JP2013169496A - Method for packing catalyst in fixed bed multitubular reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst packing method for packing reaction tubes equipped with temperature measuring units in a fixed bed multitubular reactor, with catalysts in consideration of variation in reaction activity, and exhibiting the whole performance of the catalysts to the maximum without causing a local temperature rise in the whole fixed bed multitubular reactor.SOLUTION: A catalyst packing method includes packing reaction tubes equipped with temperature measuring units, with catalysts having high reaction activity out of all catalysts to be packed in a fixed bed multitubular reactor when packing the reactor with solid catalysts.

Description

  The present invention relates to a catalyst filling method in a fixed bed multi-tubular reactor using a solid catalyst.

  International Publication No. 2005/005037 (Patent Document 1) accurately and practically measures the temperature distribution in the longitudinal direction of a reaction tube of a fixed bed multitubular reactor packed with a catalyst, It is disclosed that, by grasping the above, it is possible to stabilize the oxidation reaction and operate under optimum conditions.

  JP-A-10-309457 (Patent Document 2) describes the mass of solid particles introduced into a tubular reactor equipped with a temperature measuring unit and a tubular reactor equipped with no temperature measuring unit. When the gas flow through the tube is directly proportional to the free cross-sectional area of the tubular reactor and the flow resistance or pressure drop in the tubular reactor, and thus the average linear velocity is proportional to the free cross-sectional area, An apparatus and method for setting up as such is described.

  In Japanese Patent Laid-Open No. 3-176440 (Patent Document 3), a plurality of catalysts having different activities adjusted by varying the catalyst composition are charged so that the activity becomes higher from the raw material gas inlet side toward the outlet side. A method is disclosed.

  Japanese Patent Laid-Open No. 2002-212127 (Patent Document 4) discloses that isobutylene and / or tertiary butanol is subjected to gas phase catalytic oxidation with molecular oxygen in the presence of a solid oxidation catalyst in a fixed bed tubular reactor. In the method for producing methacrolein and methacrylic acid, there is no place in the catalyst layer where the difference between the temperature of the heat medium bath and the temperature of the catalyst layer exceeds 50 ° C., and the temperature difference is 15 to 50 ° C. A method of providing two or more high temperature regions is disclosed.

  Further, JP-A-8-92147 (Patent Document 5) describes the temperature of a heat medium bath when propylene is vapor-phase oxidized to acrolein using a multi-tubular fixed bed reactor equipped with a heat medium bath. Discloses a method of controlling the flow of the heating medium so that the temperature rises by 2 to 10 ° C. between the inlet and outlet of the reactor.

International Publication No. 2005/005037 Japanese Patent Laid-Open No. 10-309457 Japanese Patent Laid-Open No. 3-176440 JP 2002-212127 A JP-A-8-92147

  However, in reality, the reaction activity of all the catalysts packed in the fixed bed multitubular reactor is not the same, and there are not a few variations. Accordingly, the individual reaction tubes in the fixed bed multitubular reactor, which is composed of a large number of reaction tubes, are naturally filled with catalysts having different reaction activities. It is possible to determine whether the reaction tube equipped with the temperature measurement unit among the many reaction tubes built in is at an appropriate temperature or whether a local temperature rise (hot spot) has occurred. Although it is possible, it is not possible to determine what the temperature of the majority of reaction tubes without a temperature measuring unit is, and whether a local temperature rise has occurred. In the unlikely event that a local temperature rise occurs, the activity of the catalyst may be reduced, and furthermore, temperature control to maximize the performance of all the catalysts packed in the fixed bed multitubular reactor However, there is a fate that must be inadequate.

  Factors that may cause variations in the reaction activity of the solid catalyst packed in the fixed bed multi-tubular reactor include slight fluctuations in raw material quality, slight fluctuations in the mixing amount and mixing ratio of raw materials, catalyst precursor When the body is a slurry, a slight change in the mixing state, when the slurry is dried, a slight change in temperature, pressure, processing time, etc., when performing a baking, a slight change in temperature, processing time, etc. Is mentioned. In addition to this, it is rare that the entire amount of catalyst necessary for filling the reactor can be produced by a single production, and it is often produced by a plurality of productions, resulting in variations in the reaction activity of the catalyst. It is a factor.

In order to avoid these variations, it is possible to mix all the catalysts packed in the fixed bed multitubular reactor to make the reaction activity uniform. However, it is extremely difficult to actually mix the solid catalyst uniformly. I have to say that For example, when a solid catalyst having a bulk density of 1 g / cm ³ is charged into a fixed bed multitubular reactor composed of 50,000 reaction tubes having an inner diameter of 25 mm and a length of 5 m, the catalyst filling amount per reaction tube is about Although it is 2.5 kg, the total amount of catalyst charged in the reactor is about 123 tons, and it is currently impossible to uniformly mix 123 tons of catalyst.

  Since the activity of the catalyst charged in the fixed bed multi-tubular reactor is generally measured for each catalyst production lot for quality control, catalyst production operation management, performance standard pass / fail judgment, etc., Which catalyst has the highest or lowest reaction activity, which catalyst has an average reaction activity, and the reaction activity distribution of all lots is easily known.

  However, there has been no intention of what kind of reaction activity should be filled in a reaction tube equipped with a temperature measuring unit so far, and it is not always clear what kind of reaction activity is actually filled. It wasn't.

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to consider variation in reaction activity in a reaction tube equipped with a temperature measurement unit in a fixed-bed multitubular reactor. It is an object of the present invention to provide a catalyst filling method in which the catalyst is charged and the performance of the entire catalyst is maximized without causing a local temperature rise in the entire fixed bed multitubular reactor. In particular, it is a catalyst filling method that is very effective in a gas phase catalytic oxidation reaction involving a large exothermic reaction.

  In the present invention, when a solid catalyst is charged into a fixed bed multitubular reactor, among all the catalysts charged in the reactor, a catalyst having a high reaction activity (further, a catalyst having an average reaction activity). , And / or a catalyst having a low reaction activity) is packed in a reaction tube equipped with a temperature measuring unit of each catalyst layer, and by measuring these temperatures, all the catalyst layers filled in the reactor are measured. The present invention relates to a catalyst filling method that optimizes the temperature and prevents the occurrence of local temperature rise and maximizes the catalyst performance. That is, the present invention is as follows.

  In the catalyst filling method of the present invention, when a fixed bed multitubular reactor is filled with a solid catalyst, a temperature measuring unit is provided with a catalyst having a high reaction activity among all the catalysts charged in the reactor. The reaction tube is filled.

  In the catalyst charging method of the present invention, when a solid catalyst is charged into a fixed bed multitubular reactor, a temperature measuring unit is provided with a catalyst having an average reaction activity among all the catalysts charged in the reactor. It is preferable to fill the reaction tube.

  In the catalyst filling method of the present invention, when a solid catalyst is filled in a fixed bed multitubular reactor, a temperature measuring unit is provided with a catalyst having a low reaction activity among all the catalysts charged in the reactor. It is preferable to fill the reaction tube.

  In the catalyst filling method of the present invention, the fixed bed multitubular reactor filled with the catalyst is preferably applied to an exothermic reaction, and the exothermic reaction is more preferably a gas phase catalytic oxidation reaction, and the gas phase The catalytic oxidation reaction is particularly preferably a reaction for producing chlorine from a hydrogen chloride gas and a gas containing oxygen.

  According to the present invention, in a fixed bed multitubular reactor filled with a solid catalyst, among all the catalysts charged in the reactor, a catalyst having a high reaction activity (further, a catalyst having an average reaction activity). , And / or a catalyst having a low reaction activity) is filled in a reaction tube equipped with a temperature measuring unit of each catalyst layer, and by measuring these temperatures, all the reaction tubes filled in a large number of reaction tubes are measured. Provided is a catalyst filling method capable of generating a local temperature rise in a catalyst layer and maximizing the catalyst performance of the entire reactor.

  In the catalyst filling method of the present invention, when a fixed bed multitubular reactor is filled with a solid catalyst, a temperature measuring unit is provided with a catalyst having a high reaction activity among all the catalysts charged in the reactor. Fill the reaction tube. In this way, by controlling the peak temperature of the catalyst layer, the maximum effect is exhibited in preventing the occurrence of local temperature rise in the majority of reaction tubes not equipped with a temperature measurement unit. . As the catalyst having a high reaction activity, a catalyst having a reaction activity of 90% or more in the distribution of the reaction activity number per mass or volume of the total catalyst charged in the fixed bed multitubular reactor is suitable.

  In the catalyst filling method of the present invention, the reaction tube provided with the temperature measurement unit other than the reaction tube provided with the temperature measurement unit filled with the catalyst having a high reaction activity among all the above-described catalysts is further averaged. It is preferable to charge a catalyst having a typical reaction activity. By measuring the peak temperature of the catalyst layer and the temperature distribution of the catalyst layer in the longitudinal direction of the reaction tube, the proportion of the catalyst having the average reaction activity with respect to the total catalyst amount is the highest. It is most effective in maximizing performance such as overall reaction rate and selectivity. As a catalyst having an average reaction activity, a catalyst having a reaction activity of 50 ± 10% in the distribution of reaction activity numbers of all catalysts is suitable.

  In the catalyst filling method of the present invention, the reaction tube equipped with a temperature measurement unit other than the reaction tube equipped with the temperature measurement unit filled with a catalyst having a high reaction activity among all the catalysts described above is low in the reaction tube. It is preferable to charge a catalyst having reaction activity. As a result, components of the raw material gas or reaction product gas are selectively adsorbed by the high-boiling substances on the catalyst having a low catalyst layer temperature, causing reaction inhibition and suddenly decreasing or blocking the reaction activity. The effect of preventing is exhibited. As the catalyst having a low reaction activity, a catalyst having a reaction activity of 10% or less in the reaction activity number distribution of all the catalysts is suitable.

  In the catalyst filling method of the present invention, a reaction tube equipped with at least two temperature measurement units has a catalyst having a high reaction activity among all the catalysts and a low reaction activity among all the catalysts. You may make it each fill with a catalyst. In addition, a reaction tube equipped with at least three temperature measuring units has a high reaction activity among all the catalysts, a catalyst with an average reaction activity, and a low reaction activity among all the catalysts. Each catalyst may be filled, and this embodiment is most preferred.

  The “fixed-bed multitubular reactor” to which the present invention is applied is a system having at least three reaction tubes and removing heat of reaction from the outside of the reaction tubes. There are no particular restrictions on the inner diameter, outer diameter, length, material, reaction heat removal equipment, and reaction heat removal method. As a medium for removing reaction heat, a heat medium such as Dowsum may be used, or a molten salt composed of potassium nitrate, sodium nitrite, etc., or boiler water may be supplied to generate steam. Also good.

  If the solid catalyst to which the present invention is applied is a catalyst that maintains a solid state before and after the reaction and during the reaction, there is no limitation on the shape, particle size, particle length, and the like. Naturally, a catalyst suitable for the target reaction is applied.

  For example, in the production of acrylic acid by vapor-phase catalytic oxidation of propylene, as a catalyst for synthesizing acrolein from the first stage propylene, a molybdenum-bismuth multi-way catalyst and acrylic acid from the second stage acrolein are synthesized. As the catalyst, a molybdenum-vanadium multi-way catalyst is generally used.

  In the production of methacrylic acid by gas phase catalytic oxidation of isobutylene or tertiary butanol, molybdenum-bismuth multi-component composite oxide catalyst as the catalyst for synthesizing methacrolein from the first stage isobutylene or tertiary butanol, the second stage As a catalyst for synthesizing methacrylic acid from methacrolein, a phosphorus-molybdenum heteropolyacid catalyst is used.

  In the production of chlorine by the gas phase catalytic oxidation reaction of hydrogen chloride, a ruthenium oxide catalyst, a chromium oxide catalyst, or the like is used.

  As a unit for measuring the temperature of the catalyst layer filled in the reaction tube or the temperature distribution in the longitudinal direction of the reaction tube, the apparatus and method described in JP-A-10-309457, which is a conventional technique, and JP-A No. 2002-212127 are disclosed. The method described in the publication, the method described in International Publication No. 2005/005037, and the like can be applied, and there is no particular limitation.

  The raw material supplied to the fixed bed multitubular reactor may be supplied from the upper part of the reactor or from the lower part.

  In general, the raw material is often heated or cooled to a temperature suitable for the reaction before being supplied to the reactor, but the present invention can be applied regardless of the presence or absence of heating and cooling.

  The operation pressure of the fixed bed multitubular reactor is not particularly limited as long as it is operated at a pressure suitable for the reaction.

  The fixed bed multitubular reactor filled with the catalyst obtained by the catalyst filling method of the present invention is preferably applied to an exothermic reaction, and the exothermic reaction is more preferably a gas phase catalytic oxidation reaction. In the case of the gas phase catalytic oxidation reaction, oxygen or air can be used as the oxygen source to be used. The molar ratio, flow rate, temperature, and pressure of the reaction raw materials also vary depending on the target reaction and the catalyst used, but are not particularly limited.

  The inside of the shell of the multi-tube heat exchange reactor described in JP 2005-306734 A relating to a chlorine production reactor and a chlorine production method is divided into a plurality of regions by partition plates in the tube axis direction, It is also possible to apply a temperature control means for the heat medium that circulates in this region, and to fill the catalyst with different catalyst activities in layers from the inlet to the outlet of the reaction tube of the reactor.

  In general, the heat of reaction per unit time in the gas phase catalytic oxidation reaction is large near the inlet of the catalyst layer having a high raw material concentration. Therefore, the present invention can be applied even when the catalyst at the inlet is diluted with inert particles and packed. Is possible.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited by this Example.

(Catalyst adjustment)
Titanium oxide (STR-60R manufactured by Sakai Chemical Co., Ltd., 100% rutile type) and α-alumina (AES-12 manufactured by Sumitomo Chemical Co., Ltd.) were mixed at a mass ratio of 34:66, respectively, and then purified water And kneaded. This mixture was extruded into a cylindrical shape having a diameter of 3.0 mm and cut to a length of about 5 mm to obtain a molded body. This molded body was calcined in air at 800 ° C. for 3 hours to obtain a carrier made of a mixture of titanium oxide and α-alumina. The mass of ruthenium chloride is obtained in advance so that 2% by mass of ruthenium oxide is supported on the carrier, and pure water is added to the mass of ruthenium chloride to mix and dissolve, and then the ruthenium chloride aqueous solution is subjected to a pore filling method. After impregnating the support, drying, and calcining in air at 250 ° C. for 2 hours, the hydrogen chloride oxidation catalyst Lot. 1 was obtained. Lot. 1 and the same catalyst preparation method was repeated. 2-32 catalysts were obtained.

(Measurement of hydrogen chloride oxidation reaction activity of each Lot catalyst)
Lot. 1 catalyst (1.0 g) was diluted with 12 g of α-alumina sphere having a diameter of 2 mm (SSA995 manufactured by Nikkato Co., Ltd.), and a reaction tube made of Ni having an inner diameter of 14 mm (outer diameter of 3.8 mm with a sheath tube for measuring the catalyst layer temperature) Then, a thermocouple is inserted in the sheath tube), and 12 g of α-alumina spheres having a diameter of 2 mm manufactured by Nikkato Co., Ltd. are filled in the upper part of the catalyst layer to form a raw material gas preheating layer.

  This reaction tube itself is immersed in a molten salt bath (mixture of calcium nitrate and sodium nitrite) equipped with an electric heater, and hydrogen chloride gas 0.214 mol / h and oxygen gas 0.107 mol / h are sufficiently premixed. It was supplied from the upper part of the reaction tube. The temperature of the molten salt was controlled so that the temperature of the catalyst layer was 282 ° C.

  When 1.5 hours had elapsed after the start of the reaction, the reaction gas at the outlet of the reaction tube was started to flow in a 30 wt% aqueous potassium iodide solution and sampled for 20 minutes. The chlorine production amount of this sampling solution was measured by the iodine titration method, the chlorine production rate (mol / h) was determined, and the hydrogen chloride oxidation reaction activity was calculated from the following formula.

Hydrogen chloride oxidation reaction activity (% / g-catalyst) = [chlorine production rate (mol / h) × 2 / [hydrogen chloride supply rate (mol / h)] × 100
Lot. 1 in the same manner as in Lot. 2-Lot. Table 1 shows the results of measuring the hydrogen chloride oxidation reaction activity of 32.

<Example>
Three Ni reaction tubes with an inner diameter of 25 mm, an outer diameter of 27 mm, and a length of 5.7 m (each reaction tube is inserted with a 6 mm outer shell for temperature measurement) and molten salt (potassium nitrate / sodium nitrite = The temperature of the molten salt was controlled to be a constant value with an electric heater, using a fixed bed multitubular reactor equipped with a jacket having a heat ratio of 1/1 mass ratio).

  In these three reaction tubes, Lot. 26 catalyst having the highest reaction activity, Lot. 17 catalysts, Lot. With the lowest reaction activity. Each of 5 catalysts was charged. After filling the catalyst, air was flowed at a predetermined flow rate from the lower part of the reactor, and the pressure loss of each reaction tube was measured, and it was confirmed that they were almost the same.

  After adjusting the molten salt temperature at the start of the reaction to 290 ° C., a mixed gas of hydrogen chloride gas 0.79 mol / min and oxygen gas 0.42 mol / min heated to 260 ° C. was introduced from the upper part of the reactor. The inlet pressure of the reactor was adjusted to 0.5 MPaG. After starting the reaction, the thermocouple attached to the temperature measurement sheath tube was moved to measure the peak temperature of the catalyst layer of each reaction tube.

  The same operation was performed with each lot of new catalyst under the conditions of 300, 310, and 320 ° C. molten salt temperatures at the start of the reaction.

  In addition, it has been confirmed in advance that this hydrogen chloride oxidation catalyst increases the rate of decrease in reaction activity when it exceeds 450 ° C.

  Table 2 shows the measurement results of the molten salt temperature at the start of the reaction and the peak temperature of each reaction active catalyst layer.

  From Table 2, when the molten salt temperature at the start of the reaction is 310 ° C., the peak temperature of the catalyst layer of the high reaction active catalyst reaches 530 ° C., but the average reaction active catalyst and the low reaction active catalyst The peak temperatures were 415 ° C. and 374 ° C., respectively. Furthermore, when the molten salt temperature at the start of the reaction is set to 320 ° C., the peak temperature of the catalyst layer is 550 ° C. or higher for both the catalyst having high reaction activity and the average reaction active catalyst. The peak temperature of was 429 ° C.

  Therefore, the Lot. 1-Lot. When all 32 catalysts are packed in a fixed bed multi-tubular reactor, it is necessary that the molten salt temperature at the start of the reaction be at least about 300 ° C. or less. 26 was filled into a reaction tube equipped with a temperature measuring unit.

Claims (6)

  When filling a fixed bed multitubular reactor with a solid catalyst, a catalyst having a high reaction activity among all the catalysts charged in the reactor is filled in a reaction tube equipped with a temperature measuring unit. And a catalyst filling method.   When filling a fixed bed multitubular reactor with a solid catalyst, a catalyst having an average reaction activity among all the catalysts charged in the reactor is charged into a reaction tube equipped with a temperature measuring unit. The method of claim 1, wherein:   When filling a fixed bed multitubular reactor with a solid catalyst, a catalyst having a low reaction activity among all the catalysts charged in the reactor is filled in a reaction tube equipped with a temperature measuring unit. The method according to claim 1 or 2.   4. The process according to claim 1, wherein a fixed bed multitubular reactor filled with a catalyst is applied to an exothermic reaction.   The method according to claim 4, wherein the exothermic reaction is a gas phase catalytic oxidation reaction.   6. The method according to claim 5, wherein the gas phase catalytic oxidation reaction is applied to a reaction for producing chlorine from a gas containing hydrogen chloride gas and oxygen.