Heterogeneous metal oxide catalysts are widely studied for the aerobic oxidations of C1–C4 alkanes to form olefins and oxygenates. In this review, we outline the properties of supported metal oxides, mixed-metal oxides, and zeolites and detail their most common applications as catalysts for partial oxidations of light alkanes. By doing this we establish similarities between different classes of metal oxides and identify common themes in reaction mechanisms and research strategies for catalyst improvement. For example, almost all partial alkane oxidations, regardless of the metal oxide, follow Mars–van Krevelen reaction kinetics, which utilize lattice oxygen atoms to reoxidize the reduced metal centers while the gaseous O2 reactant replenishes these lattice oxygen vacancies. Many of the most-promising metal oxide catalysts include V5+ surface species as a necessary constituent to convert the alkane. Transformations involving sequential oxidation steps (i.e., propane to acrylic acid) require specific reacti...

Aerobic Oxidations of Light Alkanes over Solid Metal Oxide Catalysts

The present invention relates to processes for purifying a composition containing (meth)acrylic acid, at least one impurity and water, wherein the composition has a water content in the range of 0.55 to 90, based on the composition, to form a purified phase containing (meth)acrylic acid and at least one impurity, wherein, in the purified phase, the quantity of at least one impurity is less than 7% by weight, based on (meth)acrylic acid in the purified phase.

meth)acrylic acid crystal and method for the production and purification of aqueous (meth)acrylic acid

A memory device has a global input/output line pair configured for data transfer The memory device includes a sense amplifier, a detecting unit and a detect control signal generating unit The sense amplifier is coupled to the global input/output line pair The detecting unit detects a potential difference between the global input/output line pair The detect control signal generating unit disables an operation of the sense amplifier and precharges the global input/output line pair to a predetermined voltage A precharge operation of a memory device may be performed at a higher speed so that a high speed operation of the memory device may be achieved In addition, the operating time of the sense amplifier may be decreased so that the power consumption of the memory device may be reduced

Memory device and method of operating the same

A catalyst comprising a promoted mixed metal oxide is useful for the vapor phase oxidation of an alkane or a mixture of an alkane and an alkene to an unsaturated carboxylic acid and for the vapor phase ammoxidation of an alkane or a mixture of an alkane and an alkene to an unsaturated nitrile.

Promoted multi-metal oxide catalyst

A process for the catalytic gas-phase oxidation of propene to acrylic acid, in which the reaction gas starting mixture is oxidized, with a high propene loading, in a first reaction stage, over a first fixed-bed catalyst which is housed in two successive reaction zones A, B, the reaction zone B being kept at a higher temperature than the reaction zone A, and the acrolein-containing product gas mixture of the first reaction stage is then oxidized in a second reaction stage, with a high acrolein loading, over a second fixed-bed catalyst which is housed in two successive reaction zones C, D, the reaction zone D being kept at a higher temperature than the reaction zone C.

Method for the catalytic gas phase oxidation of propene into acrylic acid

A method for producing an unsaturated carboxylic acid, which comprises subjecting an alkane to a vapor phase catalytic oxidation reaction in the presence of a catalyst containing a mixed metal oxide comprising, as essential components, Mo, V, Te, O and X wherein X is at least one element selected from the group consisting of niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, wherein the proportions of the respective essential components, based on the total amount of the essential components exclusive of oxygen, satisfy the following formulas: 0.25<r.sub.Mo <0.98 0.003<r.sub.V <0.5 0.003<r.sub.Te <0.5 0.003<r.sub.X <0.5 wherein r Mo , r V , r Te and r X are molar fractions of Mo, V, Te and X, respectively, based on the total amount of the essential components exclusive of oxygen.

Method for producing an unsaturated carboxylic acid

PURPOSE:To produce an alpha, beta-unsaturated carboxylic acid in high yield by adding steam to a raw material gas in catalytically oxidizing an aliphatic saturated hydrocarbon in vapor phase in the presence of a compound metal oxide catalyst. CONSTITUTION:In producing an alpha, beta-unsaturated carboxylic acid by catalytically oxidinzing a 3-8C aliphatic saturated hydrocarbon in a vapor phase in the presence of a compound metal oxide catalyst, a gas comprising an aliphatic saturated hydrocarbon, steam and an oxygen-containing gas in the molar ratio of hydrocarbon:oxygen:a diluting gas:H2O=1:(0.1-10.0):0-20:(0.2-70) is used as a raw material gas and one or more of (i) Mo, V, Te, >=1 kind metal selected from among X and oxygen, (ii) Bi, No, >=1 kind metal selected from among X and oxygen, (iii) V, >=1 kind metal selected from among X and oxygen and (ir)Fe, >=1 kind metal selected from among X and oxygen as essential components are used as the compound metal oxide catalyst. Especially the component (i) is preferable. X :Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rk, Ni, Pd, Pt, Sb, Bi, B, In, Cs;X : V, Nb, Tl, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, P, B, Pb, Ga, In, Ce, Li, Na, K, Rb, Cs, Tl, Cu, Ag; X : Fe, Sb, P, Li, Na, K, Rb, Cs, W, Ti, Al, Zr, Sn, Ge, In; X : Sb, P, Cr, Ti, Mo, Al, Zr, Sn, Ge, In.

Production of alpha, beta-unsaturated carboxylic acid

A catalyst for the production of a nitrile from an alkane, which satisfies the following conditions 1 and 2: 1 the catalyst is represented by the empirical formula: Mo.sub.a V.sub.b Te.sub.c X.sub.x O.sub.n (1) wherein X is at least one element selected from the group consisting of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B and Ce, when a=1, b=0.01 to 1.0, c=0.01 to 1.0, x=0.01 to 1.0, and n is a number such that the total valency of the metal elements is satisfied; and 2 the catalyst has X-ray diffraction peaks at the following angles of 2θ in its X-ray diffraction pattern: Diffraction angles of 2θ (°) 22.1±0.3 28.2±0.3 36.2±0.3 45.2±0.3 50.0±0.3.

Catalyst for the production of nitriles

PURPOSE: To produce unsaturated carboxylic acids through a one-step process from alkane in a high yield. CONSTITUTION: In the presence-of a catalyst which comprises, as essential components, Mo, V, Te, O and X (X is one or more elements selected from the group consisting of Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In and Ce) where the ratios of individual essential components to the total essential elements except oxygen are 0.25<rMO<0.98; 0.003< rV<0.5; 0.003<rT e <0.5; 0.003<r x <0.5, respectively (rMO, rV, rT e and r x are molar fractions of Mo, V, Te, and X based on these essential components except oxygen, respectively), alkane is subjected to gas-phase catalytic oxidation to give unsaturated carboxylic acid. COPYRIGHT: (C)1994,JPO

Production of unsaturated carboxylic acid

Catalyst particles are efficiently separated from particles substantially inactive in a reaction and the catalyst particles are optionally separated into groups of different kinds to thereby enable the efficient regeneration of the catalyst. A solid catalyst ingredient which has deteriorated in a reaction is regenerated via a discharge step in which a catalyst-containing ingredient containing the solid catalyst ingredient is discharged from a fixed-bed reactor. When the solid catalyst ingredient comprises two or more components of different shapes, a catalyst component separation step for separating the solid catalyst components from each other is conducted after the discharge step, and the solid catalyst components are then regenerated. When the catalyst-containing ingredient contains an inactive ingredient, an inactive-ingredient separation step for separating the inactive ingredient is conducted after the discharge step, and the solid catalyst ingredient is then regenerated.

Hiroya Nakamura

Papers

Method for producing an unsaturated carboxylic acid

Production of alpha, beta-unsaturated carboxylic acid

Catalyst for the production of nitriles

Production of unsaturated carboxylic acid

Method of regenerating catalyst