Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
  • B01J23/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B61/00—Other general methods
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
  • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
  • C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
  • C07C45/35—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds in propene or isobutene
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C47/00—Compounds having —CHO groups
  • C07C47/20—Unsaturated compounds having —CHO groups bound to acyclic carbon atoms
  • C07C47/21—Unsaturated compounds having —CHO groups bound to acyclic carbon atoms with only carbon-to-carbon double bonds as unsaturation
  • C07C47/22—Acryaldehyde; Methacryaldehyde
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/215—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of saturated hydrocarbyl groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/23—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups
  • C07C51/235—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups of —CHO groups or primary alcohol groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C57/00—Unsaturated compounds having carboxyl groups bound to acyclic carbon atoms
  • C07C57/02—Unsaturated compounds having carboxyl groups bound to acyclic carbon atoms with only carbon-to-carbon double bonds as unsaturation
  • C07C57/03—Monocarboxylic acids
  • C07C57/04—Acrylic acid; Methacrylic acid

Definitions

• the present invention relates to a method for producing the corresponding unsaturated aldehyde or unsaturated carboxylic acid by gas-phase catalytic oxidation of an alkene with molecular oxygen or a molecular oxygen-containing gas.
• Patent Document 1 Methods for producing the corresponding unsaturated aldehydes and/or unsaturated carboxylic acids using propylene, isobutylene, tertiary butyl alcohol, etc. as raw materials are widely used industrially (for example, Patent Document 1).
• Patent Document 1 relates to a catalyst for improving the yield of the target product, unsaturated aldehyde and/or unsaturated carboxylic acid, but it also discloses several technologies related to not only the catalyst itself but also the method of packing the catalyst, as described below.
• Patent Document 2 discloses a technology for using a catalyst whose activity is adjusted by changing the volume occupied by the catalyst molded body and the calcination temperature of the catalyst. This is a method for packing a catalyst containing a specific inert carrier so that the activity becomes higher from the reaction gas inlet side to the outlet side in order to suppress the occurrence of localized high temperature areas (hot spots) in the catalyst layer.
• Patent Document 3 discloses a technology for obtaining a target product with high yield and high activity by packing the catalyst so that the composition ratio of the active components changes from the reaction gas inlet side to the outlet side.
• Patent Document 4 discloses a technology for suppressing hot spots and obtaining a high yield of unsaturated aldehyde by specifying the packing length ratio of each layer of a catalyst packed in two layers.
• Patent Document 5 discloses a technology for suppressing hot spot temperature and obtaining a high yield by specifying reaction conditions and catalysts to control the temperature change of the hot spot per reaction bath temperature.
• the reaction bath temperature is controlled by measuring the temperature of the heat medium in the reactor with a thermocouple and heating the heat medium with a heater, but the feedback of the heater temperature control is not always perfect. For example, hunting due to poor feedback, or feedback failure due to unintended disturbances or component defects may occur, causing the reaction bath temperature to fluctuate rather than always being constant. As a result, the yield of the target product also changes sharply, making it impossible to obtain the target product stably over time.
• a method for packing a catalyst that shows a higher yield of the target product in a wider reaction bath temperature range than in the past has been required, but such a method has not been disclosed so far.
• a method for producing an unsaturated aldehyde or unsaturated carboxylic acid as the target product in a method for catalytically oxidizing an alkene with molecular oxygen or a molecular oxygen-containing gas in the gas phase it can be said that a method for packing a catalyst that shows a higher yield of the target product in a wider reaction bath temperature range than in the past has not been disclosed.
• the inventors have thoroughly investigated the above-mentioned current situation and problems, and as a result, have focused on packing the catalyst so as to widen the reaction bath temperature range (hereinafter referred to as the operation window) in which the combined yield of unsaturated aldehydes and unsaturated carboxylic acids, particularly the combined yield (effective yield) of acrolein and acrylic acid, is stable when the reaction is carried out in a packing having a catalyst layer divided into two or more layers, in a method for producing the corresponding unsaturated aldehyde or unsaturated carboxylic acid by partially oxidizing an alkene using a fixed-bed multitubular reactor.
• the operation window the reaction bath temperature range in which the combined yield of unsaturated aldehydes and unsaturated carboxylic acids, particularly the combined yield (effective yield) of acrolein and acrylic acid, is stable when the reaction is carried out in a packing having a catalyst layer divided into two or more layers, in a method for producing the corresponding unsaturated aldehyde
• the inventors have found that by optimally setting the slope of the raw material conversion rate with respect to the reaction bath temperature of the catalyst in each layer (hereinafter referred to as temperature sensitivity), the packing length ratio, and the dilution rate in accordance with the raw material load, which is the reaction condition, the operation window can be widened (i.e., a high effective yield can be stably achieved in a wider reaction bath temperature range), and further the effective yield itself can be increased, making it possible to operate the plant with a higher yield and more stable.
• the present invention relates to the following 1) to 8).
• n is the total number of catalyst layers in the reaction tube.
• the subscript i is a natural number from 1 to n.
• the catalyst layers do not include an inert layer that is intentionally filled with only inert materials.
• 2) The method for producing an unsaturated aldehyde or unsaturated carboxylic acid according to the above item 1), wherein the production parameter T satisfies the following formula (V): 9.5 ⁇ T ⁇ 16.5 (V) 3)
• n catalyst layers (n is 2 or more) are provided in the gas flow direction of the reaction tube,
• the method for producing an unsaturated carboxylic acid of the present invention is characterized in that a production parameter T satisfies the following formula (I).
• a production parameter T satisfies the following formula (I).
• the lower limit of the production parameter T may be 0, and is preferably 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0.
• the upper limit of the production parameter T is more preferably 19.0, 18.5, 18.0, 17.5, 17.0, 16.5, 16.0, 15.5, 15.0, 14.5, 14.3.
• the manufacturing parameter T is preferably 0 or more and 20.5 or less, more preferably 0.5 or more and 20.5 or less, more preferably 1.0 or more and 20.5 or less, more preferably 1.5 or more and 20.5 or less, more preferably 2.0 or more and 20.5 or less, more preferably 2.5 or more and 20.5 or less, more preferably 3.0 or more and 20.5 or less, more preferably 3.5 or more and 20.5 or less, more preferably 4.0 or more and 20.5 or less, more preferably 4.5 or more and 20.5 or less, more preferably 5.0 or more and 20.5 or less, and more preferably 5.5 or more and 20.
• a slight change in reaction bath temperature or a difference in reaction bath temperature between multiple reaction tubes causes a sharp change in the hot spot on the most active outlet catalyst, thereby preventing thermal runaway and the associated damage and explosion of the reaction tube.
• the advantage is that the effective yield can be stably maintained high at a lower reaction bath temperature, and the above-mentioned problems can be solved.
• the temperature-sensitive parameter CBi of the catalyst of the present invention is defined as the rate of change in the raw material conversion rate (x) with respect to the reaction bath temperature (BT) in the temperature range of the reaction bath temperature of the i-th catalyst layer from 340°C to 360°C.
• the catalyst layers closest to the inlet side among all catalyst packed layers are numbered as 1st layer, 2nd layer, etc., and the corresponding CBi are named CB1, CB2, etc. (other parameters are defined in the same way in the present invention).
• CBi The total number of catalyst layers is defined as n.
• CBi is defined in more detail as follows.
• the catalyst in the i-th layer is packed into a differential reactor, and the feed gas conversion rate x (340°C) (unit: %) obtained at a reaction bath temperature (hereinafter sometimes referred to as BT) of 340°C and the feed gas conversion rate x (360°C) (unit: %) obtained at a BT of 360°C are plotted, and the slope of the straight line connecting these points is defined as CBi. That is, CBi is expressed by the following formula.
• CBi (%/°C) (x (360°C) (%) - x (340°C)) (%) / 20 (°C)
• the temperature sensitivity parameter of a catalyst calculated at a stage where the layer number to be packed has not yet been determined is simply referred to as the CB of that catalyst in this invention.
• the above-mentioned raw gas conversion rate x is calculated in the present invention by the following method.
• the raw gas conversion rate x is calculated by the following formula using a calibrated gas chromatograph. The formula for the calculation when the raw material gas is propylene is shown below.
• the number of moles of reacted propylene is the value obtained by subtracting the number of moles of propylene remaining after the reaction from the number of moles of propylene supplied.
• Propylene conversion rate x (mol%) (number of moles of reacted propylene/number of moles of supplied propylene) x 100
• Savg is a packing parameter determined by the catalyst type and packing package, and when a single catalyst layer is packed, Savg is S1.
• Savg (%/°C) (S1 (%/°C) +...+Sn (%/°C)) ⁇ n (III)
• the number n of catalyst layers is preferably 2 to 5 layers, more preferably 2 to 4 layers, particularly preferably 2 to 3 layers, and most preferably 3 layers.
• the production parameter T is calculated from Savg and the space velocity SVo of the raw material according to the following formula (IV).
• T (% ⁇ hr/°C) Savg(%/°C) ⁇ SVo(/hr) ⁇ 10000 (IV)
• the lower limit of Savg is preferably 0.090, 0.100, 0.150, 0.170, 0.190, 0.200, 0.220, and particularly preferably 0.240.
• the upper limit of Savg is preferably 0.300, 0.290, 0.280, 0.275, and particularly preferably 0.270. That is, Savg is preferably 0.090 or more and 0.300 or less, more preferably 0.100 or more and 0.300 or less, more preferably 0.150 or more and 0.300 or less, more preferably 0.170 or more and 0.300 or less, more preferably 0.190 or more and 0.290 or less, more preferably 0.200 or more and 0.280 or less, more preferably 0.220 or more and 0.275 or less, and most preferably 0.240 or more and 0.270 or less.
• the operation window of the present invention will be defined more specifically below.
• the reaction bath temperature at which the combined yield of the unsaturated aldehyde and the unsaturated carboxylic acid (hereinafter referred to as the effective yield) is the highest is defined as A (°C)
• A1 (°C) and A2 (°C) are defined as A1 (°C) and A2 (°C).
• A is higher than A1, and A2 is higher than A
• (A2-A1) is defined as the narrow operation window of the present invention.
• (A2-A1) is preferably 23°C or higher.
• (A2-A1) is the reaction bath temperature range (operation window of the present invention) at which the effective yield is stable, and the larger (A2-A1) is, the wider the reaction bath temperature range at which the unsaturated aldehyde and the unsaturated carboxylic acid can be obtained, which is desirable. It is not necessary to calculate A1 and A2 from the relationship between the actual effective yield and BT, but a method of calculating from interpolation or extrapolation of a series of data obtained by measuring the yield of unsaturated aldehyde and unsaturated carboxylic acid while changing BT may be used (in this case, the extrapolated value is calculated by linear approximation by the least squares method from at least three points of actual measurement data).
• the measurement point with the higher selectivity is set as A in the present invention.
• the reason for the decrease in the effective yield around A1 is due to the decrease in the reaction rate of the raw material
• the reason for the decrease in the effective yield around A2 is due to the generation of decomposition products such as carbon dioxide and acetaldehyde, which are typified by the successive oxidation reaction of unsaturated aldehyde and unsaturated carboxylic acid.
• the catalyst used in the present invention is preferably a catalyst having a composition represented by the following formula (1).
• Mo, Bi, Ni, Co and Fe represent molybdenum, bismuth, nickel, cobalt and iron, respectively;
• X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium and titanium;
• Y represents at least one element selected from sodium, potassium, cesium, rubidium and thallium;
• Z represents an element belonging to Groups 1 to 16 of the periodic table; and means at least one element selected from elements other than Co, Fe, X, and Y, and a, b, c, d, e, f, g, h, and i represent the numbers of atoms of molybdenum, bismuth, nickel,
• the preferred ranges of b to h are as follows:
• the lower limit of b is, in order of preference, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70
• the upper limit is, in order of preference, 6.0, 5.0, 4.0, 3.0, 2.0, 1.8, 1.5, 1.2, and 1.0. That is, b is preferably 0.10 to 6.0, more preferably 0.10 to 5.0, more preferably 0.10 to 4.0, more preferably 0.20 to 3.0, more preferably 0.30 to 2.0, more preferably 0.40 to 1.8, more preferably 0.50 to 1.5, more preferably 0.60 to 1.2
• the most preferred range is 0.70 to 1.0.
• the lower limit of c is preferably 0.20, 0.50, 0.80, 1.0, 1.2, 1.5, 1.6, and 1.7
• the upper limit is preferably 8.0, 7.0, 6.0, 5.0, 4.0, 3.5, 3.4, and 3.3. That is, c is preferably 0.20 or more and 8.0 or less, more preferably 0.50 or more and 7.0 or less, more preferably 0.80 or more and 6.0 or less, more preferably 1.0 or more and 5.0 or less, more preferably 1.2 or more and 4.0 or less, more preferably 1.5 or more and 3.5 or less, more preferably 1.6 or more and 3.4 or less, and the most preferable range is 1.7 or more and 3.3 or less.
• the lower limit of d is preferably 1.0, 2.0, 3.0, 4.0, and 5.0
• the upper limit is preferably 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, 6.8, 6.7, and 6.6. That is, d is preferably 1.0 to 9.5, more preferably 1.0 to 9.0, more preferably 1.0 to 8.5, more preferably 1.0 to 8.0, more preferably 1.0 to 7.5, more preferably 2.0 to 7.0, more preferably 3.0 to 6.8, more preferably 4.0 to 6.7
• the most preferred range is 5.0 to 6.6.
• the lower limit of c+d is preferably 1.2, 2.0, 4.0, 6.0, 6.5, 6.6, and 6.7, and the upper limit is preferably 20.0, 15.0, 12.5, 11.0, 10.2, 10.1, 10.0, and 9.9. That is, c+d is preferably 1.2 or more and 20.0 or less, more preferably 1.2 or more and 15.0 or less, more preferably 2.0 or more and 12.5 or less, more preferably 4.0 or more and 11.0 or less, more preferably 6.0 or more and 10.2 or less, more preferably 6.5 or more and 10.1 or less, more preferably 6.6 or more and 10.0 or less, and the most preferred range is 6.7 or more and 9.9 or less.
• the lower limit of e is preferably 0.10, 0.20, 0.50, 0.80, 1.0, 1.5, and 1.6
• the upper limit is preferably 4.5, 4.0, 3.5, 3.0, 2.5, 2.4, 2.3, and 2.2. That is, e is preferably 0.10 to 4.5, more preferably 0.10 to 4.0, more preferably 0.20 to 3.5, more preferably 0.50 to 3.0, more preferably 0.80 to 2.5, more preferably 1.0 to 2.4, more preferably 1.5 to 2.3, and the most preferable range is 1.6 to 2.2.
• the upper limit of f is preferably 1.8, 1.5, 1.0, 0.80, and 0.50, and the lower limit is preferably 0.
• a more preferable range for f is 0 or more and 0.50 or less, and 0 is most preferable.
• the lower limit of g is preferably 0.010, 0.020, and 0.030, and the upper limit is preferably 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, and 0.090.
• g is preferably 0.010 or more and 2.0 or less, more preferably 0.010 or more and 1.0 or less, more preferably 0.010 or more and 0.50 or less, more preferably 0.010 or more and 0.40 or less, more preferably 0.010 or more and 0.30 or less, more preferably 0.010 or more and 0.20 or less, more preferably 0.020 or more and 0.10 or less, and the most preferred range is 0.030 or more and 0.090 or less.
• the upper limit of h is preferably 4.0, 3.0, 2.0, 1.8, 1.5, 1.0, 0.80, and 0.50, and the lower limit is preferably 0. That is, a more preferable range for h is 0 or more and 0.50 or less, and 0 is most preferable.
• X is preferably tungsten, antimony, zinc, magnesium, calcium or cerium, and particularly preferably antimony or zinc.
• Y is preferably sodium, potassium or cesium, more preferably potassium or cesium.
• Z in the formula (1) is preferably vanadium, copper, niobium, zirconium, calcium, beryllium, strontium, barium, lead or phosphorus.
• the composition of the active component of the catalyst contained in the first layer is preferably a catalyst represented by the following formula (1-1).
• the catalyst layer closest to the inlet side of the reaction raw material gas is preferably a catalyst represented by the following formula (1-1).
• all layers except the layer closest to the outlet side contain a catalyst having the composition represented by formula (1-1).
• Mo, Bi, Ni, Co, Fe, and Cs represent molybdenum, bismuth, nickel, cobalt, iron, and cesium, respectively;
• X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium;
• Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from the elements other than Mo, Bi, Ni, Co, Fe, Cs, and X.
• b1 to f1, h1, X, and Z are the same as those of b to h, X, and Z in formula (1), including preferred embodiments thereof.
• the lower limit of g1 is preferably 0.0010, 0.0050, 0.010, 0.015, 0.020, and 0.030, and the upper limit is preferably 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, 0.090, and 0.060.
• g1 is preferably 0.0010 or more and 2.0 or less, more preferably 0.0010 or more and 1.0 or less, more preferably 0.0010 or more and 0.50 or less, more preferably 0.0010 or more and 0.40 or less, more preferably 0.0050 or more and 0.30 or less, more preferably 0.010 or more and 0.20 or less, more preferably 0.015 or more and 0.15 or less, more preferably 0.020 or more and 0.090 or less, and the most preferred range is 0.030 or more and 0.060 or less.
• the composition of the active component of the catalyst contained on the most outlet side is preferably a catalyst represented by the following formula (1-2).
• the third layer is also a catalyst represented by formula (1-2)
• the catalyst on the most outlet side is this catalyst.
• Mo, Bi, Ni, Co, Fe, and K represent molybdenum, bismuth, nickel, cobalt, iron, and potassium, respectively;
• X represents at least one element selected from tungsten, antimony, tin, zinc, chromium, manganese, magnesium, silicon, aluminum, cerium, and titanium;
• Z represents at least one element belonging to Groups 1 to 16 of the periodic table and selected from elements other than Mo, Bi, Ni, Co, Fe, K, and X.
• b2 to f1, h2, and X and Z are the same as b to h, and X and Z in formula (1), including preferred embodiments.
• the lower limit of g2 is preferably 0.0010, 0.0050, 0.010, 0.015, 0.020, 0.030, 0.040, and 0.050, and the upper limit is preferably 2.0, 1.0, 0.50, 0.40, 0.30, 0.20, 0.15, and 0.10.
• g2 is preferably 0.0010 or more and 2.0 or less, more preferably 0.0010 or more and 1.0 or less, more preferably 0.0050 or more and 0.50 or less, more preferably 0.010 or more and 0.40 or less, more preferably 0.020 or more and 0.30 or less, more preferably 0.030 or more and 0.20 or less, more preferably 0.040 or more and 0.15 or less, and the most preferred range is 0.050 or more and 0.10 or less.
• the shape of the catalyst contained in the catalyst layer used in the present invention is not particularly limited, and it can be spherical, cylindrical, ring-shaped, powdery, etc., but spherical is particularly preferred.
• both the catalyst contained in the upper layer and the catalyst contained in the lower layer may be diluted with an inert substance, but it is more preferable to not dilute either the upper or lower layer.
• the preferred range of the dilution rate di by the inert substance is described below.
• the dilution rate here is a numerical value indicating the mass ratio of the catalyst to the catalyst layer composed of the catalyst and the inert substance.
• a catalyst layer diluted by 80% by mass means that the catalyst is 80% by mass and the inert substance is 20% by mass.
• the dilution rate is calculated based on the mass of the catalyst including the inert carrier.
• n 2 and 3
• the essence of the present invention is to keep the packing length of the nth catalyst layer relative to the packing length of the other catalyst layers within a certain range when the reaction tube is divided into n parts in the gas flow direction, so it is not limited to this.
• the middle layer is a catalyst containing a catalytically active component represented by formula (1-1) and the dilution rate is 100 mass %
• the upper layer is a catalyst obtained by diluting the middle layer catalyst with an inert substance
• the lower layer is a catalyst containing a catalytically active component represented by formula (1-2) and the dilution rate is 100 mass %.
• the inactive substance includes known substances such as silica, alumina, titania, zirconia, niobia, silica alumina, silicon carbide, carbide, magnesia, and mixtures thereof. Among these, silica, alumina, or mixtures thereof are preferred, silica and alumina are particularly preferred, and a mixture of silica and alumina is most preferred.
• the shape of the inactive substance is not particularly limited, but is preferably spherical, and the average particle size is preferably 3 mm to 10 mm, more preferably 3.5 mm to 9 mm, and particularly preferably 4 mm to 8 mm.
• the catalyst used in the present invention can be produced, for example, by the following steps a) to e). ⁇ Step a) Preparation>
• the starting materials of each element constituting the catalytic active component are not particularly limited.
• molybdenum component raw material molybdenum oxide such as molybdenum trioxide, molybdic acid, molybdic acid or its salt such as ammonium molybdate, heteropolyacid containing molybdenum such as phosphomolybdic acid and silicomolybdic acid or its salt can be used. It is preferable to use ammonium molybdate, because it is possible to obtain a high-performance catalyst.
• ammonium molybdate compounds such as ammonium dimolybdate, ammonium tetramolybdate, and ammonium heptamolybdate, and among them, it is most preferable to use ammonium heptamolybdate.
• Bismuth nitrate, bismuth subcarbonate, bismuth sulfate, bismuth acetate and other bismuth salts, bismuth trioxide, metallic bismuth, etc. can be used as the bismuth component raw material, but bismuth nitrate is more preferable, as the use of this material produces a high-performance catalyst.
• raw materials for iron, cobalt, nickel and other elements, oxides or nitrates, carbonates, organic acid salts, hydroxides, etc. that can be converted to oxides by ignition, or mixtures thereof can be used.
• the iron component raw material and the cobalt component raw material and/or nickel component raw material are dissolved and mixed in water at a desired ratio under conditions of 10 to 80°C, mixed with a separately prepared molybdenum component raw material and Z component raw material aqueous solution or slurry under conditions of 20 to 90°C, heated and stirred for about 1 hour under conditions of 20 to 90°C, and then an aqueous solution in which the bismuth component raw material has been dissolved and, if necessary, X component raw material and Y component raw material are added to obtain an aqueous solution or slurry containing the catalyst components.
• the mixed liquid (A) both are collectively referred to as the mixed liquid (A).
• the prepared liquid (A) does not necessarily need to contain all of the catalytically active component elements, and some of the elements or some of the amounts may be added in a subsequent step. Furthermore, when preparing the prepared liquid (A), if the amount of water in which each component raw material is dissolved, or if an acid such as sulfuric acid, nitric acid, hydrochloric acid, tartaric acid, or acetic acid is added for dissolution, is not suitable for preparation, for example, in the range of 5% to 99% by mass, the acid concentration in the aqueous solution sufficient to dissolve the raw materials, the prepared liquid (A) may take the form of a clay-like lump. In this case, an excellent catalyst cannot be obtained.
• the prepared liquid (A) is preferably in the form of an aqueous solution or a slurry, as this produces an excellent catalyst.
• the preparation liquid (A) obtained above is dried to obtain a dry powder.
• the drying method is not particularly limited as long as it can completely dry the preparation liquid (A), and examples thereof include drum drying, freeze drying, spray drying, and evaporation to dryness.
• spray drying is particularly preferred, which can dry the slurry into powder or granules in a short time.
• the drying temperature of the spray drying varies depending on the concentration of the slurry, the liquid sending speed, etc., but is generally 70 to 150°C at the outlet of the dryer. It is also preferable to dry the mixture so that the average particle size of the dry powder obtained at this time is 10 to 700 ⁇ m. In this way, a dry powder (B) is obtained.
• Step c) Pre-firing>
• the resulting dry powder (B) is calcined under air flow at 200°C to 600°C, preferably 300°C to 600°C, which tends to improve the moldability, mechanical strength, and catalytic performance of the catalyst.
• the calcination time is preferably 1 hour to 12 hours. In this way, a pre-calcined powder (C) is obtained.
• the pre-sintered powder (C) may be molded into a spherical shape using a molding machine, but a method in which the pre-sintered powder (C) (containing a molding aid and a strength improver, if necessary) is supported on a carrier such as an inactive ceramic is preferred.
• the supporting method include a rolling granulation method, a method using a centrifugal fluidized coating device, and a wash coat method.
• the method there are no particular limitations on the method as long as it can uniformly support the pre-calcined powder (C) on the carrier, but when considering the production efficiency of the catalyst and the performance of the catalyst prepared, it is more preferable to use an apparatus having a flat or uneven disk at the bottom of a fixed cylindrical container, in which the disk is rotated at high speed to vigorously stir the carrier charged in the container by repeated rotation and revolution of the carrier itself, and to which the pre-calcined powder (C) and, if necessary, a molding aid and/or a strength improver are added to support the powder components on the carrier.
• binders that can be used include water, ethanol, methanol, propanol, polyhydric alcohols, polyvinyl alcohol as a polymer binder, and silica sol aqueous solution as an inorganic binder.
• Ethanol, methanol, propanol, and polyhydric alcohols are preferred, and diols such as ethylene glycol and triols such as glycerin are more preferred.
• a catalyst with particularly high performance can be obtained when an aqueous solution of glycerin with a concentration of 5% by mass or more is used.
• the amount of these binders used is usually 2 to 80 parts by mass per 100 parts by mass of the pre-calcined powder (C).
• An inert carrier with a diameter of about 2 to 8 mm is usually used, and the pre-calcined powder (C) is supported on it.
• the support rate is determined taking into consideration the catalyst use conditions, such as the space velocity of the reaction raw materials and the raw material concentration, and is usually 20% to 80% by mass.
• the support rate is expressed by the following formula.
• Loading rate (mass%) 100 ⁇ (mass of pre-calcined powder (C) used for molding/(mass of pre-calcined powder (C) used for molding+mass of inert carrier used for molding)) (2)
• the molded body (D) obtained in step d) tends to have improved catalytic activity and selectivity by calcining it at a temperature of 200 to 600°C for about 1 to 12 hours.
• the calcination temperature is preferably 400°C to 600°C, more preferably 500°C to 600°C.
• Air is the preferred gas to be circulated because it is simple, but other inert gases such as nitrogen, carbon dioxide, nitrogen oxide-containing gas for creating a reducing atmosphere, ammonia-containing gas, hydrogen gas, and mixtures thereof can also be used. In this way, catalyst (E) is obtained.
• the first method is a method in which, in a preparation step in which each of the supply source compounds containing molybdenum, bismuth, and iron is added to a solvent or solution, and then combined and heated to prepare a preparation, the pH of the preparation is adjusted to a range of 1.0 to 7.5, more preferably to a range of 3.0 to 6.0, before the iron raw material is added.
• the pH adjustment method includes, as will be described in detail later, a method of lowering the pH by adding nitric acid or the like, or a method of raising the pH by adding aqueous ammonia or the like.
• pH adjusters in the method for lowering the pH, those skilled in the art can use acids commonly used for pH adjustment as catalyst raw materials, such as nitric acid, sulfuric acid, hydrochloric acid, and oxalic acid.
• acids commonly used for pH adjustment such as nitric acid, sulfuric acid, hydrochloric acid, and oxalic acid.
• pH adjusters that leave elements remaining after calcination such as phosphoric acid, boric acid, molybdic acid, and iron nitrate
• bases commonly used for pH adjustment as catalyst raw materials such as ammonia water, pyridine, and ammonium carbonate aqueous solution.
• potassium hydroxide and cesium hydroxide can also be used, but ammonia water is the most preferable.
• the most preferred embodiment is a method for preparing a slurry in the following order: adding the iron raw material, stirring, and then adding the bismuth raw material to the prepared liquid.
• the pH adjuster is dropped, for example, while stirring at a stirring power of 0.01 to 5.00 kW/ m3 .
• the lower limit of the stirring power is preferably 0.05 kW/ m3 , 0.10 kW/ m3 , 0.50 kW/ m3 , or 1.00 kW/ m3
• the upper limit of the stirring power is preferably 4.50 kW/ m3 , 4.00 kW/ m3 , 3.50 kW/ m3 , or 3.00 kW/ m3 .
• the most preferable range of the stirring power is 1.00 to 3.00 kW/ m3 .
• the drop time of the pH adjuster is between 1 second and 5 minutes, but the lower limit of the drop time is preferably 5 seconds, 10 seconds, or 15 seconds, and the upper limit of the drop time is preferably 4 minutes, 3 minutes, 2 minutes 30 seconds, 2 minutes, 1 minute 30 seconds, 1 minute, 45 seconds, or 30 seconds. That is, the most preferable range of the drop time is 15 to 30 seconds.
• the liquid temperature of the preparation when the pH adjuster is dropped is 5 to 80° C., but the lower limit of the liquid temperature is preferably 10° C., 20° C., or 30° C., and the upper limit of the liquid temperature is preferably 70° C., 60° C., 50° C., or 40° C. In other words, the most preferable range of the liquid temperature is 30 to 40° C.
• the second method is the optimization of the rotation speed of the atomizer in the case of spray drying.
• the optimal rotation speed of the atomizer cannot be generally determined because it is influenced by the structure of the atomizer or spray dryer, the temperature, pH, viscosity, and the blending ratio of the catalyst components of the liquid to be dried, but is preferably 10,000 rpm or more and 18,000 rpm or less.
• a more preferable upper limit of the atomizer rotation speed is 17,000 rpm, particularly preferably 16,000 rpm, and most preferably 15,000 rpm.
• a more preferable lower limit is 11,000 rpm, a particularly preferable lower limit is 12,000 rpm, and the most preferable lower limit is 13,000 rpm.
• the most preferable range of the atomizer rotation speed is 13,000 rpm or more and 15,000 rpm or less.
• the rotation speed of the atomizer is also expressed by the relative centrifugal acceleration, and is preferably 6000 G or more and 20000 G or less. More preferable lower limits are 7500 G, 8500 G, and 10000 G, respectively, and more preferable upper limits are 18000 G, 16000 G, and 14000 G, respectively. That is, the most preferable range of the rotation speed of the atomizer is 10000 G or more and 14000 G or less.
• the hot air temperature supplied to the sprayer for spray drying (hereinafter sometimes referred to as the inlet temperature) and the spray dryer outlet temperature (hereinafter sometimes referred to as the outlet temperature) also affect the above parameter (CB, production parameter T).
• the inlet temperature is preferably 180°C or higher and 320°C or lower. More preferred lower limits are 200°C, 220°C, and 230°C, respectively, and more preferred upper limits are 300°C, 280°C, and 270°C, respectively. That is, the inlet temperature is most preferably 230°C or higher and 270°C or lower.
• the outlet temperature is preferably 100° C. or more and 150° C. or less.
• More preferable lower limits are 101° C., 102° C., 103° C., 104° C., and 105° C., respectively, and more preferable upper limits are 140° C., 130° C., and 120° C., respectively. That is, the inlet temperature is most preferably 105° C. or more and 120° C. or less.
• the difference between the inlet temperature and the outlet temperature is preferably 30° C. or more and 220° C. or less. More preferable lower limits are 50° C., 80° C., 100° C., and 120° C., respectively, and more preferable upper limits are 200° C., 180° C., 165° C., and 150° C., respectively. That is, the difference between the inlet temperature and the outlet temperature is most preferably 120° C. or more and 150° C. or less.
• the parameter SD given by the following formula is preferably in the range of 22 to 51. More preferred lower limits are 26, 28, 30, 32, 34, and 35, respectively, and more preferred upper limits are 48, 44, 42, and 40, respectively.
• the third method is a method of controlling the composition of the active components of the catalyst in more detail, specifically, by one or a combination of the following composition ratios. That is, in the above composition formula (1), the upper limit of e/b is preferably 2.90, more preferably 2.80, and the lower limit of e/b is 0.10, 0.50, 1.00, 1.40, 1.50, and 1.90, in that order of desirability.
• e/b is preferably 0.10 to 2.90, more preferably 0.50 to 2.90, more preferably 1.00 to 2.90, more preferably 1.40 to 2.90, more preferably 1.50 to 2.90, and particularly preferably 1.90 to 2.80.
• the upper limit of d/b is, in order of desirability, 9.0, 8.0, and 7.0
• the lower limit of d/b is, in order of desirability, 2.0, 3.0, 4.0, 5.0, 5.5, and 6.5. Therefore, d/b is preferably 2.0 to 9.0, more preferably 3.0 to 9.0, more preferably 4.0 to 9.0, more preferably 5.0 to 9.0, more preferably 5.5 to 8.0, and particularly preferably 6.5 to 7.0.
• the upper limit of c/e is, in order of desirability, 4.0, 3.0, 2.5, and 2.0, and the lower limit of c/e is, in order of desirability, 1.0, 1.5, 1.7, and 1.9. Therefore, c/e is preferably 1.0 to 4.0, more preferably 1.5 to 3.0, more preferably 1.7 to 2.5, and particularly preferably 1.9 to 2.0.
• the upper limit of c/d is preferably 2.0, 1.0, and 0.8, and the lower limit of c/d is preferably 0.1 and 0.3. Therefore, c/d is preferably 0.1 to 2.0, more preferably 0.1 to 1.0, and particularly preferably 0.3 to 0.8.
• the upper limit of g/d is, in order of preference, 0.100, 0.050, 0.040, 0.030, 0.020, and 0.015
• the lower limit of g/d is, in order of preference, 0.007, 0.008, 0.009, 0.010, and 0.011. Therefore, g/d is preferably 0.007 or more and 0.100 or less, more preferably 0.007 or more and 0.050 or less, more preferably 0.008 or more and 0.040 or less, more preferably 0.009 or more and 0.030 or less, more preferably 0.010 or more and 0.020 or less, and particularly preferably 0.011 or more and 0.015 or less.
• g/c is preferably 0.015 or more and 0.040 or less, more preferably 0.020 or more and 0.035 or less, and particularly preferably 0.025 or more and 0.030 or less.
• the fourth method is to control the firing temperature, firing time, or firing atmosphere in the preliminary firing or main firing, or both, described below.
• the firing temperature is set to 200°C or higher and 600°C or lower, preferably 300°C or higher and 550°C or lower, and more preferably 460°C or higher and 550°C or lower.
• the firing time is set to 0.5 hours or longer, preferably 1 hour or higher and 40 hours or lower, more preferably 2 hours or higher and 15 hours or lower, and most preferably 2 hours or higher and 9 hours or lower.
• the firing atmosphere has an oxygen concentration of 10% by volume or higher and 40% by volume or lower, preferably 15% by volume or higher and 30% by volume or lower, and most preferably an air atmosphere.
• the fifth method involves controlling the rate at which the catalyst surface temperature drops (temperature drop rate) from the maximum temperature reached during the calcination process (pre-calcination temperature or main calcination temperature) to room temperature during the pre-calcination or main calcination, or both, described below. That is, the temperature drop rate is set to 1°C/min to 200°C/min, preferably 5°C/min to 150°C/min, more preferably 10°C/min to 120°C/min, and most preferably 50°C/min to 100°C/min.
• the sixth method is a technique for controlling the application of mechanical impact and shear stress to the catalyst precursor and/or the granules formed in each step described below.
• the mechanical impact and shear stress are preferably controlled to 100 kgf or less, more preferably 50 kgf or less, more preferably 20 kgf or less, even more preferably 10 kgf or less, and most preferably 5 kgf or less.
• the seventh method is to use high-purity raw materials of reagent grade.
• the details are not important, but for example, the raw materials used have a sulfur and its compounds, lithium, halogens and their compounds, and lead content of 10,000 ppm by weight or less, preferably 1,000 ppm by weight or less, more preferably 100 ppm by weight or less, and most preferably 10 ppm by weight or less.
• the eighth method is a method of controlling the time during which the cobalt raw material and the nickel raw material are mixed with other raw materials in the blending kettle, and/or the time for reaction, and/or the time for slurrying, and/or the time for residence, in the catalyst blending process described later, so as to be as short as possible. More specifically, this is a method of shortening the residence time in a situation where there are no metal salt raw materials other than molybdenum and alkali metals in the blending kettle and the cobalt raw material and the nickel raw material are present, or a method of shortening the residence time in a situation where the cobalt raw material and the nickel raw material are present when the pH in the blending kettle is in a specific range.
• the residence time is preferably 24 hours or less, more preferably 1 hour or less, even more preferably 30 minutes or less, and most preferably 10 minutes or less.
• the pH range of the solution in the blending kettle is preferably 2 to 10, more preferably 2 to 8, and most preferably 3 to 7. The same applies to the iron raw material and the bismuth raw material, and the molybdenum raw material and the bismuth raw material.
• the ninth method is to add each raw material all at once in the catalyst preparation process described below without dividing it during the preparation process, or to reduce the nitric acid concentration in the preparation liquid.
• the above method of adding all at once means adding the next raw material after all the required amounts of each raw material have been added.
• the nitric acid concentration in the preparation liquid is adjusted so that the concentration of nitrate ions in the preparation liquid when preparation is completed and the next process is carried out is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and most preferably 25% by mass or less.
• the catalytic gas phase oxidation reaction of an alkene in the present invention is carried out by introducing a mixed gas consisting of 6 to 12 volume % of an alkene (more preferably 6 to 10 volume %), 5 to 18 volume % of molecular oxygen, 0 to 60 volume % of water vapor and 20 to 70 volume % of an inert gas such as nitrogen or carbon dioxide onto the catalyst prepared as described above at a temperature in the range of 250 to 450° C. and a pressure of normal pressure to 10 atm, preferably normal pressure to 5 atm, more preferably normal pressure to 3 atm, for a contact time of 0.5 to 10 seconds.
• the volume ratio of alkene to oxygen is 1.0 or more and 1.9 or less. More preferable upper limits of oxygen/alkene are 1.8, 1.7, and 1.6, respectively, and more preferably 1.5. More preferable lower limits are 1.1, 1.2, and 1.3, respectively. From the above, the most preferable range of oxygen/alkene is 1.3 or more and 1.5 or less.
• alkene includes alcohols that produce alkenes in their intramolecular dehydration reaction, such as tertiary butyl alcohol.
• the higher the space velocity of the reaction substrate (raw material) such as alkene relative to the catalyst volume (SVo reaction substrate supply rate (NL/hr)/catalyst packed space volume (L)), the better from the viewpoint of production efficiency.
• the space velocity is preferably 40 to 200 hr -1 , and more preferably 60 to 180 hr -1 .
• NL represents the volume of the reaction substrate under standard conditions (1 atm, 0°C).
• the conversion rate of the alkene is preferably near the conversion rate at which a high yield of unsaturated aldehyde is obtained, and is usually 90 to 99.9%, preferably 95 to 99.5%, and more preferably 96 to 99%.
• the activity of the entire catalyst layer will decrease, and the reaction bath temperature required to obtain the target product by obtaining the usual raw material conversion rate will rise too much, causing the hot spot to become hot, resulting in catalyst deterioration and performance deterioration.
• early deterioration of the catalyst on the gas inlet side may cause a high hot spot in the highly active catalyst layer on the gas outlet side, which may cause a sudden decrease in the selectivity and yield of the target product.
• the reaction bath temperature is set appropriately depending on the catalyst characteristics, usage conditions, required catalyst life, etc., so it cannot be generalized, but the reaction bath temperature at the beginning of the reaction is preferably 390°C or less, and the upper limit is preferably 380, 370, 360, and 350, and 340°C or less is most preferable.
• the lower limit is 300°C or more, and more preferably 310°C or more.
• the reaction bath temperature does not mean the temperature during the temperature rise process, but means the set temperature for realizing an appropriate conversion rate of the raw materials.
• L/Ln is 0.1 or more and 1.0 or less.
• the preferable lower limit of L/Ln is 0.2, 0.3, and 0.4, in that order, and the preferable upper limit is 0.9. Therefore, L/Ln is more preferably 0.2 or more and 1.0 or less, more preferably 0.3 or more and 1.0 or less, and particularly preferably 0.4 or more and 0.9 or less.
• the effective yield is defined as follows.
• Propylene conversion (mol%) (number of moles of reacted propylene/number of moles of supplied propylene) x 100
• Effective yield (mol%) (number of moles of acrolein and acrylic acid produced/number of moles of propylene supplied) x 100
• Effective selectivity (mol%) (number of moles of acrolein and acrylic acid produced/number of moles of propylene reacted) x 100
• Ammonium molybdate and cesium nitrate were dissolved in distilled water while heating and stirring to obtain an aqueous solution (prepared solution 1).
• the amount of distilled water used was 3.5 times the mass of ammonium molybdate, and the water temperature at the time of adding ammonium molybdate was 85 ° C.
• cobalt nitrate, nickel nitrate, and ferric nitrate were dissolved in distilled water to prepare an aqueous solution (prepared solution 2), and bismuth nitrate was dissolved in distilled water acidified with concentrated nitric acid to prepare an aqueous solution (prepared solution 3).
• preparation 2 and preparation 3 were mixed in sequence while vigorously stirring, the resulting suspension was dried using a spray dryer, and the resulting granules were calcined at 440 ° C for 6 hours to obtain a pre-calcined powder.
• the powder obtained by mixing the pre-calcined powder with crystalline cellulose was adjusted to an inert carrier (a spherical material with a diameter of 4.0 mm mainly composed of alumina and silica) so that the loading rate defined by the above formula was 60 mass %.
• an inert carrier a spherical material with a diameter of 4.0 mm mainly composed of alumina and silica
• a 33 mass % glycerin aqueous solution was used as a binder to support and mold into a sphere with a diameter of 5.1 mm to obtain a supported catalyst.
• This supported catalyst was calcined at a calcination temperature of 520 ° C for 4 hours in an air atmosphere to obtain catalyst 1.
• a reaction tube with an inner diameter of 28.4 mm was filled with 4 g of catalyst 1 diluted with an inert material to prevent hot spots, and the molar ratio of propylene:oxygen:nitrogen:water was 1:1.7:6.4:3.0, the space velocity of propylene (SVo) was set to 400 hr -1 , and the reaction bath temperature was set to 340°C to 360°C while changing the BT, to determine the propylene conversion.
• the results and the calculated CB are shown in Table 1-1.
• the results of evaluation in the same manner as catalyst 1 and the calculated CB are shown in Table 1-2.
• Table 1-3 The results of evaluation in the same manner as catalyst 1 and the calculated CB are shown in Table 1-3.
• the results of evaluation in the same manner as catalyst 1 and the calculated CB are shown in Tables 1-4.
• the results of evaluation in the same manner as catalyst 1 and the calculated CB are shown in Tables 1-5.
• Catalyst 6 was obtained in the same manner as in the preparation of catalyst 1, except that the calcination temperature was 510° C. The results of evaluation in the same manner as in the preparation of catalyst 1 and the calculated CB are shown in Tables 1-6.
• Catalyst 7 was obtained in the same manner as catalyst 2, except that the calcination temperature was 530° C. The results of evaluation in the same manner as catalyst 1 and the calculated CB are shown in Tables 1-7.
• Example 1 A jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis of a stainless steel reactor with an inner diameter of 25 mm, and a temperature sheath for the thermocouple with an outer diameter of 3 mm was installed.
• the catalyst 1 dilution layer, catalyst 1, and catalyst 2 were filled in the order of the first to third layers as shown in Table 2-1.
• the supplied raw material was circulated so that the space velocity of propylene (SVo) was 90 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 50 kPaG, and when 300 hours had passed since the start of the reaction, the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-1.
• Example 2 As shown in Table 2-2, the catalyst 3 dilution layer, catalyst 3, and catalyst 4 were packed in the order of the first to third layers, and a propylene oxidation reaction was carried out under exactly the same reaction conditions and aging method as in Example 1. The reaction performance was investigated by changing the reaction bath temperature, and the results are shown in Table 3-2.
• Example 3 As shown in Table 2-3, the catalyst 3 dilution layer, catalyst 3, and catalyst 4 were packed in the order from the first layer to the third layer, and the raw material was passed through so that the space velocity of propylene (SVo) was 120 hr -1 . Except for this, the oxidation reaction of propylene was carried out under exactly the same reaction conditions and aging method as in Example 1. The reaction performance was investigated by changing the reaction bath temperature, and the results are shown in Table 3-3.
• the feed material was circulated so that the space velocity (SVo) of propylene was 140 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 90 kPaG, and when 300 hours had passed since the start of the reaction, the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-5.
• Example 5 As shown in Table 2-6, the first layer was filled with catalyst 3, then catalyst 4 in the second layer, and the oxidation reaction of propylene was carried out under the same reaction conditions and aging method as in Example 4. The reaction performance was investigated by changing the reaction bath temperature, and the results are shown in Table 3-6.
• Example 6 A jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis of a stainless steel reactor with an inner diameter of 27 mm, and a temperature sheath for the thermocouple with an outer diameter of 3 mm was installed.
• the catalyst 3 dilution layer, catalyst 3, and catalyst 4 were packed in the order of the first to third layers as shown in Table 2-8.
• the supplied raw material was circulated so that the space velocity (SVo) of propylene was 84 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 35 kPaG, and when 300 hours had passed since the start of the reaction, the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-8.
• thermocouple temperature sheath was installed in a stainless steel reactor with an inner diameter of 28 mm, and a jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis.
• Catalyst 1 and catalyst 7 were packed in the first and second layers in this order as shown in Table 2-10.
• the feed material was circulated so that the space velocity (SVo) of propylene was 180 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 80 kPaG, and 300 hours had passed since the start of the reaction.
• the reaction bath temperature was changed to carry out the oxidation reaction of propylene. The results of the reaction performance when the reaction bath temperature was changed are shown in Table 3-10.
• Example 8 As shown in Table 2-11, the first layer was filled with catalyst 6, then catalyst 2 in the second layer, and the oxidation reaction of propylene was carried out under the same reaction conditions and aging method as in Example 7. The reaction performance was investigated by changing the reaction bath temperature, and the results are shown in Table 3-11.
• the feed material was circulated so that the space velocity (SVo) of propylene was 125 hr -1 , and when the pressure at the outlet side of the reaction tube during the total gas flow was 57 kPaG and 300 hours had passed since the start of the reaction, the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• Table 3-12 The results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-12.
• Example 10 A jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis of a stainless steel reactor with an inner diameter of 24.9 mm, and a temperature sheath for the thermocouple with an outer diameter of 7 mm was installed.
• the catalyst 8 dilution layer, catalyst 8, and catalyst 7 were packed in the order of the first layer, second layer, and third layer as shown in Table 2-13.
• the supplied raw material was circulated so that the space velocity of propylene (SVo) was 100 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 57 kPaG, and 300 hours had passed since the start of the reaction.
• the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-13.
• Example 11 A jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis of a stainless steel reactor with an inner diameter of 25.2 mm, and a temperature sheath for the thermocouple with an outer diameter of 3.2 mm was installed.
• the catalyst 8 dilution layer, catalyst 8, and catalyst 7 were packed in the order of the first layer, second layer, and third layer as shown in Table 2-14.
• the supplied raw material was circulated so that the space velocity of propylene (SVo) was 115 hr -1 , and the pressure at the outlet side of the reaction tube during the total gas flow was 52 kPaG, and 300 hours had passed since the start of the reaction.
• the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-14.
• Example 12 A jacket for circulating molten salt as a heat medium and a thermocouple for measuring the catalyst layer temperature were installed on the tube axis of a stainless steel reactor with an inner diameter of 27.8 mm, and a temperature sheath for the thermocouple with an outer diameter of 3.2 mm was installed.
• the catalyst 8 dilution layer, catalyst 8, and catalyst 7 were packed in the order of the first layer, second layer, and third layer as shown in Table 2-15.
• the supplied raw material was circulated so that the space velocity of propylene (SVo) was 76 hr -1 , and when the pressure at the outlet side of the reaction tube during the total gas flow was 43 kPaG and 300 hours had passed since the start of the reaction, the reaction bath temperature was changed to carry out the oxidation reaction of propylene.
• the results of the reaction performance examined by changing the reaction bath temperature are shown in Table 3-15.
• the present invention makes it possible to achieve high yields over a wide reaction bath temperature range even in industrial plants when producing the corresponding unsaturated aldehydes and unsaturated carboxylic acids using alkenes or alcohols that can produce alkenes through an intramolecular dehydration reaction as raw materials, and the wide range of (A2-A1) means that high yields can be maintained over a wider reaction bath temperature range.
• the present invention makes it possible to maintain high yields over a long period of time.

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