There is provided a method for producing isobutylene, in which isobutylene is produced from isobutanol with a high selectivity while suppressing a decrease in the isobutanol conversion rate under pressure. In the method for producing isobutylene according to the present invention, a raw material gas containing isobutanol is brought into contact with a catalyst to produce isobutylene from isobutanol, the method including bringing the raw material gas containing isobutanol into contact with a catalyst at a linear velocity of 1.20 cm/s or more under a pressure of 120 kPa or more in terms of absolute pressure to produce isobutylene from isobutanol.

The present invention provides a production method which is capable of stably producing a catalyst that enables a production of methacrylic acid with high selectivity. A method of producing a catalyst used for a production of methacrylic acid includes (i) preparing a slurry A1 containing a heteropolyacid containing at least phosphorus and molybdenum or a salt of the heteropolyacid containing at least phosphorus and molybdenum, (ii) preparing a slurry A2 satisfying the following Formula (I) and Formula (II) using the slurry A1, (iii) mixing the slurry A2 and a raw material liquid B containing a cationic raw material to prepare a slurry C, and (iv) drying the slurry C, α.sub.A2/α.sub.A1≤0.95 (I), 2≤D.sub.A2≤50 (II), wherein, in Formula (I), α.sub.A1 represents a half-value width (μm) of a particle size distribution of the slurry A1, α.sub.A2 represents a half-value width (μm) of a particle size distribution of the slurry A2, and in Formula (II), D.sub.A2 represents a median diameter (μm) of the particle size distribution of the slurry A2.

The present invention provides a production method which is capable of stably producing a catalyst that enables a production of methacrylic acid with high selectivity. A method of producing a catalyst used for a production of methacrylic acid includes (i) preparing a slurry A1 containing a heteropolyacid containing at least phosphorus and molybdenum or a salt of the heteropolyacid containing at least phosphorus and molybdenum, (ii) preparing a slurry A2 satisfying the following Formula (I) and Formula (II) using the slurry A1, (iii) mixing the slurry A2 and a raw material liquid B containing a cationic raw material to prepare a slurry C, and (iv) drying the slurry C, α.sub.A2/α.sub.A1≤0.95 (I), 2≤D.sub.A2≤50 (II), wherein, in Formula (I), α.sub.A1 represents a half-value width (μm) of a particle size distribution of the slurry A1, α.sub.A2 represents a half-value width (μm) of a particle size distribution of the slurry A2, and in Formula (II), D.sub.A2 represents a median diameter (μm) of the particle size distribution of the slurry A2.

The present invention relates to a high-performance polyoxometalate catalyst and a method of preparing the same. More particularly, the present invention provides a high-performance polyoxometalate catalyst, the activity and selectivity of which may be improved by controlling the content of vanadium and the like and which has superior reproducibility and may unsaturated carboxylic acid from unsaturated aldehyde in a high yield for a long time, a method of preparing the same, and the like.

The present invention relates to a high-performance polyoxometalate catalyst and a method of preparing the same. More particularly, the present invention provides a high-performance polyoxometalate catalyst, the activity and selectivity of which may be improved by controlling the content of vanadium and the like and which has superior reproducibility and may unsaturated carboxylic acid from unsaturated aldehyde in a high yield for a long time, a method of preparing the same, and the like.

The invention relates to a catalyst system for producing maleic anhydride by means of the catalytic oxidation of n-butane, comprising at least one reactor tube, which has two catalyst layers consisting of different catalyst particles, characterized in that the geometric surface area per catalyst particle is greater in the catalyst layer that is first in the gas flow direction than in the second catalyst layer. The invention further relates to a process for producing maleic anhydride by means of the catalytic oxidation of n-butane, wherein a mixture of oxygen and n-butane is fed through the catalyst system according to the invention and the at least one reactor tube is at elevated temperature.

A method for producing xylylenediamine, including performing a first hydrogenation including hydrogenating a mixed solution including dicyanobenzene and a solvent including liquid ammonia in a fixed-bed reactor such that a reaction product (A) is produced, performing ammonia separation including separating and removing liquid ammonia included in the reaction product (A) or a reaction product (D) such that a reaction product (B) or (E) is produced, performing solid-liquid separation including subjecting the reaction product (B) or (A) to solid-liquid separation and removing a solid component such that a reaction product (C) or the reaction product (D) is produced, and performing a second hydrogenation including hydrogenating the reaction product (C) or (E) in a fixed-bed reactor. After the first hydrogenation is performed, the ammonia separation and the solid-liquid separation are performed in this order or reverse order, followed by the second hydrogenation.

Disclosed is a method for preparing a heteropolyacid salt catalyst, comprising dissolving the lead compounds for each element to prepare a suspension and dispersion slurry of catalyst precursor, which comprises all of the catalyst components; drying the catalyst precursor, mixing them with an organic compound, molding, and calcining to produce the catalyst.

Disclosed is a method for preparing a heteropolyacid salt catalyst, comprising dissolving the lead compounds for each element to prepare a suspension and dispersion slurry of catalyst precursor, which comprises all of the catalyst components; drying the catalyst precursor, mixing them with an organic compound, molding, and calcining to produce the catalyst.

A catalytic bed for the partial oxidation of n-butane to maleic anhydride which comprises at least one first catalytic layer and at least one second catalytic layer, wherein each catalytic layer consists of a vanadium and phosphorus mixed oxide (VPO) catalyst and only the catalyst of the second catalytic layer further comprises tungsten, and wherein the second catalytic layer constitutes 25% to 45% of the total length of the catalytic bed and is arranged consecutively after the first catalytic layer along the direction in which the mixture of gases comprising the oxidation reagents flows. The present invention also relates to a process for producing maleic anhydride by partial oxidation of n-butane which uses the catalytic bed.