E.i. Dupont De Nemours and Company

Other

Rashmikant M Contractor

Sang-Hak Hwang

Harold S Horowitz

Daniel Campos

Birol Kirayoglu

Mark William Andersen

Gerard Hecquet

Michel Simon

Roland Kotwica

Charlotte Pham

Mireille Stojanovic

Jean-Pierre Schirmann

Arthur W Sleight

Donald I Garnett

Earl Edwin Seppala

John Donal Sullivan

William Carter Dodson, Jr

Gregg Mason Sisler

James John Hentges

William Joseph Letts

Gregory Scott Patience

An improved method for the selective vapor phase oxidation of propylene to acrolein in a recirculating solids reactor system using a bismuth molybdate multimetal oxide involving specific reactant concentrations (preferably 5 mol % to 30 mol % propylene, 0 to 20 mol % oxygen, and the remainder inert gas), particle size (1 to 300 micrometers), temperature (250 to 450&deg; C.) and gas (1 to 15 seconds) and solids (2 to 60 seconds) residence times. Such a process leads to improved selectivity and propylene conversion.

Vapor phase oxidation of propylene to acrolein

An improved method for the selective vapor phase oxidation of acrolein to acrylic acid in a recirculating solids reactor system using a particulate molybdenum vanadate multimetal oxide as oxidant involving specific reactant concentrations (preferably 5 mol % to 30 mol % propylene, 0 to 20 mol % oxygen, 0 to 70 mol % water, and the remainder inert gas), solids particle size (20 to 300 micrometers), temperature (250 to 450&deg; C.) and gas (1 to 15 seconds) and solids (2 to 60 seconds) residence times. Such a process leads to improved selectivity, conversion and solids conversion ratio.

Vapor phase oxidation of acrolein to acrylic acid

A method for manufacturing of an improved attrition resistant catalyst having an oxide-rich surface layer involving forming a slurry comprising; catalyst, catalyst precursor or catalyst support particles (e.g., transition metal oxides), a colloidal oxide sol (e.g., colloidal silica), and a solution of a solvent and solute wherein the solute consist essentially of a precursor of said oxide-rich surface with particle size no greater than 5 nm (e.g., aqueous silicic acid or polysilicic acid) and then spray drying the slurry to form porous microspheres of attrition resistant catalyst; and, calcining the spray dried microspheres. Such a catalyst is particularly useful in oxidation processes wherein the oxidation is performed by an oxidized form of the catalyst and the resulting reduced form of the catalyst is separately regenerated (e.g., two-step vapor phase processes carried out in recirculating solids reactors, transport bed reactors or circulating fluidized bed reactors and the like).

Process for manufacture and use of improved attrition resistant catalyst

An improved process for calcination and activation of a catalyst containing mixed oxides of vanadium and phosphorus (V/P/O) involving the addition of spray dried catalyst precursor to a fluidizing oxygen containing gas at a controlled rate such that the temperature is maintained at a range of 370 to 410.degree. C. (preferably 390.+-.5.degree. C.). The catalyst precursor experiences, in addition to rapid temperature rise, dehydration/calcination at this elevated temperature in the fluidized state for an average range of residence time of less than about 4 hours at 3.5 atm of air or above, and up to 20 hours at 1 atm of air while simultaneously and continuously maintaining an average V.sub.ox of 4.55 or less. Such a process is useful in preparing a V/P/O catalyst that exhibits enhanced activity for the oxidation of n-butane to maleic anhydride. The novel process also provides an improved method for start-up of a commercial scale recirculating solids reactor.

Process for the calcination/activation of V/P/O catalyst

An improved process for calcination and activation of a catalyst containing mixed oxides of vanadium and phosphorus (V/P/O) comprising the steps of calcining a hydrated V/P/O or V/P/O- SiO.sub.2 catalyst precursor at a temperature range of 375.degree. to 400.degree. C. for sufficient time to dehydrate said catalyst precursor while simultaneously and continuously controlling the oxygen level such as to maintain the Vox in the range of 3.825 to 4.175; and then activating the dehydrated catalyst precursor by further heating at a range of 340.degree. to 500.degree. C. in the presence of a gaseous atmosphere containing n-butane at a partial pressure not exceeding 0.20 atm while simultaneously and continuously controlling the oxygen level such as to maintain the Vox in the range of 3.95 to 4.15. Such a V/P/O catalyst is useful in the preparation of maleic anhydride from n-butane.

An improved process for selective vapor phase oxidation of n-butane to maleic anhydride involving the use of a recirculating solids reactor having a reaction zone and a catalyst regeneration zone wherein n-butane is converted to maleic acid in the reaction zone by use of a vanadium/phosphorous oxide (V/P/O) catalyst in oxidized form and the reduced vanadium/phosphorous oxide catalyst is regenerated by contact with oxygen in the regeneration zone. Replenishment of the inherent catalyst losses associated with the catalyst recycling process is accomplished by adding to the catalyst in the regeneration zone vanadium/phosphorous oxide catalyst precursor at a rate of addition that effectuates in situ calcination and activation of the vanadium/phosphorous oxide catalyst precursor while simultaneously maintaining the desired operating temperature of the n-butane to maleic anhydride conversion reaction. Such a process is useful in maintaining the high operating capacity of the reactor over an extended period of time.

Vapor phase catalytic oxidation of N-butane to maleic anhydride

The oxidation of butane to maleic anhydride in a recirculating solids reactor using a stoichiometric excess of oxygen, a vanadium-phosphorus oxide catalyst in oxidized form, and separate regeneration of the resultant reduced catalyst is disclosed.

Vapor phase catalytic oxidation of butane to maleic anhydride

Oxidation of butane to maleic anhydride using a vanadium-phosphorus oxide catalyst, in oxidized form, wherein the resulting reduced catalyst is separately regenerated. A recirculating solids reactor can be employed. Less than the stoichiometric amount of oxygen, based on the total amount of butane converted, can be employed.

Improved vapor phase catalytic oxidation of butane to maleic anhydride

Process is disclosed which is suitable for high speed production of uniform, lightweight webs by air-laydown of textile fibers. A toothed disperser roll doffs the fibers into an air stream of high uniform velocity and low turbulence to form a thin fiber layer from which the fibers are deposited in web form on a moving screen. A curved disperser plate, shrouds a portion of the disperser roll up to the point of fiber doffing. By using a disperser plate with a rough surface, preferably one having lateral grooves, web uniformity is remarkably improved.

Air lay-down process for producing uniform lightweight webs from textile

The tensile strength of nonwoven fabric made by traversing a fibrous web on an apertured support with fine columnar streams of liquid is increased when the fine columnar streams are divided up into an array of a plurality of rows of streams, instead of a single row, with the streams in each row being staggered from one another and the rows being spaced 10 to 80 mils apart.

Process for making nonwoven fabric

A compressed batt of fibers is fed against a rotating toothed roll for dispersion of the fibers from the batt and this dispersion of fibers is fed through the point of closest clearance between the toothed roll and a feed roll rotating in the opposite direction. Downstream of this point of closest clearance, a stationary shoe is provided spaced from the surface of the toothed roll to permit the dispersion of fibers to follow the surface of the toothed roll. The shoe is closely fitted to the surface of the feed roll which has the effect of forming a pinch point where the feed roll enters beneath the shoe. In accordance with the invention, the shoe is equipped with passages for the flow of air to exit at the pinch point to prevent fibers from entering the pinch point, i.e., between the feed roll and shoe.

Prevention of fibers from entering the pinch point between a rotating

A staple fiber batt of improved uniformity is made by the fibers falling onto a moving conveyor, skimming off the top of the batt by jets of air flowing across the top of the batt, which thereby determines the level of the batt, and redepositing the skimmed off fibers onto said batt. The batt can then be compacted for further processing.

Process for forming a staple fiber batt

The tensile strength of apertured nonwoven fabric can be increased by a change in the two-stage process of impinging fine columnar streams of liquid, first onto one face of a fibrous web and then onto the opposite face thereof, the change being that the asymmetrical woven wire screen on which the web is positioned during the second stage of the process is oriented with the wire forming the higher knuckle in the screen running in the direction of passage of the web beneath the fine columnar streams, with the area weight of the web being from 0.5 to 2.0 oz/yd.sup.2.

Process for making an apertured nonwoven fabric

Apparatus for depositing staple fibers onto a conveyor belt to form a batt, including a chute feeder having an adjustable weir plate provided with a row of air jets along the bottom edge for maintaining a uniform fiber level at the exit from the chute. Fibers are supplied in an air stream from which they are separated by condenser means and fall into the chute over distributing baffles.

Apparatus for forming a batt from staple fibers

Process and apparatus are disclosed which are suitable for high speed production of uniform, lightweight webs by air-laydown of textile fibers. A toothed disperser roll doffs the fibers into an air stream of high uniform velocity and low turbulence to form a thin fiber stream from which the fibers are deposited in web form on a moving screen. A curved disperser plate, shrouds the disperser roll and prevents premature doffing. By using a disperser plate with a rough surface, preferably one having lateral grooves, web uniformity is remarkably improved.

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Wilmington, DE, United States of America

Rashmikant M Contractor