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AssigneeExxon Research & Engineering Co.
InventorRobert L. Seiver
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A catalytic reforming process for the operation of a magnetically stabilized fluidized bed. The process utilizes catalyst compositions characterized as a particulate material which can be oriented within, and formed into a magnetically stabilized fluidized bed which comprises: (i) particles of average size ranging from about 10 micrometers (.mu.m) to about 4000 .mu.m, each containing a nonferromagnetic component and a catalytically active component composited with a single elongate ferromagnetic component or plurality of parallelly aligned elongate ferromagnetic components. The ferromagnetic component, or components, are multidomain, having dimensions of at least 1 .mu.m in all directions and a length:diameter (L/D) ratio of at least 2 but not more than 17.3, and the ferromagnetic component, or components, is present in the composite particles as inclusions within a nonferromagnetic matrix constituting at least 0.5%, preferably at least 5%, but not more than 3/2(L/D).sup.2 of the total volume of each particle, where the L/D is the ratio of the longest dimension of a ferromagnetic inclusion relative to the shortest dimension. The particles can, in said magnetically stabilized fluidized bed, rotate or turn to line up the long dimensions of the ferromagnetic components parallel to the direction of the field and the short dimensions perpendicular to the direction of the field.
A process for conducting a reforming reaction via fluid-solids contacting wherein a particulate material which can be oriented within, and formed into a magnetically stabilized fluidized bed to provide an effective demagnetization coefficient of from about 0.0027 to about 0.174, which comprises contacting the fluid with a bed of particles comprising particles containing a non-ferromagnetic refractory, porous inorganic oxide component composited with a single elongated ferromagnetic component, the ferromagnetic component being multidomain, having dimensions of at least 1 .mu.m in all directions and a length:diameter (L/D) ratio of at least 2 but not more than 17.3, said ferromagnetic component being present in the composite particles as inclusions within a nonferromagnetic matrix constituting at least 0.5%, but not more than 3/2(L/D).sup.2 of the total volume of each particle, where the L/D ratio is the ratio of the longest dimesion of the ferromagnetic component relative to the shortest dimension, and the particles can, in said magnetically stabilized fluidized bed rotate, or turn to line up the long dimension of a ferromagnetic component parallel to the direction of the field and a short dimension perpendicular to the direction of the field, and wherein a catalytically effective amount of a metal selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, and platinum, based on the weight of the catalyst composition, is dispersed on the surface of the composite particle, and the composite particle is catalytically active for conducting the reforming reaction.
A process for conducting a reforming reaction via fluid-solids contacting wherein particulate material is oriented within, and formed into a magnetically stabilized fluidized bed to provide an effective demagnetization coefficient of from about 0.0027 to about 0.174, which comprises contacting a fluid with a bed of particles containing a non-magnetic refractory, porous inorganic oxide component composited with a plurality of elongate ferromagnetic components, a ferromagnetic component being multidomain, having dimensions of at least 1 .mu.m in all directions, elongated in one or two directions, and having a length:diameter (L/D) ratio of at least 2 but not more than 19.5 where the ferromagnetic components are elongated in one direction, or an L/D ratio of not more than 313 where the ferromagnetic components are elongated in two directions, said ferromagnetic components being present in the composite particles as inclusions within a nonferromagnetic matrix, and oriented in such a way that there is a preferred direction in each particle such that all the ferromagnetic components in that particle have a long dimension essentially parallel with said preferred direction and constituting at least 0.5%, but for particles elongated in one direction not more than 2.pi./3(L/D+1).sup.2, and for particules elongated in two directions not more than .pi./2(L/D+1), of the total volume of each particle, where L/D is the average ratio of the longest dimension of a ferromagnetic component relative to the shortest dimension, and, in said magnetically stabilized bed, the particles can rotate, or turn to line up said preferred direction parallel to the direction of the field such that essentially all of the ferromagnetic components have a long dimension essentially parallel to the direction of the field, and a catalytically effective amount of a metal selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, and platinum, based on the weight of the catalyst composition, is dispersed on the surface of the composite particle, and the composite particles are catalytically active for conducting the reforming reaction.
Dependencies are inferred from the claim text.
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Iron group metals: iron
Characterised by their physical properties: mechanical properties
Catalysts, in general, characterised by their form or physical properties: characterised by their shape or configuration
Characterised by their shape or configuration: bars or plates
Term ended 17 Sep 2002 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
Recently it has been discovered that a fluidized bed of magnetizable particulate solids can be stabilized when operated under the influence of a magnetic field, and that such a bed is useful for conducting various fluid-solids contacting processes; inclusive particularly of adsorption, absorption, particulate removal and catalytic processes. Notable among these are gas-solids contacting processes primarily designed for particulate capture but which may also feature a catalytic reaction, or reactions; or the process may be primarily designed for conducting a chemical reaction, or reactions, with or without the feature of particulate capture. Processes of this type are conducted with composites wherein a ferromagnetic component is incorporated with the nonferromagnetic component, or components, to render the composite ferromagnetic.
Like conventional fluidized processes a fluid, notably a gas, is injected upwardly at velocity sufficient to overcome the free fall velocities of the individual particles (due to gravity) and cause bed expansion and fluidization of the particles without sweeping significant amounts of the particles, catalytic or otherwise, from the bed. In conventional fluidized processes, however, the injection of gas at velocity sufficient to produce expansion of the bed (i.e., transform the fixed bed from a fixed packed bed to a fluidized bed) is accompanied by significant bubble formation whereas, in contrast, in a fluidized bed subjected to the influence of a magnetic field at conditions which does not increase the weight of the bed there exists an interim, or quiescent zone wherein there is little, if any, motion exhibited by the particles within the fluidized bed. Thus, within this zone the formatin of bubbles and slugs are virtually eliminated due to the interaction between the fluidized ferromagnetic particles and the magnetic field; operation within such zone characterizing that of a magnetically stabilized bed.
Magnetically stabilized bed processes offer advantages over both fixed and fluidized bed operations. They provide superior operation over conventional fluidized bed operations in that they provide better counter-current contacting, low gas and solids back mixing, and lower particle attrition. They provide better operation as contrasted with fixed bed operations in that they provide lower pressure drop, better ability to transfer solids, and virtually eliminate bed plugging problems. A process disclosing a magnetically stabilized bed and its mode of operation for conducting catalytic reactions, and the capture of particulates to provide a filtering action is disclosed in U.S. Pat. No. 4,115,927 by Ronald E. Rosensweig.
Magnetic composite materials were prepared from atomized 410 stainless steel powder in a range of concentrations, matrices, and particle sizes. Preparative techniques included: (1) mixing the 410 stainless steel powder with a silica-alumina gel or an alumina gel and spray-drying the mixture to form a composite powder, (2) spray-drying as in (1) and then calcining the resulting powder; (3) mixing the 410 stainless steel powder with alumina powder or polypropylene powder and pressing a pellet of the mixture in a hydraulic press; and (4) mixing the stainless steel powder with silica-alumina gel and allowing the entire mixture to harden in a tray, then crushing the resulting block to form a composite powder. Concentration of stainless steel in the finished composites varied from 0.4 wt. % to 78 wt. %, and from 0.09 Vol. % to 39 Vol. %. In all cases, the volume percent stainless steel in the composite was substantially less than the volume percent stainless steel in the pure stainless steel powder (47%), so that there was substantially no direct contact of stainless steel particles within any of these composites. A very fine mesh cut of the atomized stainless steel, with particle sizes from 0 to 30 .mu.m, was used in some preparations. A coarser cut, with particle sizes from 20 to 44 .mu.m, was used in the other preparations. A total of 20 different composites were prepared.
The magnetic properties of all these samples were measured using a Princeton Applied Research Model 155 Vibrating Sample Magnetometer and a conventional laboratory electromagnet. Sample shape was varied as much as the magnetometer sample holder would permit; all samples were approximately cylindrical, with their cylinder axis perpendicular to the applied field in the magnetometer. Sample diameters could only be varied from 0.32 to 0.38 cm, but sample lengths were varied from 0.25 to 0.97 cm.
It was found that stainless steel content was the only one of these variables that had a major influence on the magnetic properties of the composite. Magnetic moment at saturation was directly proportional to stainless steel content, with a proportionality constant of 171.5 emu/g stainless steel. In addition, the magnetic moment resulting when a given field was applied to an initially demagnetized sample was found to be principally determined by the stainless steel content. In particular, when an applied field of 200 oersteds was applied to each of the twently initially demagnetized samples, the induced magnetic moment averaged 12.4 emu per gram of stainless steel in the sample, with a standard deviation of only .+-.1.5 emu/g.