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Title: Naphthene upgrading with pillared synthetic clay catalysts

Abstract

Catalytic hydrotreatment of methylcyclohexane was investigated to model upgrading of coal-derived naphthenes. Nickel-substituted synthetic mica montmorillonite (NiSMM), alumina-pillared NiSMM and Zirconia-pillared NiSMM were prepared and tested for hydrocracking and hydroisomerization of methylcyclohexane. Infrared and thermal desorption studies of the pyridine-adsorbed catalysts indicated the presence of Lewis and Bronsted acid sites. Total acidity and surface area increased with pillaring of NiSMM with polyoxy aluminum and polyoxy zirconium cations. Methylcyclohexane was reacted with these catalysts under a variety of conditions. Pillared clays gave higher gas yields and higher hydrocracking but lower hydroisomerization activity than nonpillared clay. The majority of the products were branched alkanes (isoparaffinic). These catalysts effectively use hydrogen as indicated by the minimal formation of aromatic hydrocarbons, coke, or other oligomeric materials. The effect of various operating conditions, i.e., reaction temperature, contact time, H{sub 2} pressure, and catalyst, on the product distribution will be described.

Authors:
;  [1]
  1. Univ. of North Dakota, Grand Forks, ND (United States)
Publication Date:
OSTI Identifier:
214728
Report Number(s):
CONF-950801-
TRN: 96:000922-0199
Resource Type:
Conference
Resource Relation:
Conference: 210. national meeting of the American Chemical Society (ACS), Chicago, IL (United States), 20-25 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of 210th ACS national meeting. Part 1 and 2; PB: 1866 p.
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; MONTMORILLONITE; CATALYTIC EFFECTS; NICKEL; HYDROAROMATICS; REFINING; ZIRCONIUM OXIDES; ALUMINIUM OXIDES; CATALYSTS; CLAYS; COAL; COKE; DESORPTION; HYDROCRACKING; PYRIDINE; SURFACE AREA; CATALYTIC CRACKING; SURFACE PROPERTIES; PH VALUE; TIME DEPENDENCE; PRESSURE DEPENDENCE; TEMPERATURE DEPENDENCE

Citation Formats

Sharma, R.K., and Olson, E.S. Naphthene upgrading with pillared synthetic clay catalysts. United States: N. p., 1995. Web.
Sharma, R.K., & Olson, E.S. Naphthene upgrading with pillared synthetic clay catalysts. United States.
Sharma, R.K., and Olson, E.S. 1995. "Naphthene upgrading with pillared synthetic clay catalysts". United States. doi:.
@article{osti_214728,
title = {Naphthene upgrading with pillared synthetic clay catalysts},
author = {Sharma, R.K. and Olson, E.S.},
abstractNote = {Catalytic hydrotreatment of methylcyclohexane was investigated to model upgrading of coal-derived naphthenes. Nickel-substituted synthetic mica montmorillonite (NiSMM), alumina-pillared NiSMM and Zirconia-pillared NiSMM were prepared and tested for hydrocracking and hydroisomerization of methylcyclohexane. Infrared and thermal desorption studies of the pyridine-adsorbed catalysts indicated the presence of Lewis and Bronsted acid sites. Total acidity and surface area increased with pillaring of NiSMM with polyoxy aluminum and polyoxy zirconium cations. Methylcyclohexane was reacted with these catalysts under a variety of conditions. Pillared clays gave higher gas yields and higher hydrocracking but lower hydroisomerization activity than nonpillared clay. The majority of the products were branched alkanes (isoparaffinic). These catalysts effectively use hydrogen as indicated by the minimal formation of aromatic hydrocarbons, coke, or other oligomeric materials. The effect of various operating conditions, i.e., reaction temperature, contact time, H{sub 2} pressure, and catalyst, on the product distribution will be described.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1995,
month =
}

Conference:
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  • Catalytic hydrotreatment of methylcyclohexane was investigated to model upgrading of coal-derived naphthenes. Nickel-substituted synthetic mica montmorillonite (NiSMM), alumina-pillared NiSMM, and zirconia-pillared NiSMM were prepared and tested for hydrocracking and hydroisomerization of mediylcyclohexane. Infrared and thermal desorption studies of the pyridine-adsorbed catalysts indicated the presence of Lewis as well as Bronsted acid sites. Total acidity and surface area increased with pillaring of NiSMM with polyoxy aluminum and polyoxy zirconium cations. Most of the products were branched alkanes (isoparaffins). These compositions are highly desirable for environmentally acceptable transportation fuels. Furthermore, dehydrogenation was not a major pathway, as indicated by the minimal formationmore » of aromatic hydrocarbons, coke, or other oligomeric materials. This paper describes the effect of various operating conditions, which included reaction temperature, contact time, hydrogen pressure, and catalyst on the product distribution.« less
  • Synthetic clays with nickel substitution in the lattice structure are highly active catalysts for hydrogenation and hydroisomerization and, consequently, have considerable promise for the catalytic upgrading of coal liquids. Nickel-substituted synthetic mica montmorillonite (NiSMM) was prepared and subsequently impregnated with molybdenum and sulfided. The reaction of model compounds with these catalysts in the presence of hydrogen has been investigated to provide mechanistic models for coal liquefaction. The results indicate that NiSMM has active Bronsted acid sites for hydrocracking and hydroisomerization. The hydrogen-activating ability of the molybdenum and nickel sulfide sites proximate to the acid sites results in effective depolymerization catalysis.
  • Fe-exchanged TiO{sub 2}-pillared clay (PILC) catalysts were prepared and used for selective catalytic reduction (SCR) of NO{sub x} by ammonia. They were also characterized for surface area, pore size distribution, and by XRD, H{sub 2}-TPR, and FT-IR methods. The Fe-TiO{sub 2}-PILC catalysts showed high activities in the reduction of NO{sub x} by NH{sub 3} in the presence of excess oxygen. SO{sub 2} further increased the catalytic activities at above 350 C, whereas H{sub 2}O decreased the activity slightly. The catalysts were about twice as active as commercial-type V{sub 2}O{sub 5}-WO{sub 3}/TiO{sub 2} catalyst in the presence of H{sub 2}O andmore » SO{sub 2}. Moreover, compared to the commercial catalyst, the Fe-TiO{sub 2}-PILC catalysts had higher N{sub 2}/N{sub 2}O product selectivities (e.g., 0--1% vs 9% N{sub 2}O at 400 C) and substantially lower activities (by 74--88%) for SO{sub 2} oxidation to SO{sub 3} under the same reaction conditions. The activity was further increased to over three times that of the vanadia-based catalyst when Ce was added. The high activity and low N{sub 2}O selectivity for the Fe-TiO{sub 2}-PILC catalysts were attributed to their low activity in the oxidation of ammonia, as compared with vanadia catalysts. XRD patterns of Fe-TiO{sub 2}-PILC were similar to those of TiO{sub 2}-PILC, showing no peaks due to iron oxide, even when the iron content reached 20.1%. The TPR results indicated that iron in the Fe-TiO{sub 2}-PILC catalysts with lower iron contents existed in the form of isolated Fe{sup 3+} ions. The activities of Fe-TiO{sub 2}-PILC catalysts were consistent with their surface acidities, which were identified by FT-IR of the NH{sub 3}-adsorbed samples. The enhancement of activities by H{sub 2}O + SO{sub 2} was attributed to the increase of surface acidity resulting from the formation of surface sulfate species of iron.« less
  • High-surface-area pillared clays were prepared from naturally occurring montmorillonites by exchanging interlayer ions with polyoxocations containing (i) iron, (ii) aluminum, (iii) discrete mixtures of (i) and (ii), or (iv) iron and aluminum located within the same complex. The valence state, solid-state properties, and stability of these pillars were determined following reduction and oxidation using Moessbauer spectroscopy, X-ray diffraction, and BET surface area measurements. Controlled atmosphere electron microscopy and transmission electron microscopy were also used to follow the nucleation and sintering behavior of the pillars during reduction. Moessbauer data suggested interlayer formation of metallic iron domains following reduction of types (i)more » and (iii) pillared systems. The magnetic properties and the oxidation behavior deduced from Moessbauer analysis and the complementary insights provided by XRD strongly indicated that these crystallites were in the form of thin-film/pancake-shape islands most likely conforming to the geometry of the interlayer region. The expanded structures of types (ii) and (iii) pillared systems were found to be relatively stable following reduction up to 723 K due to the irreducible nature of discrete aluminum pillars under these conditions. Intercalation of clays with mixtures of chemically distinct pillars appears to provide a unique method for preparing highly dispersed metallic or even bimetallic catalysts possessing two-dimensional sieve-like behavior with high overall surface areas and high loadings of the active metal.« less