JP2016170117A - Catalyst life prediction method and catalyst life analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst life prediction method and a catalyst life analyzer for analyzing catalytic performance at each position and predicting catalyst life, even when deterioration in catalytic performance is not uniform and varies with each position in the catalyst layer, like a chemical reaction process using a catalyst comprising a fixed bed circulation type catalytic reaction tower.SOLUTION: Provided are a catalyst life prediction method and a catalyst life analyzer that, in a chemical reaction process using a catalyst comprising a fixed bed circulation type reaction tower, calculate change in catalytic performance as a change amount of activation energy on the basis of a total amount of a target product within a use period of a catalyst, and that analyze temporal change of the catalytic performance from the change amount of the activation energy in order to predict catalyst life.SELECTED DRAWING: Figure 1

Description

  In the present invention, in a chemical reaction process using a catalyst, a change in catalyst performance is calculated as a change in activation energy based on the total amount of target products within the catalyst use period, and a change in catalyst performance with time is analyzed. The present invention relates to a catalyst life prediction method and a catalyst life analyzer that can predict the catalyst life.

  Among the methods for producing vinyl chloride monomer (VCM), a method called a balanced oxychlorination process, that is, (1) production of 1,2-dichloroethane (EDC) by direct chlorination of ethylene, (2) A process comprising VCM production by EDC thermal decomposition reaction and (3) EDC production by ethylene oxychlorination reaction is widely adopted in the petrochemical industry.

  Among these, the method for producing EDC by the oxychlorination reaction of ethylene is a chemical reaction process using a catalyst using a catalyst, an air method using air as an oxygen raw material used for the reaction, and using a small amount of molecular oxygen for air. An oxygen enrichment method and an oxygen method using molecular oxygen as an oxygen source are known.

  In general, the performance (activity) of a catalyst decreases with time. Therefore, in a chemical reaction process using a catalyst consisting of a fixed bed flow type reaction tower, it is necessary to replace the catalyst by judging that the stage where the activity of the catalyst has been reduced to a necessary minimum level is the catalyst life.

  Usually, the catalyst replacement time is determined in advance, and the production is continued with the catalyst whose performance has deteriorated without performing the catalyst replacement during the planned production period. This is because unplanned catalyst replacement is very costly and labor-intensive for replacement work, and the loss due to production cuts while the equipment is stopped. Therefore, the catalyst life is estimated in advance, the next replacement period is planned, and the production plan is made so that the catalyst activity does not decrease to the minimum necessary level and the maximum catalyst performance is exhibited until that time. Establishing is an important technical issue.

It is disclosed that a simulation technique is used for this problem.
For example, a simulation method for hydrodesulfurization reaction is disclosed (see Patent Document 1). However, in this method, since a factor is experimentally determined for the deterioration of the catalyst, the life of the catalyst cannot be predicted with high accuracy when the operating conditions change.

  Also, a reformer simulator is disclosed (see Patent Document 2). This method is a simulator that takes into account the deterioration of the life of the catalyst, but this simulator is for training the operator and does not predict the actual operating state of the apparatus.

  A method by simulation is disclosed for the purification process (Patent Documents 3 to 4). This method is a method for optimizing the purification conditions by paying attention to the deterioration phenomenon of the catalyst due to the deposition of carbon and metal in the catalyst pores in the hydrorefining reaction. However, it is not effective at all for reactions where the volume of carbonaceous and metal is not responsible for catalyst degradation.

  Since the oxychlorination catalyst reaction is an exothermic reaction, the temperature of the catalyst layer increases with the generation of heat, and a rapid decrease in catalyst performance occurs particularly at hot spots where the temperature has increased.

  As a method of analyzing thermal degradation, a method by simulation is disclosed for an exhaust gas purification catalyst of an automobile (Patent Documents 5 to 6). In order to analyze the thermal deterioration of the catalyst, these are methods in which the time during which the catalyst is exposed to a high temperature and the degree of deterioration are correlated in advance and analyzed as the deterioration rate of the catalyst. The deterioration rate obtained by this method is an average value obtained by collectively analyzing the decrease in the overall catalyst performance from the inlet to the outlet.

  In a fixed bed flow reaction tower such as a chemical reaction process using an oxychlorination catalyst, temperature distribution is generated in the catalyst layer due to heat generation from the reaction bed inlet to the outlet, which is not uniform. Therefore, the performance degradation of the catalyst is not uniform from the inlet to the outlet. Using such a catalyst whose performance deterioration varies depending on the position of the catalyst layer and optimizing the production by performing simulation technology to optimize the operating conditions cannot meet the requirement at all with the information on the average value of the catalyst performance.

  Like the chemical reaction process using a catalyst consisting of a fixed bed flow-type reaction tower, the performance of the catalyst at each position can be analyzed accurately and produced even when the catalyst performance declines at the position of the catalyst layer. There is a demand for a catalyst life prediction method and a catalyst life analysis apparatus that can optimize operating conditions according to a plan.

US Pat. No. 5,341,313 Japanese Examined Patent Publication No. 7-108372 Japanese Patent No. 3,931,083 Japanese Patent No. 4,612,006 Japanese Patent No. 3,135,499 Japanese Patent No. 4,747,984

  Even if the catalyst performance degradation is not uniform at the position of the catalyst layer and varies from position to position, as in the case of chemical reaction processes using a catalyst consisting of a fixed bed flow reaction tower, the catalyst performance at each position is analyzed. Predict the catalyst life, plan the next replacement time, and operate according to the production plan so that the catalyst activity does not decrease to the minimum necessary level until the replacement time is reached and the maximum catalyst performance is exhibited. The present invention provides a catalyst life prediction method and a catalyst life analysis apparatus capable of optimizing conditions.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors activated changes in catalyst performance based on the total amount of target products within the catalyst use period in a chemical reaction process using a catalyst. The present inventors have found a catalyst life prediction method and a catalyst life analysis apparatus that can calculate the amount of change in energy and analyze the change in catalyst performance over time from the amount of change in activation energy to predict the catalyst life, thereby completing the present invention. .

  That is, according to the present invention, in a chemical reaction process using a catalyst, a change in the catalyst performance is calculated as a change amount of the activation energy based on the total amount of the target product within the catalyst use period, and the change amount of the activation energy is calculated. The present invention relates to a catalyst life prediction method and a catalyst life analysis apparatus that can predict a catalyst life by analyzing changes in catalyst performance over time.

  Hereinafter, the present invention will be described in detail.

  The catalyst life prediction method and the catalyst life analysis apparatus according to the present invention are used in a chemical reaction process using a catalyst comprising a fixed bed flow type reaction tower, and a change in activation energy based on the total amount of the target product within the catalyst use period. A method for predicting catalyst life and a catalyst life analyzer by calculating the amount of catalyst, analyzing the change in catalyst performance with time from the amount of change in the activation energy, and predicting the catalyst layer temperature from the change in catalyst performance with time It is characterized by.

  The present inventor has organized the catalyst performance degradation phenomenon based on the reaction kinetics, and found that the performance degradation is caused by a change in activation energy. That is, when the activation energy of the catalyst having different use periods was measured separately for each position of the reaction tube, a change as shown in FIG. 1 was confirmed. This is a change based on the change over time of the catalyst, and the change was modeled. Based on this model, the amount of change in activation energy is calculated based on the total amount of the target product within the catalyst use period, and the amount of change in activation energy is arranged based on the reaction kinetics, thereby obtaining a catalyst. Changes in performance over time can be analyzed. Since the amount of change in the obtained activation energy is not uniform at the position of the catalyst layer and can be calculated with a different value for each position, it is possible to analyze the change in the catalyst performance with time for each position.

The amount of change ΔEa of the activation energy is the total amount of the target product within the period of use of the catalyst, W is a constant indicating the degree of deterioration of the catalyst, and the reaction tube is filled with the catalyst in the reaction tower. Equation (1) as a function of L and W, where L _{0 is} the length to the outlet and L is the position from the inlet of the reaction tube;
ΔEa (L, W) = KW ⁿ × (L−L ₀ ) (1)
(Where n is greater than 0 and less than 1)
It is represented by KW ^{n in} equation (1) is a value corresponding to the slope of a straight line having the slope of FIG.

As shown in FIG. 1, assuming that the slope is expressed as a function of W, Procedure 1: The start point M advances in the L direction on the unused Ea line (dashed line in FIG. 1) along with the start of use of the catalyst. A straight line is drawn in the direction. Procedure 2: ΔEa rises from the entrance to M, and ΔEa is obtained from Equation (1), assuming that ΔEa remains unchanged (ie, ΔEa = 0) from M to the exit. By examining the relationship between the obtained inclination and W, the change of the inclination with respect to W can be given as a function. When the slope is plotted as shown in FIG. 2 to obtain the relationship with W, it can be approximated to KW ⁿ , where n is greater than 0 and less than 1, and n in the example shown in FIG. 2 is 0.5. It was. The movement of M can be expressed by a function having W as a variable. When D is a constant, it can be approximated to DW ^m , where m is 0 to 1.

When analyzing the change in the catalyst performance with time using the change amount of the activation energy, a reaction rate constant according to the Arrhenius equation can be generally used. Assuming that the reaction rate constant after the period of use is k, the frequency factor is A, the initial activation energy is Ea ₀ , the gas constant is R, and the catalyst layer temperature is T (L, W), it is a function of L and W. Formula (2);
k (L, W) = Aexp (− (Ea ₀ + ΔEa (L, W)) / RT (L, W)) (2)
It is represented by

It can be analyzed the time course of catalyst performance by comparing with the reaction rate constant k and the initial reaction rate constant k _0.

  In the catalyst layer at the inlet of the reaction tube, when the reaction raw material generates a reaction product at the calculated reaction rate, reaction heat is generated according to the reaction amount. This reaction heat is removed from the reaction tube, or moves to the next catalyst layer together with the flowing gas. The temperature of the next catalyst layer is determined by this heat balance and mass balance, and the reaction rate can be calculated. Therefore, by repeating this, it is possible to display the change in the catalyst performance with time as the catalyst layer temperature distribution from the inlet to the outlet of the reaction tube.

  Furthermore, the distribution of the catalyst layer temperature predicted by calculating taking into account the change in operating conditions and the future change in catalyst performance can be used for judgment of life prediction.

  The catalyst life analysis apparatus using the catalyst life prediction method that analyzes the change in the catalyst performance with time from the amount of change in the activation energy and predicts the catalyst life is as follows. Means for integrating the total amount, catalyst layer temperature detecting means for detecting the catalyst layer temperature when the catalyst is used, and the amount of change in the catalyst performance based on the total production amount of the target product within the catalyst use period. An arithmetic means for calculating the amount of change and an arithmetic means for predicting the catalyst layer temperature are provided. Furthermore, a means for inputting information necessary for the analysis, a means for outputting the analysis result, and a means for recording the analysis result may be provided.

  Hereinafter, in a chemical reaction process using a catalyst consisting of a fixed-bed flow reaction tower, the amount of change in catalyst performance is activated based on the total amount of target products within the catalyst use period and the catalyst layer temperature after the use period has elapsed. The means constituting the catalyst life analysis device using the catalyst life prediction method that calculates the change in energy and analyzes the change in the catalyst performance with time from the change in the activation energy to predict the catalyst life Will be described.

  The catalyst layer temperature detection means for detecting the catalyst layer temperature when the catalyst is used is an apparatus for measuring the temperature of the catalyst layer installed in the fixed bed flow type reaction tower. The measured temperature of the catalyst layer is recorded for each position of the catalyst layer and every elapsed time.

  The means for measuring the total amount of the target product within the period of use of the catalyst is an apparatus for determining by analyzing the amount of product flowing out from the outlet of the fixed bed flow type reaction tower. By recording the measured product amount every unit time and integrating the product amount within the use period, the total amount of the target product within the use period can be obtained.

  The calculation means for calculating the change amount of the catalyst performance as the change amount of the activation energy based on the total production amount of the target product within the catalyst use period measures the total amount of the target product within the use period. A calculation unit that calculates the change amount of the activation energy based on the total amount of the target product measured by the means, and a calculation unit that analyzes the change in the catalyst performance with time from the change amount of the activation energy.

  The means for inputting information necessary for analyzing the change in the catalyst performance with time is an operating condition for controlling the fixed-bed flow reaction tower used for the calculation to the calculation means for calculating the change amount of the activation energy, It is an apparatus for inputting information on the temperature of the catalyst layer during operation, the total amount of the target product within the period of use, and the physical properties and properties of the catalyst.

  The amount of change in activation energy is calculated by a calculation unit that calculates the amount of change in activation energy based on the total amount of the target product measured by a device that measures the total amount of the target product within the period of use. It calculates for every position of a catalyst layer using Formula (1). The change rate of the catalyst performance at each position of the catalyst layer from the change amount of the activation energy at each position of the catalyst layer calculated by the arithmetic unit that analyzes the change of the catalyst performance with time from the change amount of the activation energy. Analysis is performed using the constant equation (2).

  In the catalyst layer at the inlet of the reaction tube, when the reaction raw material generates a reaction product at the calculated reaction rate, reaction heat is generated according to the reaction amount. This reaction heat is removed from the reaction tube, or moves to the next catalyst layer together with the flowing gas. The temperature of the next catalyst layer is determined by this heat balance and mass balance, and the reaction rate can be calculated. By repeating this, the change in the catalyst performance with time can be displayed as the distribution of the catalyst layer temperature from the inlet to the outlet of the reaction tube.

  In the calculation unit that predicts the catalyst layer temperature from the change in catalyst performance over time, the calculation that analyzes the change in catalyst performance over time from the amount of change in activation energy calculated taking into account changes in operating conditions and future changes in catalyst performance The temperature of the catalyst layer is predicted by calculating according to the heat balance and the mass balance using the reaction rate constant calculated by the apparatus according to the Arrhenius equation. From the predicted distribution of the catalyst layer temperature, it is possible to analyze the influence on the reaction tower due to a decrease in catalyst performance. A catalyst life prediction method for predicting the catalyst life by comparing the predicted value of the calculated catalyst layer temperature with the actual temperature measured at a later date by the catalyst layer temperature detecting means for detecting the catalyst layer temperature when the catalyst is used. And the accuracy of the catalyst life analysis apparatus using this prediction method can be known.

  From the above, in this catalyst life prediction method and the catalyst life analysis apparatus using this prediction method, the activity of the catalyst does not decrease to the necessary minimum level until the planned replacement time is reached, and the maximum catalyst is obtained. Future search of catalyst bed temperature can be made to search for and optimize operating conditions that demonstrate performance.

  Search for possible operating conditions for the reaction tower, predict the catalyst layer temperature in the future, and if it is judged that the production amount according to the production plan cannot be obtained, reset the operating conditions and reset the catalyst. The information necessary for analyzing the change with time of the performance is re-inputted into the device for inputting information, and recalculated. Even if recalculation is performed in this manner, if it is determined that it is no longer possible to obtain a production amount according to the production plan within the range of operating conditions in which the reaction column is possible, the catalyst life is determined.

  Therefore, if the time determined to be the catalyst life as described above is set as the next replacement time, the catalyst activity will not be reduced to the minimum required level until that time and the maximum catalyst performance will be exhibited. It is possible to make a production plan.

  The means for outputting the analysis result is an apparatus for outputting the catalyst layer temperature predicted from the time-dependent change of the catalyst performance and the time-dependent change of the catalyst performance at each position of the catalyst layer obtained by the analysis.

  The means for recording the analysis result is a catalyst life analysis program for the information necessary for the analysis and the catalyst layer temperature obtained from the change in the catalyst performance at each position of the catalyst layer obtained by the analysis and the change in the catalyst performance with time. An apparatus for recording on a stored computer-readable recording medium.

  As used herein, “recording medium” means a computer-readable medium capable of recording a program. For example, a semiconductor memory, an IC card, an optical disk, a magnetic disk, a magneto-optical disk, a magnetic tape, a digital video disk, and the like are included.

  The catalyst life prediction method and the catalyst life analysis apparatus according to the present invention can be suitably used particularly for a process for producing 1,2-dichloroethane by reacting ethylene, hydrogen chloride and oxygen.

  By using the catalyst life prediction method and the catalyst life analyzer according to the present invention, the plan for the next catalyst replacement time can be determined efficiently, and the activity of the catalyst does not decrease to the minimum necessary level until the replacement time is reached. In addition, the operating conditions can be optimized so as to exhibit the maximum catalyst performance.

FIG. 1 is a diagram showing a change in activation energy measured separately for each position of a reaction tube of a catalyst having a different use period. FIG. 2 is a graph in which the slope obtained from FIG. 1 is plotted against the total amount W of the target product within the period of use. FIG. 3 is a diagram comparing the temperature distribution in the reaction tube output from the catalyst life analyzer of the oxychlorination reactor according to the present invention and the actually measured temperature in the reaction tube. FIG. 4 is a diagram comparing the temperature distribution in the reaction tube output from the catalyst life analysis device of the oxychlorination reactor according to the present invention after continuing the operation conditions of FIG. 3 for one year with the actually measured temperature in the reaction tube. FIG. 5 shows the output from the catalyst life analyzer of the oxychlorination reactor according to the present invention when the operating conditions are changed in order to obtain the same production volume as in FIGS. It is a figure of the temperature distribution in a reaction tube and the operation upper limit temperature.

  The catalyst life analysis apparatus using the oxychlorination reaction apparatus according to the present invention will be described based on an actual use example.

  The oxychlorination reactor is equipped with a fixed bed flow type reaction tower, and the catalyst is packed in the reaction tower. In order to analyze this catalyst, the area from the inlet to the outlet of the reaction tube is divided into 100 and displayed.

  The raw material gas containing air as ethylene, hydrogen chloride, and oxygen raw material is supplied in its entirety from the inlet of the reaction tube, and when the raw material gas passes through the catalyst layer, reaction heat corresponding to the raw material conversion amount is generated by the reaction. The reaction is carried out in such a way that unreacted raw materials and products flow out from the outlet while changing the temperature. The reaction rate of each section divided by 100 using the formula (1) and the formula (2) is obtained, the reaction heat is calculated from the reaction amount in the section, and the temperature of the catalyst layer is calculated. The temperature distribution of the 100 catalyst layers predicted in this way is as shown in FIG. It can be seen that the measured temperature shown in FIG. 3 is in good agreement with the temperature distribution curve obtained by simulation. Thereafter, the measured temperature after one year of continuous operation and the temperature distribution curve obtained by simulation are shown in FIG. As shown in FIG. 4, it can be seen that the measured temperature is in good agreement with the temperature distribution curve obtained by simulation even after one year. Thus, the fact that the actual measurement value and the result of the simulation are in good agreement indicates that the models of the equations (1) and (2) are appropriate. Further, FIG. 5 shows a temperature distribution curve obtained by simulation after two years, assuming continuous operation. Although the operating conditions were changed so that the same production amount as in FIGS. 3 and 4 could be maintained, the operating upper limit temperature was not lowered and the catalyst life was determined to be two years.

  In this way, by actively utilizing the temperature analysis information, the catalyst life is estimated in advance, the next catalyst replacement period is planned, and the activity of the catalyst does not decrease to the minimum necessary level until that time, In addition, the production plan can be made so that the maximum catalyst performance can be exhibited, and the catalyst can be used effectively.

Claims (10)

In the chemical reaction process using a catalyst, when calculating the amount of change in activation energy based on the total amount of the target product within the catalyst use period, the change amount of activation energy ΔEa, the purpose within the catalyst use period Assuming that the total amount of the product is W, the constant indicating the degree of deterioration of the catalyst is K, the length of the reaction tube is L ₀ , and the position from the reaction tube inlet is L, ΔEa is a function of L and W (1 );
ΔEa (L, W) = KW ⁿ × (L−L ₀ ) (1)
(Where n is greater than 0 and less than 1)
The catalyst life prediction is characterized in that the catalyst life is calculated by analyzing the change in the catalyst performance over time from the amount of change in the activation energy and predicting the catalyst layer temperature from the change in the catalyst performance over time. Method. 2. The change in catalyst performance with time is analyzed by calculating a reaction rate constant k after the period of use from the change amount ΔEa of activation energy and comparing it with an initial reaction rate constant k _0. The catalyst life prediction method as described. Assuming that the frequency factor is A, the initial activation energy is Ea ₀ , the gas constant is R, and the catalyst layer temperature is T (L, W), the reaction rate multiplier k is a function of L and W (2);
k (L, W) = Aexp (− (Ea ₀ + ΔEa (L, W)) / RT (L, W)) (2)
The catalyst life prediction method according to claim 2, wherein   The catalyst life prediction method according to any one of claims 1 to 3, wherein a catalyst layer temperature predicted from a change in operating conditions and catalyst performance is used for judgment of life prediction.   The catalyst life prediction method according to any one of claims 1 to 4, wherein the chemical reaction process using a catalyst is a process for producing 1,2-dichloroethane by reacting ethylene, hydrogen chloride and oxygen. In chemical reaction processes using catalysts, means to integrate the total amount of target products, means to detect the temperature of the catalyst layer when using the catalyst, and activate the amount of change in catalyst performance based on the total production during the catalyst usage period Means for calculating the change amount of the activation energy and a calculation means for predicting the catalyst layer temperature, and the change amount ΔEa of the activation energy after the catalyst use period has elapsed is the total amount of the target product within the use period of the catalyst Is a constant indicating the degree of deterioration of the catalyst, K is a constant of the reaction tube, L _{0 is} a length from the reaction tube inlet, and L is a position from the reaction tube inlet.
ΔEa (L, W) = KW ⁿ × (L−L ₀ ) (1)
(Where n is greater than 0 and less than 1)
A catalyst life analyzer for a chemical reaction process using a catalyst characterized by the following. 7. The change in catalyst performance with time is analyzed by calculating a reaction rate constant k after the period of use from the change amount ΔEa of activation energy and comparing it with the initial reaction rate constant k _0. Catalyst life analyzer for chemical reaction process using the described catalyst. Assuming that the frequency factor is A, the initial activation energy is Ea ₀ , the gas constant is R, and the catalyst layer temperature is T (L, W), the reaction rate constant k after the period of use is a function of L and W. (2);
k (L, W) = Aexp (− (Ea ₀ + ΔEa (L, W)) / RT (L, W)) (2)
The catalyst life analysis apparatus for chemical reaction processes using the catalyst of Claim 7 characterized by the above-mentioned.   9. A catalyst life analysis apparatus for a chemical reaction process using a catalyst according to claim 6, wherein the catalyst layer temperature predicted from changes in operating conditions and catalyst performance is used for judgment of life prediction.   The catalyst for a chemical reaction process using the catalyst according to any one of claims 6 to 9, wherein the chemical reaction process using the catalyst is a process for producing 1,2-dichloroethane by reacting ethylene, hydrogen chloride and oxygen. Life analysis device.

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