【DESCRIPTION】
【Invention Title】
HIGH-PERFORMANCE POLYOXOMETALATE CATALYST AND
METHOD OF PREPARING THE SAME
5 【Technical Field】
[0001] [CROSS-REFERENCE TO RELATED APPLICATION(S)]
[0002] This application claims the priority benefit of Korean Patent
Application No. 10-2015-0113111, filed on August 11, 2015 in the Korean
Intellectual Property Office, the disclosure of which is incorporated herein by
10 reference.
[0003]
[0004] The present invention relates to a polyoxometalate catalyst
and a method of preparing the same, and more particularly to a catalyst used to
produce unsaturated carboxylic acid from unsaturated aldehyde gas by vapor15
phase partial oxidation in a shell-and-tube heat exchanger and a method of
preparing the same.
【Background Art】
[0005] A process of preparing unsaturated fatty acids, via unsaturated
aldehydes, from olefin is a representative example of catalytic vapor-phase
20 oxidation.
[0006] In partial oxidation of olefin, molybdenum oxide, and
transition metal oxide are used to prepare a catalyst. As representative
processes, there are a process of producing(meth)acrylic acid, via methacrolein,
3
by oxidizing propylene or isobutylene, a process of producing phthalic
anhydride by oxidizing naphthalene or ortho-xylene, and a process of
preparing maleic anhydride by partially oxidizing benzene, butylene or
butadiene
5 [0007]
[0008] In the first step, propylene or isobutylene is oxidized by
oxygen, diluted inert gas, water vapor, and a predetermined amount of catalyst,
thereby mainly producing methacrolein. In step 2, the methacrolein is
oxidized by oxygen, diluted inert gas, water vapor and a predetermined amount
10 of a catalyst, thereby producing (meth)acrylic acid. A reactor used for such
processes may be configured to perform both processes in one apparatus, or to
perform each of the processes in a different apparatus.
[0009]
[0010] (Meth)acrylic acid, which is reacted with alcohol, is mainly
15 used to prepare (meth)acrylate used as a coating agent for paint, textile
assistants, and paper. High-purity (meth)acrylic acid is used as a raw material
for highly hygroscopic resins, demand for which has rapidly increased in
recent years.
[0011]
20 [0012] In general, a metal oxide catalyst is produced by
coprecipitation reaction, hydrothermal synthesis, sol-gel synthesis, physical
mixing reaction, etc. In such reaction processes, the metal oxide catalyst is
precipitated in a polyanion, metal oxide, or metal hydroxylate form. Here,
the physical properties and morphology of a precipitate are changed depending
25 upon the pH, concentration, reaction temperature, and aging time of an
aqueous solution, whereby the physical state, particle size, and crystal structure
of the metal oxide catalyst are affected.
4
[0013] As examples of ligands bound to oxo anions and transition
metal precursors which are used in catalysts for producing unsaturated fatty
acid, there are -NH4,
-NH2, -NOx, -Cl, -F, -N, -OH (hydroxyl), -SOx, -CO, -
COO, -CnHmOx, alkoxide (O-Metal), and the like. Such ligands, which are
essential ingredients 5 for dissolving or purifying metal oxide, may be utilized as
factors for changing physicochemical characteristics of a catalyst according to
a suitable control method and thus controlling the activity of the catalyst.
[0014]
[0015] In the related art, “Technology for Preparing Catalyst”
10 introduced in Japanese Patent No. 4295521, a catalyst is prepared by powdercoating
and firing a massive carrier. Here, the prepared catalyst is an acrylic
catalyst characterized in that a mass reduction rate of a dried product thereof is
5 to 40 % by mass at a catalyst drying temperature of 300°C in an air
atmosphere. However, such a preparation method causes structural change of
15 the catalyst due to a relatively high drying temperature, thereby negatively
affecting the performance of the catalyst and thus a conversion rate tends to be
poor.
[0016] In addition, KR 10-0746971 B1 introduces a catalyst, which
includes molybdenum and vanadium, and a catalyst poison in a content of 10
20 to 100 ppb measured by ion chromatography, further includes at least one
volatile catalyst poison ingredient, and generates acrylic acid by catalytic
vapor-phase oxidation between oxygen and acrolein, and a method of
preparing acrylic acid, which includes a step of performing contact vaporphase
oxidation between oxygen and acrolein using the catalyst.
25 [0017] The catalyst, which is prepared by artificially adding a catalyst
poison ingredient, i.e., aqueous ammonia, can lower hot spot temperature and
inhibit reaction efficiency reduction accompanied by deterioration, thereby
highly, stably maintaining an acrolein conversion rate for a long time.
5
However, when a reducing substance, such as ammonia, is present in the
catalyst, the reducing substance acts as a catalyst poison, thereby greatly
increasing reaction temperature and, after a long period of operation, activating
the catalyst. Accordingly, although the reducing substance can be used as a
catalyst poison for controlling 5 catalytic activity, there is considerable difficulty
in quantitatively controlling the amount of the reducing substance in a process
of producing the catalyst.
[0018] Meanwhile, treatment with an inorganic salt present in a
catalyst precursor should be performed to be decreased during a process of
10 preparing a catalyst. However, such an inorganic salt is additionally added,
and thus, there is a disadvantage in that a process of removing the reducing
substance is additionally required. Accordingly, there is a need for a
technology for simply controlling, through sublimation, a type of ligands
included in a catalyst and the amount thereof, when the catalyst is calcined,
15 while providing superior reproducibility.
【Disclosure】
【Technical Problem】
[0019] Therefore, the present invention has been made in view of the
above problems, and it is one object of the present invention to provide a high20
performance polyoxometalate catalyst which may control activity and
selectivity, has superior reproducibility, may produce unsaturated carboxylic
acid from unsaturated aldehyde in a high yield for a long time, a method of
preparing the same, and the like.
[0020]
25 [0021] The above and other objects can be accomplished by the
present invention described below.
6
【Technical Solution】
[0022] In accordance with the present invention, the above and other
objects can be accomplished by the provision of a polyoxometalate catalyst,
including a metal oxide represented by Formula 1 below:
5 [0023] [Formula 1]
[0024] MoaAbVcBdCeDfOg,
[0025] wherein A is one or more elements selected from the group
consisting of W and Cr; B is one or more elements selected from the group
consisting of P, As, B, Sb, Ce, Pb, Mn, Nb and Te; C is one or more elements
10 selected from the group consisting of Si, Al, Zr, Rh, Cu, Ni, Ti, Ag, Fe, Co and
Sn; D is one or more selected from the group consisting of Na, K, Li, Rb, Cs,
Ta, Ca, Mg, Sr and Ba; and a, b, c, d, e, f, and g represent atomic ratios of the
respective elements, wherein, when a=12, b is 0.01 to 15; c is 0.01 to 15, d is 0
to 20, e is 0 to 20, f is 0 to 20; and g is determined depending upon oxidation
15 states of the respective ingredients, and wherein a mole ratio of V to A (V/A) is
0.01 to 10.
[0026] Each of d, e and f may be, for example, 0.01 to 20.
[0027] The vanadium (V) may include, for example, 30 % or more of
vanadium having an oxidation number of 4+.
20 [0028] The polyoxometalate catalyst may include, for example, an
inert carrier, as a supporter of the metal oxide.
[0029] A loading amount of a metal oxide coated on the inert carrier
may be, for example, 30 to 80 % by weight.
[0030] The polyoxometalate catalyst may be, for example, a catalyst
25 for vapor-phase partial oxidation to produce unsaturated carboxylic acid from
7
unsaturated aldehyde.
[0031]
[0032] In accordance with another aspect of the present invention,
there is provided a method of preparing the polyoxometalate catalyst according
to claim 1, 5 the method including: (A) a step of preparing a suspension
including metal precursors to produce a metal oxide represented by Formula 1
and, as needed, adjusting pH to 0 to 7.5 by adding an acid, followed by
increasing a viscosity by means of a homogenizer to form polyoxometalate; (B)
a step of loading 20 to 50 % by weight of the formed polyoxometalate to an
10 inert carrier to prepare a loaded substance; (C) a step of drying the loaded
substance to obtain a loaded substance having a ligand sublimation rate of 0 %
or more calculated by Equation 1 below; and (D) a step of firing the dried
loaded substance to obtain a polyoxometalate catalyst:
[0033] [Equation 1]
15 [0034] Ligand sublimation rate (%) = (mass of sublimated
ligand/mass of ligand before sublimation) X 100.
[0035]
[0036] A vanadium (V) precursor represented by Formula 1 may be,
for example, a compound containing vanadium with an oxidation number of
20 4+.
[0037] The compound containing vanadium with oxidation number of
4+ may be, for example, a vanadyl-containing compound.
[0038] In step (A), the polyoxometalate may have, for example, a
viscosity of 1,000 to 15,000 cps or 3,000 to 8,000 cps.
25 [0039] The polyoxometalate formed in step (A) may be, for example,
8
dried and then filtered and dried, followed by pulverization.
[0040] The loading of step (B) may be carried out, for example, by
spraying the polyoxometalate onto the inert carrier or spraying the
polyoxometalate along with water onto the inert carrier.
5 [0041]
[0042] A ligand of the metal precursor may be one or more selected
from, for example, -NH4,
-NH2, -NOx, where x is an integer of 1 to 4, -Cl, -F, -
N, -OH, -Sox, wherein x is an integer of 1 to 4, -CO, -COO, -SCN, -CN, -NCS,
-ONO, -NC, -CnHmOx, where n is an integer of 1 to 20, m is an integer of 1 to
10 40 and x is an integer of 1 to 10, and C1 to C20 alkoxide.
[0043] In step (A), the concentration of the suspension may be 25 to
45 % by weight or 30 to 40 % by weight.
[0044] The drying of step (C) may be, for example, hot air drying.
[0045] The loading of step (B) may be carried out, for example, by
15 repeating a process of coating the inert carrier with the polyoxometalate and
drying the coated inert carrier once or more.
[0046] The drying of step (C) may be carried out, for example, at 100
to 230°C.
[0047] In step (A), the viscosity of the suspension may be increased,
20 for example, by means of a homogenizer at 25 to 50°C, thereby forming
polyoxometalate.
[0048] The firing of step (D) may be performed, for example, at 350
to 500°C for 1 to 10 hr.
[0049]
9
[0050] In accordance with yet another aspect of the present invention,
there is provided a method of preparing unsaturated carboxylic acid, wherein
vapor-phase partial oxidation to produce the unsaturated carboxylic acid from
unsaturated aldehyde gas is carried out at 240 to 450°C under 0.1 to 10 atm in
5 a fixed-bed catalytic reactor filled with the polyoxometalate catalyst.
[0051] The fixed-bed catalytic reactor may be, for example, a shelland-
tube heat exchanger.
【Advantageous effects】
[0052] As apparent from the above description, the present invention
10 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.
15 【Best Mode】
[0053] Hereinafter, the present invention is described in more detail.
[0054] A polyoxometalate catalyst of the present invention includes a
metal oxide represented by Formula 1 below:
[0055] [Formula 1]
20 [0056] MoaAbVcBdCeDfOg,
[0057] wherein A is one or more elements selected from the group
consisting of W and Cr; B is one or more elements selected from the group
consisting of P, As, B, Sb, Ce, Pb, Mn, Nb and Te; C is one or more elements
selected from the group consisting of Si, Al, Zr, Rh, Cu, Ni, Ti, Ag, Fe, Co and
10
Sn; D is one or more selected from the group consisting of Na, K, Li, Rb, Cs,
Ta, Ca, Mg, Sr and Ba; and a, b, c, d, e, f, and g represent atomic ratios of the
respective elements, wherein, when a=12, b is 0.01 to 15; c is 0.01 to 15, d is 0
to 20, e is 0 to 20, f is 0 to 20; and g is determined depending upon oxidation
5 states of the respective ingredients, and wherein a mole ratio of V to A (V/A) is
0.01 to 10.
[0058]
[0059] In the present disclosure, the term "polyoxometalate" has a
generally defined meaning, unless specified otherwise.
10 [0060] In the present disclosure, the term "ligand" refers to a group of
anions bound to metal cations in a metal precursor, and has a generally defined
meaning unless specified otherwise.
[0061]
[0062] In another embodiment, a mole ratio of V to A may be 0.05 to
15 5, preferably 0.5 to 4, more preferably 0.5 to 3. Within this range, an
oxidation state of vanadium is affected, whereby the catalyst has superior
activity and selectivity. In particular, tungsten (W) functions as a structural
promoter in the catalyst and thus increases the amount of V4+ in the catalyst,
thereby increasing catalytic activity.
20 [0063]
[0064] The vanadium (V) may include, for example, 30 (mol) % or
more, 40 % or more, or 50 % or more of vanadium with an oxidation number
of 4+. Within this range, activity and selectivity of the catalyst are increased,
superior reproducibility is exhibited, and unsaturated carboxylic acid may be
25 produced in a high yield for a long time.
[0065] In the metal oxide, a mole ratio of V4+ to a total content of
11
vanadium (V) (V4+/(V4++V5+)) is, for example, 0.3 to 1, 0.4 to 0.8, or 0.5 to 0.8.
Within this range, the activity and selectivity of the catalyst are increased,
superior reproducibility is provided, and unsaturated carboxylic acid is
produced in a high yield for a long time.
5 [0066]
[0067] b may be, for example, 0.1 to 10, 1.0 to 6.0, or 1.5 to 5.0.
Within this range, the activity, selectivity, and lifespan of the catalyst are
greatly improved.
[0068] c may be, for example, 0.5 to 10, 1.0 to 5.0, or 2.0 to 3.0.
10 Within this range, the activity, selectivity, and lifespan of the catalyst are
greatly improved.
[0069]
[0070] Each of d, e, and f may be, for example, 0.01 to 20 or 0.05 to
10.
15 [0071] In another embodiment, d may be 0.01 to 0.5, 0.05 to 0.4, or
0.1 to 0.3, e may be 0.1 to 8.0, 0.5 to 7.0, or 1.0 to 5.5, and f may be 0.1 to 5.0,
0.5 to 2, or 0.8 to 1.3. Within this range, the catalyst exhibits superior activity
and selectivity.
[0072] A may be, for example, W, B may be, for example, Nb or Mn
20 or a combination thereof, C may be, for example, one or more selected from
the group consisting of Cu, Fe, and Co, D may be, for example, Sr. In this
case, the activity and selectivity of the catalyst are increased, superior
reproducibility is provided, and unsaturated carboxylic acid is produced in a
high yield for a long time.
25 [0073]
12
[0074] The polyoxometalate catalyst may include, for example, an
inert carrier, as a supporter of the metal oxide.
[0075] The inert carrier may be one or more selected from the group
consisting of, for example, porous aluminosilicate, silicon carbide alumina, and
5 silica.
[0076] A loading amount of a metal oxide coated on the inert carrier
may be, for example, 30 to 80 % by weight, 40 to 70 % by weight, or 50 to 60 %
by weight. Within this range, the catalyst has superior activity and selectivity.
[0077]
10 [0078] The polyoxometalate catalyst may be, for example, a catalyst
for vapor-phase partial oxidation to produce unsaturated carboxylic acid from
unsaturated aldehyde.
[0079]
[0080] A method of preparing polyoxometalate catalyst of the present
15 invention includes (A) a step of preparing a suspension including metal
precursors to produce a metal oxide represented by Formula 1 and, as needed,
adjusting pH to 0 to 7.5 by adding an acid, followed by increasing a viscosity
by means of a homogenizer to form polyoxometalate; (B) a step of loading 20
to 50 % by weight of the formed polyoxometalate to an inert carrier to prepare
20 a loaded substance; (C) a step of drying the loaded substance to obtain a loaded
substance having a ligand sublimation rate of 0 % or more calculated by
Equation 1 below; and (D) a step of firing the dried loaded substance to obtain
a polyoxometalate catalyst:
[0081] [Equation 1]
25 [0082] Ligand sublimation rate (%) = (mass of sublimated
ligand/mass of ligand before sublimation) X 100.
13
[0083]
[0084] A vanadium (V) precursor represented by Formula 1 may be,
for example, a compound containing vanadium with an oxidation number of
4+, preferably a vanadyl-containing compound. Within this range, the
activity and 5 selectivity of the catalyst are increased, superior reproducibility is
provided, and unsaturated carboxylic acid is produced in a high yield for a long
time.
[0085] The vanadyl-containing compound may be, for example,
vanadyl acetylacetonate, vanadyl sulfate, or the like.
10 [0086]
[0087] In step (A), the polyoxometalate may have, for example, a
viscosity of 1,000 to 15,000 cps or 3,000 to 8,000 cps. Within this range, the
catalyst exhibits superior activity and selectivity.
[0088] The pH adjusted in step (A) may be, for example, 3 to 5,
15 preferably 4 to 5. Within this range, the catalyst exhibits superior activity,
selectivity, and lifespan and a drying time and temperature are decreased.
[0089]
[0090] The polyoxometalate formed in step (A) may be, for example,
dried and then filtered and dried, followed by being pulverization.
20 [0091] The filter may be used, for example, to remove inorganic salts
from slurry-type polyoxometalate through a filter and/or a filter press.
[0092]
[0093] A ligand of the metal precursor may be one or more selected
from, for example, -NH4,
-NH2, -NOx, where x is an integer of 1 to 3, -Cl, -F, -
25 N, -OH, -Sox, wherein x is an integer of 3 to 4, -CO, -COO, -SCN, -CN, -NCS,
14
-ONO, -NC, -CnHmOx, where n is an integer of 1 to 20, m is an integer of 1 to
40 and x is an integer of 1 to 10, and C1 to C20 alkoxide. In this case, the
oxidation states and morphologies of the transition metal and transition metal
oxide are affected, thereby improving the activity and selectivity of the catalyst.
5 [0094]
[0095] In step (A), the concentration of the suspension may be 25 to
45 % by weight or 30 to 40 % by weight. Within this range, the catalyst
exhibits superior activity and selectivity.
[0096]
10 [0097] In an embodiment, in step (A), the viscosity of the suspension
is increased at 25 to 50°C, preferably 20 to 40°C, by means of a homogenizer,
thereby forming polyoxometalate. Within this range, the catalyst exhibits
superior activity and selectivity. Here, the polyoxometalate may correspond
to a precursor of the polyoxometalate catalyst of the present disclosure.
15 [0098] The viscosity of the polyoxometalate may be, for example,
1,000 to 15,000 cps or 3,000 to 8,000 cps. Within this range, the catalyst
exhibits superior activity and selectivity.
[0099]
[0100] The polyoxometalate of step (A) may further include, for
20 example, a surfactant. In this case, a layer separation phenomenon in a
coprecipitated solution may be alleviated.
[0101] The surfactant may be, for example, a nonionic or neutral
surfactant.
[0102] The nonionic surfactant may be, for example,
25 CH3(CH2)15(EO)nOH, where n is an integer of 2 to 20.
15
[0103] The neutral surfactant may be, for example, CH3(CH2)n-1NH2,
wherein n is an integer of 12 to 16.
[0104] The surfactant may be included, for example, in an amount of
0.1 % by weight or less, 0.001 to 0.1 % by weight, or 0.01 to 0.05 % by weight
based on a total weight of 5 a slurry solution. Within this range, a layer
separation phenomenon in a coprecipitated solution may be alleviated.
[0105]
[0106] In step (A), the method of forming polyoxometalate may be a
general polyoxometalate formation method, such as hydrothermal reaction,
10 coprecipitation, or the like, without any specific limitation, unless specified
otherwise.
[0107]
[0108] The coating of the step (B) may be carried out, for example,
by spraying polyoxometalate onto the inert carrier or spraying polyoxometalate
15 along with water onto the inert carrier.
[0109] The spraying with polyoxometalate may be carried out, for
example, by spraying slurry-type polyoxometalate, which has not been filtered
or dried, onto the inert carrier using a nozzle to coat the slurry-type
polyoxometalate on the inert carrier.
20 [0110]
[0111] The spraying with polyoxometalate and water may be carried
out, for example, by spraying polyoxometalate, which has been filtered and/or
dried, along with water onto the inert carrier to coat the slurry-type
polyoxometalate on the inert carrier.
25 [0112]
16
[0113] In the loaded substance of step (B), the loading amount of
polyoxometalate calculated by Equation 2 below may be, for example, 15 to
50 %, 20 to 50 %, 20 to 40 %, or 20 to 30 %. Within this range, the catalyst
exhibits superior activity and selectivity.
5 [0114] [Equation 2]
[0115] Loading amount (%) = (total mass of catalyst precursors/total
mass of loaded substance) X 100
[0116]
[0117] The loading of step (B) may be carried out, for example, by
10 repeating a process of coating polyoxometalate onto the inert carrier and
drying the coated polyoxometalate once or more, once to ten times, once to
eight times, or five times to eight times. Within this range, the catalyst
exhibits superior activity and selectivity.
[0118]
15 [0119] The drying of step (C) may be, for example, hot air drying.
[0120] The drying may be carried out, for example, in a silicon
carbide (SiC) container, an alumina container, a stainless steel container, a
metal container, or a container made of an incombustible material having heat
transfer ability.
20 [0121] The drying of step (C) may be carried out, for example, at 100
to 230°C, 110 to 200°C, or 120 to 150°C for 3 to 10 hours or 5 to 8 hours.
[0122] The ligand sublimation rate of step (C) may be, for example,
1.7 % or more, or 1.7 to 4 %. Within this range, the activity, selectivity, and
lifespan of the catalyst are greatly improved.
25 [0123]
17
[0124] The firing of step (D) may be performed, for example, at 350
to 550°C or 400 to 500°C for 1 to 10 hours or or 3 to 5 hours.
[0125]
[0126] In steps (A) to step (D), a total weight reduction rate (%)
calculated by Equation 5 3 below may be, for example, 30 to 50 %, 35 to 45 %,
or 40 to 45 %. Within this range, the catalyst exhibits superior activity and
selectivity:
[0127] [Equation 3]
[0128] T total weight reduction rate (%) = (mass of removed
10 materials/mass of a total of added materials including a solvent) X 100
[0129]
[0130] In steps (A) to (D), the total ligand sublimation rate (%)
calculated by Equation 4 below may be, for example, 0.1 to 20 %, 1 to 10 %,
or 2 to 5 %. Within this range, the catalyst exhibits superior activity and
15 selectivity:
[0131] [Equation 4]
[0132] Total ligand sublimation rate (%) = (mass of removed
ligand/mass of a total of added materials including a solvent) X 100
[0133]
20 [0134] The polyoxometalate catalyst may have, for example, a
cylindrical shape, a hollow cylindrical shape), or a spherical shape.
[0135] An external diameter of the polyoxometalate catalyst may be,
for example, 3 to 10 mm, or 5 to 8 mm.
[0136] A ratio of the length to the diameter (external diameter) (L/D)
18
of the cylinder type catalyst may be, for example, 1 or less, 0.1 to 1, or 1.0 to
1.3.
[0137]
[0138] A method of preparing the unsaturated carboxylic acid of the
5 present invention is characterized in that vapor-phase partial oxidation to
produce unsaturated carboxylic acid from unsaturated aldehyde gas is carried
out at 240 to 450°C under 0.1 to 10 atm in a fixed-bed catalytic reactor filled
with the polyoxometalate catalyst.
[0139] The unsaturated aldehyde may be, for example, methacrolein.
10 [0140] The unsaturated carboxylic acid may be, for example,
unsaturated fatty acid. In another embodiment, the unsaturated carboxylic
acid may be (meth)acrylic acid or the like.
[0141] The fixed-bed catalytic reactor may be, for example, a fixedbed
catalytic reactor filled with a catalyst using a method by which an
15 occupation volume of the catalyst is decreased.
[0142] The unsaturated aldehyde gas may be added, for example,
along with unsaturated fatty acid.
[0143]
[0144] The vapor-phase partial oxidation may be carried out, for
20 example, at 240 to 370°C and 0.4 to 3 atm. In another embodiment, the
vapor-phase partial oxidation may be carried out at 250 to 310°C and 1 to 3
atm.
[0145] The vapor-phase partial oxidation may be carried out, for
example, by introducing unsaturated aldehyde at a space velocity of 80 to 100
25 hr-1, 20 % by volume or less of oxygen (not including 0 % by volume), 50 %
19
by volume or less of water vapor (not including 0 % by volume), and 20 to 80 %
by volume or less of an inert gas into the reactor.
[0146] In another embodiment, the vapor-phase partial oxidation may
be carried out by introducing a raw material gas, which includes unsaturated
aldehyde, oxygen, steam, and 5 nitrogen, at a space velocity of 500 to 3000 hr-1
(STP), into the reactor.
[0147]
[0148] The fixed-bed catalytic reactor may be, for example, a shelland-
tube heat exchanger.
10 [0149] A material of the shell-and-tube heat exchanger may be, for
example, silicon carbide (SiC), stainless steel, a metal, or a material having
superior heat transfer ability.
[0150]
[0151] The aforementioned description is provided only to illustrate
15 embodiments according to the present invention. Those skilled in the art will
appreciate that various modifications, additions and substitutions are possible,
without departing from the scope and spirit of the invention. Therefore, it is
obvious that the modifications, additions and substitutions are included in the
scope of the present invention.
20 [0152]
[0153] Example 1
[0154] 246 g of ammonium tungstate, 1,000 g of ammonium
molybdate, and 12 g of niobium oxalate (NbC2O4) were added while stirring
3000 ml of distilled water at 100°C, thereby preparing a solution (1) composed
25 of Mo, A, and B ingredients of Formula 1. Separately, 276 g of vanadyl
20
sulfate was dissolved in 1000 ml of distilled water, thereby preparing the
solution (2).
[0155] The solution (1) was mixed with the solution (2), and then 570
g of Cu(CH3COO)2·H2O, 99 g of strontium nitrate, 23 g of manganese nitrate,
and 95 g 5 of iron nitrate, as C and D ingredients of Formula 1, were added
thereto, thereby preparing a suspension. The pH of the suspension was
adjusted to 4 to 5 using dilute sulfuric acid, and then a homogenizer was
operated until polyoxometalate formed a slurry in which viscosity was
sufficiently increased.
10 [0156] Subsequently, the slurry-type polyoxometalate was coated on
a spherical carrier, aluminosilicate (Saint Gobain, SA5218) with an external
diameter of 4.0 mm to 8.0 mm, by means of a spray nozzle and was
sufficiently dried at 120°C. This process was repeated eight times. As a
result, a loaded substance loaded in an amount of 25 % by weight was prepared.
15 [0157] Subsequently, the loaded substance was fired at 500°C for five
hours or more, thereby preparing a spherical polyoxometalate catalyst with a
final external diameter of 4.7 mm, 5.4 mm, or 7.8 mm which was slightly
larger, particularly 0.2 to 0.4 mm larger, than the external diameter of the
carrier. In this case, the compositions of elements, except for oxygen, of a
20 generated polyoxometalate catalyst are as follows:
[0158] Mo12 V5.0 W2.0 Nb0.1 Cu5.0 Sr1.0 Mn0.2 Fe0.5
[0159]
[0160] Example 2
[0161] A polyoxometalate catalyst was prepared in the same manner
25 as in Example 1, except that ammonium tungstate was used in an amount of
123 g. The compositions of elements, except for oxygen, of a generated
21
catalyst ingredient are as follows:
[0162] Mo12 V5.0 W5.0 Nb0.1 Cu5.0 Sr1.0 Mn0.2 Fe0.5
[0163]
[0164] Comparative Examples 1
5 [0165] A polyoxometalate catalyst was prepared in the same manner
as in Example 1, except that vanadyl sulfate was not used. The compositions
of elements, except for oxygen, of a generated catalyst ingredient are as
follows:
[0166] Mo12 W5.0 Nb0.1 Cu5.0 Sr1.0 Mn0.2 Fe0.5
10 [0167]
[0168] Comparative Examples 2
[0169] A polyoxometalate catalyst was prepared in the same manner
as in Example 1, except that ammonium tungstate was not used. The
compositions of elements, except for oxygen, of a generated catalyst ingredient
15 are as follows:
[0170] Mo12 V5.0 Nb0.1 Cu5.0 Sr1.0 Mn0.2 Fe0.5
[0171]
[0172] Reference Example 1
[0173] A polyoxometalate catalyst was prepared in the same manner
20 as in Example 1, except that ammonium vanadate was used instead of vanadyl
sulfate. The compositions of elements, except for oxygen, of a generated
catalyst ingredient are as follows:
[0174] Mo12 V5.0 W2.0 Nb0.1 Cu5.0 Sr1.0 Mn0.2 Fe0.5
22
[0175]
[0176] [Test example]
[0177] The properties of the polyoxometalate catalyst prepared
according to each of Examples 1 and 2, Comparative Examples 1 and 2, and
Reference Example 5 1 was measured by the following methods. Results are
summarized in Table 1 below.
[0178] * Ratios of V4+ and V5+: Measured using the prepared
catalysts by means of XPS (ESCA) (device name: X-ray photoelectron
spectroscopy, model name: UK-Multilab 2000, manufacturer: Thermos VG).
10 Here, vanadium having an oxidation number of 2+ or 3+ was not detected.
[0179] * Ligand sublimation rate: the mass of sublimated ligand was
measured and calculated according to Equation 1 below:
[0180] [Equation 1]
[0181] Ligand sublimation rate (%) = (mass of sublimated
15 ligand/mass of ligand before sublimation) X 100.
[0182] * Viscosity (cps): Measured by means of a Brookfield
viscometer with #63 spindle at 2 RPM and room temperature (resistance: 5 to
6 %).
[0183]
20 [0184]
[0185] Using a stainless steel reactor filled with the catalyst, which
was obtained according to each of Examples 1 to 2, Comparative Examples 1
and 2, and Reference Example 1, as a fixed bed, aldehyde was introduced with
a mixed gas, which was composed of oxygen, water vapor, and an inert gas, at
25 a space velocity of 100 hr-1 and 240 to 310°C under a reaction pressure of 1 to
23
3 atm, whereby vapor-phase partial oxidation occurred. A conversion rate,
selectivity, and yield of the reactant (acrolein) were respectively calculated
according to Equations 5 to 7 below. Results are summarized in Table 1
below.
5 [0186] [Equation 5]
[0187] Conversion rate of acrolein (%) = [number of moles of reacted
acrolein/number of moles of supplied acrolein] X 100
[0188] [Equation 6]
[0189] Selectivity of acrolein (%) = [number of moles of generated
10 acrylic acid/number of moles of reacted acrolein] X 100
[0190] [Equation 7]
[0191] Yield (%) = [number of moles of generated acrylic
acid/number of moles of supplied acrolein] X 100
[0192]
15 [0193] 【Table 1】
Classification
Ligand
sublim
a-tion
rate (%
by
weight)
Mole
ratio
of
V/W
pH of
reaction
solution
Ratio n
of
V4+/(V4
+V5+)
Acrolein
conversion
rate (%)
Acrolein
selectivity
(%)
Acrylic
acid
yield
(%)
Example 1 2.8 2.5 4 to 5 0.70 97.75 96.20 93.41
Example 2 2.8 1 4 to 5 0.60 97.0 95.1 92.24
Comparative 2.5 0 4 to 5 0.0 60.04 80.5 48.33
24
Examples 1
Comparative
Examples 2
2.8 ∞ 4 to 5 0.0 57.18 78.4 44.82
Reference
Example 1
2.8 2.5 4 to 5 0.55 97.30 95.2 92.62
[0194]
[0195] As shown in Table 1, it can be confirmed that the
polyoxometalate catalysts (Example 1 to 2), in which the V/A value was
adjusted, according to the present invention, exhibit superior conversion rate,
5 selectivity, yield, and the like, compared to a conventional technology and
Comparative Examples 1 and 2, which were outside the V/A range of the
present invention.
[0196] In addition, it can be confirmed that, when the V4+-containing
precursor is used as a vanadium precursor, selectivity and yield considerably
10 increase, compared to the case in which the V5+-containing precursor is used.
[0197] In addition, it can be confirmed that the ligand sublimation
rate, the pH of the suspension, and the like have some effect on catalytic
activity, selectivity, and yield.
[0198] Further, it can be confirmed that the polyoxometalate catalysts
15 of the present invention (Examples 1 and 2) may be reacted in a broader
reaction temperature range, i.e., 250 to 310°C, than a reaction temperature
range, i.e., 270 to 310°C, of a conventional technology, and thus, may be
reacted for a longer time, compared to the conventional cases.

We Claim:
【Claim 1】
A polyoxometalate catalyst, comprising a metal oxide represented by
Formula 1 below:
5 [Formula 1]
MoaAbVcBdCeDfOg,
wherein A is one or more elements selected from the group
consisting of W and Cr; B is one or more elements selected from the group
consisting of P, As, B, Sb, Ce, Pb, Mn, Nb and Te; C is one or more elements
10 selected from the group consisting of Si, Al, Zr, Rh, Cu, Ni, Ti, Ag, Fe, Co and
Sn; D is one or more selected from the group consisting of Na, K, Li, Rb, Cs,
Ta, Ca, Mg, Sr and Ba; and a, b, c, d, e, f, and g represent atomic ratios of the
respective elements,
wherein, when a=12, b is 0.01 to 15; c is 0.01 to 15, d is 0 to 20, e is
15 0 to 20, f is 0 to 20; and g is determined depending upon oxidation states of the
respective ingredients, and
wherein a mole ratio of V to A (V/A) is 0.01 to 10.
【Claim 2】
The polyoxometalate catalyst according to claim 1, wherein each of
20 d, e and f is 0.01 to 20.
【Claim 3】
The polyoxometalate catalyst according to claim 1, wherein the
vanadium (V) comprises 30 % or more of vanadium having an oxidation
number of 4+.
25 【Claim 4】
The polyoxometalate catalyst according to claim 1, wherein the
polyoxometalate catalyst comprises an inert carrier, as a supporter of the metal
26
oxide.
【Claim 5】
The polyoxometalate catalyst according to claim 4, wherein a
loading amount of a metal oxide coated on the inert carrier is 30 to 80 % by
5 weight.
【Claim 6】
The polyoxometalate catalyst according to claim 1, wherein the
polyoxometalate catalyst is a catalyst for vapor-phase partial oxidation to
produce unsaturated carboxylic acid from unsaturated aldehyde.
10 【Claim 7】
A method of preparing the polyoxometalate catalyst according to
claim 1, the method comprising: (A) a step of preparing a suspension
comprising metal precursors to produce a metal oxide represented by Formula
1 and, as needed, adjusting pH to 0 to 7.5 by adding an acid, followed by
15 increasing a viscosity by means of a homogenizer to form polyoxometalate; (B)
a step of loading 20 to 50 % by weight of the formed polyoxometalate to an
inert carrier to prepare a loaded substance; (C) a step of drying the loaded
substance to obtain a loaded substance having a ligand sublimation rate of 0 %
or more calculated by Equation 1 below; and (D) a step of firing the dried
20 loaded substance to obtain a polyoxometalate catalyst:
[Equation 1]
Ligand sublimation rate (%) = (mass of sublimated ligand/mass of
ligand before sublimation) X 100.
【Claim 8】
25 The method according to claim 7, wherein a vanadium (V) precursor
represented by Formula 1 is a compound containing vanadium with an
oxidation number of 4+.
27
【Claim 9】
The method according to claim 8, wherein the compound containing
vanadium with oxidation number of 4+ is a vanadyl-containing compound.
【Claim 10】
5 The method according to claim 7, wherein, in step (A), the
polyoxometalate has a viscosity of 5,000 to 20,000 cps.
【Claim 11】
The method according to claim 7, wherein, in step (A), the
polyoxometalate is dried and then filtered and dried, followed by pulverization.
10 【Claim 12】
The method according to claim 7, wherein the loading of step (B) is
carried out by spraying the polyoxometalate onto the inert carrier or spraying
the polyoxometalate along with water onto the inert carrier.
【Claim 13】
15 The method according to claim 7, wherein a ligand of the metal
precursor is one or more selected from -NH4,
-NH2, -NOx, where x is an
integer of 1 to 3, -Cl, -F, -N, -OH, -Sox, wherein x is an integer of 3 to 4, -CO,
-COO, -SCN, -CN, -NCS, -ONO, -NC, -CnHmOx, where n is an integer of 1
to 20, m is an integer of 1 to 40 and x is an integer of 1 to 10, and C1 to C20
20 alkoxide.
【Claim 14】
The method according to claim 7, wherein, in step (A), a
concentration of the suspension is 25 to 45 % by weight.
【Claim 15】
25 The method according to claim 7, wherein the drying of step (C) is
hot air drying.
28
【Claim 16】
The method according to claim 7, wherein the loading of step (B) is
carried out by repeating a process of coating the inert carrier with the
polyoxometalate and drying the coated inert carrier once or more.
5 【Claim 17】
The method according to claim 7, wherein the drying of step (C) is
carried out at 100 to 230°C.
【Claim 18】
The method according to claim 7, wherein, in step (A), a viscosity of
10 the suspension is increased by means of a homogenizer at 25 to 50°C, thereby
forming polyoxometalate.
【Claim 19】
The method according to claim 7, wherein the firing of step (D) is
performed at 350 to 550°C for 1 to 10 hr.
15 【Claim 20】
A method of preparing unsaturated carboxylic acid, wherein vaporphase
partial oxidation to produce the unsaturated carboxylic acid from
unsaturated aldehyde gas is carried out at 240 to 450°C under 0.1 to 10 atm in
a fixed-bed catalytic reactor filled with the polyoxometalate catalyst according
20 to claim 1.