Process for producing (meth)acrolein and/or (meth)acrylic acid

1. A method for producing methacrolein and/or methacrylic acid by passing a raw material gas comprising isobutylene and/or tertiary butanol and oxygen through a catalyst layer in a tubular type of fixed bed reactor which is filled with a solid oxidation catalyst, which comprises passing a gas comprising isobutylene and/or tertiary butanol in a concentration lower than that of said raw material gas, and oxygen through said catalyst layer for a period of one hour or more prior to passing said raw material gas through said catalyst layer.

2. A method for producing methacrolein and/or methacrylic acid, which comprises:

filling a tubular type of fixed bed reactor with a solid oxidation catalyst;

elevating a temperature of the resultant catalyst layer to a range of 250° C. to 400° C. while passing a gas including oxygen, nitrogen, water vapor and 0 to 0.5% by volume of isobutylene and/or tertiary butanol through said catalyst layer;

passing a gas including 1 to 3.8% by volume of isobutylene and/or tertiary butanol, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor through said catalyst layer at a temperature of 250° C. to 400° C. for a period of one hour or more; and thereafter

passing a raw material gas including 4 to 9% by volume of isobutylene and/or tertiary butanol, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor through said catalyst layer at a temperature of 250° C. to 400° C.

3. The method for producing methacrolein and/or methacrylic acid according to claim 1 or 2 , wherein said solid oxidation catalyst is a compound oxide represented by the following formula (1):

Mo a Bi b Fe c A d X e Y f Z g O h   (1)

wherein Mo, Bi, Fe and O represent molybdenum, bismuth, iron and oxygen, respectively; A represents nickel and/or cobalt; X represents at least one element selected from the group consisting of magnesium, zinc, chromium, manganese, tin and lead; Y represents at least one element selected from the group consisting of phosphorus, boron, sulfur, tellurium, silicon, germanium, cerium, niobium, titanium, zirconium, tungsten and antimony; Z represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium; and each of a, b, c, d, e, f, g and h represents an atomic ratio of each element, wherein 0.1≦b≦5, 0.1≦c≦5, 1≦d≦12, 0≦e≦10, 0≦f≦10 and 0.01≦g≦3 when a=12, and h means an atomic ratio of oxygen necessary to satisfy the atomic valence of each of said elements.

4. A method for producing acrolein and/or acrylic acid by passing a raw material gas comprising propylene and oxygen through a catalyst layer in a tubular type of fixed bed reactor which is filled with a solid oxidation catalyst, which comprises passing a gas comprising propylene in a concentration lower than that of said raw material gas, and oxygen through said catalyst layer for a period of one hour or more prior to passing said raw material gas through said catalyst layer.

5. A method for producing acrolein and/or acrylic acid, which comprises:

filling a tubular type of fixed bed reactor with a solid oxidation catalyst;

elevating a temperature of the resultant catalyst layer to a range of 250° C. to 400° C. while passing a gas including oxygen, nitrogen, water vapor and 0 to 0.5% by volume of propylene through said catalyst layer;

passing a gas including 1 to 3.8% by volume of propylene, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor through said catalyst layer at a temperature of 250° C. to 400° C. for a period of one hour or more; and thereafter

passing a raw material gas including 4 to 9% by volume of propylene, 7 to 16% by volume of oxygen and 5 to 50% by volume of water vapor through said catalyst layer at a temperature of 250° C. to 400° C.

6. The method for producing acrolein and/or acrylic acid according to claim 4 or 5 , wherein said solid oxidation catalyst is a compound oxide represented by the following formula (2):

Mo a′ Bi b′ Fe c′ A′ d′ X′ e′ Y′ f′ Z′ g′ Si h′ O i   (2)

wherein Mo, Bi, Fe, Si and O represent molybdenum, bismuth, iron, silicon and oxygen, respectively; A′ represents nickel and/or cobalt; X′ represents at least one element selected from the group consisting of magnesium, zinc, chromium, manganese, tin, strontium, barium, copper, silver and lead; Y′ represents at least one element selected from the group consisting of phosphorus, boron, sulfur, tellurium, aluminum, gallium, germanium, indium, lanthanum, cerium, niobium, tantalum, titanium, zirconium, tungsten and antimony; Z′ represents at least one element selected from the group consisting of potassium, sodium, rubidium, cesium and thallium; each of a′, b′, c′, d′, e′, f′, g′, h′ and i represents an atomic ratio of each element, wherein 0.01≦b′≦5, 0.01≦c′≦5, 1≦d′≦12, 0≦e′≦10, 0≦f′≦10, 0.001≦g′≦3 and 0≦h′≦20 when a′=12, and i means an atomic ratio of oxygen necessary to satisfy the atomic valence of each of said elements.