Abstract: A process for conducting long-term ammoxidation of propylene in the presence of a metal oxide catalyst for ammoxidation of propylene at a temperature of from 300.degree. C. to 500.degree. C. to produce acrylonitrile and hydrogen cyanide, wherein in the process each of (A) elemental phosphorus or a phosphorus compound and (B) elemental tellurium or a tellurium compound is added as a regenerating agent at least once to the ammoxidation reaction system in accordance with the progress of the reaction, the regenerating agent (A) being added when the yields of both of acrylonitrile and hydrogen cyanide are reduced, and the regenerating agent (B) is chosen when the yield of acrylonitrile is reduced and the yield of hydrogen cyanide is unchanged or increased, to thereby maintain high levels of yields of acrylonitrile and hydrogen cyanide.

Abstract: A process for producing 2,6-dichlorobenzonitrile by ammoxidation comprising contacting a starting gas consisting of 2,6-dichlorotoluene, air and ammonia, which comprises carrying out this reaction under the following conditions:(a) the concentration of 2,6-dichlorotoluene in the starting gas is 2.6 mole % or more.(b) the reactor effluent gas is contacting with water to cool to a temperature in the range of 50.degree. to 90.degree. C., whereby 2,6-dichlorobenzonitrile in the reactor effluent gas is collected as a slurry in which solidified 2,6-dichlorobenzonitrile is dispersed in water, and 2,6-dichlorobenzonitrile is obtained from the slurry, and(c) the cooled reactor effluent gas from which 2,6-dichlorobenzonitrile has been removed is contacted with water again to cool to a temperature in the range of 0.degree. to 40.degree. C., whereby unreacted 2,6-dichlorotoluene in the gas is collected as a dispersion in which it is dispersed in water and 2,6-dichlorotoluene is recovered from the dispersion.

Abstract: The activity of a tellurium-free metal oxide catalyst used for ammoxidation of organic compounds at a temperature of from 300.degree. C. to 600.degree. C. is improved in the presence of (a) elemental tellurium or a tellurium compound which is in contact with said catalyst or in the presence of (a) elemental tellurium or a tellurium compound and (b) a molybdenum compound which are in contact with said catalyst. This activity improvement process can be applied to both the fresh catalysts and the spent catalyst having a deteriorated activity. The above described component (a) is preferably composed of a tellurium containing solid to be used in a state of a dry physical mixture with said catalyst. The above described components (a) and (b) are preferably composed of a tellurium containing solid and a molybdenum containing solid respectively or a tellurium-molybdenum containing solid to be used in a state of a dry physical mixture with said catalyst.

Abstract: Iron-antimony metallic oxide catalysts which have become deactivated after being used for the production of aldehydes, acids, nitriles, or dienes through oxidation, ammoxidation, or oxidative dehydrogenation of organic compounds in fluidized-bed reactors are regenerated by adding to the catalyst a molybdenum-enriched catalyst formed by supporting a molybdenum component which is volatile or capable of forming a volatile compound under reaction conditions on a metallic oxide catalyst. The metallic oxide catalysts contain as essential components (I) Fe, (II) Sb, (III) at least one element selected from the group consisting of V, Mo and W, and (IV) Te.

Abstract: A process for improving the activity of tellurium containing metal oxide catalysts useful as catalysts for oxidation, ammoxidation or oxidative dehydrogenation of organic compounds by heating the catalysts together with a tellurium containing solid and an optional molybdenum containing solid to a temperature up to about 900.degree. C. in a gaseous atmosphere. The process can be effectively applied to deteriorated or spent catalysts, the activity of which has been deteriorated due to use for a long period of time. The tellurium containing solid used as an activity improving agent is elemental tellurium and the molybdenum containing solid is selected from the group consisting of (i) a molybdenum compound, (ii) at least one molybdenum compound supported on an inert carrier, and (iii) a molybdenum enriched catalyst prepared by adding a Mo component to a metal oxide catalyst (which may be a fresh catalyst or a deteriorated catalyst).

Abstract: A process for improving the activity of tellurium containing metal oxide catalysts useful as catalysts for oxidation, ammoxidation or oxidative dehydrogenation of organic compounds by heating the catalysts together with an activity-improving agent to a temperature up to about 900.degree. C. in a gaseous atmosphere. The process can be effectively applied to deteriorated or spent catalysts, the activity of which has been deteriorated due to use for a long period of time.

Abstract: A regeneration process for tellurium-containing metal oxide catalysts used in the process for oxidation, ammoxidation or oxidative dehydrogenation of organic compounds at a temperature of about 300.degree. C. to about 600.degree. C. The process can be effectively applied to such catalysts which have become partially deactivated during the reaction.

Abstract: Iron-antimony metallic oxide catalysts which have become deactivated after being used for the production of aldehydes, acids, nitriles, or dienes through oxidation, ammoxidation, or oxidative dehydrogenation of organic compounds in fluidized-bed reactors are regenerated by adding to the catalyst a solid molybdenum component which is volatile or capable of forming a volatile compound under reaction conditions. The metallic oxide catalysts contain as essential components (I) Fe, (II) Sb, (III) at least one element selected from the group consisting of V, MO, and W, and (IV) Te.