JP5826051B2 - Continuous fixed bed catalytic reactor and catalytic reaction method using the same - Google Patents

Description

  The present invention relates to a reaction apparatus for performing a chemical reaction of a fluid using a bulk catalyst and a technique of a catalytic reaction method using the reaction apparatus.

  In a chemical reaction of a fluid using a fixed bed catalytic reaction vessel filled with a catalyst, when a solid precipitate is generated by the catalytic reaction, the solid precipitate often accumulates in a space between the catalysts in the catalyst layer. As a result, there is a problem that the catalyst layer is blocked and cannot be vented.

  For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 2010-77219), hydrogen, carbon dioxide, water vapor, and a tar-containing gas are brought into contact with a catalyst containing nickel, cerium, and aluminum in a fixed bed catalytic reaction apparatus. A technique for reforming is disclosed. In this technique, solid carbon is deposited on the surface of the catalyst during the reforming, and in order to remove it, it is necessary to perform a regeneration treatment in which water vapor or air is brought into contact with the carbon. Is described.

  Patent Document 1 also exemplifies the use of moving bed type and fluidized bed type catalytic reaction vessels. In these systems, carbon deposited on the catalyst surface can be removed during the reaction operation. However, such a reaction vessel is more complicated than the fixed bed catalyst reaction vessel, and in the case of a fluidized bed type, the operation tends to become unstable. It is not common as a reaction vessel for processing a fluid.

  On the other hand, in a fixed bed reaction vessel that does not have the above-mentioned problems in moving bed type and fluidized bed type catalyst reaction vessels, spaces are usually provided on both sides of the catalyst layer, and fluid is circulated from one space to the other. To react. In order to form a space on both sides of the catalyst layer, a catalyst holding mechanism is necessary. A typical example of the catalyst holding mechanism is described in Patent Document 2 (Japanese Patent Laid-Open No. 2011-6289). The catalyst is held and ventilated by using a punching metal plate or net having a smaller hole diameter. An example is shown in FIG. 6, in which the catalyst 2 is accommodated in the catalyst reaction vessel 1, and the catalyst is held by a punching metal plate or a net 3. In FIG. 1, the raw material gas 4 flows in from the inlet 5 and flows out as the reformed gas 7 from the outlet 6.

  As a means for preventing clogging of the catalyst layer due to the deposition of solid precipitates during the reaction, for example, Patent Document 2 discloses a gas flowing out from the first catalyst layer in a free space in which a gas passes between the two catalyst layers. A technique for preventing clogging in the second catalyst layer by supplementing the dust inside is described. However, in this case, it is impossible to prevent clogging of the catalyst layer due to dust generated inside the catalyst layer and adhering to and depositing on the catalyst in the space between the catalysts.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2009-48797) describes a technique for flowing out and removing water generated on a catalyst by irradiating the catalyst layer in the cell for the fuel cell with ultrasonic waves. . Ultrasonic waves can act only in the vicinity of the irradiation source because they are greatly attenuated in free space and in the granular layer and powder layer. For this reason, it is effective for a relatively small catalyst layer such as a catalyst layer in a fuel cell, but it is difficult to vibrate the entire catalyst layer by ultrasonic waves in a large catalyst layer that processes a large amount of fluid. It is.

  Patent Document 4 (Japanese Patent Laid-Open No. 2008-120604) describes a technique for suppressing coking by performing steam reforming of hydrocarbons at a low temperature. However, there are optimum reaction temperature conditions for the catalytic reaction from the viewpoint of catalyst durability and reaction rate, and clogging of the catalyst layer due to coking occurs under these optimum conditions. For this reason, if the catalyst reaction temperature is lowered, the optimum conditions for the reaction are lost, and there is a problem that the catalyst performance is lowered.

  Patent Document 5 (Japanese Patent Laid-Open No. 8-24622) describes, as a conventional technique, removing a partial blockage of a catalyst layer due to accumulated dust in a moving bed catalyst reaction vessel with a striking device or a vibrator. In this case, there is a problem that the packing ratio of the catalyst increases due to beating or vibration, the space between the catalysts is narrowed, and the fluidity of the catalyst is deteriorated.

JP 2010-77219 A JP 2011-6289 A JP 2009-48797 A JP 2008-120604 A JP-A-8-24622

  As described above, in the prior art, there is no means for effectively removing the solid product generated and deposited in the large fixed bed catalyst layer. An object of the present invention is to provide a continuous fixed bed catalytic reactor equipped with a means effective for removing a solid product produced and deposited in a large fixed bed catalyst layer, and a raw material gas, particularly a tar-containing raw material using the same. To provide a catalytic reaction method for reforming a gas with high efficiency.

  In order to solve the above-mentioned problems, the following solutions have been invented as a result of the inventor's research.

(1) a source gas inflow path and a reformed gas outflow path for catalytic reaction;
A catalytic reaction vessel connected to the inflow path and the outflow path, and in contact with the inner wall of the reaction container, the catalytic reaction container containing the catalyst layer of the bulk catalyst;
A catalyst holder that has air permeability that allows fluid to pass through and that holds the catalyst layer;
A continuous fixed bed catalyst reaction apparatus having a drive mechanism for raising and lowering the catalyst layer by raising and lowering the catalyst holder ,
A continuous fixed bed catalytic reactor characterized in that the raw material gas is a gas containing hydrocarbon, and the product of catalytic reaction is a gas and solid hydrocarbon or solid carbon .

  (2) The height of the catalyst layer is not more than twice the thickness of the catalyst reaction vessel and not less than three times the maximum value of the representative length of the outer surface of the bulk catalyst. ) Continuous fixed bed catalytic reactor.

  (3) The continuous fixed bed catalytic reactor according to (1) or (2) above, wherein the speed when the drive mechanism is lowered is faster than the speed when the drive mechanism is raised.

(4) As the catalyst holder, a catalyst holder having a structure in which the bulk catalyst is held at a tip portion of pins arranged substantially in parallel and the raw material gas can flow through the space between the pins is used. The continuous fixed bed catalytic reactor according to any one of (1) to (3) above,

( 5 ) The continuous fixed bed catalytic reactor according to any one of (1) to (4) above, wherein the catalytic reaction fluid is a gas containing tar.

( 6 ) The catalyst is a composite oxide containing nickel, magnesium, cerium, and aluminum, and is made of a composite oxide not containing alumina, and the composite oxide is NiMgO, MgAl ₂ O ₄ , CeO. The continuous fixed bed catalytic reactor according to ( 5 ) above, comprising _two crystal phases.

(7) wherein the catalyst is a catalyst comprising a composite oxide containing nickel, magnesium, cerium, zirconium, aluminum, the complex _{oxide, NiMgO, MgAl 2 O 4,} Ce x Zr 1-x O 2 (0 <X <1) The continuous fixed bed catalytic reactor according to ( 5 ) above, comprising a crystalline phase.

( 8 ) The catalyst is
A tar-containing gas reforming catalyst which is a composite oxide represented by aM · bNi · cMg · dO,
a, b, and c satisfy a + b + c = 1, 0.02 ≦ a ≦ 0.98, 0.01 ≦ b ≦ 0.97, and 0.01 ≦ c ≦ 0.97,
d is a value at which oxygen and positive elements are electrically neutral;
M is Ti, Zr, Ca, W, Mn, Zn, Sr, Ba, Ta, Co, Mo, Re, platinum, runium, palladium, rhodium, Li, Na, K, Fe, Cu, Cr, La, Pr , At least one element selected from Nd,
At least one oxide selected from silica, alumina, and zeolite is added to the composite oxide, and the content of the oxide selected from silica, alumina, and zeolite is 1 to 90% by mass with respect to the composite oxide. Is,
The continuous fixed bed catalytic reactor according to ( 5 ) above, wherein

( 9 ) A continuous fixed bed catalytic reaction method, wherein the catalytic reaction is carried out using the continuous fixed bed catalytic reaction apparatus according to any one of (1) to ( 8 ) above.

  Here, the background of the inventor's arrival at the present invention will be described as follows.

As a result of the inventors' investigation, it has been found that the mechanism for depositing the generated solid carbon between the catalysts in the fixed bed catalyst layer is as follows.
(1) In the inter-catalyst space formed by a plurality of adjacent catalysts in the fixed bed catalyst layer, the raw material gas (partially reformed) flows from the gap on the upstream side of the mainstream, and from the gap on the downstream side of the mainstream The reformed gas (a part of the remaining raw material gas) flows out as the reformed gas.
(2) When the raw material gas supplied to the inter-catalyst space is reformed by a catalytic reaction, a part of the solid carbon generated on the catalyst surface adheres to the catalyst surface.
(3) When the raw material gas supplied to the inter-catalyst space is reformed by a catalytic reaction, the solid carbon fine particles generated on the catalyst surface and separated from the catalyst surface by the air flow are solid carbon particles already attached to the catalyst surface. A carbon sphere having a diameter of several tens μm to about 1 mm grows on the catalyst surface.
(4) The above-mentioned carbon spheres are sometimes detached from the catalyst surface and reattached on other carbon spheres already present, so that the thickness composed of multi-layer carbon spheres on the catalyst surface is several millimeters. A deposited layer of solid carbon is formed.
(5) Since this solid carbon deposition layer is substantially porous, a large pressure loss occurs when high-speed gas flows.
(6) If the ventilation resistance in a specific inter-catalyst space becomes excessive, the mainstream preferentially ventilates other inter-catalyst spaces having lower ventilation resistance. However, since the solid carbon deposition layer is porous, the gas flow to the inter-catalyst space is not completely blocked even in a space where the ventilation resistance is excessive due to the deposition of the solid carbon. The material gas continues to be supplied at a low flow rate. As a result, the growth of solid carbon by gas reforming on the catalyst surface always proceeds (however, since the exposed area on the catalyst surface decreases, the reforming rate is greatly reduced compared to the initial stage).
(7) When solid carbon deposits in most of the inter-catalyst space in the catalyst layer, the pressure loss of the entire catalyst layer becomes excessive and a “clogged state” occurs (in the catalyst reaction vessel, the raw material gas is supplied at a given flow rate). No matter which catalyst space is vented at this given gas flow rate, the pressure loss can be prevented from exceeding the allowable value of the reactor (determined by gas transfer capacity, vessel strength, etc.). In the absence, the catalyst layer is substantially “clogged”).

  A reforming reaction of hydrogen, carbon dioxide, water vapor, and tar-containing gas is performed, and the solid carbon deposit layer is taken out from the catalyst surface of the fixed bed catalytic reactor that has become clogged, and it is placed in the container and shaken lightly. When mechanical external force was applied, it was easily separated and pulverized at the boundaries of the carbon spheres as the constituent units. In order to remove the solid carbon from the catalyst layer clogged by such solid carbon deposition, the present inventors have tried various measures.

  As a first countermeasure, an attempt was made to backwash the catalyst layer by blowing from the outside of the catalyst layer. More specifically, a nitrogen gas supply pipe was provided in the reaction vessel on the downstream side of the catalyst layer, and a high-speed nitrogen flow was jetted onto the catalyst layer to attempt backwashing of the catalyst layer. Backwashing is a technique that is generally used as a countermeasure when a filter for removing dust is blocked.

  As a result, a part of the solid carbon was removed, but the change in the pressure loss of the catalyst layer was slight, and there was no effect of eliminating the blockage. The reason is considered as follows.

  1) In the case of a filter, dust particles larger than the opening of the filter among dust particles flowing into the filter from upstream are collected on the spot. The filter usually has a larger opening toward the upstream. Accordingly, when backwashing is performed by supplying a high-speed flow from the downstream side of the main flow to the filter block, the collected dust particles separated from the filter eyes are transferred to the high-speed air flow and flowed into the main flow. When traveling to the upstream side of the filter, it passes through a larger mesh, so it is less likely to be collected again by the mesh and can be discharged out of the filter.

  On the other hand, a deposited layer of solid carbon or the like, which is a by-product of the catalytic reaction of the present invention, does not flow from the upstream of the main stream, but generates gas as a raw material in the space between the catalysts. For this reason, the size of the deposited carbon is not necessarily smaller than the gap between the inflow and the outflow of the intercatalyst space, and there is a large amount of the deposited carbon that cannot flow out from the intercatalyst space as it is.

  If the carbon deposit layer is destroyed and pulverized, there is a possibility that it can flow out from the space between the catalysts. However, since the stress exerted on the deposited carbon by the airflow is generally small (even if a large pressure difference is given to the entire catalyst layer, the catalyst is usually loaded in a large number of layers in the catalyst layer. The difference between the pressure on the inlet side and the outlet side becomes very small and a large stress cannot be applied to the deposited carbon), and the deposited carbon layer cannot be destroyed.

  2) When a part of the carbon is removed, a narrow channel that connects a small number of inter-catalyst spaces with reduced ventilation resistance as a result of carbon removal is newly formed in the catalyst layer. Concentrates in the flow path. At this time, since the air flow hardly passes through the space between the catalyst other than the newly formed flow path, no more carbon is removed. For this reason, since the flow velocity increases in a narrow flow path through which the main flow passes and a large pressure loss occurs, the closed state is not improved so much. Since the new flow path formed in this way is re-closed rapidly as new carbon is generated and deposited in the flow path, the effect of backwashing must be short. On the other hand, such inter-catalyst space re-occlusion does not occur in the inter-catalyst space constituted (enclosed) by the catalyst that has deactivated early. However, in the first place, if the main stream comes into contact with only the deactivated catalyst and passes through the catalyst layer, the gas cannot be reformed, so that the performance as a catalyst reaction vessel cannot be exhibited.

From these, we can conclude as follows.
That is, in general, in a catalyst layer that has clogged,
[Size of individual deposited carbon]> [Gap in the space between the catalysts]
It is in the state of
[Size of individual deposited carbon] <[Gap in the space between the catalysts]
Unless this is true, a large amount of carbon cannot be removed from the catalyst layer, and backwashing of the catalyst layer by blowing from the outside of the catalyst layer is not effective for this.

  Therefore, as a second countermeasure, the outer surface of the reaction vessel was beaten to try to destroy the deposited carbon layer or expand the space between the catalysts.

  As a result, when striking after the first occurrence of clogging (the first striking), a part of the deposited carbon could be removed, the pressure loss was reduced to about half, and a certain effect was seen. Thereafter, when striking again after the occurrence of re-occlusion (second striking), removal of the deposited carbon was minute, there was no change in pressure loss, and clogging could not be avoided. That is, it was found that the strike on the outer surface of the reaction vessel was not effective for removing the deposited carbon after the second time. The reason is considered as follows.

1) Normally, when the catalyst is stacked in the reaction vessel, it is simply dropped from the top, so that the catalyst in the catalyst layer is not in the closest packing state. When the first strike is added here, the catalyst is in a state of close packing or close to that by vibration (for the sake of simplicity, this will be referred to as “closest emphasis” hereinafter). In the process of close-packing, the relative position between the catalysts moves by a total of about 30% of the catalyst representative length. At the time of this relative position movement (ie, relative movement between the catalysts), a part of the deposited carbon is destroyed by contact stress with the catalyst and becomes smaller, and the interval between the catalysts temporarily increases.
[Size of individual deposited carbon] <[Gap in the space between the catalysts]
The above relationship was realized, and it dropped in the catalyst layer and was finally removed from the catalyst layer.

  2) On the other hand, since the catalyst layer is closely packed after the first strike, the relative position between the catalysts hardly changes even after the second and subsequent strikes, and the deposited carbon is destroyed. Further, there is no widening of the interval between the catalysts. For this reason, the effect of removing the deposited carbon was not recognized in the second and subsequent strikes.

From these, we can conclude as follows.
That is, in many cases, the one-time clogging relieving effect cannot satisfy the required processing duration in the catalytic reaction vessel, so that the strike on the outer surface of the reaction vessel is insufficient for the continuous removal of the deposited carbon. . In order to continuously remove deposited carbon from the catalyst layer,
[Size of individual deposited carbon] <[Gap in the space between the catalysts]
After that, a means for eliminating the closest packing state of the catalyst layer is required.

  Based on the above conclusion, as a third countermeasure, an attempt was made to move the catalyst layer itself in the reaction vessel. More specifically, an attempt was made to raise and lower the entire catalyst layer by raising and lowering a cage provided at the bottom of the catalyst layer while the catalyst was in contact with the inner wall of the reaction vessel in a stationary reaction vessel. As a result, after several raising / lowering operations, the raising / lowering movement of the catalyst layer reaches a stable state (after one cycle of the raising / lowering operation, the catalyst layer returns to the state of the starting point of the cycle on average). In this stable state, when the cage is raised, the amount of rise at the upper end of the catalyst layer is generally smaller than the amount of rise at the lower end of the catalyst layer, and after the cage is lowered, both the upper and lower ends of the catalyst layer return to the starting position. Therefore, the average packing rate of the catalyst layer fluctuates within the cage ascending / descending cycle (the catalyst layer average packing rate increases when the cage rises and decreases when the cage descends), and at least within the catalyst layer. Relative motion between the catalysts in the vertical direction occurs. The difference between the rising amounts of the upper and lower ends of the catalyst layer when the cage is raised and lowered increases as the catalyst layer height (distance between the upper and lower ends of the catalyst layer) increases, and finally the upper end of the catalyst layer hardly rises. It reaches. In the state where the upper end of the catalyst layer does not move, the catalyst in the vicinity of the upper end of the catalyst layer does not move by raising and lowering the cage in the first place, so that no relative movement between the catalysts occurs. As a result, in this region, the deposited carbon between the catalysts cannot be removed by raising and lowering the cage. Therefore, in order to remove the carbon deposited between the catalysts by raising and lowering the cage in the entire catalyst layer, not only simply changing the average filling rate of the catalyst layer by raising and lowering the cage, but also a sufficient raising and lowering stroke at the upper end of the catalyst layer. It turns out that it is necessary to secure.

  Fig. 4 shows a mechanism in which a catalyst layer is formed by filling a catalyst in a duct-shaped reaction vessel having a rectangular cross section with a constant cross-sectional area, and a retainer is provided below the catalyst layer to hold the catalyst layer. The catalyst layer upper end height expressed as a displacement of the catalyst layer upper end height in the stable state after raising and lowering the catalyst layer in the stationary reaction vessel 5 times while the catalyst is in contact with the inner wall of the reaction vessel by raising the vessel by 27 mm Indicates. The vertical axis represents the catalyst layer upper end height, and 0 mm serving as a reference corresponds to the vertical position of the catalyst layer upper end before the cage rises. The catalyst layer height / reaction vessel thickness on the horizontal axis is an index also referred to as “aspect ratio” of the catalyst layer in the following, and the reaction vessel thickness is the shortest of the representative lengths of the reaction vessel in the horizontal plane. For example, when the horizontal cross section of the reaction vessel is rectangular, it corresponds to the length of its short side, and when it is circular, it corresponds to its diameter.

  From FIG. 4, when the aspect ratio of the catalyst layer (catalyst layer height / reaction vessel thickness)> 2, the amount of rise of the catalyst layer (from the height before the start of raising / lowering finally recognized after five raising / lowering operations) It can be seen that the increase amount is much smaller than the increase amount of the cage (27 mm) and the catalyst outer dimension (diameter) of 15 mm. This means that the catalyst filling rate increases when the cage rises (when the catalyst layer rises) and decreases when the cage descends (when the catalyst layer descends). Here, even when the cage is raised and lowered, the lower the catalyst, the higher the moving speed. Therefore, the moving speed of each catalyst in the catalyst layer height direction is different. Under this condition (aspect ratio> 2), the rising amplitude of the upper end portion of the catalyst layer is small, so the relative motion between the catalysts in this portion is relatively small, and the ability to discharge deposited carbon between the catalysts is low.

  On the other hand, when the aspect ratio of the catalyst layer ≦ 2 (aspect ratio = 1.8), the rising amount of the upper end of the catalyst layer is slightly smaller than the rising amount of the cage (an increase of 20 mm with respect to the raising amount of the cage of 27 mm). ) That is, under this condition, the relative movement between the catalysts in the entire catalyst layer is such that the upper and lower strokes of the catalyst layer satisfy the same lifting stroke as that of the cage, and also ensure the fluctuation of the catalyst layer filling rate due to the raising and lowering of the cage. And the ability to discharge deposited carbon between the catalysts is high.

  In addition to the effect of the relative movement between the catalysts in the vertical direction, in the present invention, the catalyst layer moves up and down while the catalyst is in contact with the inner wall of the reaction vessel, so that the catalyst layer also moves in the thickness direction and the width direction. The effect of generating relative movement between the catalysts can be exhibited. That is, when the change in the relative position between the catalysts during the change in the packing rate accompanying the raising and lowering of the catalyst layer is considered, the restraint state with respect to the movement of each catalyst in the catalyst layer thickness direction (the same in the reaction vessel thickness direction) is different. This is due to the fact that the closer the catalyst is to the wall surface due to friction with the wall surface, the greater the restraint and the lower the initial ascent / descent speed. As a result, the movement speed of each catalyst in the catalyst layer thickness direction is different, so that relative movement between the catalysts occurs.

  Thus, when the catalyst layer is brought into contact with the inner wall of the vessel in the reaction vessel and the catalyst layer itself is raised and lowered, the change in the relative position between the catalysts when the filling rate changes accompanying the raising and lowering of the catalyst layer becomes large. When the lifting stroke is 30 mm, it is about 30% of the catalyst representative length (for example, 15 mm) every time the lifting stroke is performed.

  As described above, the catalyst is brought into contact with the inner wall of the reaction vessel in the reaction vessel, and the catalyst layer itself is moved up and down to move the relative position between the individual catalysts. It was found that the solids such as carbon deposited during the reforming reaction of the gas containing tar content can be efficiently dropped from the catalyst and removed from the catalyst layer.

  In particular, when the cage is lowered when descending, it is faster than the free fall speed of the lower part of the catalyst layer, more preferably faster than the free fall rate of the catalyst at the lower end of the catalyst layer. Since the catalyst is piled up one after another on the cage previously stopped at the lower end position, even if the catalyst layer is close-packed, it can be reduced by reordering the catalyst. At the same time, a moment in which the gap between the catalysts becomes extremely large during the fall of the catalyst can occur, so that the solid deposited between the catalysts can be efficiently removed.

  On the other hand, when the cage and the reaction vessel are moved up and down at the same speed, the entire catalyst layer is moved up and down at the same speed as the cage and the reaction vessel, so that relative movement between the catalysts does not occur. For this reason, the effect of removing solid carbon or the like on the catalyst surface is low (similar to strike from outside the reaction vessel). The same applies to the case where the entire catalyst is put in a car or the like and the car and the catalyst layer are moved up and down simultaneously.

  From the above, it was found that in order to remove solid deposits generated and deposited on the catalyst in the fixed bed catalyst layer, it is necessary to move the catalyst layer together with its retainer relative to the reaction vessel. It was. This is the basic principle of the present invention. According to the present invention, the entire catalyst layer is applied to the catalytic reaction in which a solid product such as solid carbon is generated for a short time by stirring the entire catalyst layer (moving the relative position between the individual catalysts). In this case, the solid product deposited between the catalysts can be effectively dropped from the catalyst and removed from the catalyst layer. The solid product removed from the catalyst layer can be dropped through the opening of the cage, and the solid product that has fallen and accumulated below can be discharged out of the system, for example, when the catalyst is replaced. .

  The present invention can be suitably applied to the removal of a solid product produced and deposited on a catalyst in a fixed bed catalyst layer. For example, in a reforming reaction of a tar-containing gas with a composite metal oxide catalyst containing nickel, magnesium, cerium, zirconium, and aluminum, the amount of solid carbon deposited on the catalyst surface is larger than other reactions, and it is removed. Needs are higher. In the present invention, the efficiency of the solid product produced / deposited on the catalyst is obtained even when the tar-containing gas reforming catalyst having a large amount of solid carbon deposited on the catalyst surface as compared with other reactions is used. Allows for efficient removal.

  Unlike the fixed catalyst bed, which is the subject of the present invention, the moving bed in principle moves the catalyst continuously (and stirred) during the reaction. On the other hand, in the present invention, it is only necessary to intermittently move the catalyst layer in the reaction vessel for a short time, so that it is not necessary to stir the catalyst during the reaction. Further, in the moving bed, a certain amount of catalyst is discharged out of the system during the reaction and the same amount of catalyst is supplied from outside the system. In contrast, in the present invention, the catalyst is not replaced during the reaction (because the catalyst layer is a fixed bed).

  According to the catalyst reaction apparatus of the present invention, solid deposits that are generated and deposited on the catalyst in the fixed bed catalyst layer to lower the catalyst performance and cause clogging of the catalyst layer are moved up and down the entire catalyst layer. By doing so, it can be efficiently removed. Therefore, it is possible to continuously operate the reaction apparatus without having to stop the operation in order to wash the closed catalyst holder as in the prior art. In addition, the catalytic reaction apparatus can be used to perform a catalytic reaction that generates a solid product such as solid carbon with high efficiency.

It is a schematic diagram explaining the reaction apparatus of the 1st Embodiment of this invention. It is a schematic diagram explaining the reaction apparatus of the 2nd Embodiment of this invention. It is a schematic diagram explaining the reaction apparatus of the 3rd Embodiment of this invention. It is a graph which shows the relationship between a catalyst layer aspect ratio and a catalyst layer upper end height. It is a graph which shows the relationship between a catalyst layer aspect-ratio and a peak load / reference | standard peak load. It is a schematic diagram explaining the catalyst reaction container of a prior art. It is a figure of the holder | retainer used for the reaction apparatus of the 2nd Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(Overall structure)
FIG. 1 shows a continuous fixed bed catalytic reactor 10 according to a first embodiment of the present invention. In this figure, (a) is a plan view, (b) is a front view, and (c) is a side view. The catalytic reaction apparatus 10 of the present invention includes a reaction vessel 11, in which a catalyst layer 13 having a lower portion supported by a cage 12 is accommodated, and is adjacent to the inner wall of the reaction vessel among the catalysts in the catalyst layer 13. A catalyst (not shown) is in contact with the inner wall of the reaction vessel. In the present invention, since the catalyst layer is moved up and down by bringing the catalyst into contact with the inner wall of the reaction vessel, the inner surface of the reaction vessel 11 is preferably smooth so as not to hinder the movement of the catalyst during the lifting operation. A drive mechanism 20 for moving the catalyst layer 13 up and down by moving the cage up and down is located under the cage 12. The drive mechanism 20 is configured to move the elevator device 21 and the elevator device 21 to the cage 12. The connecting shaft 22 is connected.

  A raw material gas 14 is supplied to the reaction vessel 11 from below and reacts in the catalyst layer 13, and the reformed gas 15 from the catalyst layer 13 is discharged from above the reaction vessel 11. An example of the source gas 14 may be a gas containing hydrocarbons, a gas containing tar together with hydrocarbons, or the like. An example of the reformed gas 15 may be a reformed gas obtained by reforming a gas containing hydrocarbon. As an example of the catalyst, a bulk catalyst for hydrocarbon reforming may be used, and a solid substance such as solid carbon is deposited on the surface as a by-product of the catalytic reaction. When the catalytic reaction is an endothermic reaction, the temperature and heat necessary for the reaction may be provided by placing the catalytic reaction vessel 11 in, for example, a heating furnace (not shown). When the catalytic reaction is an exothermic reaction, the reaction heat may be removed by flowing a refrigerant through a refrigerant flow path (not shown) provided outside the catalytic reaction vessel. In some cases, the raw material gas to the reaction vessel 11 can be supplied so as to flow downward from above the catalyst layer 13, contrary to FIG.

(Reaction vessel shape)
The reaction vessel 11 may have any shape as long as it has openings 16a and 17a at both ends and can accommodate the catalyst between these openings. The opening 16a communicates with a supply pipe constituting the inflow path 16 for the catalytic reaction fluid (raw material gas), and corresponds to the inlet of the raw material gas for catalytic reaction to the reaction vessel 11. The opening 17 a communicates with a discharge pipe constituting the reformed gas outflow path 17 of the reaction vessel 11 and corresponds to an outlet of the reformed gas from the reaction vessel 11. For example, the reaction vessel 11 may have a cylindrical shape, a rectangular duct shape, or the like. Hereinafter, a rectangular duct-shaped reaction vessel will be described as an example.

  In the following description, the “center axis of the container” is defined as a centroid of a horizontal section of the container connected in the vertical direction. “Reaction vessel thickness” corresponds to the minimum length of the representative length of the reaction vessel in the horizontal section, and “Reaction vessel width” is the maximum length of the representative length of the reaction vessel in the horizontal plane. It corresponds to. When the container is a cylinder, the “width” and “thickness” of the container may be replaced with “diameter”.

(Reaction vessel material)
Any material can be used as the material of the reaction vessel 11 as long as it has strength to hold the catalyst, heat resistance / corrosion resistance to the fluid involved in the catalyst reaction, and contamination resistance to the reaction product. For example, carbon steel, stainless steel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium, titanium alloy and other metal materials, silica, alumina, silicon nitride, silicon carbide and other ceramic materials (those processed into bricks) Glass materials such as soda glass and fused silica can be used.

(Reaction vessel dimensions)
The lower limit of the thickness of the reaction vessel must be equal to or larger than the representative dimension (eg, diameter) of the bulk catalyst (for example, 10 mm). In general, in the catalytic reaction, heat is generated or absorbed, and the heat is transferred to the outside through the surface of the reaction vessel. Therefore, there is an upper limit on the thickness in order to ensure heat transfer to the inside of the catalytic reaction vessel. The upper limit value may be determined in terms of engineering by reaction heat, flow rate, heat transfer characteristics, etc. (for example, 200 mm).

  There is no particular limitation on the width of the reaction vessel in terms of function. Based on the volume of the catalyst layer to be retained and the thickness of the reaction vessel, it may be determined from an engineering viewpoint (for example, 5000 mm) in consideration of structural and strength constraints.

  The height of the reaction vessel must be greater than the height of the catalyst layer. On the other hand, the upper limit of the reaction vessel height is not limited in terms of function, and may be determined in terms of engineering in consideration of structural and strength limitations (for example, 5000 mm).

(Catalyst layer cage)
The cage 12 that supports the catalyst layer 13 includes a net, punching metal, a plurality of rods, the rods arranged in parallel to each other in a horizontal direction so as to create a space between the rods, and the like. Can be used. The cage 12 shown in FIG. 1 is an example of one produced by fixing both ends of a plurality of rods 18 with a fixture 19.

  When the opening ratio of the cage 12 becomes small, the air permeability and the permeability of solid carbon and the like deteriorate. When the aperture ratio is high, the number of parts for holding the catalyst in the cage decreases, and the strength of the cage is insufficient. In the case of any of the above types of cages, the aperture ratio of the cage 12 is preferably about 30 to 70%.

  The material of the cage 12 is preferably a metal material having heat resistance, corrosion resistance, and strength. Examples of such metal materials include stainless steel, Ni alloys such as Hastelloy (registered trademark) and Inconel (registered trademark), titanium, titanium alloys, and the like.

(Catalyst layer drive mechanism)
In the present invention, the cage 12 is moved up and down to raise and lower the catalyst layer 13 in the reaction vessel 11. For this purpose, the reaction vessel 11 of the present invention is equipped with a drive mechanism 20 for raising and lowering the catalyst holder 12. As the drive mechanism 20, a general drive mechanism such as an elevating device 21 using a gear such as an air cylinder or a rack and pinion can be used. The cage 12 is coupled to the lifting device 21 using the conduction shaft 22. When the elevating device 21 is operated, the entire cage 12 moves along the axis of the reaction vessel 11, and the entire catalyst layer 13 is also moved up and down along the axis of the reaction vessel 11.

  At least a part of the conduction shaft 22 on the side of the cage 12 needs to exist inside the reaction vessel 11 or the raw material gas inflow furnace 16 or the reformed gas outflow passage 17 that can exist below the reaction vessel 11. The elevating device 21 can be provided outside the reaction vessel 11. In the case where the reaction vessel 11 is arranged in a heating device (not shown) such as a heating furnace, the elevating device 21 can be provided outside the heating device. In this case, while a commercially available lifting device can be used, it is necessary to seal the portion where the conductive shaft 22 penetrates the reaction vessel 11 with high-temperature packing or the like.

  In the case where the entire drive mechanism 20 is provided in the reaction vessel 11 as shown in FIG. 1, in order to protect the elevating device 21 from, for example, high temperatures and corrosive substances in the reaction vessel 11, it is heat and corrosion resistant. It is necessary to. As an example, this can be realized by making the entire air cylinder of the drive mechanism 20 made of a heat-resistant alloy such as Hastelloy (registered trademark). In this case, a supply air pipe (not shown) to the air cylinder passes through the reaction vessel 11, but since this part is a non-movable part, the pipe may be welded around the circumference and the like may be sealed.

  Since a part of the cage 12 may bite into the catalyst layer 13 when the cage is raised (particularly when the pin type cage of the second embodiment described below is used), the cage 12 is only raised. It is preferable to drive even when the vehicle is lowered.

(Climbing stroke of cage)
In order to sufficiently perform the relative movement between the catalysts, it is preferable that the raising / lowering stroke of the cage 12 is large. For example, even with a lifting stroke of about 0.1 times the representative dimension (eg, diameter) of the outer surface of the catalyst, there is an effect of vibration, so that the removal effect of deposits such as solid carbon on the catalyst surface is to a certain extent. can get. However, in order to obtain a sufficient deposit removal effect, the raising / lowering stroke of the cage 12 is preferably 0.5 times or more, more preferably 1 time or more, of the catalyst outer surface representative dimension.

  On the other hand, when the lift stroke is extremely large, the reaction vessel 11 and the drive mechanism 20 are increased in size, which is not efficient. Moreover, the effect similar to a bigger raising / lowering stroke is acquired by repeatedly raising / lowering a small stroke (however, 1 times or more). Therefore, the lifting stroke is preferably 10 times or less of the representative dimension of the catalyst outer surface.

(Lifting speed)
The required ascending force required to raise the catalyst layer 13 together with the cage 12 is smaller as the ascent rate is smaller. As a result of the investigation by the present inventors, it has been found that the required ascending force when raising the catalyst layer together with the cage at 10 mm / s needs to be double that when raising at 1 mm / s. Further, at a high rising speed, the catalyst is easily destroyed. Therefore, it is preferable that the rising speed is small. However, the difference in required ascending force between the case of raising at 1 mm / s and the case of raising at 0.5 mm / s is small, so it is not always necessary to make it slower than 1 mm / s. Further, even if the rising speed is 10 mm / s, it may be applied as long as the catalyst is not destroyed.

  As described above, the descending speed of the cage is preferably large. In particular, if the cage is lowered at a speed (for example, 100 mm / s) larger than the free fall speed of the catalyst at the lowermost end, the catalyst is detached from the cage and the restriction between the catalysts is reduced, and the relative relationship between the catalysts is reduced. It is preferable because a large amount of exercise can be taken. However, there is no difference in the effect obtained even if the cage is lowered at a speed extremely higher than the free fall speed of the catalyst.

(Catalyst size)
In general, a catalyst configured by supporting a substance having a catalytic action on a porous simple substance needs to remain in the catalyst layer 13 located on the cage 12. Therefore, the catalyst needs to have a size that does not pass through the opening of the cage 12.

(Catalyst shape)
As described above, when a catalyst is held by a specific cage, a minimum value exists in the smallest representative dimension of the same catalyst outer surface. When the volume of the catalyst layer 13 is constant, generally, the greater the number of catalysts, the greater the total surface area of the catalyst, and the reaction rate of the reaction vessel 11 can be improved. Therefore, a sphere or a catalyst having a shape close to a sphere is preferable because the number of catalysts can be easily increased in a certain volume. Even if the volume surrounded by the outer periphery of the catalyst is the same, a shape having a larger surface area, for example, a cylindrical shape or a ring shape is also preferable. On the other hand, a rod-like or disk-like shape is not preferable because it is difficult to hold.

  When the catalyst layer 13 rises, the force acting between the catalysts becomes more isotropic in the catalyst layer, and a force equivalent to the vertical force for pushing up the catalyst layer 13 is generated in the other directions, A frictional force proportional to this force is generated between the catalysts. The downward component of this frictional force acts as a resistance force for pushing up the catalyst layer. When the catalyst layer 13 is pushed up from the lower end, the reaction force between the catalysts and the force acting between the catalyst and the inner wall of the reaction vessel are larger toward the lower side of the catalyst layer. Since the vertical force in the rising catalyst layer must be greater than or equal to the sum of the vertical components of the resistance force above that position, the force required to push up rapidly increases at the lower side of the catalyst layer. To do. The maximum pressing force is at the lower end of the catalyst layer, and if this force is excessive, the catalyst and the reaction vessel may be destroyed.

  From this point of view, the lower the catalyst layer, the better. A test was conducted in which a general catalyst (cylindrical shape) having a crushing strength of 100 N and an angle of repose of 35 ° was held and moved up and down by the pin type cage of the second embodiment described below. The result is shown in FIG. The horizontal axis of this figure is the catalyst layer height / reaction vessel thickness ratio (catalyst layer aspect ratio), and the vertical axis is the catalyst layer push-up normalized based on the push-up peak load when pushing up the catalyst layer under specific conditions. The peak load. From this figure, it can be seen that when the aspect ratio of the catalyst layer (catalyst layer height / reaction vessel thickness ratio) exceeds 2, the push-up load increases rapidly. It was found that the catalyst hardly breaks if the aspect ratio of the catalyst layer (catalyst layer height / reaction vessel thickness ratio) is 2 or less. Further, as described above, the aspect ratio is preferably 2 or less in order to cause the catalyst to move relative to the entire catalyst layer.

  On the other hand, when the catalyst layer height is extremely low, the relative movement between the catalyst due to the relative movement of the inner wall of the reaction vessel and the catalyst is limited to the vicinity of the inner wall surface of the reaction vessel in the thickness direction of the reaction vessel, and the center in the thickness direction of the reaction vessel. This is not preferable because the relative movement between the catalysts does not occur in the portion. In particular, when the catalyst height is equal to or less than the height of two layers of catalyst (the maximum height in which two catalysts are stacked vertically), the upper layer catalyst is less constrained, so the catalyst is easily Since it becomes densely packed and cannot be lowly filled, the relative movement is further prevented. Therefore, the catalyst layer height is preferably at least three times the height of the catalyst (the maximum height obtained by stacking three catalysts in the vertical direction), that is, at least three times the maximum value of the catalyst outer surface representative length. .

(Catalyst fluidity)
The catalyst raised together with the cage 12 in the reaction vessel 11 is suspended in the reaction vessel (the catalyst layer 13 is lifted by the cage 12 and then the cage 12 is lowered to cause self-locking between the catalysts. Cause the catalyst not to descend). From the viewpoint of preventing the catalyst from hanging in the reaction vessel 11, the fluidity of the catalyst as the particle group in the catalyst layer 13 is preferably low, and the angle of repose is preferably less than 50 °.

  On the other hand, in order to maintain the anisotropy (upward force is superior) in the catalyst layer of the force applied from the cage to the catalyst layer 13 when the cage 12 is raised, to a higher position of the catalyst layer 13, the catalyst It is preferable that the fluidity is not extremely low, and the angle of repose is preferably 10 ° or more. This is because the cage 12 can be raised with a smaller thrust, and the catalyst is less likely to be broken, as the region with higher force anisotropy in the catalyst layer is wider.

(Catalyst material and action)
The material and catalytic action of the catalyst to which the catalytic reaction apparatus of the present invention can be applied are not particularly limited as long as it is a catalyst used for a catalytic reaction using a fluid, particularly a gas as a raw material. Catalytic reaction in which the fluid is a gas, and the product of the catalytic reaction is a gas and a solid or liquid. In particular, the catalytic reaction fluid is a gas containing hydrocarbons, and the product of the catalytic reaction is a gas and a solid or liquid. In particular, the catalyst reaction fluid is a gas containing tar, and the product of the catalyst reaction can be suitably used for a catalyst used in a catalytic reaction containing solid hydrocarbon or solid carbon.

  In general, it can be widely used for oxide catalysts used in the catalytic reaction as described above. In particular, the catalytic reaction fluid is a gas containing tar, and the product of the catalytic reaction is solid hydrocarbon or solid carbon. It can apply suitably for the oxide catalyst used for the catalytic reaction containing.

Specific examples of the catalyst that can be suitably used in the catalytic reactor of the present invention include, for example, oxides containing nickel, magnesium, cerium, and aluminum, including at least one complex oxide, and as a single compound Mention may be made of catalysts for reforming tar-containing gases not containing alumina (WO 2010/134326). A preferred example of this composite oxide is a crystal phase of NiMgO, MgAl ₂ O ₄ , and CeO ₂ , and among the crystal phases, the (200) plane of the NiMgO crystal phase determined by X-ray diffraction measurement is used. The crystallite size is 1 nm to 50 nm, the crystallite size of the (311) plane of the MgAl ₂ O ₄ crystal phase is 1 nm to 50 nm, and the crystallite size of the (111) plane of the CeO ₂ crystal phase is 1 nm to 50 nm. This catalyst contains a large amount of hydrogen sulfide generated when a carbonaceous raw material is thermally decomposed, and even if it is a condensed polycyclic aromatic-based tar-containing gas that easily causes carbon deposition, the accompanying heavy hydrocarbon such as tar Is converted to light hydrocarbons mainly composed of hydrogen, carbon monoxide, and methane, and when the catalyst performance deteriorates, at least one of water vapor and air is converted to the catalyst at a high temperature. By contacting, the carbon is removed from the catalyst and adsorbed sulfur, and the catalyst performance is restored to enable stable operation over a long period of time.

Further, a reforming catalyst for tar-containing gas, which is composed of a composite oxide containing nickel, magnesium, cerium, zirconium and aluminum, can be mentioned (Japanese Patent Application No. 2010-082576). Suitable examples of the composite oxide, NiMgO, include _{MgAl 2 O 4, Ce x Zr} 1-x O 2 (0 <x <1) crystal phase, and further, among the crystalline phase, X-rays diffraction the crystallite size of (220) plane of NiMgO crystalline phase determined by the measurement is 1 nm to 50 nm, a crystallite size of (311) plane of the MgAl ₂ O ₄ crystalline phase _{1nm~50nm, Ce x Zr 1-x} O 2 crystals The crystallite size of the (111) plane of the phase is preferably 1 nm to 50 nm. According to this catalyst, the tar-containing gas generated when coal or biomass is pyrolyzed can be stably converted into light chemical substances such as carbon monoxide and hydrogen. In particular, even if the tar-containing gas contains a high concentration of hydrogen sulfide in the tar-containing gas, it is brought into contact with the catalyst without desulfurization to reform the tar in the crude gas, or a refined gas The tar-containing gas can be stably converted into light chemical substances such as carbon monoxide and hydrogen by reforming the hydrocarbon component therein.

  Furthermore, a catalyst for reforming a tar-containing gas that is a composite oxide represented by aM · bNi · cMg · dO, wherein a, b, and c are a + b + c = 1, 0.02 ≦ a ≦ 0. 98, 0.01 ≦ b ≦ 0.97 and 0.01 ≦ c ≦ 0.97 are satisfied, d is a value at which oxygen and a positive element are electrically neutral, M is Li, Mention may be made of a catalyst for reforming a tar-containing gas which is at least one element selected from Na and K (Japanese Patent Application Nos. 2010-081867, 2010-08197, and 2010-083527). A suitable example of this composite oxide is formed by adding at least one oxide selected from silica, alumina, and zeolite, and further contains at least one oxide selected from silica, alumina, and zeolite. It is preferable that it is 1-90 mass% with respect to the whole complex oxide. According to this catalyst, the tar-containing gas generated when coal or biomass is pyrolyzed can be stably converted into light chemical substances such as carbon monoxide and hydrogen. In particular, even if the tar-containing gas contains a high concentration of hydrogen sulfide in the tar-containing gas, it is brought into contact with the catalyst as it is without desulfurization treatment to reform the tar in the crude gas or in the purified gas. Thus, the tar-containing gas can be stably converted to light chemical substances such as carbon monoxide and hydrogen.

(Other applicable examples)
The present invention can be suitably used for the following catalytic reaction apparatus that causes coking, in addition to the catalytic reaction apparatus and catalyst exemplified above.
1) Methane reforming catalytic reactor: “Comparative Example” of Japanese Patent Application Laid-Open No. 2006-35172 describes that a large amount of coking (carbon deposition) occurs using methane gas as a raw material gas.
2) City gas reforming catalytic reactor: Patent Document 2 describes a case of coking.
3) In addition, catalytic reactors for reforming various petroleum refining gases such as LPG and natural gas, and fuel cells that generate hydrogen by generating gas by acting hydrogen-containing gas and oxidant gas. The present invention can be applied to a catalytic reactor (eg, JP 2009-48797 A).

  Next, the continuous fixed bed catalytic reactor of the second embodiment will be described with reference to FIG. (A) of this figure is a plan view, (b) is a front view, and (c) is a side view. The catalyst reaction device 10 of FIG. 2 is the same as that of the first embodiment described with reference to FIG. 1 except that the catalyst holder uses a large number of pins as shown in FIG. It is the same.

  The catalyst reaction vessel 11 in this embodiment has a catalyst holder 12 ′ in the lower part which is an inlet to the reaction vessel 11. The catalyst holder 12 ′ is a structure in which a large number of pins 25 are held by a bottom plate 26, and is a catalyst holding unit that holds the massive catalyst of the catalyst layer 13 at the tip of the pins 25. By setting the distance between the pins 25 to be smaller than the size of the bulk catalyst, it is possible to hold the bulk catalyst at the tips of these pins 19, and the gap between the pins is the inlet of the catalyst reaction fluid or It functions as an outlet for the product fluid.

  In the illustrated catalyst holder 12 ′, the pin 25 can be made of, for example, a round bar. The pins 25 are generally the same shape, but are not necessarily the same shape. It is only necessary to hold the massive catalyst at the tip of the pin 25 and to allow fluid to flow through the gap between the pins 25, and the size, length and angle of the pins need not be the same, and the pins are limited to be linear. Absent. In the illustrated catalyst holder 12 ′, the tip of the pin 25 forms the same plane, but the surface formed by the tip of the pin 25 is curved, or exceptionally, some pins form the tip. You may protrude from the surface to do. According to such a catalyst holder 25, a high opening ratio and prevention of clogging are realized.

  The arrangement of the pins 25 in the catalyst holder 12 ′ is an isosceles triangle in which all the triangles formed by the centers of three adjacent pins with the center of the pin on the plane perpendicular to the axis of the pin as a vertex are congruent. In particular, an equilateral triangle is preferable. As a result, a catalyst holding structure can be realized with a minimum number of pins for the required cross-sectional area of the catalyst to be held.

  All the pins 25 are preferably arranged so that the central axes of the pins are parallel to each other. This is because the opening on the side surface of the pin becomes uniform and becomes more difficult to close. In a region where the pin shafts are extremely close to each other, blockage between the pin side surfaces is likely to occur. The length of the portion where the pins are parallel is determined so as to form a space in which the raw material fluid and the reformed fluid can freely flow without closing the gap between the pins.

  If there is a design convenience, the distance between the central axes gradually increases or decreases toward the catalyst direction, and the axis of the pin 25 does not necessarily have to be parallel. Similarly, although the central axes of the pins are parallel, the interval between the pins may be set so as to gradually widen or narrow. The length of the portion where the pins are substantially parallel is determined so as to form a space in which the reaction fluid can freely flow without closing the gap between the pins.

  The distance between the pins is such that the distance between the shafts excluding the diameters (outer diameters) of all the pins is the smallest mesh opening size (sieving sieve) through which the catalyst can pass, particularly at the top (pin tip) of the catalyst holder. Smaller than the apparent dimension). In this way, the catalyst mass does not fall between the pins and can be supported by these pins. Some catalyst dimensions are exceptionally smaller than the distance between the axes excluding the pin diameter, such as a small piece of catalyst caused by catalyst failure, but may fall between the pins. By providing a sufficient storage space for fallen objects below and below 12 ', there is no particular problem at least from the viewpoint of clogging the catalytic reaction vessel. From the viewpoint of air permeability and resistance to blockage of the cage, the opening ratio (1- [total pin cross-sectional area] / [apparent cross-sectional area of the channel]) in the vertical cross section in the main flow direction of the air flow is 90% or more. It is preferable. The upper limit of the aperture ratio is restricted by the cross-sectional area of each pin determined from the buckling resistance of the pin.

  The length of the pin is preferably [apparent cross-sectional area of fluid flow at the gas inlet (outlet)] ≧ [apparent cross-sectional area of fluid in the catalyst layer]. When the thickness and width (diameter) of the catalytic reaction vessel are given, the height of the pin can be changed to adjust the apparent flow sectional area of the fluid at the inlet (outlet). However, this is not the case when the apparent cross-sectional area of the fluid in the catalyst layer is extremely large (the reaction vessel is flat in the main flow direction, etc.). Here, the “fluid apparent sectional area” is an area of a region surrounded by the side wall of the catalyst reaction vessel on a plane perpendicular to the main flow of the raw material fluid and the reforming fluid.

  The aspect ratio (length / diameter ratio) of the pin is preferably 100 or less, more preferably 20 or less, from the viewpoint of buckling prevention. However, when the maximum load applied to the pin is sufficiently small, a value larger than this may be used. Further, in order to set the apparent flow sectional area of the fluid at the inlet (outlet) sufficiently large, the pin aspect ratio is preferably 1 or more, and more preferably 5 or more.

  As the material of the pin, any material can be used as long as it has strength to hold the catalyst, heat resistance / corrosion resistance to the fluid in contact, and contamination resistance to the reaction product. For example, carbon steel, stainless steel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium, titanium alloy and other metal materials, silica, alumina, silicon nitride, silicon carbide and other ceramic materials, soda glass, fused quartz, etc. Glass material, can be used. Since the catalytic reactor for tar reforming is usually operated at a high temperature of 800 ° C. or higher, nickel alloys such as stainless steel, Hastelloy (registered trademark), and Inconel (registered trademark) are particularly preferable.

  The method for fixing the pins to the bottom plate is not particularly limited. For example, all the pins can be fixed to the bottom plate by welding.

  By using such a catalyst holder, the strength can be maintained even if the aperture ratio is increased unlike the case of punching metal or mesh, so that the substantial aperture ratio (in the contact portion of the pin row to the catalyst) The ratio of the space in the plane perpendicular to the pin axis can be set to a high value of 90% or more, which cannot be realized by the conventional technology. More than 95% is possible.

  In addition, each pin 25 of the catalyst retainer 12 ′ is isolated in the vertical cross section of the pin central axis, and the spaces extending between the pin rows are connected to each other, so that a solid such as carbon is temporarily deposited on the surface of the pin. Even so, it is not easy for this solid to bridge between adjacent pins to close the opening.

The bulk catalyst in the catalyst layer 13 of the reaction vessel 10 of this embodiment must satisfy the dimensional constraints on the pin. For example, the catalyst of the following Example 1 can be used.
(Example 1) When a spherical catalyst lump having a diameter of 10 mm is placed in a cylindrical catalyst reaction vessel having an apparent cross section of 100 mm in diameter, a pin height of 100 mm is sufficient. On the other hand, since the pin diameter can be set to 5 mm, the aspect ratio of the pin at this time is about 20, which is feasible.

On the other hand, since the dimensional constraints on the pin cannot be satisfied, the catalyst of Example 2 below cannot be used.
(Example 2) When a spherical catalyst lump having a diameter of 0.1 mm is placed in a cylindrical catalyst reaction vessel having an apparent cross section of 100 mm in diameter, the pin height needs to be at least several tens of mm. On the other hand, the pin diameter must be smaller than the catalyst mass diameter. Therefore, the pin aspect ratio exceeds 100, which is not feasible.

  The size of the catalyst is determined from the efficiency of the catalytic reaction and is not general. The distance between the pins of the catalyst holder may be determined in consideration of the dimensions of the catalyst. However, if necessary, the dimension of the catalyst can be determined in consideration of the distance between the pins of the catalyst holder of the present invention.

  As described above, when a catalyst is held by a specific catalyst holder, a minimum value exists in the smallest representative dimension of the same catalyst outer surface. When the volume of the catalyst reaction vessel is constant, generally, the greater the number of catalysts, the greater the total surface area of the catalyst, and the reaction rate of the reaction vessel can be improved. Accordingly, a sphere or a shape close to a sphere is preferable because the number of catalysts can be easily increased in a certain volume. Moreover, even if the volume enclosed by the outer periphery of a catalyst is the same, the shape with a large surface area of a catalyst lump, for example, a cylindrical shape or a ring shape, is also preferable.

On the other hand, a shape such as a disk that has an extremely small representative length only in one direction is generally unfavorable because it is difficult to hold in the present invention (comparison: conventional meshes and punching metals are not preferred than the mesh size). The slightly larger disk was the shape that could increase the number of catalysts most). Further, the rod-like shape is not preferable because it is difficult to hold as in the prior art.
The outer dimension of the catalyst mass is preferably about 5 to 50 mm from the viewpoint of easy retention in the catalyst cage and securing a high specific surface area for reactivity.

  Also in this embodiment, the material and action of the catalyst are the same as those of the first embodiment described above.

  The catalyst holder 12 ′ in this embodiment can be moved up and down by the drive mechanism 20 similarly to the holder 12 of the first embodiment described above with reference to FIG. The catalyst layer 13 can be moved up and down. The drive mechanism 20 can use a general drive mechanism such as an elevating device 21 that uses gears such as an air cylinder and a rack and pinion as described above for the first embodiment, and a cage. 12 ′ is coupled to the lifting device 21 using a conduction shaft 22.

  Next, a continuous fixed bed catalytic reactor according to a third embodiment will be described with reference to FIG. In this figure, (a) is a plan view, (b) is a front view, and (c) is a side view. The catalyst reaction apparatus 10 of FIG. 3 is the same as that of the second embodiment described with reference to FIG. 2 except for a drive mechanism for raising and lowering the catalyst holder.

  In the second embodiment, the drive mechanism 20 for raising and lowering the catalyst holder 12 ′ moves the entire holder 12 ′ along the axis of the reaction vessel 11, whereas the third embodiment The cage 12 ′ has a cantilever structure in which one end of the bottom plate 26 is connected to the rotary shaft 27 and the other end is connected to the conduction shaft 22 of the drive mechanism 20. The drive mechanism 20 moves up and down one side (left side in FIG. 3B) of the cage 12 ′ to move the catalyst relatively, thereby efficiently removing the solid product generated and deposited in the catalyst layer 13. be able to. In the present embodiment, the relative displacement between the catalysts can be given more by the effect of shearing the entire catalyst layer as compared with the lifting method of the second embodiment or the like with the same lifting stroke. Note that when the cage is raised, all the tips of the pins of the cage move to the rotating shaft 27 side. Therefore, in order to prevent the catalyst from falling off the pin due to interference between the inner wall of the reaction vessel adjacent to the pin due to the movement of the pin tip or an increase in the gap, the pin of the cage should be arranged in advance toward the drive mechanism 20 side. Can do.

  The following examples further illustrate the present invention. However, the present invention is not limited to these examples.

[Example 1]
Tested with the apparatus shown in FIG.

(Composition of the entire reaction system)
Coal was supplied from a coal supply device (coal hopper quantitative supply device) to a heated kiln at a rate of 20 kg / hr to continuously generate coal dry distillation gas (including water vapor caused by moisture in the coal). The inlet of the catalyst reactor was connected to the kiln by a heat insulating tube, and the outlet of the catalyst reactor was connected to the induction fan via a scrubber by the heat insulating tube. In coal dry distillation gas, tar in the gas is reformed in a catalytic reaction vessel to produce light gas (hydrogen, etc.), which is then introduced into the atmosphere via a flare stack (burning reformed gas) by an induction fan as reformed gas. Dissipated. The catalytic reaction vessel was accommodated in an electric heating furnace in which the furnace temperature was controlled at a constant temperature. The induction fan was able to adjust the flow rate and was controlled to a flow rate corresponding to the generation rate of coal dry distillation gas.

(catalyst)
As the catalyst, a component system of Ni _0.1 Ce _0.1 Mg _0.8 O was used.
Nickel nitrate, cerium nitrate, and magnesium nitrate were precisely weighed so that the molar ratio of each metal element was 1: 1: 8, and a mixed aqueous solution was prepared by heating at 60 ° C., and heated to 60 ° C. A potassium carbonate aqueous solution was added to coprecipitate nickel, magnesium, and cerium as hydroxides, and the mixture was sufficiently stirred with a stirrer. Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. The precipitate obtained after washing was dried at 120 ° C. and coarsely pulverized, then baked (calcined) at 600 ° C. in the air, crushed, put into a beaker, added with alumina sol, and a mixer equipped with stirring blades Then, the mixture was transferred to a flask which was mixed well and attached to a rotary evaporator, and the water was evaporated by suction while stirring. The nickel, magnesium, cerium, and alumina compounds attached to the flask wall are transferred to an evaporating dish, dried at 120 ° C., calcined at 600 ° C., and pressed into a 3 mmφ tablet using a compression molding machine. A cylindrical molded body having an outer diameter of 15 mm, an inner diameter of 5 mm, and a height of 15 mm was obtained.

The molded body was fired in air at 950 ° C. to prepare a catalyst molded body in which 50% by mass of alumina was mixed with Ni _0.1 Ce _0.1 Mg _0.8 O. As a result of confirming the component of the molded body by ICP analysis, it was confirmed to be a desired component. Moreover, when the molding was measured with the Kiyama-type hardness meter, it was found that a high strength of about 100 N was maintained.

(Catalytic reactor)
The catalytic reactor used was as follows.
・ Reaction vessel shape: Duct shape with a rectangular cross-section with a constant central axis shape ・ Reaction vessel material: Stainless steel ・ Reaction vessel thickness: 120 mm
・ Reaction vessel width: 300 mm
・ Catalyst layer height: 400mm
Catalyst layer aspect ratio: 3.3
・ Driver lifting stroke: 15mm
・ Driver ascent speed: 2 mm / sec ・ Driver descent speed: 100 mm / sec ・ Catalyst retainer: Pin type made of slender rod ・ Pin: Diameter 5.1 mm, length 90 mm, top is flat, corner 1 mm Chamfering ・ Pin arrangement: An isosceles triangle with a bottom of 16 mm (in the reaction vessel width direction) and a height of 13.5 mm (in the reaction vessel thickness direction), all welded to the bottom plate of the catalyst cage ・ Pin opening ratio: 92%
・ Amount of catalyst used: 7kg
The above catalyst was accommodated in the catalyst reaction apparatus shown in FIG. 2, and a thermocouple was inserted at the center position of the catalyst layer.
Before starting the reforming reaction, the reactor was first heated to 800 ° C. in a nitrogen atmosphere, and then reduced for 30 minutes while flowing hydrogen gas at 80 Nl / min. Thereafter, coke oven gas was adjusted and introduced, and the reaction was evaluated under normal pressure.
Regarding the operation timing of the driving device, the first and second ascending and descending operations were performed two reciprocations each three hours and four hours after the start of the ventilation of the coal dry distillation gas.

(Process conditions)
The working conditions were as follows:
・ Coal dry distillation kiln temperature: 750 ℃
・ Electric heating furnace temperature: 800 ℃
・ Coal dry distillation gas flow rate: 10Nm ³ / h on average
・ Coal dry distillation aeration time: 5 hours

(result)
The test results were as follows.
・ Breathability (pressure loss)
Immediately after the start of ventilation: 0.1 kPa
During the first lift: 4 kPa (immediately before) → 0.3 kPa (immediately after)
During the second lift: 4 kPa (immediately before) → 1.0 kPa (immediately after)
As described above, recovery of air permeability by raising and lowering the catalyst layer was observed.

・ Reforming characteristics (hydrogen amplification rate = hydrogen flow rate in reformed gas / hydrogen flow rate in feed gas)
Immediately after the start of ventilation: 3.5
During the first lift: 2.5 (immediately before) → 2.3 (immediately after)
During the 2nd lift: 1.8 (immediately before) → 1.7 (immediately after)
As described above, it was found that in this example having a catalyst layer aspect ratio of 3.3 (greater than 2), the effect of recovering the reforming characteristics by raising and lowering the catalyst layer is limited.

  After the test, the device was disassembled and the inside was examined. As a result, 40 g of solid carbon was deposited on the cage bottom plate, but only a thin solid carbon film was formed on the cage surface. There was no adhesion of solid carbon to the pins, and the ventilation resistance of the cage was the same as at the time of installation.

[Comparative example]
A catalyst reaction vessel without a driving mechanism (the catalyst holder is fixed) in Example 1 was used, and the test was carried out with an apparatus using a striking device that periodically hits the outer wall of the catalyst reaction vessel with a weight.
As for the operation timing of the striker, the first and second strikes were carried out 10 times each 3 hours and 3.5 hours after the start of the aeration of the coal dry distillation gas.
The other conditions were the same as in Example 1.

(result)
The test results were as follows.
・ Breathability (pressure loss)
Immediately after the start of ventilation: 0.1 kPa
First strike: 4 kPa (immediately before) → 2.5 kPa (immediately after)
During the second strike: 4 kPa (immediately before) → 4 kPa (immediately after)
As described above, the effect of restoring the air permeability by the hitting was not recognized at the second time, and the effect at the first time was smaller than that of Example 1. Since the pressure loss did not decrease, it was judged as a blockage, and aeration was stopped at 4 hours after the start of aeration.

[Example 2]
The catalyst layer height was 150 mm, the catalyst amount was 2.5 kg, the raw material gas (coal dry distillation gas) / catalyst volume ratio was the same as in Example 1, and the drive device had the following conditions: : 20mm
・ Drive device ascending speed: 2 mm / sec ・ Drive device descending speed: 10 mm / sec, and the operation timing is 1st and 2nd, respectively, 3 hours and 5 hours after the start of aeration of coal dry distillation gas The test was carried out in the same manner as in Example 1 except that the lifting and lowering were performed two reciprocations each.

(result)
The test results were as follows.
・ Breathability (pressure loss)
Immediately after the start of ventilation: 0.1 kPa
During the first lift: 4 kPa (immediately before) → 0.25 kPa (immediately after)
During the second lift: 4 kPa (immediately before) → 0.6 kPa (immediately after)
As described above, recovery of air permeability by raising and lowering the catalyst layer was observed.

・ Reforming characteristics (hydrogen amplification rate = hydrogen flow rate in reformed gas / hydrogen flow rate in feed gas)
Immediately after the start of ventilation: 3.3
During the first lift: 2.4 (immediately before) → 2.8 (immediately after)
During the 2nd lift: 1.4 (immediately before) → 2.0 (immediately after)
As described above, in this example having a catalyst layer aspect ratio of 1.25 (less than 2), recovery of the catalyst reforming performance was recognized by the lifting operation. This can be said to be the effect that the whole catalyst of the catalyst layer could be stirred.

  After the test, 70 g of solid carbon was deposited on the cage bottom plate, but only a thin solid carbon film was formed on the cage surface, and there was no adhesion of bulk solid carbon to the pins. The airflow resistance of the cage was the same as when installed.

[Reference Example 1]
To the one prepared by precisely weighing nickel nitrate, cerium nitrate, zirconium nitrate oxide and magnesium nitrate so that the molar ratio of each metal element is 1: 1: 1: 7, and preparing a mixed aqueous solution by heating at 60 ° C., A potassium carbonate aqueous solution heated to 60 ° C. was added to coprecipitate nickel, cerium, zirconium, and magnesium as hydroxides, and the mixture was sufficiently stirred with a stirrer.

Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C. The precipitate obtained after washing is dried at 120 ° C and coarsely pulverized, then the material calcined at 600 ° C in the air is crushed and then placed in a beaker, mixed with alumina sol and thoroughly mixed in a mixer equipped with stirring blades The product was transferred to a flask made of eggplant, attached to a rotary evaporator, and sucked with stirring to evaporate water. The nickel, magnesium, and alumina compounds attached to the flask wall are transferred to an evaporating dish, dried at 120 ° C, calcined at 600 ° C, and then pressed into 3mmφ tablets using a compression molding machine. Got the body. The molded body was fired in air at 950 ° C. to prepare a catalyst molded body in which 50% by mass of alumina was mixed with Ni _0.1 Ce _0.1 Zr _0.1 Mg _0.7 O.

As a result of confirming the component of the molded body by ICP analysis, it was confirmed to be a desired component. As a result of this preparation was subjected to XRD measurement, NiMgO, proved to consist of _{MgAl 2 O 4, Ce x Zr} 1-x O 2 phases, the size of each crystallite, 14 nm, 11 nm, 22 nm met It was.

  This catalyst was fixed with quartz wool so as to be located at the center of the reaction tube made of SUS, a thermocouple was inserted at the center position of the catalyst layer, and these fixed bed reaction tubes were set at predetermined positions.

Before starting the reforming reaction, the reaction vessel was first heated to 800 ° C. in a nitrogen atmosphere, and then reduced for 30 minutes while flowing hydrogen gas at 100 mL / min. Then, a simulated gas (hydrogen: nitrogen = 1: 1, containing 2000 ppm of H ₂ S, total flow rate 125 mL / min) of coke oven gas (crude gas) is prepared and introduced into the reaction vessel, and tar generated during coal dry distillation As a representative substance, 1-methylnaphthalene, which is a liquid substance that is actually contained in tar and has a low viscosity at room temperature, is introduced into a reaction vessel at a flow rate of 0.025 g / min as a representative substance, and reacted under normal pressure. I let you.

  As a result of collecting and observing the catalyst after the test was completed, a large amount of bulk carbon was deposited between the catalysts. As a result of sieving the catalyst and the deposit, most of the bulk solid carbon on the catalyst surface was detached from the catalyst surface by several slight vibrations and dropped through the sieve eyes.

  Therefore, when this catalyst was used, it turned out that most of the solid carbon deposited between the catalysts passes between the catalysts and falls with slight catalyst stirring. From this result, it is considered that, in the reforming reaction using the present catalyst, if the apparatus of Example 1 or 2 is used, the adhesion / clogging of the product at the catalyst layer holding part can be largely avoided.

[Reference Example 2]
A potassium carbonate aqueous solution heated to 60 ° C. was prepared by accurately weighing the atomic weight% of nickel, magnesium and sodium to 10%, 80% and 10%, respectively, and preparing a mixed aqueous solution by heating at 60 ° C. Was added, nickel, magnesium and sodium were coprecipitated as hydroxides and stirred well with a stirrer. Thereafter, the mixture was aged for a certain period of time while being kept at 60 ° C., and then subjected to suction filtration and sufficiently washed with pure water at 80 ° C.

The precipitate obtained after washing is dried at 120 ° C. and coarsely pulverized, and then baked (calcinated) at 600 ° C. in the air, and then pulverized into a 3 mmφ tablet using a compression molding machine. Press molding was performed to obtain a tablet molding. The molded body was fired in air at 950 ° C. to prepare a Ni _0.1 M _0.1 Mg _0.8 O catalyst molded body.

  This catalyst was fixed with quartz wool so as to be located at the center of the reaction tube made of SUS, a thermocouple was inserted at the center position of the catalyst layer, and these fixed bed reaction tubes were set at predetermined positions.

Before starting the reforming reaction, the temperature of the reaction vessel was raised to 800 ° C. in a nitrogen atmosphere, and then reduction treatment was performed for 30 minutes while flowing hydrogen gas at 100 mL / min. Then, a simulated gas (hydrogen: nitrogen = 1: 1, containing 2000 ppm of H ₂ S, total flow rate 125 mL / min) of coke oven gas (crude gas) is prepared and introduced into the reaction vessel, and tar generated during coal dry distillation As a representative substance, 1-methylnaphthalene, which is a liquid substance that is actually contained in tar and has a low viscosity at room temperature, is introduced into a reaction vessel at a flow rate of 0.025 g / min as a representative substance, and the reaction is performed under normal pressure. I let you.

  As a result of collecting and observing the catalyst after the test was completed, a large amount of bulk carbon was deposited between the catalysts. As a result of sieving the catalyst and the product, most of the bulk solid carbon on the catalyst surface was detached from the catalyst surface by several vibrations and dropped through the sieve mesh.

  Therefore, when this catalyst was used, it turned out that most of the solid carbon deposited between the catalysts passes between the catalysts and falls with slight catalyst stirring. From this result, it is considered that, in the reforming reaction using the present catalyst, if the apparatus of Example 1 or 2 is used, the adhesion / clogging of the product at the catalyst layer holding part can be largely avoided.

DESCRIPTION OF SYMBOLS 10 Continuous type fixed bed catalyst reaction apparatus 11 Reaction container 12, 12 'Catalyst holder 13 Catalyst layer 14 Raw material gas 15 Reformed gas 16 Raw material gas inflow path 17 Reformed gas outflow path 18 Bar 19 Fixing device 20 Drive mechanism 21 Lifting device 22 Conduction shaft 25 pin 26 Bottom plate

Claims (9)

A source gas inflow path and a reformed gas outflow path for catalytic reaction;
A catalytic reaction vessel connected to the inflow path and the outflow path, and in contact with the inner wall of the reaction container, the catalytic reaction container containing the catalyst layer of the bulk catalyst;
A catalyst holder that has air permeability that allows fluid to pass through and that holds the catalyst layer;
A continuous fixed bed catalyst reaction apparatus having a drive mechanism for raising and lowering the catalyst layer by raising and lowering the catalyst holder ,
A continuous fixed bed catalytic reactor characterized in that the raw material gas is a gas containing hydrocarbon, and the product of catalytic reaction is a gas and solid hydrocarbon or solid carbon .   The height of the catalyst layer is not more than twice the thickness of the catalyst reaction vessel and not less than three times the maximum value of the representative length of the bulk catalyst outer surface. Continuous fixed bed catalytic reactor.   The continuous fixed-bed catalytic reactor according to claim 1 or 2, wherein a speed when the drive mechanism is lowered is faster than a speed when the drive mechanism is raised. As the catalyst holder, a catalyst holder having a structure in which the bulk catalyst is held at a tip portion of pins arranged substantially in parallel and the source gas can flow through the space between the pins is used. The continuous fixed bed catalytic reactor according to any one of claims 1 to 3. The continuous fixed bed catalytic reactor according to any one of claims 1 to 4, wherein the raw material gas is a gas containing tar. The catalyst is a composite oxide containing nickel, magnesium, cerium, and aluminum, and is a composite oxide not containing alumina. The composite oxide is a crystal of NiMgO, MgAl ₂ O ₄ , or CeO ₂ . The continuous fixed bed catalytic reactor according to claim 5 , comprising a phase. Wherein the catalyst is a catalyst comprising a composite oxide containing nickel, magnesium, cerium, zirconium, aluminum, the complex _{oxide, NiMgO, MgAl 2 O 4,} Ce x Zr 1-x O 2 (0 <x < The continuous fixed bed catalytic reactor according to claim 5 , comprising the crystal phase of 1). The catalyst is
A tar-containing gas reforming catalyst which is a composite oxide represented by aM · bNi · cMg · dO,
a, b, and c satisfy a + b + c = 1, 0.02 ≦ a ≦ 0.98, 0.01 ≦ b ≦ 0.97, and 0.01 ≦ c ≦ 0.97,
d is a value at which oxygen and positive elements are electrically neutral;
M is Ti, Zr, Ca, W, Mn, Zn, Sr, Ba, Ta, Co, Mo, Re, platinum, runium, palladium, rhodium, Li, Na, K, Fe, Cu, Cr, La, Pr , At least one element selected from Nd,
At least one oxide selected from silica, alumina, and zeolite is added to the composite oxide, and the content of the oxide selected from silica, alumina, and zeolite is 1 to 90% by mass with respect to the composite oxide. Is,
The continuous fixed bed catalytic reactor according to claim 5 , wherein A continuous fixed-bed catalytic reaction method, wherein the catalytic reaction is carried out using the continuous fixed-bed catalytic reactor according to any one of claims 1 to 8 .