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Title: Deactivation of hydrotreatment catalysts used for coal liquids: Semi-annual report, 12 May 1988--11 November 1988

Abstract

Coal liquid hydrotreatment catalysts deactivate rapidly due to deposition of coke and metals inside the pores of the catalyst particles. The deactivation can be due to the gradual choking of the catalyst pores and/or due to the suppression of active sites on the catalyst. The objective of the proposed work is to determine which of these two mechanisms of deactivation is predominant, and this done by using the Constant Deactivation Arrhenius Plot (CDAP) technique. The Catalysts Co-Mo/Al/sub 2/O/sub 3/ and Ni-Mo/Al/sub 2/O/sub 3/ which have previously been deactivated to different extents in run number 242 at Wilsonville's coal liquefaction facility, are used in this study. The hydrodesulfurization of thiophene, which does not deactivate the catalyst, is used to characterize the relative activities of these catalysts. Arrhenius plots for these catalysts are being obtained. From the Arrhenius plots, the CDAP technique determines the intrinsic reaction rate constants and the effective diffusivities for each of these catalysts. 1 fig., 2 tabs.

Authors:
Publication Date:
Research Org.:
West Virginia Univ., Morgantown (USA). Dept. of Chemical Engineering
OSTI Identifier:
6088818
Report Number(s):
DOE/PC/79808-T2
ON: DE89014725
DOE Contract Number:
FC22-88PC79808
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; COAL LIQUEFACTION; CATALYSTS; COBALT; DEACTIVATION; MOLYBDENUM; NICKEL; THIOPHENE; DESULFURIZATION; ALUMINIUM OXIDES; ARRHENIUS EQUATION; COAL LIQUIDS; PROGRESS REPORT; STABILITY; ALUMINIUM COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; DOCUMENT TYPES; ELEMENTS; EQUATIONS; FLUIDS; HETEROCYCLIC COMPOUNDS; LIQUEFACTION; LIQUIDS; METALS; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; THERMOCHEMICAL PROCESSES; TRANSITION ELEMENTS; 010405* - Coal, Lignite, & Peat- Hydrogenation & Liquefaction

Citation Formats

Dadyburjor, D. B.. Deactivation of hydrotreatment catalysts used for coal liquids: Semi-annual report, 12 May 1988--11 November 1988. United States: N. p., 1988. Web. doi:10.2172/6088818.
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Dadyburjor, D. B.. Deactivation of hydrotreatment catalysts used for coal liquids: Semi-annual report, 12 May 1988--11 November 1988. United States. doi:10.2172/6088818.
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Dadyburjor, D. B.. Fri . "Deactivation of hydrotreatment catalysts used for coal liquids: Semi-annual report, 12 May 1988--11 November 1988". United States. doi:10.2172/6088818. https://www.osti.gov/servlets/purl/6088818.
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@article{osti_6088818,
title = {Deactivation of hydrotreatment catalysts used for coal liquids: Semi-annual report, 12 May 1988--11 November 1988},
author = {Dadyburjor, D. B.},
abstractNote = {Coal liquid hydrotreatment catalysts deactivate rapidly due to deposition of coke and metals inside the pores of the catalyst particles. The deactivation can be due to the gradual choking of the catalyst pores and/or due to the suppression of active sites on the catalyst. The objective of the proposed work is to determine which of these two mechanisms of deactivation is predominant, and this done by using the Constant Deactivation Arrhenius Plot (CDAP) technique. The Catalysts Co-Mo/Al/sub 2/O/sub 3/ and Ni-Mo/Al/sub 2/O/sub 3/ which have previously been deactivated to different extents in run number 242 at Wilsonville's coal liquefaction facility, are used in this study. The hydrodesulfurization of thiophene, which does not deactivate the catalyst, is used to characterize the relative activities of these catalysts. Arrhenius plots for these catalysts are being obtained. From the Arrhenius plots, the CDAP technique determines the intrinsic reaction rate constants and the effective diffusivities for each of these catalysts. 1 fig., 2 tabs.},
doi = {10.2172/6088818},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 1988},
month = {Fri Jan 01 00:00:00 EST 1988}
}
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Technical Report:
View Technical Report (0.29 MB)
DOI:  10.2172/6088818
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  • Coal liquid hydrotreatment catalysts deactivate rapidly due to deposition of coke and metals inside the pores of the catalyst particles. The deactivation can be due to the gradual choking of the catalyst pores and/or due to the suppression of active sites on the catalyst. The objective of the proposed work is to determine which of these two mechanisms of deactivation is predominant, and this is done by using the Constant Deactivation Arrhenius Plot (CDAP) technique. The inertness of the solvent (m-Xylene) was checked over Co-Mo/Al/sub 2/O/sub 3/ (Houdry HR-801) and Ni-Mo/Al/sub 2/O/sub 3/ (Shell 324M) catalyst. This test was carriedmore » out at or near extreme conditions to be employed for further experiments. In order to test the accuracy of the results obtained from the continuous flow reactor unit, rate constants obtained for the HDS of thiophene over fresh Co-Mo/Al/sub 2/O/sub 3/ (Houdry HR-801) were compared with those obtained by Froment et al. over Co-Mo/Al/sub 2/O/sub 3/ catalyst (Procatalyse HR 306) under the same reaction conditions. Tests were also carried out to determine if the catalyst needed to be pre-sulfided before every reaction run at each temperature or if it was sufficient to pre-sulfide the catalyst only once. 1 ref., 3 figs., 7 tabs.« less

  • ;
    In an earlier report the details of a Fourier method developed to unfold the metallic cobalt x-ray spectrum from the x-ray spectrum of Co-ZSM-5 were presented. This method has been utilized to obtain spectra on three Cobalt-ZSM-5 catalysts after exposure to a number of thermal and gas environments in a in situ x-ray diffraction camera. The resulting spectra of metallic cobalt and the various forms of cobalt oxides were analyzed for diffracting particle size and microstrain using both the Scherrer equation and a single profile analysis technique. Results are discussed and tabulated.

  • It was concluded that: (1) the deactivation of Ni/Al/sub 2/O/sub 3/ methanation catalysts is caused by particle size growth and surface site blockage (probably by carbon deposition); (2) the particle size growth in Ni/Al/sub 2/O/sub 3/ methanation catalysts results from the formation of volatile Ni(CO)/sub 4/, vapor phase transport and subsequent decomposition of Ni(CO)/sub 4/; (3) a region of safe operation conditions is found, and justified by thermodynamic equilibrium calculations, the proposed criterion is in terms of the equilibrium Ni(CO)/sub 4/ partial pressure, it can also be applied to other Ni/Al/sub 2/O/sub 3/ systems with different loading and/or geometry; (4)more » the mechanism of methanation in the unsafe region may be different from that in the safe region; and (5) in-situ Moessbauer spectroscopy has been performed for the first time on a working iron catalyst at high pressure Fischer-Tropsch reaction conditions. In our brief studies, it was clearly shown that under these reactions conditions: (A) the top layer of a precipitated iron catalyst bed is present as a chi-carbide phase, and (B) the bottom layer of a precipitated iron catalyst bed may contain appreciable amounts of magnetite, depending on the CO conversion.« less

  • An automated Catalyst Life Test Unit was operated with three trickle bed reactors in parallel to assess the loss in activity of two cobalt-molybdenum-alumina catalysts and one nickel-molybdenum-alumina catalyst during hydrotreatment of FMC oil, Synthoil I liquid, Synthoil II liquid, and Rasyn liquid at 1500 psig and 371/sup 0/ to 454/sup 0/C. The nickel-molybdenum-alumina catalyst performed better than the cobalt-molybdenum-alumina catalyst for sulfur and nitrogen removal. Hydrotreatment with the cobalt-molybdenum-alumina catalyst resulted in reactor plugging within 200 to 372 hr for Rasyn liquid at 371/sup 0/C, whereas the nickel catalyst prevented plugging. The surface areas and pore volumes of spentmore » catalysts were considerably less than that of the fresh catalysts. On regeneration, most of the surface area and pore volume was recovered. A semimechanistic model was developed to represent the data. Carbonaceous depositions seem to be the main cause for loss of catalyst activity, but inorganic depositions are also responsible, and inhibitive adsorption of nitrogen containing compounds may be involved as well.« less