AU2019101001A4

AU2019101001A4 - Method for synthesizing sodium zirconate and application thereof

Info

Publication number: AU2019101001A4
Application number: AU2019101001A
Authority: AU
Inventors: Muhammad Zaki Hassan Memon; Fan Wang; Ming Zhao
Original assignee: Research Institute For Environmental Innovation Suzhou Tsinghua; Tsinghua University
Current assignee: Research Institute For Environmental Innovation (suzhou) Tsinghua; Tsinghua University
Priority date: 2018-12-20
Filing date: 2019-04-16
Publication date: 2019-10-10
Anticipated expiration: 2027-04-16
Also published as: CN109574072A; CN109574072B

Abstract

Abstract Disclosed are a method for synthesizing sodium zirconate and application thereof, belonging to the field of solid waste resourcing. The method comprises two steps: (1) mixing a certain amount of YSZ solid with sodium carbonate solid; and (2) calcining a product obtained in step (1) at a calcining temperature of 750 °C to 850 °C for a calcining time of 5-8 hours. The present invention can achieve the recycling of the crown material waste, and realize the reduction and resourcing effect of the dental solid waste; and the sodium zirconate synthesized by the simple and easy-to-operate synthesis method of the invention can be used as a carbon dioxide adsorbent with excellent carbon dioxide adsorption capacity, and can also be used in hydrogen production process from biomass and biomass waste pyrolysis.

Description

Method for synthesizing sodium zirconate and application thereof

Technical Field

The present invention belongs to the field of solid waste resourcing, and particularly relates to a method for synthesizing sodium zirconate and an application thereof.

Background Art

Zirconium dioxide can be used to produce crown materials because of its high hardness, good chemical stability, corrosion resistance, high mechanical strength and good biocompatibility. Also, because of the high strength, high safety and natural color of the crown made of zirconium dioxide, it is well appreciated by many patients. However, zirconia is in a monoclinic phase at room temperature, which is unsuitable for producing dental crowns, it is necessary to stabilize the zirconia with yttria at a concentration of 3 mol% to obtain a tetragonal phase, expressed as YSZ, and then the YSZ disk is treated using the CAD/CAM (Computer Aided Design and Computer Aided Manufacturing) method to prepare the desired dental crowns. The CAD/CAM method would leave around thirty percent of YSZ powdery waste residue. YSZ is not a hazardous material and can be disposed of by landfills, but discarding such material just increases the final processing cost of the landfill operation and would not play a role of recycling solid wastes.

Carbon dioxide is one of the main gases of greenhouse gases. With the emergence of the greenhouse effect and the increasing global warming, the capture of carbon dioxide has attracted the attention of all countries. Solid adsorbents are widely concerned in the field of carbon dioxide capture due to their ease of handling, reusability, and low raw material loss. Among the existing CO2 solid adsorbent, CaO adsorbent is one of the most studied adsorbents because its high adsorption capacity and a large storage capacity. But CaO also has some disadvantages, such as the tendency to sinter during multiple cycles of use, resulting in a rapid decline in its ability to adsorb CO2. Therefore, it is particularly important to synthesize a CO2 adsorbent with better adsorption activity and higher cycle stability. Sodium zirconate is one of carbon dioxide high-temperature solid adsorbents with lower cost than other zirconates, and can adsorb CO2 from room temperature to 800 °C with better cyclic adsorption stability. Lorena Martinez-dl Cruz published an article “Cyclic CO2 chemisorption-desorption behavior of Na2ZrO3: Structural, microstructural and kinetic variations produced as a function of temperature” in 2013, which disclosed a solid phase synthesis method of sodium zirconate comprising utilizing pure sodium carbonate and zirconia, firstly mechanically mixing, and then calcining at 850 °C for 6 h; wherein the amount of sodium carbonate was increased by 20 percent than the theoretical adding amount. The carbon dioxide was adsorbed 20 cycles each lasting an adsorption time of 30. The adsorption

2019101001 16Apr2019 capacity 17% (0.1705 gCOi/gNaiZrCh) was 71.7% of the theoretical adsorption capacity (theoretical adsorption capacity is 0.2378 gCOi/gNaiZrCh) when adsorbed at 500 DEG; the adsorption capacity reached 80.2% (0.1907 gCOi/gNaiZrCh) at 550 DEG; the adsorption capacity reached 75-85% at 600 DEG and 700 DEG, and the adsorption capacity of the first cycle reached 91.9% (0.2185 g CCh/gNazZrCh) at 800 DEG but decreased to 58.2% after 20 cycles (0.1384 gCOi/gNaiZrO;)· The desorption experiment was carried out at 800 DEG, and the adsorption experiment was carried out at 500 and 550 DEG, the desorption time was 15 min, and the desorption time increased with the increase of the adsorption temperature. The adsorption and desorption time of pure sodium zirconate synthesized by the solid-phase synthesis method were longer, the number of adsorption times was less, and there was still certain room for increase in the adsorption capacity

Summary of the Invention

The present invention provides a method for synthesizing sodium zirconate and an application thereof, which can realize the effective use of crown material wastes, saving cost, green and environment-friendly, reducing and recycling dental solid waste; and the sodium zirconate synthesized by the simple and easy-to-use synthesis method can be used as a carbon dioxide adsorbent with excellent carbon dioxide adsorption capacity, and can also be used for and promoting hydrogen production from biomass waste pyrolysis.

The technical scheme for realizing the above-mentioned purposes is as follows: a method for synthesizing sodium zirconate comprising the following steps:

(1) mixing crown material waste with sodium carbonate solid; and (2) calcining a product obtained in step (1) at a calcining temperature of 750 °C-850 °C for a calcining time of 5-8 hours.

After the above two steps, sodium zirconate can be obtained, namely DW-NZ in the present description. The synthesis operation steps are simple, the operating conditions are easy to control, and the prepared sodium zirconate can adsorb carbon dioxide with good the adsorption cycle stability while realizing the recycle of the crown material waste.

Preferably, the crown material waste is YSZ.

Preferably, the YSZ solid in step (1) is milled prior to or after mixing with the sodium carbonate solid, followed by the step (2). Milling allows for a more sufficient mixing of the YSZ solid with the sodium carbonate solid, resulting in a more complete reaction, higher product yield and better product quality.

Preferably, the YSZ solid in step (1) is milled after mixing with the sodium carbonate solid using a ball mill at a speed of 500-550 rpm for a ball milling time of 1.5h-2h.

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Preferably, the YSZ solid in step (1) is milled after mixing with the sodium carbonate solid using a ball mill at a speed of 500 rpm for a ball milling time of 2h.

Preferably, the molar mass ratio of the zirconium dioxide to the sodium carbonate solid contained in the YSZ solid in step (1) is 1:(1-1.2).

Preferably, the molar mass ratio of the zirconium dioxide to the sodium carbonate solid contained in the YSZ solid in step (1) is 1:1.

Preferably, the content of zirconium dioxide in the YSZ solid in step (1) is greater than 90%. YSZ with high content of zirconium dioxide is selected as the raw material, leading to a better performance of the sodium zirconate synthesized.

Preferably, the calcining temperature in step (2) is 850 °C and the calcining time is 6 hours. With this condition, the synthesis rate is higher, and the carbon dioxide adsorption effect by sodium zirconate is better.

Preferably, the synthesized sodium zirconate can be used as a carbon dioxide adsorbent.

Preferably, the sodium zirconate synthesized can be used in the hydrogen production process from biomass or biomass waste pyrolysis.

Preferably, the biomass is a sample of methyl cellulose or spirulina or willow, and the biomass waste is sludge.

The sodium zirconate synthesized by the present invention can also be used in the hydrogen production process from biomass and biomass waste pyrolysis. Biomass refers to all organic matter formed by the photosynthesis of green plants, including all plants and microorganisms. Biomass waste is the waste produced and consumed by humans in the process of utilizing biomass, which still belongs to the macroscopical category of biomass with significantly reduced energy density, availability, etc. There are different sources and different methods for H2 preparation, but the most important source is fossil fuels (approximately 96%). The hydrogen production from biomass, currently the world’s largest non-traditional energy source, has attracted widespread attention and research due to its renewable and carbon neutral properties. Sorption enhanced reforming (SER) is a thermal chemical conversion process that utilizes in-situ CO2 capture to facilitate the forward progress of the reaction to enhance hydrogen production. The normal working range of Na2ZrO3 is consistent with the temperature range of biomass pyrolysis gasification. Therefore, Na2ZrO3 can adsorb CO2 generated during pyrolysis gasification in situ. At the same time, sodium carbonate formed in the reaction of sodium zirconate with CO2 is an effective catalyst for promoting tar cracking and steam reforming, which can reduce the tar content of the system while promoting the improvement of gasification yield. Therefore, as a bifunctional material, Na2ZrO3 can theoretically promote the production of H2 in biomass pyrolysis products from both kinetic and thermodynamic aspects. The realization of both catalytic

2019101001 16Apr2019 and absorption functions on the same material theoretically enhances the absorption rate and process strengthening in the reactor. The main component of the sodium zirconate synthesized by the invention is sodium zirconate, so it can be used in the hydrogen production process from biomass and biomass waste pyrolysis, adsorbing CO2 while promoting hydrogen production in the process of hydrogen production from biomass pyrolysis, thus achieving both catalytic and absorption functions, simplifying the reactor operating unit.

The method of the present invention can achieve the reuse of crown material wastes, and realize the reduction and recycling effects for the dental solid waste; and the sodium zirconate synthesized by the simple and easy-to-use synthesis method can be used as a carbon dioxide adsorbent with excellent carbon dioxide adsorption capacity. Meanwhile, the product of the present invention can also be used for and greatly promoting in the process of hydrogen production from biomass and biomass waste pyrolysis.

Brief Description of the Drawings

Fig. 1 is an X-ray diffraction (XRD) spectrum of the product DW-NZ of Example 1;

Fig. 2 shows a CO2 cycle adsorption performance graph of the product DW-NZ of Example 1;

Fig. 3 shows product gas generation rate graphs for pyrolysis of methylcellulose alone;

Fig. 4 shows product gas generation rate graphs for co-pyrolysis of methyl cellulose with the product DW-NZ of Example 1;

Fig. 5 shows product gas generation rate graphs for pyrolysis of the sludge alone;

Fig. 6 shows product gas generation rate graphs for co-pyrolysis of the sludge with the product DW-NZ of Example 1;

Fig. 7 shows product gas generation rate graphs for pyrolysis of the of spirulina alone;

Fig. 8 shows product gas generation rate graphs for co-pyrolysis of the spirulina with the product DW-NZ of Example 1;

Fig 9 shows product gas generation rate graphs for pyrolysis of a willow sample alone;

Fig. 10 shows product gas generation rate graphs for co-pyrolysis of the willow sample with the product DW-NZ of Example 1;

Fig. 11 is an X-ray diffraction (XRD) spectrum of the product DW-NZ of Example 2;

Figure 12 shows a CO2 cycle adsorption performance graph of the product DW-NZ of Example 2; Figure 13 shows a CO2 cycle adsorption performance graph of the product DW-NZ of Example 3; Fig. 14 shows CO2 cycle adsorption performance original data graphs of the product DW-NZ of Example 1 (obtained from analytical software Universal Analysis);

Fig. 15 shows CO2 cycle adsorption performance original data graphs of the product DW-NZ of Example 2 (obtained from analytical software Universal Analysis); and

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Fig. 16 shows CO2 cycle adsorption performance original data graphs of the product DW-NZ of Example 3 (obtained from analytical software Universal Analysis).

Detailed Description of the Invention

To facilitate understanding of those skilled in the art, the concepts of the present invention are further described below in connection with examples. At the same time, the various raw materials referred to in the description are commercially available, and the crown materials used in this batch of examples are available from a batch of crown materials produced by Beijing Jingyi All-ceramic Machining Center.

Example 1

1.1476 G of sodium carbonate solid and 1.4389 g of crown material waste having a zirconia content of 92.53% analyzed by X-ray fluorescence (XRF) were weighed, mixed, and placed in a ball mill for milling at 500 rpm for 2 h. The resulting powder was then placed in a muffle furnace for calcination based on a procedure comprising raising the temperature from 20 °C to 850 °C and calcining at a constant temperature 850 °C for 6 h to obtain the product.

Example 2

1.3779 G of sodium carbonate solid and 1.4389 g of crown material waste having a zirconia content of 92.53% analyzed by X-ray fluorescence (XRF) were weighed, mixed, and placed in a ball mill for milling at 550 rpm for 1.5 h. The resulting powder was then placed in a muffle furnace for constant temperature calcination at 800 °C for 5 h to obtain the product.

Example 3

1.1476 G of sodium carbonate solid and 1.4389 g of crown material waste having a zirconia content of 92.53% analyzed by X-ray fluorescence (XRF) were weighed, mixed, and the resulting powder was then culminated at a constant temperature 750 °C for 8 h to obtain the product. Example 4

1) Adsorption effect test for the product produced in Example 1 of the present invention

Firstly, the product obtained in Example 1 was subjected to an X-ray diffraction (XRD) characterization to obtain an X-ray diffraction (XRD) spectrum as shown in FIG. 1.

Table 1 Intensity ratios of different marked peaks of Figure 1

Marked Peaks	2Θ	Hexagonal Crystal Form	Monoclinic Crystal Form	Sodium Zirconate Synthesized By This Patent
Ia/Imax	16.16	1	0.37	0.48
Ib/Imax	32.2	0.06	0.23	0.19
Ic/Imax	33.6	0.1	0.4	0.41

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Id/Imax	38.7	0.02	1	0.85
Ie/Imax	50.6	0.06	0.12	0.19
li/Imax	55.3	0.1	0.25	0.30
Ig/Imax	56.6	0.06	0.27	0.37

It can be seen from the XRD test that the main component of the product obtained by the method is NaiZrCh, which is an active component for absorbing carbon dioxide. The hexagonal crystal form and the monoclinic crystal form are two crystal forms of Na^ZrCL. Among them, the monoclinic crystal form has stronger adsorption activity, and is more favorable for carbon capture. In the XRD spectrum, the peaks of the two crystal form appear in a same position, so it is necessary to determine which crystal form is more consistent by calculating the peak intensity ratio (the peak intensity at the x position compared with the intensity of the maximum intensity peak appearing in the spectrum, denoted as Ix/Imax). The intensities of different marked peaks of the NaiZrCh sample synthesized in Example 1 of the present patent were as shown in Table 1. It can be seen that the seven peaks of a-g were more consistent with the monoclinic crystal form.

The material obtained in Example 1 was placed in a thermogravimetric analyzer (TGA) for cycle stability test and CO2 adsorption performance test. The procedure for TGA to carry out the cycle stability test comprised: 1. selecting nitrogen as the sample gas; 2. keeping a constant temperature for 10 min; 3. raising the temperature to 850 °C from room temperature at a rate of 10 °C/min; 4. keeping a constant temperature for 10 min; 5. decreasing the temperature from 850 °C to 600 °C at a rate of 10 °C/min; 6. selecting carbon dioxide as the sample gas; 7. keeping a constant temperature for 10 min; and 8. cycling 30 times from the third step. The concentration at which carbon dioxide was absorbed at 600 °C was 15%, and the balance was nitrogen. The original graph obtained as shown in Fig. 14 shows that the left Y-l axis was the weight axis and the right Y-2 axis was the temperature axis. With the adsorption and desorption process, the weight and temperature varied with time to form a Y-1 weight variation line and a Y-2 temperature variation line. The original Figure 14 was processed by software to obtain the Figure 2. The theoretical adsorption capacity of NihZrCL for CO2 is 23.7%. It can be seen from the analysis of the two graphs that, when the adsorption and desorption time were both 10 min, the carbon dioxide adsorption capacity was stabilized at 17% or more and the highest was up to 18.1% when the carbon dioxide concentration was 15% from the second cycle, reaching more than 70% of the theoretical adsorption capacity of Na2ZrOs, and the highest being up to 76.4%. It can be seen from the figure that up to the last cycle of the experimental test, that is, the 30^th cycle, the product of the present invention can still maintain a stable adsorption capacity.

Lorena Martinez-dlCruz et.al prepared sodium zirconate by using a solid phase synthesis method,

2019101001 16Apr2019 comprising: using pure sodium carbonate and zirconia, firstly mechanical mixing, and calcining at 850 DEG C for 6h. The amount of sodium carbonate was increased by 20 percent than the theoretical adding amount. When the adsorption temperature were 600 DEG and 700 DEG, the atmosphere was pure carbon dioxide, the adsorption time was 30 min, the temperature of desorption of carbon dioxide was 800 DEG, the atmosphere was nitrogen, and desorption time was more than 15 min. The adsorption time and desorption time were too long. At the same time, the number of cycles completed was small, and pure sodium carbonate and zirconia samples were required, and the amount of sodium carbonate added was 1.2 times the theoretical amount. Example 5

Methylcellulose (Vetec) was mixed with the product synthesized in Example 1 at 1:1, and then tested in a thermogravimetric mass spectrometer (TGA-MS). The TGA model was SDT Q600, and the MS model was HPR20. The heating procedure of the TGA was such that the temperature was raised from room temperature to 900 °C at a heating rate of 40 °C/min. It can be seen from the comparison between Fig. 3 and Fig. 4 that the secondary generation temperature of hydrogen was advanced from 600 DEG to before 500 DEG, which was conducive to the reduction of energy consumption, and there was a clear peak of carbon monoxide between 600 DEG and 800 DEG, demonstrating that the steam reforming reaction was enhanced: CH4+H2O—3H2+CO. It can be seen from Table 1 that the hydrogen production added with the synthetic product was nearly doubled compared to the hydrogen production without the addition of the synthetic product.

Table 1 Sample cumulative gas production (ml g'¹)

Sample	h₂	ch₄	CO	CO₂
Methylcellulose	111	28	110	92
Methyl cellulose	mixed with 218	22	181	114
DW-NZ at 1:1

Example 6

The sludge sample (the sixth sewage treatment plant in Kunming, Yunnan Province) was firstly placed in a dry box, dried at 105 ⁰ C for 12 h, and the dried sample was pulverized by a pulverizer; the samples capable of passing through an 80-mesh sieve were selected, mixed with the product (DW-NZ) synthesized in Example 1 at 1:1 and then tested in a TGA-MS. The TGA model was SDT Q600, and the MS model was HPR20. The heating procedure of the TGA was such that the temperature was raised from room temperature to 900 °C at a heating rate of 40 °C/min. It can be seen from the comparison between Fig. 5 and Fig. 6 that the generation temperature of hydrogen was advanced from 500 DEG to nearly 400 DEG, which was conducive to the reduction of energy consumption, and there was a clear peak increasing of carbon monoxide between 600 DEG and

800 DEG, demonstrating that the steam reforming reaction was enhanced: CFL+HiO^.SHi+CO. It can be seen from Table 2 that the hydrogen production added with the DW-NZ was nearly doubled compared to the hydrogen production without the addition of the DW-NZ.

Table 2 Sample cumulative gas production (ml g'¹)

Sample	h₂	ch₄	co	co₂
sludge	67	7	41	42
sludge mixed with DW-NZ	136	10	81	72

at 1:1

Example 7

The spirulina sample (Valley) was mixed with the sample synthesized in Example 1 (DW-NZ) at 1:1 and then tested in a TGA-Ms. The TGA model was SDT Q600, and the MS model was HPR20. The heating procedure of the TGA was such that the temperature was raised from room temperature to 900 °C at a heating rate of 40 °C/min. It can be seen from the comparison between Fig. 7 and Fig. 8 that the generation temperature of hydrogen was advanced from 480 DEG to nearly 450 DEG, which was conducive to the reduction of energy consumption. During the pyrolysis process of adding DW-NZ, the hydrogen generation rate is up to 39.03 ml min¹ g'¹, which was nearly four times higher than the hydrogen generation rate of the pyrolysis process without adding DW-NZ (the highest hydrogen production rate of the spiral pyrolysis alone was 10.77 ml min¹ g'¹); and there was a clear peak increasing of carbon monoxide between 600 DEG and 800 DEG, demonstrating that the steam reforming reaction was enhanced: Ctfr+tEO^ 3H2+CO. It can be seen from Table 3 that the hydrogen production added with the DW-NZ was nearly doubled compared to the hydrogen production without the addition of the DW-NZ.

Table 3 Sample cumulative gas production (ml g'¹)

Sample H₂ CH₄ CO CO₂

Spirulina

14 33 68 spirulina mixed with DW-NZ 207 13 103 88 at 1:1

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Example 8

The willow sample (Chenzhou City, Hunan Province) was firstly placed in a dry box, dried at 105 °C for 12 h, and the dried sample was pulverized by a pulverizer; the samples capable of passing through a 42-mesh sieve were selected, mixed with the synthetic product (DW-NZ) in Example 1 at 1:1 and then tested in a TGA-MS. The TGA model was SDT Q600, and the MS model was HPR20. The heating procedure of the TGA was such that the temperature was raised from room temperature to 900 °C at a heating rate of 40 °C/min. It can be seen from the comparison between Fig. 9 and Fig. 10 that the secondary generation temperature of hydrogen was advanced from 513 DEG to nearly 442 DEG, which was conducive to the reduction of energy consumption, and there was a clear peak increasing of carbon monoxide between 600 DEG and 800 DEG, demonstrating that the steam reforming reaction was enhanced: CH4+H2O—3H2+CO. It can be seen from Table 3 that the hydrogen production added with the DW-NZ was increased by 59 ml g'¹ compared to the hydrogen production without the addition of the DW-NZ.

Table 4 Sample cumulative gas production (ml g ^_1)

Sample	h₂	ch₄	CO	CO₂
willow sample	166	5	90	73
willow sample	mixed with 225	6	145	73
DW-NZ at 1:1

Example 9

1) Adsorption effect test for the product produced in Example 2 of the present invention

Firstly, the product obtained in Example 2 was subjected to an X-ray diffraction (XRD) characterization to obtain an X-ray diffraction (XRF) spectrum as shown in FIG. 11.

Marked Peak	20	Hexagonal Crystal Form	Monoclinic Crystal Form	Sodium Zirconate Synthesized In This Example
Ia/Imax	16.16	1	0.37	0.47
Ib/Imax	32.2	0.06	0.23	0.2
Ic/Imax	33.6	0.1	0.4	0.38
Id/Imax	38.7	0.02	1	0.82

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Ie/Imax	50.6	0.06	0.12	0.36
li/Imax	55.3	0.1	0.25	0.25
Ig/Imax	56.6	0.06	0.27	0.34

It can be seen from the XRD test that the main component of the product obtained by the method is NaiZrCh, which is an active component for absorbing carbon dioxide. The hexagonal crystal form and the monoclinic crystal form are two crystal forms of NaiZrCh. Among them, the monoclinic crystal form has stronger adsorption activity, and is more favorable for carbon capture. In the XRD spectrum, the peaks of the twocrystal form appear in a same position, so it is necessary to determine which crystal form is more consistent by calculating the peak intensity ratio (the peak intensity at the x position compared with the intensity of the maximum intensity peak appearing in the spectrum, denoted as Ix/Imax). The intensities of different marked peaks of the NaiZrCh sample synthesized in the Example 2 of the present patent were as shown in Table 1. It can be seen that the seven peaks of a-g were more consistent with the monoclinic crystal form. The material obtained in Example 2 was placed in a thermogravimetric analyzer (TGA) for cycle stability test and CO2 adsorption performance test. The procedure for TGA to carry out the cycle stability test comprised: 1. selecting nitrogen as the sample gas; 2. keeping a constant temperature for 10 min; 3. raising the temperature to 850 °C from room temperature at a rate of 10 °C/min; 4. keeping a constant temperature for 10 min; 5. decreasing the temperature from 850 °C to 600 °C at a rate of 10 °C/min; 6. selecting carbon dioxide as the sample gas; 7. keeping a constant temperature for 10 min; and 8. cycling 30 times from the third step to obtain adsorption result original graphs of 30 cycles as shown in Figure 15 and the processed graphs as shown in Figure 12. The theoretical adsorption capacity of Na^ZrCh to CO2 is 23.7%. The adsorption time and desorption time were both 10 min. The adsorption capacity of carbon dioxide in the second cycle reached 18.9%. After that, the cycle adsorption results up to the 30^th cycle indicate that the carbon dioxide adsorption capacity was maintained above 20% and increased continuously.

Example 10

The material obtained in Example 3 was placed in a thermogravimetric analyzer (TGA) for cycle stability test and CO2 adsorption performance test. The procedure for TGA to carry out the cycle stability test comprised: 1. selecting nitrogen as the sample gas; 2. keeping a constant temperature for 10 min; 3. raising the temperature to 850 °C from room temperature at a rate of 10 °C/min; 4. keeping a constant temperature for 10 min; 5. decreasing the temperature from 850 °C to 600 °C at a rate of 10 °C/min; 6. selecting carbon dioxide as the sample gas; 7. keeping a constant temperature for 10 min; and 8. cycling 30 times from the third step to obtain adsorption result original graphs of 30 cycles as shown in Figure 16 and the processed graphs as shown in Figure 13.

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The theoretical adsorption of Na₂ZrO3 to CO₂ is 23.7%. The adsorption time and desorption time were both 10 min in the example. Although the adsorption capacities in the first few cycles were relatively low, with the increase in the number of cycles, the carbon dioxide adsorption continued to rise up to the 30^th cycle of the test.

Claims

1. A method for synthesizing sodium zirconate, comprising the following steps:

2. The method for synthesizing sodium zirconate of claim 1, wherein the crown material waste is YSZ.

3. The method for synthesizing sodium zirconate of claim 1, wherein the calcining temperature is 850 °C and the calcining time is 6 hours in step (2).

4. The method for synthesizing sodium zirconate of claim 1, wherein the molar mass ratio of zirconium dioxide to the sodium carbonate solid contained in the YSZ solid in step (1) is 1:(1-1.2).

5. The method for synthesizing sodium zirconate of claim 1, wherein the YSZ is milled prior to or after mixing with the sodium carbonate solid in step (1).

6. The method for synthesizing sodium zirconate of claim 5, wherein the YSZ solid is milled prior to or after mixing with the sodium carbonate solid in step (1) using a ball mill at a speed of 500-550 rpm for a ball milling time of 1.5h-2h.

7. The method for synthesizing sodium zirconate of claim 6, wherein the speed of the ball mill is 500 rpm, the ball milling time is 2h, and the molar mass ratio of zirconium dioxide to the sodium carbonate solid contained in the YSZ solid in step (1) is 1:1.

8. Use of the method for synthesizing sodium zirconate of any one of claims 1-7 in a carbon dioxide adsorbent.

9. Use of the method for synthesizing sodium zirconate of any one of claims 1-7 in hydrogen production process from biomass or biomass waste pyrolysis.

10. The use of claim 9, wherein the biomass is methyl cellulose or spirulina or willow sample, and the biomass waste is sludge.