A preparation method of an acid-modified encapsulated metal catalyst for improving tar quality

Abstract

The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. 2‑ The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field of energy chemical industry. The application discloses a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, and belongs to the technical field

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy chemical industry, and particularly relates to a preparation method of acid-modified encapsulated metal catalyst for improving tar quality. BACKGROUND

[0002] Since the Ni-based catalyst prepared by the encapsulation method makes the metal Ni mainly participate in the activation of the hydrogen-rich gas, no other active sites participate in the cracking of the tar except the acidity of the molecular sieve, so the cracking performance of the tar needs to be enhanced.

[0003] Studies have shown that the acid sites in the catalyst play a very important role in the catalytic cracking of the tar, can reduce the activation energy required in the cracking process of the tar, and promote the bond breaking by accepting an electron pair or providing a proton H. The solid acid catalyst is widely used in the fields of petroleum chemical industry and biomass conversion as a common acid catalyst, and the solid acid catalyst can be recycled and reused, which meets the theme of environment-friendly development. The sulfated metal oxide catalyst (SO4 2- / M x O y ) as one of the solid acid catalysts has excellent acid properties and no corrosivity, and is widely used in the catalytic industry. The researchers produce mesopores through alkali treatment desilication, which also causes the loss of part of the acid sites, so the subsequent SO4 2- / ZrO2 (SZ) is loaded to improve the acidity and acid amount of the molecular sieve. It is found that compared with the non-catalytic, the total yield of the light components in the tar is obviously improved, because the super strong acid sites formed by the SZ increase the cracking of the heavy tar components and improve the yield of the light components. However, when the proportion of H2SO4 continues to increase, the excessive H2SO4 will cause the destruction of the HZSM-5 molecular sieve structure, the amorphous deposits appear and further accumulate on the surface of the molecular sieve and block the pore structure of the molecular sieve, so that the active components are lost in large amounts and the tar cracking activity is poor. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, load metal zirconium and use ammonium sulfate for acidification, enhance the acidity of the catalyst, thereby improve the tar cracking capacity, encapsulate the metal active sites in the inside of the molecular sieve, activate the H2, CH4 and other hydrogen-rich gases generated in the pyrolysis system, thereby generate ·H and ·CH x and other small molecule free radicals to stabilize the tar cracking fragments, and further realize the purpose of improving the tar quality and the light oil yield.

[0005] To achieve the above object, the application provides a preparation method of acid-modified encapsulated metal catalyst for improving tar quality, which comprises the following steps: 2- The application also provides a preparation method of Ni@HZSM-5-SZ molecular sieve, which comprises the following steps:

[0006] S1, preparing Ni@HZSM-5 molecular sieve;

[0007] S2, preparing Ni@HZSM-5-SZ molecular sieve by using the Ni@HZSM-5 molecular sieve prepared in S1.

[0008] Preferably, the specific operation of S1 is as follows:

[0009] S11, putting a certain amount of TPAOH, H2O and KH-590 into a beaker, mixing and stirring for 8 h, then adding a certain amount of Ni(NO3)2·6H2O solution with a certain concentration into the mixed solution and stirring for 0.5 h, and then slowly adding a certain amount of TEOS into the mixed solution and stirring for 13 h;

[0010] S12, preparing a transparent solution by using a certain amount of TPAOH, H2O, NaOH and Al2(SO4)3·18H2O, and slowly adding the solution into the mixed solution of S11 and stirring for 2 h in a water bath at 80 ℃;

[0011] S13, putting the obtained gel into a reactor and crystallizing in a homogeneous reactor;

[0012] S14, centrifuging the catalyst obtained after crystallization to neutral, drying overnight, and calcining the dried sample in a muffle furnace to obtain a Ni@NaZSM-5 molecular sieve sample;

[0013] S15, preparing an NH4NO3 solution, stirring the Ni@NaZSM-5 molecular sieve and the NH4NO3 solution in an oil bath, repeating the operation once after filtration and washing, drying and calcining to obtain a Ni@HZSM-5 molecular sieve.

[0014] Preferably, the specific operation of S2 is as follows:

[0015] S21, dissolving a certain amount of Zr(NO3)2·5H2O in deionized water, then adding the prepared Ni@HZSM-5 molecular sieve into the solution, ultrasonically treating the mixture for 3 h, drying after filtration and washing, and calcining under N2 atmosphere to obtain a sample, which is denoted as Ni@HZSM-5-Z molecular sieve;

[0016] S22, preparing (NH4)2SO4 solution, mixing the sample prepared in S21 with (NH4)2SO4 solution and stirring, then filtering and washing to neutral, drying, and then calcining, and the obtained catalyst is named as Ni@HZSM-5-SZ molecular sieve;

[0017] S23, after calcining the obtained Ni@HZSM-5-SZ molecular sieve at 700 DEG C under H2 atmosphere for 2h, tabletting the Ni@HZSM-5-SZ molecular sieve, crushing and sieving to 20-40 meshes, and then an acid-modified encapsulated metal catalyst is obtained.

[0018] Preferably, the mass fraction of the loaded zirconium is 1%, 3%, 5%, or 7%.

[0019] Preferably, the crystallization process in S13 is first crystallization at 100 DEG C for 48h, and then crystallization at 170 DEG C for 24h.

[0020] Preferably, the drying temperature in S14 is 100 DEG C, the calcination temperature in the muffle furnace is 550 DEG C, and the calcination time is 5h.

[0021] Preferably, the concentration of the NH4NO3 solution in S15 is 1mol / L, and the solid-liquid ratio of the Ni@NaZSM-5 molecular sieve and the NH4NO3 solution is 1:15.

[0022] Preferably, the oil bath temperature in S15 is 80 DEG C, the oil bath stirring time is 4h, the drying temperature is 100 DEG C, the drying time is 12h, the calcination temperature is 500 DEG C, and the calcination time is 5h.

[0023] Preferably, the amount of the deionized water in S21 is 75mL, the amount of the Ni@HZSM-5 molecular sieve is 5g, the drying temperature is 80 DEG C, the drying time is 12h, the calcination temperature is 300 DEG C, and the calcination time is 3h.

[0024] Preferably, the concentration of the (NH4)2SO4 solution in S22 is 0.5mol / L, the solid-liquid ratio of the sample and the (NH4)2SO4 solution is 1:15, the drying temperature is 110 DEG C, the drying time is 12h, the calcination temperature is 600 DEG C, and the calcination time is 5h.

[0025] The present application is based on a Ni@HZSM-5 molecular sieve catalyst, and different proportions of SZ are loaded to enhance the acidity of the catalyst. Since H2SO4 is used in the preparation process and can damage the structure of the molecular sieve, ammonium sulfate is used for acidification, thereby creating a catalyst for tar cracking and hydrogen-rich gas activation and hierarchical regulation, and the change rule of the properties of the tar in the in-situ lightening process of the tar is investigated.

[0026] Therefore, the application adopts the above-mentioned preparation method of the acid-modified encapsulated metal catalyst for improving tar quality, and has the following beneficial effects.

[0027] (1) The application uses (NH4)2SO4 to modify the acid of Ni@HZSM-5 molecular sieve, which prevents the destruction of the structure of HZSM-5 molecular sieve caused by the use of H2SO4.

[0028] (2) The Ni@HZSM-5-SZ molecular sieve catalyst prepared by the application has SO4 2- which is usually combined with ZrO2 in a coordination form to form superacid sites.

[0029] (3) The Ni@HZSM-5-SZ molecular sieve catalyst prepared by the application and applied to the process of coal pyrolysis tar lightening significantly improves the acidity of the catalyst and avoids the problem of insufficient tar cracking performance. It has important significance for the lightening of tar and the improvement of tar quality, and also provides a new way and idea for realizing the directional regulation of substances in the process of tar lightening.

[0030] The technical solutions of the application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the NH3-TPD curve of different molecular sieve catalysts in the preparation method of the acid-modified encapsulated metal catalyst for improving tar quality of the application;

[0032] Figure 2 is the N2 adsorption-desorption curve of different molecular sieve catalysts in the preparation method of the acid-modified encapsulated metal catalyst for improving tar quality of the application. DETAILED DESCRIPTION

[0033] The technical solutions of the application will be further described in detail below with reference to the drawings and examples.

[0034] Unless otherwise defined, the technical terms or scientific terms used in the application should be understood as the usual meanings understood by those skilled in the art to which the application belongs.

[0035] EMBODIMENT

[0036] The application provides a preparation method of an acid-modified encapsulated metal catalyst for improving tar quality, which acidifies Ni@HZSM-5 by loading SO4 2- / ZrO2 to prepare Ni@HZSM-5-SZ molecular sieve, and the mass fraction of zirconium in the loading is 1%, 3%, 5%, and 7%, and the method specifically includes the following steps:

[0037] S1, preparing Ni@HZSM-5 molecular sieve, the specific operation is:

[0038] S11, a certain amount of TPAOH, H2O and KH-590 are put into a beaker, mixed and stirred for 8h, then a certain amount of Ni(NO3)2·6H2O solution is added to the mixed solution and stirred for 0.5h, and a certain amount of TEOS is slowly added to the mixed solution, and stirred for 13h.

[0039] S12, a certain amount of TPAOH, H2O, NaOH and Al2(SO4)3·18H2O are prepared into a transparent solution, which is slowly added to the mixed solution of S11, and stirred at 80℃ water bath for 2h.

[0040] TPAOH acts as a template agent for synthesizing ZSM-5 molecular sieve, and plays a role of channel growth regulator. KH-590 is a silane coupling agent, which complex metal ions on the material by using special groups. Ni(NO3)2·6H2O is the Ni source in the preparation process of the catalyst, Al2(SO4)3·18H2O is the Al source, which provides metal source for the synthesis process of the molecular sieve, TEOS is the silicon source, which hydrolyzes to form SiO2 under high temperature and high pressure, and forms molecular sieve crystals with other metal sources. NaOH provides an alkaline environment for the synthesis process.

[0041] S13, the obtained gel is loaded into the reactor, and crystallized at 100℃ for 48h in a homogeneous reactor, and then crystallized at 170℃ for 24h.

[0042] S14, the obtained catalyst after crystallization is centrifuged to neutral, dried at 100℃ overnight, and the dried sample is calcined at 550℃ in a muffle furnace for 5h, to obtain a Ni@NaZSM-5 molecular sieve sample.

[0043] S15, a 1mol / L NH4NO3 solution is prepared, the Ni@NaZSM-5 molecular sieve and the NH4NO3 solution are stirred at a solid-liquid ratio of 1:15 in an 80℃ oil bath for 4h, after filtration and washing, the operation is repeated once, dried at 100℃ for 12h, and calcined at 500℃ for 5h, to obtain a Ni@HZSM-5 molecular sieve.

[0044] S2, using the Ni@HZSM-5 molecular sieve prepared above to prepare Ni@HZSM-5-SZ molecular sieve, the specific operation is:

[0045] S21, a certain amount of Zr(NO3)2·5H2O is dissolved in 75mL deionized water, then 5g of prepared Ni@HZSM-5 molecular sieve is added to the solution, the mixture is ultrasonically treated for 3h, filtered and washed, dried at 80℃ for 12h, and calcined at 300℃ under N2 atmosphere for 3h, to obtain a sample represented as Ni@HZSM-5-Z molecular sieve.

[0046] S22, a 0.5 mol / L (NH4)2SO4 solution was prepared, the sample prepared in S21 was mixed with the (NH4)2SO4 solution at a solid-liquid ratio of 1:15, followed by filtration and washing to neutral, drying at 110°C for 12h, and then calcining at 600°C for 5h, and the obtained catalyst was named as Ni@HZSM-5-SZ molecular sieve.

[0047] S23, the obtained Ni@HZSM-5-SZ molecular sieve was calcined at 700°C for 2h under H2 atmosphere, and then the Ni@HZSM-5-SZ molecular sieve was tablet-pressed, crushed, and sieved to 20-40 mesh to obtain an acid-modified encapsulated metal catalyst.

[0048] In the following examples, the coal sample was a Xilingol coal from Inner Mongolia, and the upgrading process of the coal tar was carried out in a stainless steel fixed bed reactor with an inner diameter of 14mm and a length of 290mm. The reactor was a vertical two-layer structure, and the coal, quartz wool, catalyst, and quartz wool were placed from top to bottom. A gas inlet was provided at the top of the reactor, and an outlet was provided at the bottom of the reactor. The liquid products generated by pyrolysis were collected by N2 carrying and -20°C cold hydrazine cooling, and the light oil content in the oil product was obtained after simulated distillation analysis. The pyrolysis oil yield and light oil yield (dry ash-free basis) were calculated as follows:

[0049]

[0050] Light oil yield = oil yield × light oil content

[0051] Wherein, W 油品 is the mass of the oil product; W0 is the mass of the coal sample; A ad is the ash content in the coal; M ad is the moisture content in the coal.

[0052] Example 1

[0053] Catalyst preparation: 0.235g of Zr(NO3)2·5H2O was dissolved in 75mL of deionized water. Then 5g of the prepared Ni@HZSM-5 molecular sieve catalyst was added to the solution, and the mixture was ultrasonicated for 3h, followed by filtration, washing, drying at 80°C for 12h, and calcining at 300°C for 3h under N2 atmosphere to obtain a Ni@HZSM-5-1Z molecular sieve.

[0054] A (NH4)2SO4 solution with a concentration of 0.5 mol / L was prepared, and the Ni@HZSM-5-1Z molecular sieve was mixed with the (NH4)2SO4 solution at a solid-liquid ratio of 1:15 and stirred for 1 h, then filtered and washed to neutral, dried at 110°C for 12 h, and then calcined at 600°C for 5 h, and the obtained catalyst was named as Ni@HZSM-5-1SZ molecular sieve. The Ni@HZSM-5-1SZ molecular sieve was calcined at 550°C for 5 h in a muffle furnace, and then calcined at 700°C for 2 h under a H2 atmosphere, and then crushed and sieved to 20-40 mesh for use.

[0055] The NH3-TPD analysis of the obtained Ni@HZSM-5-SZ molecular sieve is shown in Figure 1 The N2 adsorption-desorption curve and pore structure are shown in Figure 2 and Table 1.

[0056] Table 1 Structural characteristics of different catalysts

[0057]

[0058] Catalyst performance evaluation: Before the reaction, the catalyst was reduced and activated at 600°C under a H2 atmosphere for 1 h, the reaction temperature was 600°C, the N2 flow rate was 300 mL / min, the heating furnace reached the specified temperature within 10 min and was maintained for 30 min, the catalyst dosage was 1 g, the coal sample was 5 g, and the experiment was carried out in a fixed bed reactor.

[0059] This is because the loaded solid acid further increases the cracking of tar, and the tar fragments are timely stabilized by the hydrogen-rich free radicals generated by the activated hydrogen-rich gas and metal Ni, which realizes the lightening of tar while ensuring the yield of tar, and achieves the hierarchical regulation of hydrogen-rich gas activation and tar cracking. Figure 1 The NH3-TPD analysis of different catalysts can be seen that, after loading SZ, superacid acid sites are formed, which participate in the tar cracking process.

[0060] Example 2

[0061] Catalyst preparation: According to Example 1, the difference between this embodiment and Example 1 is that the Zr content in the Ni@HZSM-5-SZ molecular sieve catalyst is 3 wt.%, which is represented as Ni@HZSM-5-3SZ molecular sieve.

[0062] The NH3-TPD analysis of the obtained Ni@HZSM-5-3SZ molecular sieve is shown in Figure 1 The N2 adsorption-desorption curve and pore structure are shown in Figure 2 and Table 1.

[0063] Catalyst performance evaluation: the experimental conditions refer to Example 1, by Figure 1 It can be seen from the NH3-TPD analysis of different catalysts that this is due to the further increase in the number of superacidic acid sites and the further improvement in the tar cracking performance as the loading of SZ increases.

[0064] Example 3

[0065] Catalyst preparation: refer to Example 1, the difference between this example and Example 1 is that the Zr content in the Ni@HZSM-5-5SZ molecular sieve catalyst is 5wt.%, which is represented as Ni@HZSM-5-5SZ molecular sieve.

[0066] The NH3-TPD analysis of the prepared Ni@HZSM-5-5SZ molecular sieve is shown in Figure 1 The N2adsorption-desorption curve and pore structure are shown in Figure 2 and Table 1.

[0067] Catalyst performance evaluation: the experimental conditions refer to Example 1, by Figure 1 It can be seen from the NH3-TPD analysis of different catalysts that the acid sites of the Ni@HZSM-5-5SZ molecular sieve are further increased, from Figure 2 It can be seen from the N2adsorption-desorption analysis of different catalysts and Table 1 that when the loading is 5SZ, the specific surface area and pore volume of the micropore are 182m 2 / g and 0.07cm 3 / g, the total specific surface area and total pore volume are 344m 2 / g and 0.38cm 3 / g, which is slightly smaller than that of the Ni@HZSM-5-3SZ molecular sieve, indicating that the SZ accumulated on the surface of the molecular sieve blocks a small part of the pore channels of the molecular sieve.

[0068] Example 4

[0069] Catalyst preparation: refer to Example 1, the difference between this example and Example 1 is that the Zr content in the Ni@HZSM-5-7SZ molecular sieve catalyst is 7wt.%, which is represented as Ni@HZSM-5-7SZ molecular sieve.

[0070] The NH3-TPD analysis of the prepared Ni@HZSM-5-7SZ molecular sieve is shown in Figure 1 The N2adsorption-desorption curve and pore structure are shown in Figure 2 and Table 1.

[0071] Catalyst performance evaluation: the experimental conditions refer to Example 1, by Figure 1 It can be seen from the NH3-TPD analysis of different catalysts that the Ni@HZSM-5-7SZ molecular sieve has more acid sites, but fromFigure 2 The N2 adsorption-desorption analysis and the structural characteristics of different catalysts in Table 2 show that when the loading amount is 7SZ, the specific surface area and pore volume of micropores decrease to 154 m2 / g and 0.05 cm3 / g, respectively. 2 3 The total specific surface area and total pore volume decrease to 312 m2 / g and 0.34 cm3 / g, respectively. 2 3 / g, which indicates that the SZ accumulated on the surface of the molecular sieve blocks the pores of the molecular sieve, affects the mass transfer in the reaction process, and easily leads to an accelerated carbon deposition deactivation rate of the catalyst.

[0072] Comparative Example 1

[0073] Catalyst preparation: 16.5 mL of TPAOH, 4.125 mL of H2O, and 0.125 mL of KH-590 were taken into a beaker, mixed and stirred for 8 h, then 6.54 mL of a nickel nitrate solution with a concentration of 0.1 mol / L was added to the mixed solution and stirred for 0.5 h. Then 23.12 mL of TEOS was slowly added to the mixed solution, and stirring was continued for 13 h; 13.125 mL of TPAOH, 6.75 mL of water, 0.125 mL of NaOH, and 1.381 g of aluminum sulfate were prepared into a transparent solution, and the prepared transparent solution was slowly added to the previous mixed solution, stirred for 2 h under a water bath at 80°C, then loaded into a reactor, and crystallized at 100°C for 48 h and at 170°C for 24 h; the obtained catalyst was centrifuged to neutral, dried at 100°C overnight, then calcined at 550°C in a muffle furnace for 5 h, to obtain a Ni@NaZSM-5 molecular sieve.

[0074] A 1 mol / L NH4NO3 solution was prepared, the Ni@NaZSM-5 molecular sieve and the ammonium nitrate solution were stirred at a ratio of 15 mL / g in an 80°C oil bath for 4 h, after filtration and washing, the operation was repeated once, and the obtained catalyst was dried at 100°C for 12 h; calcined at 550°C in a muffle furnace for 5 h to obtain a Ni@HZSM-5 molecular sieve; the obtained Ni@HZSM-5 molecular sieve was calcined under a H2 atmosphere at 700°C for 2 h, and then crushed and sieved to 20-40 mesh for use.

[0075] The NH3-TPD analysis of the obtained Ni@HZSM-5 molecular sieve is shown in Figure 1 The N2 adsorption-desorption curve and the pore structure are shown in Figure 2 and Table 1.

[0076] Catalyst performance evaluation: the experimental conditions refer to Example 1, and since the loaded SZ forms super strong acid sites, the tar cracking process is promoted, and the Figure 1 The reaction results are consistent with the technical scheme of the present application.​​

[0077] Therefore, the application adopts the above-mentioned preparation method of acid-modified encapsulated metal catalyst for improving tar quality to modify the encapsulated metal catalyst, creates an acid-modified encapsulated metal catalyst for hierarchical regulation of tar cracking and hydrogen-rich gas activation, and achieves the purposes of improving tar cracking yield and the yield and content of light oil products. The method solves the problems of insufficient performance of encapsulated metal catalysts for tar cracking and low tar yield. It is of great significance to improve the acidity of molecular sieve catalysts, improve tar quality, and improve light tar yield.

[0078] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing an acid-modified encapsulated metal catalyst to improve tar quality, by supporting SO4 2- / ZrO2 is used to acidify Ni@HZSM-5 to prepare Ni@HZSM-5-SZ molecular sieve, characterized in that: Includes the following steps: S1. Preparation of Ni@HZSM-5 molecular sieve; the specific operation of S1 is as follows: S11. Take a certain amount of TPAOH, H2O and KH-590 and put them into a beaker. Mix and stir for 8 hours. Then add a certain amount of Ni(NO3)2·6H2O solution to the mixed solution and stir for 0.5 hours. Then slowly add a certain amount of TEOS to the mixed solution and stir for 13 hours. S12. Take a certain amount of TPAOH, H2O, NaOH and Al2(SO4)3·18H2O to prepare a transparent solution, and slowly add it dropwise to the mixed solution of S11. Stir in a water bath at 80℃ for 2 hours. S13. After the obtained gel is packed into a reactor, it is crystallized in a homogeneous reactor; S14. Centrifuge the crystallized catalyst until neutral, dry overnight, and calcine the dried sample in a muffle furnace to obtain Ni@NaZSM-5 molecular sieve sample. S15. Prepare NH4NO3 solution. Stir Ni@NaZSM-5 molecular sieve and NH4NO3 solution in an oil bath. After filtration and washing, repeat the operation once. Dry and calcine to obtain Ni@HZSM-5 molecular sieve. S2. Prepare Ni@HZSM-5-SZ molecular sieve using the Ni@HZSM-5 molecular sieve prepared in S1; the specific operation of S2 is as follows: S21. Dissolve a certain amount of Zr(NO3)2·5H2O in deionized water, then add the prepared Ni@HZSM-5 molecular sieve to the solution, sonicate the mixture for 3 hours, filter, wash and dry, and calcine under N2 atmosphere. The obtained sample is represented as Ni@HZSM-5-Z molecular sieve. S22. Prepare (NH4)2SO4 solution. Mix and stir the sample prepared in S21 with (NH4)2SO4 solution, then filter and wash until neutral, dry, and then calcine. Name the obtained catalyst Ni@HZSM-5-SZ molecular sieve. S23. The obtained Ni@HZSM-5-SZ molecular sieve was calcined at 700℃ for 2 hours under H2 atmosphere, and then the Ni@HZSM-5-SZ molecular sieve was pressed into tablets, crushed, and sieved to 20-40 mesh to obtain an acid-modified encapsulated metal catalyst.

2. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The zirconium mass fraction in the load is 1%, 3%, 5%, or 7%.

3. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The crystallization process in S13 is as follows: first crystallize at 100℃ for 48 hours, then continue crystallizing at 170℃ for 24 hours.

4. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The drying temperature in S14 is 100°C overnight, the calcination temperature in the muffle furnace is 550°C, and the calcination time is 5 hours.

5. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The concentration of the NH4NO3 solution in S15 is 1 mol / L, and the solid-liquid ratio of Ni@NaZSM-5 molecular sieve to NH4NO3 solution is 1:

15.

6. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The oil bath temperature in S15 is 80℃, the oil bath stirring time is 4h, the drying temperature is 100℃, the drying time is 12h, the calcination temperature is 500℃, and the calcination time is 5h.

7. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The amount of deionized water used in S21 is 75 mL, the amount of Ni@HZSM-5 molecular sieve is 5 g, the drying temperature is 80℃, the drying time is 12 h, the calcination temperature is 300℃, and the calcination time is 3 h.

8. The method for preparing an acid-modified encapsulated metal catalyst for improving tar quality according to claim 1, characterized in that: The concentration of (NH4)2SO4 solution in S22 is 0.5 mol / L, the solid-liquid ratio of the sample to the (NH4)2SO4 solution is 1:15, the drying temperature is 110℃, the drying time is 12h, the calcination temperature is 600℃, and the calcination time is 5h.

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