ru loading among the membranes due to difficulties in nucleating these materials on the aluminum oxide surfaces. The first series of experiments using coated membranes demonstrated that the technology needed further improvement. Specifically, observed catalytic FT activity was low. This low activity appeared to be due to: (1) low available surface area, (2) atomic deposition techniques that needed improvements, and (3) insufficient preconditioning of the catalyst surface prior to FT testing. Therefore, experimentation was expanded to the use of particulate silica supports having defined channels and reasonably high surface area. An effective FT catalyst consisting of ALD-deposited Co and Pt on a silica support has been prepared and demonstrated. This catalyst was more effective than a similar catalyst deposited upon a support of ALD-deposited Al{sub 2}O{sub 3} on silica. This result implies that the deposition of Al{sub 2}O{sub 3} to form a support is not as effective as desired. The addition of Pt as a Co-containing catalyst promoter has been demonstrated; it appears to primarily affect the catalyst pre-conditioning step. Co on Al{sub 2}O{sub 3} catalyst prepared by the Center for Applied Energy Research (CAER) is more effective than Argonne-prepared ALD-deposited Co on ALD-deposited Al{sub 2}O{sub 3} catalyst. The FT activity of ALD-coated Co catalyst on Al{sub 2}O{sub 3} is about linear with Co level from about 9 to 25%. A cooperative research effort was undertaken to test the deposition of platinum on Co FT catalysts; this Pt influences the effectiveness of catalyst conditioning and its continuing activity. In summary, the ALD Pt at a low concentration (0.1 wt %) was as effective as that of the wet chemical deposition technique of CAER (specifically incipient deposition on a Co catalyst that had been prepared and calcined before the Pt deposition.) The ALD technique appeared to be nominally better than the incipient wetness technique that involved co-deposition of Pt and Co prior to calcination. The activation energy of the rate of CO conversion was tightly grouped about an average of 29.2 Kcal/mol when all of the Co-containing catalysts other than those with high Pt promoter levels were taken into account; this implies a uniform reaction mechanism. Catalysts containing Pt and Ru that were ALD-deposited on an ALD-Al{sub 2}O{sub 3} coated catalyst support were found to be relatively inactive. Additional tests were made with a low concentration (0.1 wt %) of Ru or Ir deposited on the reference Co catalyst. The Ir coated catalysts were particularly effective. In support of the above, there was an opportunity to undertake a study of cobalt/promoter/support interaction using the Advanced Photon Source (APS) of Argonne. A number of catalysts (including reference cobalt oxide and iron oxides) were tested using temperature programmed EXAFS/XANES experiments.« less
  • Argonne National Laboratory is carrying out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (FT) chemistry - specifically, the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to needing high activity, it is desirable that the catalysts have high selectivity and stability with respect to both mechanical strength and aging properties. The broad goal is to produce diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. Originally the goal was to prepare shape-selective catalysts that would limit the formation of long-chain products and yet retain the activemore » metal sites in a protected 'cage.' Such catalysts were prepared with silica-containing fractal cages. The activity was essentially the same as that of catalysts without the cages. We are currently awaiting follow-up experiments to determine the attrition strength of these catalysts. A second experimental stage was undertaken to prepare and evaluate active FT catalysts formed by atomic-layer deposition [ALD] of active components on supported membranes and particulate supports. The concept was that of depositing active metals (i.e. ruthenium, iron or cobalt) upon membranes with well defined flow channels of small diameter and length such that the catalytic activity and product molecular weight distribution could be controlled. In order to rapidly evaluate the catalytic membranes, the ALD coating processes were performed in an 'exploratory mode' in which ALD procedures from the literature appropriate for coating flat surfaces were applied to the high surface area membranes. Consequently, the Fe and Ru loadings in the membranes were likely to be smaller than those expected for complete monolayer coverage. In addition, there was likely to be significant variation in the Fe and Ru loading among the membranes due to difficulties in nucleating these materials on the aluminum oxide surfaces. The first series of experiments using coated membranes demonstrated that the technology needed further improvement. Specifically, observed catalytic FT activity was low. This low activity appeared to be due to: (1) low available surface area, (2) atomic deposition techniques that needed improvements, and (3) insufficient preconditioning of the catalyst surface prior to FT testing. Therefore, experimentation was expanded to the use of particulate silica supports having defined channels and reasonably high surface area. This later experimentation will be discussed in the next progress report. Subsequently, we plan to evaluate membranes after the ALD techniques are improved with a careful study to control and quantify the Fe and Ru loadings. The preconditioning of these surfaces will also be further developed. (A number of improvements have been made with particulate supports; they will be discussed in the subsequent report.) In support of the above, there was an opportunity to undertake a short study of cobalt/promoter/support interaction using the Advanced Photon Source (APS) of Argonne. Five catalysts and a reference cobalt oxide were characterized during a temperature programmed EXAFS/XANES experimental study with the combined effort of Argonne and the Center for Applied Energy Research (CAER) of the University of Kentucky. This project was completed, and it resulted in an extensive understanding of the preconditioning step of reducing Co-containing FT catalysts. A copy of the resulting manuscript has been submitted and accepted for publication. A similar project was undertaken with iron-containing FT catalysts; the data is currently being studied.« less
  • Argonne National Laboratory (ANL) is carrying out a research program to create, prepare, and evaluate catalysts to promote Fischer-Tropsch (F-T) chemistry, specifically the reaction of hydrogen with carbon monoxide to form long-chain hydrocarbons. In addition to F-T catalysts needing high activity, it is desirable that they have high selectivity and stability with respect to both mechanical strength and aging properties. In this project, selectivity is directed toward the production of diesel fraction components and avoiding excess yields of both light hydrocarbons and heavy waxes. Shape-selective catalysts have the potential to both limit the formation of long-chain products and yet retainmore » the active metal sites in a protected ''cage.'' This cage also restricts their loss by attrition during use in slurry-bed reactors. Experimentation has included evaluation of samples of (1) iron-based F-T catalysts prepared at Argonne National Laboratory, (2) iron-based F-T catalysts prepared by B.H. Davis of the Center of Applied Energy Research (CAER), (3) the Davis catalyst that were sized by differential gravity separation, and (4) the Davis catalyst onto which inorganic or catalytic ''shells'' were deposited. The ANL-prepared samples had a wide range of particle size and were irregular in shape. A sizeable portion of the samples provided by Davis were spherical, because they had been prepared by spray-drying. To compare the catalytic activities of the samples, we used a micro-scale fixed-bed reactor system for F-T runs of low conversion to avoid thermal and mass transfer effects. In summary, the highest activity was that of the original Davis catalyst; additional research must be carried out to generate more permeable surface cages. A number of approaches that have been published for other applications will be tested.« less
  • In the sixth quarter work continued on the three major tasks: Task 2 - Development of Improved Supported Catalyst Compositions; Task 3 - Slurry Reactor Kinetic Studies; and Task 4 - Fuel Product Characterization. To study the effect of Co-to-promoter ratio on the performance of the silica-supported catalysts, four Co/Zr/silica catalysts were prepared by varying the Zr loading, with the Co loading held at 4%. Gas phase testing of this series of catalysts was completed this quarter. It appears that the optimum Co/Zr ratio is near 0.5 for gas phase performance, although lower ratios were not investigated. The Fe/sub 3/(CO)/submore » 12//Zr(OPr)/sub 4//silica catalyst was gas phase tested to determine the inherent water-gas shift activity. This catalyst showed very little Fischer-Tropsch activity over the entire 220/sup 0/C to 280/sup 0/C temperature range. Slurry screening tests were performed on two catalysts. One was a Zr-promoted ruthenium catalyst supported on silica and the other was on a Zr-promoted, cobalt catalyst supported on silica. The extended slurry test which was begun last quarter continued this quarter. The same load of catalyst was run at 240/sup 0/C for 1000 hours and then at 260/sup 0/C for an additional 1200 hours. At each temperature, the catalyst underwent a gradual decline in activity. All liquid organic and wax products were collected during the initial 1000 hours of operation of the Co/sub 2/(CO)/sub 8//Zr(OPr)/sub 4//SiO/sub 2/ catalyst in the extended slurry test No. 8862-1-31, in order to isolate and characterize the diesel fuel fraction. The diesel fuel produced during this period of operation had a fairly high flash point, essentially no water or sediment, low sulfur, and negligible ash and carbon residue. It showed very low corrosiveness and had an outstanding cetane index. As a result it met all specifications for the highest quality diesel fuel oil except for very small variations from viscosity, cloud point and 90% boiling point. 5 refs., 53 figs., 98 tabs.« less
  • In the second quarter work continued on the two major tasks: Task 2 - development of improved supported catalyst compositions and Task 3 - slurry reactor kinetic studies. Work accomplished under Task 2 involved catalyst preparations of cobalt supported on alumina with various levels of promoter. the bimetallic Co/Fe catalyst was again supported on alumina but at higher loadings. Also, in an effort to enhance the water-gas shift reaction, a physical mixture of the standard Co on promoted Al/sub 2/O/sub 3/ catalyst with a Cu/Zn/Al/sub 2/O/sub 3/ shift catalyst was prepared. Gas phase testing was completed on all of thesemore » catalysts. Slurry testing was completed on all of these catalysts. Slurry testing was completed on the basecase Co on promoted Al/sub 2/O/sub 3/ catalyst as well as on the Ru on promoted Al/sub 2/O/sub 3/ catalyst, an unpromoted Co on alumina catalyst, and the bimetallic Co/Fe on Al/sub 2/O/sub 3/ catalyst. Under Task 3, work is in progress to develop a computer program for the analysis of kinetic data from the laboratory reactors.« less