The present invention relates to an impregnated supported catalyst, a carbon nanotube aggregate, and a method for producing the carbon nanotube aggregate. The carbon nanotube aggregate includes a four-component catalyst in which catalytic components and active components are supported on a granular support, and bundle type carbon nanotubes grown on the catalyst. The carbon nanotube aggregate has an average particle diameter of 100 to 800 m, a bulk density of 80 to 250 kg/m.sup.3, and a spherical or potato-like shape.

The present invention relates to an impregnated supported catalyst, a carbon nanotube aggregate, and a method for producing the carbon nanotube aggregate. The carbon nanotube aggregate includes a four-component catalyst in which catalytic components and active components are supported on a granular support, and bundle type carbon nanotubes grown on the catalyst. The carbon nanotube aggregate has an average particle diameter of 100 to 800 m, a bulk density of 80 to 250 kg/m.sup.3, and a spherical or potato-like shape.

A method for producing at least one oxidation product selected from the group consisting of acrolein and acrylic acid is provided. This method can alleviate concerns about deterioration of a gas-phase oxidation catalyst and reaction runaway in a restart period after a shutdown, and can allow the reaction to proceed in a stable state. Using a fixed-bed reactor filled with a gas-phase oxidation catalyst, at least one source gas selected from the group consisting of propylene and acrolein is subjected to a gas-phase contact oxidation reaction while a heating medium is caused to contact with or circulate through the fixed-bed reactor and thereby to heat the fixed-bed reactor. The temperature of the heating medium when the load is maximum in the restart period after the shutdown is controlled to be lower than the temperature of the heating medium when the load is maximum in an initial start-up period.

A method for producing at least one oxidation product selected from the group consisting of acrolein and acrylic acid is provided. This method can alleviate concerns about deterioration of a gas-phase oxidation catalyst and reaction runaway in a restart period after a shutdown, and can allow the reaction to proceed in a stable state. Using a fixed-bed reactor filled with a gas-phase oxidation catalyst, at least one source gas selected from the group consisting of propylene and acrolein is subjected to a gas-phase contact oxidation reaction while a heating medium is caused to contact with or circulate through the fixed-bed reactor and thereby to heat the fixed-bed reactor. The temperature of the heating medium when the load is maximum in the restart period after the shutdown is controlled to be lower than the temperature of the heating medium when the load is maximum in an initial start-up period.

The present invention provides a catalyst including Mo, Bi, and Fe, wherein P/R is 0.10 or less, wherein P is a peak intensity at 2=22.90.2 and R is a peak intensity at 2=26.60.2, in X-ray diffraction analysis.

The present invention provides a catalyst including Mo, Bi, and Fe, wherein P/R is 0.10 or less, wherein P is a peak intensity at 2=22.90.2 and R is a peak intensity at 2=26.60.2, in X-ray diffraction analysis.

A catalyst system has been designed that disrupts the sedimentation process. The catalyst system achieves this by saturating key feed components before the feed components are stripped into their incompatible aromatic cores. The efficacy of this disruptive catalyst system is particularly evident in a hydrocracker configuration that runs in two-stage-recycle operation. The catalyst is a self-supported multi-metallic catalyst prepared from a precursor in the hydroxide form, and the catalyst must be toward the top level of the second stage of the two-stage system.

A catalyst system has been designed that disrupts the sedimentation process. The catalyst system achieves this by saturating key feed components before the feed components are stripped into their incompatible aromatic cores. The efficacy of this disruptive catalyst system is particularly evident in a hydrocracker configuration that runs in two-stage-recycle operation. The catalyst is a self-supported multi-metallic catalyst prepared from a precursor in the hydroxide form, and the catalyst must be toward the top level of the second stage of the two-stage system.

A hydroprocessing catalyst or catalyst precursor has been developed. The catalyst is a unique crystalline ammonia transition metal molybdotungstate material. The hydroprocessing using the crystalline ammonia transition metal molybdotungstate material or a decomposition product thereof may include hydrodenitrification, hydrodesulfurization, hydrodemetallation, hydrodesilication, hydrodearomatization, hydroisomerization, hydrotreating, hydrofining, and hydrocracking.

A hydroprocessing catalyst or catalyst precursor has been developed. The catalyst is a unique crystalline ammonia transition metal molybdotungstate material. The hydroprocessing using the crystalline ammonia transition metal molybdotungstate material or a decomposition product thereof may include hydrodenitrification, hydrodesulfurization, hydrodemetallation, hydrodesilication, hydrodearomatization, hydroisomerization, hydrotreating, hydrofining, and hydrocracking.