阅读说明：本技术 一种快速达到等温条件的动力学实验方法 (Dynamic experiment method for rapidly achieving isothermal condition ) 是由 李辉 成思萌 于 2020-05-08 设计创作，主要内容包括：本发明公开一种快速达到等温条件的动力学实验方法,包括步骤一、采用设有开孔的可控温加热炉代替热分析仪的封闭式炉体,保持恒温；步骤二、将装填有粉状物料的热分析坩埚放入炉体内进行加热反应,到达设定时间后,迅速将坩埚从炉内取出,终止反应；步骤三、将物料取出,进行相关分析化验,选择能够表征反应进度的参数,计算反应转化率；步骤四、根据等温动力学实验的要求,改变温度或者时间参数,重复步骤一至步骤三,直至完成所有实验；步骤五,对转化率-时间数据进行处理,得到物料等温动力学方程。本发明解决了常规热分析仪器在开展等温动力学测试中存在的升温时间长、无法适用于高温区域反应的问题,为等温动力学研究提供了一种改进方法。(The invention discloses a dynamic experiment method for rapidly achieving isothermal conditions, which comprises the following steps of firstly, replacing a closed furnace body of a thermal analyzer with a temperature-controllable heating furnace with an opening, and keeping constant temperature; secondly, putting the thermal analysis crucible filled with the powdery material into a furnace body for heating reaction, quickly taking the crucible out of the furnace after the set time is reached, and stopping the reaction; taking out the materials, carrying out related analysis and assay, selecting parameters capable of representing the reaction progress, and calculating the reaction conversion rate; step four, changing temperature or time parameters according to the requirements of the isothermal dynamics experiment, and repeating the steps one to three until all experiments are completed; and step five, processing the conversion rate-time data to obtain a material isothermal kinetic equation. The invention solves the problems that the conventional thermal analyzer has long temperature rise time and cannot be suitable for high-temperature region reaction in the isothermal dynamics test, and provides an improved method for isothermal dynamics research.)

1. A dynamic experiment method for rapidly achieving isothermal conditions is characterized by comprising the following steps: the method comprises the following steps:

step one, adopting a temperature-controllable heating furnace with openings to replace a closed furnace body of a thermal analyzer, controlling the temperature in the furnace to be a set temperature, and keeping the temperature constant;

secondly, putting the thermal analysis crucible filled with the powdery material into the furnace body through the opening for heating reaction, quickly taking the crucible out of the furnace after the set time is reached, and stopping the reaction;

taking out the materials in the crucible, carrying out relevant analysis and assay, selecting parameters capable of representing the reaction progress, and calculating the reaction conversion rate;

step four, changing temperature or time parameters according to the requirements of the isothermal dynamics experiment, and repeating the experiments from the step one to the step three until all experiments are completed;

and step five, carrying out mathematical treatment on the conversion rate-time data obtained by the experiment according to an isothermal dynamics algorithm, and calculating a mechanism function, activation energy and pre-exponential factors to obtain an isothermal dynamics equation of the experimental material.

2. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: the opening is formed in the top end, the side face or the bottom of the furnace body; the temperature control precision of the heating furnace is controlled to be +/-1.0 ℃.

3. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: the material addition amount of the thermal analysis crucible is below 20 mg.

4. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: in the third step, the parameters of the assay analysis are used for representing the reaction progress and calculating the reaction conversion rate; the reaction conversion rate ranges from 0 to 1, wherein 0 represents that the reaction is not started, and 1 represents that the reaction is finished.

5. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: in the fourth step, the experiment to be completed should satisfy: at least four different isothermal conditions were set, and at least 4 time points were set for each isothermal condition.

6. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: in the fifth step, the isothermal dynamics method adopted is a reduction time method or an lnln method.

7. The kinetic experimental method for rapidly achieving isothermal conditions according to claim 1, characterized in that: the measures taken to terminate the reaction include forced cooling and sealing.

Technical Field

The invention relates to the field of test analysis, in particular to a dynamic experiment method for rapidly achieving isothermal conditions.

Background

The conventional thermal analyzer is reliable in the kinetic test of the linear operation mode, but has a significant problem in the isothermal isokinetic test. Because the heating power, furnace body materials and a protection mechanism of the thermal analyzer are strictly limited (the temperature rise rate of the general thermal analyzer is limited below 50-100 ℃/min), the temperature of the thermal analyzer can reach the set temperature only after a temperature rise process is necessarily required during isothermal testing, and then the thermal analyzer enters a constant-temperature working mode. The higher the set point of the constant temperature, the longer this warming process takes. In fact, it is likely that some reaction has occurred in the sample during the temperature rise, which is a deviation from the assumption that the reaction conversion rate needs to be gradually increased from 0 to 1 under the constant temperature condition, and the higher the set constant temperature value is, the larger the deviation is. To reduce this deviation, isothermal kinetics testing is generally limited to a lower temperature range, limiting the applicability of the method to high temperature reaction zones.

In practical production applications, the reaction process under stable working conditions is usually involved, and belongs to the typical kinetic problem of isothermal process. Therefore, the traditional isothermal dynamics experiment method is improved, and the problems that the existing test method generally has long isothermal experience time and large test error caused by test delay are very necessary.

Disclosure of Invention

The invention aims to provide a dynamic experiment method for rapidly achieving isothermal conditions, which aims to solve the problems in the prior art, can shorten the time of a temperature rising section before constant temperature to the maximum extent, and can be used for isothermal dynamic testing in a high-temperature area.

In order to achieve the purpose, the invention provides the following scheme: the invention provides a dynamic experiment method for rapidly achieving isothermal conditions, which comprises the following steps:

step one, adopting a temperature-controllable heating furnace with openings to replace a closed furnace body of a thermal analyzer, controlling the temperature in the furnace to be a set temperature, and keeping the temperature constant;

secondly, putting the thermal analysis crucible filled with the powdery material into the furnace body through the opening for heating reaction, quickly taking the crucible out of the furnace after the set time is reached, and stopping the reaction;

taking out the materials in the crucible, carrying out relevant analysis and assay, selecting parameters capable of representing the reaction progress, and calculating the reaction conversion rate;

step four, changing temperature or time parameters according to the requirements of the isothermal dynamics experiment, and repeating the experiments from the step one to the step three until all experiments are completed;

and step five, carrying out mathematical treatment on the conversion rate-time data obtained by the experiment according to an isothermal dynamics algorithm, and calculating a mechanism function, activation energy and pre-exponential factors to obtain an isothermal dynamics equation of the experimental material.

Preferably, the opening is formed in the top end, the side face or the bottom of the furnace body; the temperature control precision of the heating furnace is controlled to be +/-1.0 ℃.

Preferably, the amount of the material added to the thermal analysis crucible is 20mg or less.

Preferably, in the third step, the parameters of the assay analysis are used for characterizing the reaction progress and calculating the reaction conversion rate; the reaction conversion rate ranges from 0 to 1, wherein 0 represents that the reaction is not started, and 1 represents that the reaction is finished.

Preferably, in the fourth step, the experiment to be completed should satisfy: at least four different isothermal conditions were set, and at least 4 time points were set for each isothermal condition.

Preferably, in the fifth step, the isothermal kinetic method used is a reduction time method or an lnln method.

Preferably, the measures taken to terminate the reaction include forced cooling and sealing.

The invention discloses the following technical effects: the invention solves the problems that the conventional thermal analyzer has long temperature rise time and cannot be suitable for high-temperature region reaction in the isothermal dynamics test, and provides an effective improvement method for isothermal dynamics research.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a schematic diagram of an isothermal reaction kinetics apparatus used in the examples, in which FIG. 1a is a square column furnace structure and FIG. 1b is a cylindrical furnace structure;

FIG. 2 shows the reaction conversion rates obtained by experimental analysis in the examples;

FIG. 3 is a graph of fits of ln [ -ln (1- α) ] -lnt at 700 ℃ in the examples;

FIG. 4 is a graph of fits of ln [ -ln (1- α) ] -lnt at 750 ℃ in the examples;

FIG. 5 is a graph of fits of ln [ -ln (1- α) ] -lnt at 800 ℃ in the examples;

FIG. 6 is a graph of fits of ln [ -ln (1- α) ] -lnt at 850 ℃ in the examples;

FIG. 7 is a fitting graph of lnk 1/T in the examples.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1-7, the present invention provides a kinetic experimental method for rapidly achieving isothermal conditions, comprising the steps of:

step one, adopting a temperature-controllable heating furnace with openings to replace a closed furnace body of a thermal analyzer, controlling the temperature in the furnace to be 700 ℃, and keeping the temperature constant.

And step two, weighing 20mg of materials, putting the materials into a thermal analysis crucible, putting the thermal analysis crucible filled with the powdery materials into a furnace body through an opening for heating reaction, quickly taking the crucible out of the furnace after the set time of 25s, putting the crucible into a liquid nitrogen-cooled clean beaker, and stopping the reaction through quenching. Due to sample analysis requirements, there were 10 sets of parallel experiments to be performed.

Taking out the materials in the crucible, selecting the content of the negative divalent sulfur as a parameter for representing the reaction progress, carrying out chemical analysis, and calculating the reaction conversion rate;

and step four, selecting four temperature points and six time points according to the requirements of the isothermal dynamics experiment, and repeating the steps from the first step to the third step until all experiments are completed. The four are respectively: 700 ℃, 750 ℃, 800 ℃ and 850 ℃. At each temperature point, 6 times were selected for the experiment, respectively: 25s, 30s, 35s, 40s, 45s and 50 s. And (3) carrying out 10 groups of parallel experiments on each group of temperature and time combination parameters, and mixing materials of the 10 groups of experiments to obtain an experiment sample under the temperature-time combination parameters for carrying out content analysis on the negative divalent sulfur.

And step five, performing kinetic calculation by adopting an lnln method (double logarithm method), performing mathematical processing on the data of conversion rate-time obtained by the experiment, and calculating a mechanism function, activation energy and pre-exponential factor to obtain an isothermal kinetic equation of the experimental material. The specific method comprises the following steps:

(1) the reaction rate constant k was determined from the intercept by plotting ln [ -ln (1- α) ] on the ordinate and lnt on the abscissa and performing linear fitting.

The fitting results of ln [ -ln (1- α) ] -lnt at four temperatures of 700 ℃, 750 ℃, 800 ℃ and 850 ℃ are shown in fig. 3, 4, 5 and 6. the m values are 2.158, 1.960, 1.790 and 1.757, respectively and the intercept lnk values are-8.331, -7.376, -6.557 and-6.141, respectively.

(2) And determining a mechanism function according to m.

In fig. 3, 4, 5 and 6, the average of the m values is 1.916, and the m value of the mechanism function of the chemical reaction (n ═ 4) is 1.989, which are close to each other, so that the mechanism function determined is the mechanism of the chemical reaction (n ═ 4).

(3) Taking lnk as a vertical coordinate and 1/T as a horizontal coordinate to perform linear fitting, solving the activation energy E from the slope, and solving the pre-exponential factor A from the intercept.

The result of lnk-1/T fitting is shown in FIG. 7, the slope of linear fitting is-16243.35, the intercept is 8.44, the activation energy E is 135.05kJ/mol, and the pre-exponential factor A is 4.63 × 10³s^-1。

(4) And obtaining a reaction kinetic equation of the sample under the constant temperature condition according to the determined mechanism function, the activation energy E and the pre-exponential factor A.

In the present example, the kinetic parameters determined were, respectively, the reaction mechanism was a chemical reaction (n-4), the activation energy E-135.05 kJ/mol, the index cofactor a-4.63 × 10³s^-1. Thus, the isothermal reaction kinetics equation for desulfurization of this sample is as follows:

wherein α represents the conversion, T represents the heating reaction time, T represents the reaction temperature, and R is a gas constant.

The invention solves the problem that the time lag is too long when the traditional dynamics method reaches the constant temperature condition in the experiment for testing the isothermal reaction dynamics. The material can be discharged without opening the furnace door, the temperature rise time before constant temperature is shortened to the maximum extent, and the furnace can be used for the condition of conventional high temperature. Meanwhile, the dynamics experiment method provided by the invention can also provide reference for isothermal dynamics tests in related fields.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.