阅读说明：本技术 一种测定zsm-23分子筛中白硅石相含量的方法 (Method for determining content of cristobalite phase in ZSM-23 molecular sieve ) 是由 李瑞峰 刘丽莹 包世星 于 2018-05-22 设计创作，主要内容包括：本发明涉及一种测定ZSM-23分子筛中白硅石相含量的方法,包括如下步骤：S1、制备样品：将待测ZSM-23分子筛研磨至所需粒径,该所需粒径与选用的白硅石相标样的粒径的差值为±0.5μm～±1.0μm,得到ZSM-23分子筛样品；将干燥过的干基ZSM-23分子筛样品m g,与y g白硅石相标样混合,滴加无水乙醇至样品完全湿润,湿磨、干燥后得到混合样品；S2、启动X射线衍射仪；S3、测定试样：测定ZSM-23分子筛样品、白硅石相标样、混合样品的粉末X射线衍射数据；S4、数据处理。本发明的方法能够采用粉末X射线衍射仪准确测定ZSM-23分子筛中白硅石相含量,该方法快速、精密、准确。(The invention relates to a method for determining the content of a cristobalite phase in a ZSM-23 molecular sieve, which comprises the following steps: s1, preparing a sample: grinding the ZSM-23 molecular sieve to be detected to a required particle size, wherein the difference value between the required particle size and the particle size of the selected cristobalite phase standard sample is +/-0.5 mu m- +/-1.0 mu m, and obtaining a ZSM-23 molecular sieve sample; mixing a dried dry-based ZSM-23 molecular sieve sample m g with a y g silica phase standard sample, dropwise adding absolute ethyl alcohol until the sample is completely wet, and wet-grinding and drying to obtain a mixed sample; s2, starting the X-ray diffractometer; s3, measurement sample: measuring powder X-ray diffraction data of a ZSM-23 molecular sieve sample, a cristobalite phase standard sample and a mixed sample; and S4, data processing. The method can accurately measure the content of the cristobalite phase in the ZSM-23 molecular sieve by adopting a powder X-ray diffractometer, and is rapid, precise and accurate.)

1. A method for determining the content of a cristobalite phase in a ZSM-23 molecular sieve is characterized by comprising the following steps:

S1 preparation of sample

grinding the ZSM-23 molecular sieve to be detected to a required particle size, wherein the difference value between the required particle size and the particle size of the selected cristobalite phase standard sample is +/-0.5 mu m- +/-1.0 mu m, and obtaining a ZSM-23 molecular sieve sample;

Mixing a dried dry-based ZSM-23 molecular sieve sample m g with a y g silica phase standard sample, dropwise adding absolute ethyl alcohol until the sample is completely wet, and wet-grinding and drying to obtain a mixed sample;

S2 starting X-ray diffractometer

Starting the X-ray diffractometer, checking the instrument by using silicon powder after the instrument is stable, and verifying that the comprehensive stability of the instrument is less than or equal to 0.1%;

S3, measurement sample

Measuring powder X-ray diffraction data of a ZSM-23 molecular sieve sample, a cristobalite phase standard sample and a mixed sample, respectively adopting chemometrics software and selecting a Pearson VII peak model to obtain a total intensity counting value A of a crystal face analysis line of ZSM-23(130) and a crystal face analysis line of cristobalite (101) or (111) in ZSM-23_{(101) or (111) + (130)}And ZSM-23(051) crystal face analysis line intensity counting value A₍₀₅₁₎The crystal plane analysis line intensity counting value A of the cristobalite phase standard sample (101) or (111)_{Silica white phase standard}ZSM-23(130) crystal plane analysis line, white silica (101) or (111) crystal plane analysis line in ZSM-23, white silica phase standard sample (101) or (111) crystal plane analysis line and intensity count value A'_{(101) Or (111) + (130)}and ZSM-23(051) crystal face analysis line intensity count value A'₍₀₅₁₎；

s4, data processing

Content X of white silica phase in ZSM-23 molecular sieve sample_j(mass fraction) is calculated as follows:

Wherein the content of the first and second substances,

I_jThe net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in the ZSM-23 molecular sieve sample is calculated by the following formula: i is_j＝A_{(101) Or (111) + (130)}－8.6/6.0×A₍₀₅₁₎Unit of s^-1；

I_j0The crystal face analysis line net intensity of the cristobalite phase (101) or (111) in the cristobalite phase standard sample is calculated by the following formula: i is_j0＝100/c×A_{Silica white phase standard}and c is the actual content of the silica in the silica phase standard sample, unit s^-1；

I_jIs a mixed sampleThe net intensity of the crystal face analysis line of the medium white silica phase (101) or (111) is calculated by the following formula: i is_j′＝A′_{(101) Or (111) + (130)}－8.6/6.0×A′₍₀₅₁₎unit of s^-1。

2. The method for determining the cristobalite phase content of a ZSM-23 molecular sieve as claimed in claim 1, wherein in step S2, the X-ray diffractometer operating conditions are: copper target K_α0.1542nm, and a scanning speed of 0.5 DEG/min^-1～2°·min^-1The step size is 0.01-0.03 degrees, the divergence slit is 0.5-2 degrees, the anti-divergence slit is 0.5-2 degrees, the receiving slit is 0.15-0.5 mm, and the 2 theta scanning range is 4-70 degrees.

3. The method of determining the cristobalite phase content of a ZSM-23 molecular sieve as claimed in claim 2, wherein the X-ray diffractometer operating conditions are: copper target K_α0.1542nm, and a scanning speed of 1 DEG/min^-1The step size is 0.02 degrees, the divergence slit is 1 degree, the anti-divergence slit is 1 degree, the receiving slit is 0.3mm, and the 2 theta scanning range is 17-28 degrees.

4. The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve according to claim 1, wherein in step S1, the wet milling uses absolute ethanol and the absolute ethanol is obtained by passing the absolute ethanol throughMolecular sieve dehydration.

5. The method of claim 1, wherein the ZSM-23 molecular sieve sample has a milled particle size D in step S1₍₅₀₎2-20 μm.

6. The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve according to claim 1, wherein in step S1, the wet milling is performed for 15min to 30min by using an agate bowl mill.

7. The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve according to claim 1, wherein in step S1, the drying step is: placing the wet-milled mixed sample in a fume hood for ventilation and drying at 20-30 ℃ or under the condition of infrared lamp roasting; and then the mixture is placed in a vacuum drying oven to be dried for 1 to 2 hours at the temperature of between 100 and 150 ℃.

8. The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve according to claim 1, wherein in step S2, the instrument integrated stability is a relative standard deviation of an analysis line intensity value measured within 8 hours, measured every 30min to 60min for a silicon phase standard sample (111) crystal plane analysis line intensity under the same test condition.

9. The method of claim 1, wherein in step S1, the silica white phase standard is a dry basis, NIST standard, wherein the silica white phase content is 88.2% ± 0.4 wt% or 93.98% ± 0.79 wt%.

10. The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve according to claim 1, wherein in step S1, the amount of the ZSM-23 molecular sieve sample is 0.4g to 0.8g, which is referred to as 0.0001 g; the amount of the silica white phase standard sample is 0.01 g-0.1 g, and is weighed to be 0.0001 g.

Technical Field

The invention relates to a method for determining the content of a cristobalite phase in a ZSM-23 molecular sieve, in particular to a method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve by using a powder X-ray diffractometer.

Background

The molecular sieve is used as a catalyst or a catalyst carrier and is widely applied to petrochemical engineering catalysis processes. Its purity, Si/Al ratio, unit cell parameters and crystallinity are the essential parameters for characterizing molecular sieve performance (Shenchuyu, Baokha, Lixuanping, X-ray diffraction method for measuring molecular sieve unit cell parameters and crystallinity [ J ]. physicochemical examination-physical manual, 2002,38(7): 297). ZSM-23 molecular sieve is usually accompanied by white silica mixed crystal in industrial production, but the content is different, sometimes up to 20%, the purity of the synthesized molecular sieve can be influenced by the white silica mixed crystal contained in the molecular sieve, and the purity is the absolute content (mass percentage) of the main phase of the molecular sieve and is directly related to the content of the mixed crystal phase. The molecular sieve accompanied by the cristobalite mixed crystals can deeply influence the performance indexes such as the activity, the selectivity, the stability and the like of the catalyst and further deeply influence the overall operation effect of an industrial device. Therefore, the amount of the cristobalite phase in the ZSM-23 molecular sieve is an extremely important parameter for characterizing such molecular sieves and isodewaxing catalysts.

CN106168583A discloses a method for determining the relative crystallinity of a ZSM-23 molecular sieve. At present, no patent, standard or any relevant research report for the determination of the content of the cristobalite phase in the ZSM-23 molecular sieve has been retrieved.

The determination of the content of the cristobalite phase in the ZSM-23 molecular sieve has extremely important practical significance for ensuring the development of the isodewaxing catalyst and the complete technology thereof, integrally improving the quality of the base oil products of the Chinese petroleum lubricating oil, expanding the occupation rate of the isodewaxing complete technology in domestic devices, improving the market share of the finished oil products of the lubricating oil in domestic markets and gradually putting the finished oil products of the lubricating oil in international markets.

Disclosure of Invention

In order to fill the blank of the prior art, the invention provides a method for accurately measuring the content of the cristobalite phase in the ZSM-23 molecular sieve by using a powder X-ray diffractometer, provides reliable technical support for synthesis and industrial application of the ZSM-23 molecular sieve, can be applied to development of a complete set of technology of an isodewaxing catalyst, and integrally improves the quality of petroleum lubricant base oil products in China.

Therefore, the invention provides a method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, which comprises the following steps:

S1 preparation of sample

Grinding the ZSM-23 molecular sieve to be detected to a required particle size, wherein the difference value between the required particle size and the particle size of the selected cristobalite phase standard sample is +/-0.5 mu m- +/-1.0 mu m, and obtaining a ZSM-23 molecular sieve sample;

Mixing a dried dry-based ZSM-23 molecular sieve sample m g with a y g silica phase standard sample, dropwise adding absolute ethyl alcohol until the sample is completely wet, and wet-grinding and drying to obtain a mixed sample;

S2 starting X-ray diffractometer

Starting the X-ray diffractometer, checking the instrument by using silicon powder after the instrument is stable, and verifying that the comprehensive stability of the instrument is less than or equal to 0.1%;

S3, measurement sample

Measuring powder X-ray diffraction data of a ZSM-23 molecular sieve sample, a cristobalite phase standard sample and a mixed sample, respectively adopting chemometrics software and selecting a Pearson VII peak model to obtain a total intensity counting value A of a crystal face analysis line of ZSM-23(130) and a crystal face analysis line of cristobalite (101) or (111) in ZSM-23_{(101) Or (111) + (130)}And ZSM-23(051) crystal face analysis line intensity counting value A₍₀₅₁₎The crystal plane analysis line intensity counting value A of the cristobalite phase standard sample (101) or (111)_{Silica white phase standard}ZSM-23(130) crystal plane analysis line, white silica (101) or (111) crystal plane analysis line in ZSM-23, white silica phase standard sample (101) or (111) crystal plane analysis line and intensity count value A'_{(101) Or (111) + (130)}and ZSM-23(051) crystal face analysis line intensity count value A'₍₀₅₁₎；

S4, data processing

Content X of white silica phase in ZSM-23 molecular sieve sample_j(mass fraction) is calculated as follows:

Wherein the content of the first and second substances,

I_jThe net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in the ZSM-23 molecular sieve sample is calculated by the following formula: i is_j＝A_{(101) Or (111) + (130)}－8.6/6.0×A₍₀₅₁₎unit of s^-1；

I_j0The crystal face analysis line net intensity of the cristobalite phase (101) or (111) in the cristobalite phase standard sample is calculated by the following formula: i is_j0＝100/c×A_{Silica white phase standard}And c is the actual content of the silica in the silica phase standard sample, unit s^-1；

I_j' is the net intensity of the crystal plane analysis line of the (101) or (111) cristobalite phase in the mixed sample, and the calculation formula is as follows: i is_j′＝A′_{(101) Or (111) + (130)}－8.6/6.0×A′₍₀₅₁₎Unit of s^-1。

The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve comprises the following working conditions of an X-ray diffractometer in step S2: copper target K_αPreferably 0.1542nm, and the scanning speed is preferably 0.5 DEG/min^-1～2°·min^-1The step size is preferably 0.01 to 0.03 °, the divergence slit is preferably 0.5 to 2 °, the anti-divergence slit is preferably 0.5 to 2 °, the receiving slit is preferably 0.15 to 0.5mm, and the 2 θ scanning range is preferably 4 to 70 °.

The invention discloses a method for determining the content of a cristobalite phase in a ZSM-23 molecular sieve, wherein the working conditions of an X-ray diffractometer are as follows: copper target K_αMore preferably 0.1542nm, and the scanning speed is more preferably 1 DEG/min^-1the step size is more preferably 0.02 °, the divergence slit is more preferably 1 °, the anti-divergence slit is more preferably 1 °, the receiving slit is more preferably 0.3mm, and the 2 θ scanning range is more preferably 17 ° to 28 °.

In the method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, step S1 is preferably performed by adopting absolute ethyl alcohol in the wet grinding process and subjecting the absolute ethyl alcohol to the wet grinding processMolecular sieve dehydration.

The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve comprises the step S1 of grinding a ZSM-23 molecular sieve sample to obtain a granularity D₍₅₀₎Preferably 2 to 20 μm.

In the method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, in step S1, the wet grinding is preferably performed by an agate bowl type micro powder grinding machine for 15-30 min.

In the method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, in the step S1, the drying step is preferably: placing the wet-milled mixed sample in a fume hood for ventilation and drying at 20-30 ℃ or under the condition of infrared lamp roasting; and then the mixture is placed in a vacuum drying oven to be dried for 1 to 2 hours at the temperature of between 100 and 150 ℃.

in the method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, in step S2, the comprehensive stability of the instrument is preferably the relative standard deviation of the analysis linear intensity value measured within 8 hours, wherein the analysis linear intensity of the crystal face of the silicon phase standard sample (111) is determined once every 30-60 min under the same test condition.

In the method for determining the content of the silica white phase in the ZSM-23 molecular sieve, in step S1, the silica white phase standard sample is preferably a dry-based NIST standard sample, wherein the silica white phase content is 88.2% + -0.4 wt% or 93.98% + -0.79 wt%.

In the method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve, in step S1, the dosage of the ZSM-23 molecular sieve sample is preferably 0.4g to 0.8g, and the dosage is measured to be 0.0001 g; the amount of the silica white phase standard sample is preferably 0.01 g-0.1 g, and is weighed to 0.0001 g.

The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve specifically comprises the following steps:

Step one, grinding a ZSM-23 molecular sieve sample to be detected by adopting a mechanical wet method, and collecting the granularity D₍₅₀₎A3.5 μm sample powder was dried to prepare a mixed sample of a silica white phase standard and a ZSM-23 molecular sieve sample.

Wherein the drying step is: placing the wet-milled mixed sample in a fume hood for ventilation and drying at 20-30 ℃, namely room temperature or under the condition of infrared lamp roasting, wherein the wet-milled mixed sample cannot be placed in a closed electric heating drying oven to prevent an explosion event; then the mixture is placed in a vacuum drying oven to be dried for 1 to 2 hours at the temperature of 125 ℃.

And step two, starting the X-ray diffractometer, checking the instrument by using the silica powder after the instrument is stabilized, and verifying that the comprehensive stability of the instrument is less than or equal to 0.1 percent to meet the measurement requirement.

the phase content of the white silica in the ZSM-23 molecular sieve sample is measured by using an X-ray diffractometer, the influence of different parameters in the diffraction process, such as a divergence slit, an anti-divergence slit, a receiving slit, voltage, current, scanning speed, step length and the like on the measured diffraction peak in the ZSM-23 molecular sieve sample is researched, and the optimum measurement parameter of the ZSM-23 molecular sieve is preferably selected, as shown in the following table.

TABLE 1 working conditions of the apparatus

Step three, under the same working conditions of the powder X-ray diffractometer, respectively collecting a mixed sample of a cristobalite phase standard sample and a ZSM-23 molecular sieve sample, a ZSM-23 molecular sieve sample to be detected and a sample copper target K of the cristobalite phase standard sample within the range of 17-28 DEG 2 theta_αX-ray diffraction data.

Because the white silica mixed crystals have two kinds, the strongest diffraction peaks of the white silica mixed crystals are respectively (101) crystal faces or (111) crystal faces, and the white silica mixed crystals usually exist in ZSM-23 as a mixed crystal phase; and because a ZSM-23(130) crystal face analysis line is superposed with a cristobalite (101) or (111) crystal face analysis line, and the ZSM-23(051) crystal face analysis line has no mixed crystal peak interference, the ZSM-23(130) crystal face analysis line intensity can be indirectly converted by using the theoretical intensity ratio of the ZSM-23(130) crystal face to the (051) crystal face analysis line of 8.6/6.0, and then the net intensity of the cristobalite (111) or (101) crystal face analysis line can be obtained by subtracting the ZSM-23(130) crystal face analysis line intensity through the superposed peak analysis line intensity of the ZSM-23(130) crystal face and the cristobalite (111) or (101) crystal face.

Based on the principle, chemometrics software is adopted, and a Pearson VII partial peak model is selected to obtain a combined intensity counting value A of a ZSM-23(130) crystal face analysis line and a cristobalite (101) or (111) crystal face analysis line in ZSM-23_{(101) Or (111) + (130)}And ZSM-23(051) crystal face analysis line intensity counting value A₍₀₅₁₎The crystal plane analysis line intensity counting value A of the cristobalite phase standard sample (101) or (111)_{Silica white phase standard}The sum of the crystal plane analysis line of ZSM-23(130) and the crystal plane analysis line of cristobalite (101) or (111) in ZSM-23Line-bonded strength count value A 'of (101) or (111) crystal face analysis of white silica phase standard sample'_{(101) Or (111) + (130)}And ZSM-23(051) crystal face analysis line intensity count value A'₍₀₅₁₎；

Step three, processing data, calculating according to the following formulas respectively to obtain the net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in 3 samples, calculating the average value of the net intensity, and calculating the content of the cristobalite phase in the ZSM-23 molecular sieve sample to be detected by using an external standard elimination incremental method;

Content X of white silica phase in ZSM-23 molecular sieve sample_j(mass fraction) is calculated as follows:

Wherein the content of the first and second substances,

I_jthe net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in the ZSM-23 molecular sieve sample is calculated by the following formula: i is_j＝A_{(101) Or (111) + (130)}－8.6/6.0×A₍₀₅₁₎Unit of s^-1；

I_j0the crystal face analysis line net intensity of the cristobalite phase (101) or (111) in the cristobalite phase standard sample is calculated by the following formula: i is_j0＝100/c×A_{Silica white phase standard}And c is the actual content of the silica in the silica phase standard sample, unit s^-1；

I_j' is the net intensity of the crystal plane analysis line of the (101) or (111) cristobalite phase in the mixed sample, and the calculation formula is as follows: i is_j′＝A′_{(101) Or (111) + (130)}－8.6/6.0×A′₍₀₅₁₎Unit of s^-1。

The invention relates to a method for accurately measuring the content of a cristobalite phase in a ZSM-23 molecular sieve by using a powder X-ray diffractometer, wherein the content of the cristobalite phase in the ZSM-23 molecular sieve is 2.9-20.6%; the NIST silica phase standards were found to be 88.2% ± 0.4% or 93.98% ± 0.79% (mass fraction) and were able to be used as received, but care was taken to keep the dry, sealed storage.

The invention has the beneficial effects that:

The molecular sieve is used as a catalyst or a catalyst carrier and is widely applied to petrochemical engineering catalysis processes. The purity is the absolute content (mass fraction) of the main phase of the molecular sieve and is directly related to the content of the mixed crystals. The content of the cristobalite phase in the ZSM-23 molecular sieve directly influences the pore structure and the property of the catalyst and determines the service performances of the catalyst, such as activity, selectivity, stability and the like. Therefore, the amount of the cristobalite phase in the ZSM-23 molecular sieve is an extremely important parameter for characterizing such molecular sieves and isodewaxing catalysts.

Powder X-ray diffraction is an important technique for determining the relative amounts of the phases in a mixture. The method can accurately measure the content of the cristobalite phase in the ZSM-23 molecular sieve by adopting a powder X-ray diffractometer, and is rapid, precise and accurate. Can ensure the smooth proceeding of the related research and development and the industrial production and the application of the catalyst, and fills the gap of the analysis and determination technology at home and abroad.

Drawings

FIG. 1 is an X-ray diffraction pattern of a typical ZSM-23 molecular sieve containing white silica of the present invention;

FIG. 2 is a flow chart of the method of the present invention.

Detailed Description

the following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.

The method for determining the content of the cristobalite phase in the ZSM-23 molecular sieve specifically comprises the following steps:

step one, grinding a ZSM-23 molecular sieve sample to be detected by adopting a mechanical wet method, and collecting the granularity D₍₅₀₎A3.5 μm sample powder was dried to prepare a mixed sample of a silica white phase standard and a ZSM-23 molecular sieve sample.

Wherein the drying step is: placing the wet-milled mixed sample in a fume hood for ventilation and drying at 20-30 ℃, namely room temperature or under the condition of infrared lamp roasting, wherein the wet-milled mixed sample cannot be placed in a closed electric heating drying oven to prevent an explosion event; then the mixture is placed in a vacuum drying oven to be dried for 1 to 2 hours at the temperature of 125 ℃.

And step two, starting the X-ray diffractometer, checking the instrument by using the silica powder after the instrument is stabilized, and verifying that the comprehensive stability of the instrument is less than or equal to 0.1 percent to meet the measurement requirement.

The phase content of the white silica in the ZSM-23 molecular sieve sample is determined by using an X-ray diffractometer, the influence of different parameters in the diffraction process, such as a divergence slit, an anti-divergence slit, a receiving slit, voltage, current, scanning speed, step length and the like on the measured diffraction peak in the ZSM-23 molecular sieve sample is researched, and the optimum determination parameter of the ZSM-23 molecular sieve is preferably selected, and is shown in Table 1.

Step three, under the same working conditions of the powder X-ray diffractometer, respectively collecting a mixed sample of a cristobalite phase standard sample and a ZSM-23 molecular sieve sample, a ZSM-23 molecular sieve sample to be detected and a sample copper target K of the cristobalite phase standard sample within the range of 17-28 DEG 2 theta_αX-ray diffraction data.

Because the white silica mixed crystals have two kinds, the strongest diffraction peaks of the white silica mixed crystals are respectively (101) crystal faces or (111) crystal faces, and the white silica mixed crystals usually exist in ZSM-23 as a mixed crystal phase; and because a ZSM-23(130) crystal face analysis line is superposed with a cristobalite (101) or (111) crystal face analysis line, and the ZSM-23(051) crystal face analysis line has no mixed crystal peak interference, the ZSM-23(130) crystal face analysis line intensity can be indirectly converted by using the theoretical intensity ratio of the ZSM-23(130) crystal face to the (051) crystal face analysis line of 8.6/6.0, and then the net intensity of the cristobalite (111) or (101) crystal face analysis line can be obtained by subtracting the ZSM-23(130) crystal face analysis line intensity through the superposed peak analysis line intensity of the ZSM-23(130) crystal face and the cristobalite (111) or (101) crystal face.

Based on the principle, chemometrics software is adopted, and a Pearson VII partial peak model is selected to obtain a combined intensity counting value A of a ZSM-23(130) crystal face analysis line and a cristobalite (101) or (111) crystal face analysis line in ZSM-23_{(101) Or (111) + (130)}And ZSM-23(051) crystal face analysis line intensity counting value A₍₀₅₁₎The crystal plane analysis line intensity counting value A of the cristobalite phase standard sample (101) or (111)_{Silica white phase standard}ZSM-23(130) crystal plane analysis line, white silica (101) or (111) crystal plane analysis line in ZSM-23, white silica phase standard sample (101) or (111) crystal plane analysis line and intensity count value A'_{(101) Or (111) + (130)}and ZSM-23(051) Crystal face analysis line intensity count value A'₍₀₅₁₎；

Step three, processing data, calculating according to the following formulas respectively to obtain the net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in 3 samples, calculating the average value of the net intensity, and calculating the content of the cristobalite phase in the ZSM-23 molecular sieve sample to be detected by using an external standard elimination incremental method;

Content X of white silica phase in ZSM-23 molecular sieve sample_j(mass fraction) is calculated as follows:

Wherein the content of the first and second substances,

I_jThe net intensity of the crystal face analysis line of the cristobalite phase (101) or (111) in the ZSM-23 molecular sieve sample is calculated by the following formula: i is_j＝A_{(101) Or (111) + (130)}－8.6/6.0×A₍₀₅₁₎Unit of s^-1；

I_j0The crystal face analysis line net intensity of the cristobalite phase (101) or (111) in the cristobalite phase standard sample is calculated by the following formula: i is_j0＝100/c×A_{silica white phase standard}And c is the actual content of the silica in the silica phase standard sample, unit s^-1；

I_j' is the net intensity of the crystal plane analysis line of the (101) or (111) cristobalite phase in the mixed sample, and the calculation formula is as follows: i is_j′＝A′_{(101) Or (111) + (130)}－8.6/6.0×A′₍₀₅₁₎Unit of s^-1。

The invention relates to a method for accurately measuring the content of a cristobalite phase in a ZSM-23 molecular sieve by using a powder X-ray diffractometer, wherein the content of the cristobalite phase in the ZSM-23 molecular sieve is 2.9-20.6%; the NIST silica phase standards were found to be 88.2% ± 0.4% or 93.98% ± 0.79% (mass fraction) and were able to be used as received, but care was taken to keep the dry, sealed storage.