JP5562049B2 - Catalyst for catalytic partial oxidation of hydrocarbons and process for producing synthesis gas - Google Patents

Description

  The present invention provides GTL, DME, methanol, ammonia, hydrogen production, etc. by performing partial oxidation by adding oxygen to light hydrocarbons such as natural gas and associated gas containing methane and hydrocarbons having 2 or more carbon atoms. The present invention relates to a catalyst used when producing a synthesis gas containing carbon monoxide and hydrogen as a raw material gas, and a synthesis gas production method.

  In recent years, global environmental problems caused by mass consumption of fossil fuels such as oil and coal and the problem of depletion of future petroleum resources have been taken up. Therefore, GTL (hydrocarbon liquid), which is a clean fuel produced from natural gas, etc. Fuel) and DME (dimethyl ether) are attracting attention. A raw material gas for producing GTL or DME is called a synthesis gas and contains carbon monoxide and hydrogen.

  As a method for producing such a synthesis gas, a steam reforming method (SMR) for reforming natural gas or the like with steam, a partial oxidation method (POX) using oxygen in the absence of a catalyst, or an oxidation using an oxygen burner. An autothermal reforming method (ATR method) or the like in which the reaction and the steam reforming reaction are performed in the same reactor is conventionally known. The applicant of the present invention has a simpler apparatus configuration than those of the conventional methods, and a synthesis gas employing a catalytic partial oxidation method (CPO method: Catalytic Partial Oxidation) with less problems such as soot generation and carbon deposition during the reaction. Has developed a new manufacturing process.

The CPO method is a technique in which a hydrocarbon gas separated from natural gas or the like is brought into contact with an oxygen-containing gas in the presence of a catalyst to partially oxidize the hydrocarbon gas to obtain a synthesis gas (Patent Document 1). ). The CPO method is superior to the autothermal reforming method in that it does not require a pre-reformer even if a C2 or higher component is contained because there is no burner. Further, since the reaction rate by the catalyst is extremely high, the reaction is completed even under high SV conditions of tens of thousands to several millions, so that there is an advantage that the reactor becomes small.
This reaction mainly includes the following reactions when methane is taken as an example.
(1) CH ₄ + 1 / 2O ₂ → 2H ₂ + CO ΔH298 = −36 kJ / mol
(2) CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O ΔH298 = −879 kJ / mol
(3) CO + H ₂ O → CO ₂ + H ₂ ΔH298 = −42 kJ / mol
(4) CH ₄ + H ₂ O → CO + 3H ₂ ΔH298 = + 206 kJ / mol
(5) CH ₄ + CO ₂ → 2CO + 2H ₂ ΔH298 = + 248 kJ / mol

  The reactions (1) to (5) proceed simultaneously or sequentially, and the outlet gas composition is governed by the equilibrium, but the reaction as a whole is a very large exothermic reaction. Among these reactions, the reaction rates of (1) and (2) are extremely high. In particular, since the reaction heat of complete oxidation (2) is large, the temperature rises rapidly at the catalyst layer inlet. The solid line shown in FIG. 13 is a temperature distribution in which the horizontal axis represents the position from the inlet side to the outlet side of the reactor, and the vertical axis represents the temperature of the catalyst layer. When the raw material gas is supplied at a temperature, the temperature of the catalyst layer inlet is rapidly increased to, for example, about 1200 ° C. to 1500 ° C. under the influence of the exothermic reaction. The temperature of the catalyst layer gradually decreases under the influence of the endothermic reactions (4) and (5), for example, where the reaction rate is relatively low, and eventually reaches a thermal equilibrium state at about 1000 ° C.

Such a temperature distribution of the catalyst layer changes rapidly due to, for example, a change in the composition of the raw material gas or a minute pressure fluctuation, and the position at which the temperature of the catalyst layer reaches a maximum is also changed according to these changes, for example, a broken line or It moves to the upstream side or downstream side of the reactor as indicated by the alternate long and short dash line. For example, when the temperature distribution in the reactor changes from the state indicated by the solid line in FIG. 13 to the state indicated by the broken line, the catalyst charged at the position indicated by point P _{1 on} the horizontal axis is, for example, It is heated rapidly from several hundred degrees to about 1200 ° C to 1500 ° C. Since this temperature change occurs, for example, in less than one second to several seconds, the catalyst in the region is exposed to a rapid temperature change of, for example, about 250 ° C./second to about 1300 ° C./second. On the other hand, when the temperature distribution shown by the solid line is changed to a temperature distribution shown by a dashed line, for example, the catalyst filled in the position of P ₂ points are cooled to the same extent as the P ₁ point described above Exposed to sudden temperature changes.

  Since such a change in the temperature distribution in the catalyst layer occurs continuously during the operation of the reactor, the catalyst filled in the vicinity of the inlet of the reactor is always repeatedly subjected to such rapid heating and cooling. The catalyst charged in the reactor is formed into, for example, a spherical shape, a tablet shape, a cylindrical shape, a honeycomb shape, a ring shape, a foam body, etc., so that stress changes due to rapid expansion and contraction associated with such heating and cooling, That is, the catalyst is broken and pulverized by thermal shock, and the catalyst layer is clogged. If the catalyst layer is clogged, the pressure loss of the reactor may increase and the operation may not be continued. Therefore, a catalyst having high thermal shock resistance is required for the CPO method.

  Patent Document 2 describes a catalyst used in a CPO method in which an active metal is supported on a support mainly composed of zirconia to improve the thermal shock resistance. However, the catalyst has a temperature change of 60 ° C./second to 100 ° C./second over a temperature range of 800 ° C. to 1200 ° C., which is a very mild condition compared to the temperature change described above. It is not suitable for the CPO process developed by the applicant.

JP 2007-69151 A: Paragraphs 0038 to 0042 Japanese Patent No. 4020428: Claim 1, paragraph 0027

  The present invention has been made under such circumstances, and an object thereof is to provide a catalyst for catalytic partial oxidation of hydrocarbons having high thermal shock resistance and a method for producing synthesis gas using this catalyst. It is in.

The catalyst for catalytic partial oxidation of hydrocarbons according to the present invention comprises catalytically oxidizing partial hydrocarbons by adding at least oxygen and steam to raw hydrocarbons containing at least one of methane and light hydrocarbons having 2 or more carbon atoms. And a catalyst for catalytic partial oxidation of a hydrocarbon used when producing a synthesis gas containing carbon monoxide and hydrogen, and carrying an active metal on a carrier made of an inorganic oxide,
The volume ratio A [volume%] of the total volume of pores in the pore diameter range of 1 μm or more and less than 10 μm with respect to the total pore volume of the catalyst, the thickness of the catalyst at the position where the thermal shock resistance is determined in the catalyst It is characterized in that the following condition is satisfied for the length B [mm].
When 0 <B ≦ 1.5, A ≧ 3.0,
When 1.5 <B, A ≧ 0.158B ² −0.467B + 3.411
However, the thickness B of the catalyst at the position where the thermal shock resistance is determined corresponds to the following value.
(A) When the catalyst has a cylindrical shape with a radius R and a length L,
When 2R ≦ L, B = 2R,
When 2R> L, B = L,
(B) when the catalyst is ring-shaped with a ring width D and a length L,
When D ≦ L, B = D,
When D> L, B = L
(C) when the catalyst is spherical with a radius R,
B = 2R

The catalyst may further have the following characteristics.
First, the specific surface area before Symbol catalyst 0.5 m ² / g or more, or less 7.0 m ² / g.
Second, the total pore volume of the catalyst is 0.05 cm ³ / g or more, or less 0.3 cm ³ / g.

Third, the first element of the carrier comprising the inorganic oxide is Al, the carrier in terms of Al ₂ O ₃ at 30 wt% or more per unit weight, to contain 90 wt% or less of Al.
Fourth , in addition to the first constituent element, the support made of the inorganic oxide includes an element belonging to an alkaline earth metal, an element belonging to a rare earth metal, an element group consisting of Sc, Bi, Zr, Si, and Ti. Including oxides of at least two selected elements.
Fifth , the elements belonging to the alkaline earth metal are Mg, Ca, Sr and Ba, and the elements belonging to the rare earth metal are Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, and Yb.
Sixth , the carrier made of the inorganic oxide includes zirconia stabilized by one or more elements selected from Y, Ce, Ca, Mg, Sc, and Sm.
Seventh , the stabilized zirconia is yttria stabilized zirconia stabilized by yttria.
Eighth , the yttria-stabilized zirconia contains yttria in the range of 2 mol% to 10 mol%.
Ninth , the active metal is one or more metals selected from Group VIII elements of the Periodic Table.
Tenth , the elements of Group VIII of the periodic table are Ru, Pt, Rh, Pd, Os and Ir.
11thly , the said active metal is 0.05 to 5.0 weight% per unit weight of a catalyst.

Next, a method for producing a synthesis gas according to another invention is a raw material gas obtained by adding oxygen and steam to a raw material hydrocarbon containing at least one of methane and a light hydrocarbon having 2 or more carbon atoms. Supplying a raw material gas containing hydrogen by containing hydrogen in the reactor and / or adding hydrogen into the reactor;
A synthesis gas containing carbon monoxide and hydrogen, which is prepared by bringing the catalyst for catalytic partial oxidation of hydrocarbon provided in the reactor into contact with the raw material gas in a heated state to catalytically oxidize the raw material hydrocarbon. And a step of manufacturing.

The synthesis gas production method may further include the following features.
First, in the step of producing the synthesis gas, in the region where the catalyst and the raw material gas are in contact with each other in a heated state, the catalyst is 250 ° C./second to 1300 ° C. over a temperature range of 200 ° C. to 1500 ° C. An area subject to a temperature change of / sec is included.
Second, after preheating the source gas to 200 ° C. to 500 ° C., the pressure is normal pressure to 8 MPa, and the space velocity (GHSV) is 5.0 × 10 ³ (NL / L / Hr) to 1.0 ×. Supply into the reactor under the condition of 10 ⁶ (NL / L / Hr) and contact with the catalyst under adiabatic reaction conditions.

  According to the present invention, the thickness of the catalyst at the position where the thermal shock resistance of the catalyst is determined with respect to the volume ratio of the total pore volume in the range where the pore diameter with respect to the total pore volume is 1 μm or more and less than 10 μm. By using a catalyst satisfying a predetermined relational expression, it is possible to obtain a catalyst for partial catalytic oxidation of hydrocarbons that is difficult to be destroyed or pulverized even when subjected to thermal shock. As a result, even if the catalyst is filled in an area that is repeatedly subjected to thermal shock during operation, such as the inlet of a CPO process reactor, troubles such as catalyst destruction and clogging of the catalyst layer due to pulverization are less likely to occur. It can be a high process.

It is explanatory drawing showing the external appearance structure of the catalyst for contact partial oxidation which concerns on embodiment. It is the 2nd explanatory view showing appearance composition of a catalyst for the above-mentioned contact partial oxidation. It is a top view of the catalyst which concerns on a said 2nd explanatory drawing. It is a 3rd explanatory view showing the appearance composition of the catalyst for the above-mentioned contact partial oxidation. It is the 4th explanatory view showing appearance composition of a catalyst for the above-mentioned contact partial oxidation. It is a 5th explanatory view showing appearance composition of a catalyst for contact partial oxidation. It is the schematic which shows the apparatus used for the manufacturing method of the synthesis gas of this invention. It is explanatory drawing showing the relationship between the various variables of the catalyst which concerns on an Example, and a thermal shock performance. It is an external appearance photograph which shows the result of the thermal shock experiment of the support | carrier which concerns on an Example. It is an external appearance photograph which shows the result of the thermal shock experiment of the support | carrier which concerns on another Example. It is an external appearance photograph which shows the result of the thermal shock experiment of the support | carrier which concerns on a comparative example. It is an external appearance photograph which shows the result of the thermal shock experiment of the support | carrier which concerns on another comparative example. It is a characteristic view which shows the relationship between the position in the gas flow direction in a reactor, and the temperature of a catalyst layer.

(First embodiment)
In the catalyst according to the first embodiment of the present invention, the carrier which is an inorganic oxide is produced by, for example, a powder of an alumina precursor such as boehmite, pseudoboehmite or aluminum hydroxide, or γ, η, χ, α − Alumina powder such as alumina is prepared, and for example, barium salt, for example, organic acid salt powder such as nitrate or barium acetate or aqueous solution thereof, YSZ (yttria stabilized zirconia) powder, etc., if necessary This is performed by a method in which a binder as a molding aid is mixed and water is added to the mixture to adjust moisture. Next, after appropriately adjusting the moisture, for example, extrusion molding, tableting molding, pressing, or the like is performed by pressing to form a molded body such as a columnar shape, a tablet, a honeycomb, or a ring shape.

The obtained molded body group is heated and dried as necessary, and then calcined in a firing furnace at, for example, 900 ° C. to 1800 ° C. for 24 hours, for example, so that alumina is a main component and BaO, YSZ, and Part is a complex oxide of Ba and Al (for example, BaAl ₂ O ₄ which is a spinel compound, barium hexaaluminate (BaAl ₁₁ O ₁₉ ), or the like) or a complex oxide of Ba and Zr (for example, BaZrO ₃ or the like). An inorganic oxide support containing barium oxide is obtained. The content of aluminum in the carrier is preferably 30% to 90% by weight in terms of alumina, more preferably 40% to 80% by weight, and still more preferably 50% to 80% by weight. The barium content is preferably 5 to 30% by weight, more preferably 5 to 20% by weight in terms of BaO. The content of YSZ, for example yttria _(Y 2 _{O 3)} and preferably from 5% to 40% by weight in terms of YSZ containing in the range of 2 mol% to 10 mol%, more preferably 10% to 30 The case of weight percent is preferred.

  Here, the method of adding subcomponents (Ba and YSZ) to alumina is not limited to the above-described method, and, for example, a well-known impregnation method, precipitation method, sol-gel method, or the like is generally used depending on the addition ratio of subcomponents. Of course, various known preparation methods may be used. In addition, components other than Al contained in the support are not limited to these, for example, elements belonging to alkaline earth metals such as Mg, Ca, Sr and Ba, Y, La, Ce, Pr, Nd, Elements belonging to rare earth metals such as Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb, oxides of at least two elements selected from the element group consisting of Sc, Bi, Zr, Si and Ti, and YSZ Stabilized zirconia other than may be contained. Furthermore, an element not included in these element groups may be included.

  The carrier prepared by the method described above is a fine particle having a pore diameter in the range of 0.1 μm to 1.0 μm (hereinafter referred to as the first range) provided by a conventionally used alumina carrier. In addition to the pores, a relatively large number of pores having a pore diameter in the range of 1.0 μm to 10 μm (hereinafter referred to as the second range) are included. The ratio of the total volume of pores having pore diameters in the second range to the total pore volume of the catalyst is one index indicating the thermal shock performance of the catalyst. The details will be described later.

  The baked carrier is molded into various shapes such as a columnar shape, a cylindrical shape, and a spherical shape by various molding methods. The carrier is molded by using a pressure molding method in which molding is performed while applying pressure, such as an extrusion molding method, a tableting molding method, a pressing method, and the like. The inventors have grasped that a catalyst containing a relatively large amount can be obtained.

  For a carrier prepared by the above-described method, a salt of an element of group VIII of the periodic table that is an active metal, such as Ru (ruthenium), Pt (platinum), Rh (rhodium), Pd (palladium), Os In the case of (osmium) and Ir (iridium) salts, such as Ru, an aqueous ruthenium nitrate solution is sprayed to impregnate the carrier. Subsequently, this support is dried, and then calcined in an electric furnace at, for example, 600 ° C. for 3 hours to obtain the catalyst of the present invention in which a Group VIII element such as ruthenium is supported on the support. The method of supporting the active metal is not limited to this example, and a method such as coating an aqueous solution or solution of a group VIII element on the support, or a pore filling method or selective adsorption on the support may be employed. .

  Here, as described above, it seems that the pore size distribution of the catalyst is changed by supporting the active metal on the support having a relatively large number of pores having the pore size in the second range. In this respect, the catalyst having high thermal shock resistance only needs to contain a relatively large number of pores having a pore diameter in the second range at the stage of the carrier before supporting the active metal. However, as described later, the active metal supported on the catalyst is only about 0.05 to 5.0% by weight of the total catalyst weight, and these index values are large even after the active metal is supported. Since it is not realistic to measure the index values after removing the active metal once supported, the catalyst that satisfies the above index values even if the catalyst after supporting the active metal is not It can be said that it has high thermal shock resistance. In addition, the present inventors have confirmed through experiments that the above index values hardly change before and after loading an active metal of about 0.05 wt% to 5.0 wt% of the total catalyst weight. .

The catalyst for catalytic partial oxidation of hydrocarbon according to the present embodiment having the configuration described above has a pore in the second range with respect to the total pore volume V [cm ³ / g] per unit weight of the support. The volume ratio of the total volume V ₂ [cm ³ / g] of pores having a diameter is A [volume%], and the thickness of the catalyst at the position where the thermal shock resistance of the molded catalyst is determined (hereinafter referred to as catalyst thickness). The present inventors experimentally confirmed that high thermal shock resistance performance is exhibited when the following conditions are satisfied, where B is [mm].
When 0 <B ≦ 1.5,
A ≧ 3.0 (6)
When 1.5 <B,
A ≧ 0.158B ² −0.467B + 3.411 (7)

  The thermal shock resistance required to maintain the shape of the catalyst or carrier (collectively referred to as catalyst in the description of the catalyst thickness below) is the heat transfer between the center of the catalyst and the outer surface, In particular, it depends on heat transfer by heat conduction in the solid catalyst. That is, as the heat flow rate at these parts increases, the catalyst tends to be not crushed even if its thermal shock resistance is low.

  In addition, the catalyst shape is thinner than the thicker one, and the heat flow is larger, and heat is transferred from the central part of the catalyst to the outer surface quickly (heat dissipation), and the temperature difference between the central part and the outer surface is reduced. Since it becomes difficult to produce, the thermal shock resistance for maintaining a shape becomes high (it becomes difficult to destroy). Therefore, it is necessary to define the thickness of the catalyst that determines the thermal shock resistance in consideration of the catalyst shape. In general, in heat transfer by heat conduction, factors that control the heat flow include heat transfer area, heat conductivity, temperature difference, and thickness (heat transfer distance). Considering the heat conduction (heat dissipation) in the unsteady state of a three-dimensional object between a point at the center of the catalyst and the outer surface, the heat flow increases as the thickness (heat transfer distance) decreases. Then, heat is quickly radiated from the center of the catalyst to the outer surface. In the present invention, the catalyst thickness is defined as a distance that is twice the shortest distance at the position where the shortest distance to the outer surface is the maximum among all the positions inside the structure of the solid catalyst. In other words, the catalyst thickness can be said to be the diameter of the sphere having the largest diameter among the spheres inscribed in the space covered with the surface of the catalyst.

  As a specific example, in a cylindrical catalyst, when the thermal shock resistance of the catalyst is 2R ≦ L as shown in FIG. 1A, the length in the diameter direction (2R [mm] ]) Is thinner than the thickness in the vertical direction (L [mm]), and more heat transfer (heat dissipation) from the side than heat transfer (heat dissipation) from the center of the catalyst to the upper and lower surfaces, The distance from the center of the catalyst to the side surface dominates heat transfer (heat dissipation). Accordingly, in this case, 2R, which is twice the distance between the center of the catalyst and the side surface, is the catalyst thickness that determines the thermal shock resistance.

On the other hand, in the case of a tablet-shaped catalyst of 2R> L as shown in FIG. 1B, the thickness (L) in the vertical direction is thinner than the length (2R) in the diametrical direction, and the catalyst center portion. Since heat transfer from the upper and lower surfaces (heat dissipation) is greater than heat transfer from the upper surface to the side surface (heat dissipation), the distance from the catalyst center to the upper and lower surfaces dominates the heat transfer (heat dissipation). Therefore, the distance L between the center portion of the catalyst and the upper and lower surfaces corresponds to a distance twice the shortest distance described above, and becomes the catalyst thickness that determines the thermal shock resistance.
Thus, the catalyst thickness that determines the thermal shock resistance differs depending on the catalyst shape.

  Further, as shown in FIGS. 1 (c) and 1 (d), it has concentric inner and outer diameters, and the difference between these inner and outer diameters (hereinafter referred to as ring width) is D [mm], In the case of a ring shape with a height L [mm] in the vertical direction, if D ≦ L, heat transfer (heat dissipation) from the side surfaces (inner surface and outer surface) of the ring is greater than heat transfer (heat dissipation) from the upper and lower surfaces. The distance in the radial direction of the ring dominates heat transfer (heat dissipation) inside the catalyst. Therefore, in this case, the ring width D corresponds to a distance twice the shortest distance described above, and becomes the catalyst thickness that determines the thermal shock resistance. On the contrary, if D> L, the distance twice the shortest distance, that is, the catalyst thickness is the height L in the vertical direction of the catalyst. When the catalyst is spherical with a radius R as shown in FIG. 1 (e), the radius from the center of the catalyst to the surface is constant, so this radius corresponds to the shortest distance described above and the diameter of the sphere. 2R is the catalyst thickness.

  It is considered that the porous member can relax the stress applied to the porous member to some extent due to distortion of the pores, and can increase the toughness of the catalyst. On the other hand, since the amount of deformation that occurs in the catalyst due to thermal stress increases as the catalyst becomes larger, the stress applied to the catalyst due to thermal shock also increases as the catalyst becomes larger. For this reason, it is considered that the larger the size of the catalyst, the more likely it is that damage due to thermal shock occurs. Therefore, it is necessary to improve the mechanical strength of the catalyst from the viewpoint of thermal shock resistance. Accordingly, in the catalyst for catalytic partial oxidation of hydrocarbons according to this example, the thermal shock resistance is improved by increasing the volume ratio of pores having pore diameters in the second range.

On the other hand, if the catalyst is not so large, the amount of deformation that occurs in the catalyst under thermal stress is small, so that the destruction of the catalyst can be achieved without increasing the volume ratio of pores having pore diameters in the second range. Can be suppressed.
Based on these ideas, the thermal shock performance of the catalysts formed in various sizes and shapes was examined. As shown in Examples including Al, Zr, Y, and Ba as the carrier composition described later, the catalyst thickness B and In terms of the relationship with the ratio A of the volume of the pores having the pore diameter in the second range with respect to the total pore volume, the thermal shock performance in the region satisfying the above-mentioned formulas (6) and (7) It was confirmed that a high catalyst was obtained.

  Here, the catalyst according to the present embodiment satisfying the conditions of the expressions (6) and (7) is in the range of 0.1 μm to 1.0 μm (first range) provided in a conventionally used alumina-based carrier. In addition to pores having a pore diameter of), relatively many pores having a pore diameter in the range of 1.0 μm to 10 μm (second range) are included. And it is thought that the thermal shock added to a catalyst can be absorbed by the pore formed over these wide pore ranges being distorted. As a result, the stress can be absorbed more flexibly than when the pore diameter distribution is concentrated in the first range, and as a result, the catalyst is not easily destroyed or pulverized. It is thought. Further, the second range may be a pore diameter range suitable for absorbing a thermal shock caused by a rapid temperature change from about 200 ° C to 300 ° C to about 1200 ° C to 1500 ° C. Further, when two or more metal oxides other than alumina are added as a support as in the present invention, oxides having different coefficients of thermal expansion differ from single components, resulting in rapid thermal expansion and contraction. It is thought that the stress is absorbed.

  For preparing a carrier having such characteristics, various carrier groups are prepared by, for example, preliminary experiments in combination with the above-mentioned preparation methods, and pore volume distribution is measured by a mercury intrusion method using a mercury porosimeter or the like. These are identified by screening a carrier that satisfies the above conditions from each preparation method. Then, from among the carriers remaining as a result of the screening, for example, a method for preparing the carrier with the highest thermal shock performance or a method with a low cost is selected, and a carrier with high thermal shock resistance is produced on an industrial scale by the preparation method. Good. Here, in the pore distribution measurement by the mercury intrusion method, generally the pore volume of pores having a diameter in the range of 0.003 μm to 500 μm and the distribution curve thereof can be measured. A pore volume smaller than 0.003 μm can be measured by, for example, a gas adsorption method, but is considered to be hardly contained in the carrier according to the present embodiment.

Here, the shape of the catalyst for catalytic partial oxidation of hydrocarbons with high thermal shock performance selected using the equations (6) and (7) is the cylindrical shape shown in FIGS. 1 (a) and 1 (b). (Tablet shape), the cylindrical shape shown in FIG. 1 (c) and FIG. 1 (d), and the spherical shape shown in FIG. 1 (e) are not limited. For example, it may be a trilobal shape (FIG. 2 (a)) obtained by extruding a three-leaf shaped cross section or a quadrant shape (FIG. 2 (b)) obtained by extruding a four-leaf shaped cross section, for example. Good. Specifically, the catalyst thickness in this case is obtained as follows, for example. 3 (a) and 3 (b), for example, as shown in the plan view in the case of the three leaves, the length from the center position of the cross section to the “neck” formed by overlapping the leaf-like protrusions is shown. D ₁ , where D ₂ is the maximum radius of a circle inscribed in the leaf-like projection, D ₁ or D ₂ is set to D [mm], and the extrusion direction (axial direction) when extrusion is formed Is set to L [mm]. In this case, as shown in FIG. 2, the distance of the shortest distance described above is D when “2D ≦ L”, and the distance of the shortest distance is “L” when “2D> L”. L is the catalyst thickness.

As shown in FIG. A plurality of cavities having the same shape may be formed in a columnar catalyst, or a plurality of cavities having different diameters may be formed in a columnar catalyst as shown in FIG. In these cases, the distance between the cavity and between the cavity and the outer surface and an outer surface (are marked D ₁ to D ₄ in FIG. 4) D, the height in the vertical direction of the catalyst if L, D If ≦ L, the distance D corresponds to the distance twice the shortest distance to the cavity or the outer surface among all positions of the catalyst structure, that is, the catalyst thickness. If L <D, L is the catalyst. Corresponds to thickness.

Further, these ideas are further expanded, for example, as shown in FIG. 5, the maximum distance D between the cavities of the catalyst formed in the form of foam or the position where the distance between the cavities and the catalyst side surface is minimum. Is considered to be twice the shortest distance to the cavity or the outer surface among all the positions of the catalyst structure, and the distance D may be the catalyst thickness. Further, as shown in FIG. 6, in a catalyst formed in a honeycomb shape having, for example, a prismatic cavity extending in the height direction in a prism having a height L, the cavity between the cavity and between the cavity and the outer surface and the outer surface Assuming that the shortest distance D is D _{1 to} D ₃ in FIG. 6B, the catalyst thickness corresponds to D if D ≦ L, and the catalyst thickness is L if L <D. Equivalent to.

  Next, a process to which the catalyst for catalytic partial oxidation of hydrocarbon according to the present embodiment is applied will be described. FIG. 7 is a view schematically showing an apparatus for producing synthesis gas using the catalyst of this example. 4 is a cylindrical reactor in which a catalyst layer 5 filled with the catalyst of the present invention is formed. In this apparatus, a raw material gas obtained by adding oxygen, steam, and carbon dioxide to a light hydrocarbon as a raw material is supplied from an inlet 41 at the upper part of the reactor 4 and is allowed to pass through the catalyst layer 5 to perform a partial oxidation reaction. The synthesis gas is taken out from the outlet 42 on the lower side of the reactor 4.

  Further, as disclosed in Japanese Patent Application No. 2004-298971, the raw material hydrocarbon after desulfurization is subjected to low-temperature steam reforming with steam, and the hydrocarbon having 2 or more carbon atoms is converted into methane and hydrogen, and then the raw material is fed to the reactor 4. It may be introduced and partially oxidized by contact.

In the CPO reaction, the outlet gas composition is governed by an equilibrium composition determined by the inlet temperature, pressure, and feed gas composition. For this reason, it is necessary to determine the oxygen concentration in the raw material gas by the ratio of H ₂ and CO of the synthesis gas to be obtained. In the case of the synthesis gas for GTL, DME, methanol, and ammonia, the oxygen content is determined by the number of moles of oxygen / It is preferable that the number of moles of carbon in the hydrocarbon is 0.2 to 0.8. Since steam is a factor that not only prevents carbon deposition but also dominates the above-described synthesis gas composition, the steam content is 0.2 to 3. mol of steam / mol of carbon in hydrocarbon. 0 is preferred.

In the case of GTL, DME, or methanol synthesis gas, it is preferable to contain carbon dioxide in the raw material gas in order to adjust the ratio of H ₂ and CO in the synthesis gas to be obtained. Regarding the carbon dioxide content, the number of moles of carbon dioxide / number of moles of carbon in the hydrocarbon is preferably 0.01 to 0.6, more preferably 0.1 to 0.3.

The source gas is preheated to 200 ° C. to 300 ° C. within the range of 200 ° C. to 500 ° C. and supplied into the reactor 4, and the pressure at the inlet 41 of the reactor 4 is, for example, normal pressure to 8 MPa. The space velocity (GHSV) is, for example, 5.0 × 10 ³ (NL / L / Hr) to 1.0 × 10 ⁶ (NL / L / Hr), and more preferably 2.0 × 10 ⁴ (NL / L / Hr) to 2.0 × 10 ⁵ (NL / L / Hr).

  When the raw material gas is supplied into the reactor 4, the oxidation reaction shown in the background art items (1) and (2) occurs by the catalyst and is large at the inlet of the catalyst layer 5 as described with reference to FIG. 13. Since the heat is generated, the temperature of the part increases. As described in the background art in such a region, when the position where the temperature rise occurs moves to the upstream side or the downstream side of the catalyst layer 5, the catalyst filled in the moving region is 200 ° C. to It will be exposed to the thermal shock accompanying the rapid temperature change from the temperature of about 300 degreeC to about 1200 degreeC-1500 degreeC. However, since the catalyst according to the present embodiment has a high thermal shock resistance as shown in the examples described later, it is difficult to be destroyed or pulverized even when subjected to a thermal shock.

  In the catalyst layer 5 on the downstream side of the region where the temperature suddenly increases, the above-described equations (1) to (5) proceed simultaneously to reach the equilibrium composition, so the temperature of the catalyst layer 5 is the source gas. Equilibrium temperature of the outlet gas composition determined by the composition and the reaction pressure, for example, in the case of GTL synthesis gas, it is stabilized at a temperature of about 1000 ° C. In this case, a gas having a composition determined by equilibrium at 1000 ° C., that is, a synthesis gas containing oxygen monoxide and hydrogen in a proportion suitable for the GTL synthesis gas is obtained at the outlet 42 of the reactor 4.

  This synthesis gas contains carbon dioxide, but carbon dioxide is separated from the synthesis gas in a later step, and this carbon dioxide is added to the raw material gas and supplied into the reactor 4. Used (recycled). Carbon dioxide supplied into the raw material gas is not limited to recycling from such a CPO process. For example, unreacted gas from a Fischer-Tropsch reaction process (FT process) that synthesizes GTL using synthetic gas as a raw material. The contained carbon dioxide may be recycled. Since this unreacted gas contains CO gas, this unreacted gas is recycled as a raw material gas, or a gas containing light hydrocarbons (referred to as FT synthesis off-gas) obtained in the GTL purification process is used as a raw material gas. It may be recycled.

  In the case of producing a catalyst for catalytic partial oxidation according to the present invention, if chlorine content is contained in the raw material gas and chlorine remains at a constant concentration even after calcination, the temperature condition is below the dew point downstream of the reactor. Stress corrosion cracking and thinning corrosion occur in piping and equipment. Therefore, it is preferable to use a raw material which does not contain chlorine as a raw material for producing the catalytic partial oxidation catalyst of the present invention or to remove chlorine. Chlorine remaining in the catalyst originates from raw materials such as barium and group VIII elements. Thus, a catalyst containing no chlorine can be produced by using a raw material which does not contain hydroxide, nitrate, carbonate, organic acid salt or other chlorine as a raw material. When, for example, rhodium chloride or ruthenium chloride is used as a raw material for the Group VIII element, a method of removing chlorine in the supporting step may be employed. As for this chlorine removal method, for example, it can be removed to 100 ppm or less by the method disclosed in JP-A-60-190240, but it can also be carried out by a method such as washing with an alkaline aqueous solution.

  In the above, the synthesis gas produced using the catalyst of the present invention is not limited to being used as a raw material such as GTL, methanol, DME, or hydrogen, but also includes a gas used as a synthetic raw material for ammonia gas. In this case, for example, air or oxygen-enriched air is used instead of high-purity oxygen from the oxygen plant, and the air, oxygen-enriched air and steam are added to the raw material hydrocarbon, and hydrogen, nitrogen and carbon monoxide are added. A synthesis gas containing is obtained. This synthesis gas is used as a synthesis raw material of ammonia by removing carbon monoxide and carbon dioxide in a later step.

  The present embodiment has the following effects. The thickness of the catalyst at a position that determines the thermal shock resistance of the catalyst with respect to the volume ratio of the total pore volume in the range where the pore diameter with respect to the total pore volume is 1 μm or more and less than 10 μm is a predetermined relational expression. By using a satisfying catalyst, it is possible to obtain a catalyst for catalytic partial oxidation of hydrocarbons that is difficult to be destroyed or pulverized even under thermal shock. As a result, even if the catalyst is filled in a region that receives repeated thermal shocks during operation, such as the inlet of the reactor 4 of the CPO process, troubles such as catalyst destruction and clogging of the catalyst layer 5 due to pulverization are less likely to occur. It can be a highly reliable process.

  Here, the catalyst according to the present embodiment is not limited to the case where the entire catalyst layer 5 in the reactor 4 is filled. For example, the area where the position where the rapid temperature change described above moves, for example, the upstream side of the catalyst layer 5 and the area of 1/5 to 1/2 of the entire catalyst layer is filled with the catalyst according to the present embodiment. The downstream side may be filled with a catalyst manufactured using a conventional carrier.

(Second Embodiment)
The catalyst according to the second embodiment contains alumina as a main component of the carrier and Ca oxide, Si oxide, and Mg oxide as subcomponents. The carrier production method is the same as the carrier production method according to the first embodiment, but alumina cement, silica sol, and magnesium oxide powder are added to the alumina or alumina precursor powder instead of YSZ. The content of Al in the carrier is preferably 30% by weight to 90% by weight, more preferably 40% by weight to 80% by weight, and still more preferably 50% by weight to 80% by weight in terms of Al ₂ O ₃ . The calcium content is preferably 5% by weight to 30% by weight and more preferably 10% by weight to 30% by weight in terms of CaO. The content of silicon is preferably in terms of SiO ₂ 5 wt% to 30 wt%, more preferably from 10 wt% to 20 wt%. The magnesium content is preferably 5 to 30% by weight, more preferably 10 to 30% by weight in terms of MgO. Moreover, the component contained in the said support | carrier is not limited to these, You may contain elements other than Al, Ca, Si, and Mg.

  Also in the carrier, as in the case of the first embodiment, a carrier preparation method that satisfies the conditions of the above-mentioned formulas (6) and (7) is selected from, for example, a group of carriers prepared by various preparation methods. Selected by screening.

For example, ruthenium, which is an element of group VIII, is supported as an active metal and applied to the CPO process shown in FIG. .
As described above, the catalyst according to the second embodiment is different from the catalyst according to the first embodiment in the components of the carrier, but examples include Al, Ca, Si, and Mg as the carrier composition described later. It was confirmed that it had high thermal shock resistance as shown in.

(Third embodiment)
The catalyst according to the third embodiment includes alumina as a main component of support, Mg oxide and YSZ as subcomponents, and the aluminum content is preferably 30% by weight to 90% by weight in terms of alumina. Preferably they are 40 weight%-80 weight%, More preferably, they are 50 weight%-80 weight%. Further, the magnesium content is preferably 5 to 30% by weight, more preferably 10 to 30% by weight in terms of MgO. The content of YSZ, for example yttria _(Y 2 _{O 3)} and preferably from 5% to 40% by weight in terms of YSZ containing in the range of 2 mol% to 10 mol%, more preferably 10% to 30 % By weight. The carrier preparation method, the active metal loading method, for example, the pore diameter adjustment method such as selection of the carrier preparation method by screening, and the application to the CPO process are the same as in the first embodiment described above. Therefore, explanation is omitted. Further, the components may contain oxides other than Al 2 _{O 3} is not limited to these, _MgO and YSZ contained in the carrier.

  Also in the carrier, as in the case of the first embodiment, a carrier preparation method that satisfies the conditions of the above-mentioned formulas (6) and (7) is selected from, for example, a group of carriers prepared by various preparation methods. Selected by screening. According to the catalyst of the third embodiment, high thermal shock resistance was confirmed as shown in the examples including Al, Zr, Y, and Mg as the carrier composition described later.

The components of the catalyst for catalytic partial oxidation of hydrocarbons according to the present invention are not limited to the first to third embodiments exemplified so far, but are inorganic oxides which are subcomponents. In addition to Al, oxides of elements selected from Group IIA, Group IIIA, Group IVA, Group IIB, Group IIIB, Group IVB, and lanthanoids other than Al, such as magnesium, silicon, calcium, titanium, An oxide of at least two elements selected from the element group consisting of barium, yttrium, zirconium, lanthanum, and cerium is preferably included. Also as a general index of the catalyst according to the present embodiment, the total pore volume is 0.05cm ³ /g~0.3cm ³ / g, a specific surface area of 0.5m ² /g~7.0m ² / It is preferable that it is about g.

(Experiment)
The ratio of the pore volume having a pore diameter in the second range to the total pore volume per unit weight of the support, and the shape of the support with various changes in the catalyst shape and the catalyst thickness B Each was prepared, and thermal shock was applied to these molded bodies to confirm the occurrence of destruction and pulverization. In the test, 5 g to 10 g of the carrier was heated to 1200 ° C. in a muffle furnace and held for 10 minutes, and then the carrier was taken out of the furnace and immediately put into 1 L of water held at 20 ° C. Thermal shock was applied by rapid cooling at about 1200 ° C. Thereafter, the carrier was taken out of the water, put into the muffle furnace again, and this operation was repeated 10 times to conduct a thermal shock test by rapid cooling and rapid heating. Water has a specific heat larger than that of the raw material gas, and the latent heat of vaporization of water is lost from the carrier when charged at a high temperature of 1200 ° C. Therefore, it is generated in the reactor 4 even if the temperature rise of water is taken into consideration. A thermal shock comparable to a temperature change of about 250 ° C./second to about 1300 ° C./second can be given to the carrier.

A. Experimental conditions
The ratio of the volume of pores having a pore diameter in the second range to the total pore volume per unit weight of the support A, the catalyst shape (support shape) and its catalyst thickness B, and a total of 44 types with different support compositions The catalyst was subjected to a thermal shock test to evaluate the thermal shock performance of each carrier.

B. Experimental result
As a result of the thermal shock test, 30 types of carriers exhibiting high thermal shock resistance with almost no destruction or pulverization of the carrier were taken as examples, and 14 types of carriers broken and pulverized by the thermal shock test were compared with comparative examples. did. (Table 1) shows the catalyst thickness B [mm] of the carrier according to each example and comparative example, the pore volume ratio [vol%] in the second range, the catalyst shape (carrier shape), its size, and the carrier composition. Show. As for the size of the carrier, the values of 2R and L shown in FIG. 1 (a) and FIG. 1 (b) are shown in the case of a cylindrical shape (tablet shape), and in the case of a ring shape, FIG. 1 (c) and FIG. The values of D and L shown in FIG. 1) are shown, and in the case of a sphere, the value of 2R in FIG. Here, since the granules in (Table 1) are formed in a substantially spherical particle shape, they are included in a spherical shape.
In FIG. 8, the horizontal axis represents the catalyst thickness B [mm], and the vertical axis represents the volume ratio A [vol%] of the second range of pores. FIG. 8 shows the results plotted with the filled triangle “」 ”.

  Further, as a representative experimental result of (Example 1 to Example 30), the carrier according to (Example 10) and (Example 25) is subjected to rapid heating by a muffle furnace and rapid cooling by throwing it into water 10 times. The appearance photograph after repeating is shown in FIG. 9 and FIG. 10, respectively, and the same thermal shock test is performed for (Comparative Example 4) and (Comparative Example 10) as representative experimental results of (Comparative Example 1 to Comparative Example 4). The appearance photographs of the results are shown in FIGS. 11 and 12, respectively.

(Table 1)

  According to the experimental result of (Example 10) shown in FIG. 9, each carrier was broken or pulverized despite repeated repeated thermal shocks from 1200 ° C. to room temperature and repeated heating 10 times. Was not confirmed. The same applies to the result of (Example 25) shown in FIG. In addition, in the experimental results according to each example not shown in the photograph, as in FIGS. 9 and 10, no breakage or pulverization was confirmed in each carrier. On the other hand, according to the result of (Comparative Example 4) shown in FIG. 11, most of the carriers in the spherical shape are crushed to such an extent that the original shape is hardly retained by only four thermal shocks. And powdered. Also in FIG. 12 (Comparative Example 10), the carrier formed in a tablet shape was all destroyed by 10 thermal shocks. Further, in the experimental results of each comparative example not shown in the photograph, each carrier was crushed and pulverized in the thermal shock evaluation within 10 times as in FIGS.

  According to the results of such thermal shock experiments summarized (Table 1) and the results shown in FIG. 8, regardless of the catalyst shape and the carrier composition, the carrier having high thermal shock resistance and the carrier weak to thermal shock Can be organized by the relationship between the catalyst thickness B and the pore volume ratio A in the second range. Specifically, as the catalyst thickness B increases, increasing the pore volume ratio A in the second range increases the thermal shock resistance of the carrier, while decreasing the catalyst thickness B decreases the second range. Even if the pore volume ratio A is lowered, breakage and powdering due to thermal shock hardly occur. Further, in a region where the catalyst thickness B is smaller, the correlation between the catalyst thickness B and the second range pore volume ratio A with respect to thermal shock resistance becomes smaller, and if there is a certain percentage of pores in the second range. It can be seen that the carrier has thermal shock resistance.

Therefore, in the region of B> 1.5 where the correlation between the catalyst thickness B and the pore volume ratio A in the second range is observed with respect to the thermal shock resistance of the carrier, An approximate curve is drawn based on the data, and the approximate curve is moved upward with a margin so as not to overlap the region where the example and the comparative example are mixed, and A = 0.158B ² −0.467B + 3. A boundary line of 411 was obtained. In the graph shown in FIG. 8, since a good result is obtained in the thermal shock test with the carrier in the region above (including the boundary line) the boundary line, the condition of the expression (7) is satisfied. It can be seen that a catalyst having high thermal shock resistance can be obtained by using a carrier to be filled.

  On the other hand, in the region of 0 <B ≦ 1.5 where the correlation between the catalyst thickness B and the pore volume ratio A in the second range is low, the value of A is 3.0 vol% or more, as described above. If the formula (6) is satisfied, a high thermal shock resistance performance can be obtained regardless of the catalyst thickness.

4 reactor 5 catalyst layer 41 inlet 42 outlet

Claims (15)

At least oxygen and steam are added to a raw material hydrocarbon containing at least one of methane and a light hydrocarbon having 2 or more carbon atoms to catalytically oxidize the raw material hydrocarbon to produce a synthesis gas containing carbon monoxide and hydrogen. A catalyst for catalytic partial oxidation of hydrocarbons, sometimes used, with an active metal supported on a support made of an inorganic oxide,
The volume ratio A [volume%] of the total volume of pores in the pore diameter range of 1 μm or more and less than 10 μm with respect to the total pore volume of the catalyst, the thickness of the catalyst at the position where the thermal shock resistance is determined in the catalyst A catalyst for catalytic partial oxidation of hydrocarbons, characterized by satisfying the following conditions for B [mm].
When 0 <B ≦ 1.5, A ≧ 3.0,
When 1.5 <B, A ≧ 0.158B ² −0.467B + 3.411
However, the thickness B of the catalyst at the position where the thermal shock resistance is determined corresponds to the following value.
(A) When the catalyst has a cylindrical shape with a radius R and a length L,
When 2R ≦ L, B = 2R,
When 2R> L, B = L,
(B) when the catalyst is ring-shaped with a ring width D and a length L,
When D ≦ L, B = D,
When D> L, B = L
(C) when the catalyst is spherical with a radius R,
B = 2R ^2. The catalyst for dispersing a hydrocarbon contact portion according to claim 1 , wherein the catalyst has a specific surface area of 0.5 m ² / g or more and 7.0 m ² / g or less. The total pore volume of the catalyst is 0.05 cm ³ / g or more, 0.3 cm ³ / g catalyst for catalytic partial oxidation of hydrocarbon according to claim 1 or 2, characterized in that less. The first element of the carrier comprising the inorganic oxide is Al, the carrier in terms of Al ₂ O ₃ at 30 wt% or more per unit weight, claims, characterized in that it comprises 90 wt% or less of Al Item 4. The catalyst for catalytic partial oxidation of hydrocarbon according to any one of Items 1 to 3 . The support made of the inorganic oxide is at least selected from the group consisting of elements belonging to alkaline earth metals, elements belonging to rare earth metals, Sc, Bi, Zr, Si and Ti in addition to the first constituent element. The catalyst for catalytic partial oxidation of hydrocarbon according to claim 4 , comprising an oxide of two kinds of elements. Elements belonging to the alkaline earth metal are Mg, Ca, Sr and Ba, and elements belonging to the rare earth metal are Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, The catalyst for partial oxidation of a hydrocarbon contact portion according to claim 5 , wherein the catalyst is Er and Yb. The carbonization according to claim 5 or 6 , wherein the support made of the inorganic oxide includes zirconia stabilized by one or more elements selected from Y, Ce, Ca, Mg, Sc, and Sm. Catalyst for catalytic partial oxidation of hydrogen. The catalyst for catalytic partial oxidation of hydrocarbon according to claim 7 , wherein the stabilized zirconia is yttria stabilized zirconia stabilized by yttria. The catalyst for catalytic partial oxidation of hydrocarbon according to claim 8 , wherein the yttria-stabilized zirconia contains yttria in a range of 2 mol% to 10 mol%. The catalyst for catalytic partial oxidation of hydrocarbon according to any one of claims 1 to 9 , wherein the active metal is one or more metals selected from Group VIII elements of the Periodic Table . The catalyst for catalytic partial oxidation of hydrocarbon according to claim 10 , wherein the elements of Group VIII of the periodic table are Ru, Pt, Rh, Pd, Os and Ir. The active metal, the catalyst per unit weight 0.05% by weight or more, for catalytic partial oxidation of hydrocarbon according to any one of claims 1 to 11, characterized in that it comprises 5.0 wt% or less catalyst. A raw material gas obtained by adding oxygen and steam to a raw material hydrocarbon containing at least one of methane and a light hydrocarbon having 2 or more carbon atoms, and / or hydrogen containing hydrogen in the raw material hydrocarbon Supplying a raw material gas containing hydrogen by adding to the reactor,
The catalyst according to any one of claims 1 to 12 provided in the reactor and the raw material gas are brought into contact with each other in a heated state to subject the raw material hydrocarbon to partial oxidation, so that carbon monoxide and hydrogen A process for producing a synthesis gas comprising: a synthesis gas comprising: In the step of producing the synthesis gas, in the region where the catalyst and the raw material gas are in contact with each other in a heated state, the catalyst is at a temperature of 250 ° C./second to 1300 ° C./second over a temperature range of 200 ° C. to 1500 ° C. 14. The method for producing synthesis gas according to claim 13 , wherein a region to be changed is included. After preheating the source gas to 200 ° C. to 500 ° C., the pressure is normal pressure to 8 MPa, and the space velocity (GHSV) is 5.0 × 10 ³ (NL / L / Hr) to 1.0 × 10 ⁶ (NL The method for producing a synthesis gas according to claim 13 or 14 , wherein the reaction gas is supplied into the reactor under the conditions of / L / Hr) and is brought into contact with the catalyst under the adiabatic reaction conditions.

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