A catalyst for reducing the oil production temperature of oil shale pyrolysis and its preparation method and application

Abstract

The present invention provides a catalyst for reducing the oil production temperature during pyrolysis of oil shale, as well as its preparation method and application. The preparation method comprises the following steps: adding zinc salt and Chlorella vulgaris to deionized water, stirring uniformly, and then drying and calcining to obtain the catalyst for reducing the oil production temperature during pyrolysis of oil shale. The catalyst of the present invention has the characteristics of high activity, ease of preparation, and good thermal stability. When used in the pyrolysis of oil shale, it can reduce the oil production temperature during pyrolysis of oil shale and increase its oil yield.

Description

Technical Field

[0001] The invention relates to a catalyst for reducing the oil production temperature of oil shale pyrolysis, a preparation method and application thereof, and belongs to the technical field of oil shale dry distillation and pyrolysis. Background Art

[0002] Energy is a vital material underpinning the development of the global economy and human society. Due to continued energy consumption, energy shortages and the imbalance between energy supply and demand are becoming increasingly prominent. The search for alternative energy sources has become a crucial issue in promoting sustainable development in today's society. Oil shale, as a potential unconventional energy source, has attracted widespread attention worldwide due to its widespread distribution and vast reserves.

[0003] my country has abundant oil shale reserves, distributed across 20 provinces and autonomous regions, 47 basins, and 80 mining areas. The oil content of oil shale nationwide is medium, with 266.435 billion tons of oil shale resources with an oil content of greater than 5-10%, and 126.694 billion tons with an oil content greater than 10%. Oil shale, also known as kerogen, is a sedimentary rock rich in combustible organic matter, with an oil content generally ranging from 5% to 8%. Kerogen, the organic component of oil shale, produces shale oil when heated. In recent years, the country has placed increasing emphasis on the development and utilization of unconventional oil and gas resources. In the latest guidance catalog for industrial restructuring, the development and utilization of oil shale has been included in the encouraged projects category.

[0004] One of the key indicators for the comprehensive utilization of oil shale is its oil yield. However, direct retorting and pyrolysis methods often yield low oil yields, influenced by two factors: structural parameters, such as particle size and pyrolysis furnace type; and operational parameters, such as reaction temperature, residence time, and heating rate. Adding catalysts to reduce the temperature required for oil shale oil-gas conversion and improve product quality has become a key approach to oil shale industrialization. Currently, catalysts used in oil shale pyrolysis include clay minerals, natural ores (such as montmorillonite, gypsum, and pyrite), inorganic compounds (such as metal oxides, metal sulfides, and metal salts), molecular sieves, and metal-supported catalysts. However, the low shale oil conversion rates of current catalytic systems, high catalyst costs, and the lack of reusability have severely limited the development of efficient oil shale pyrolysis technologies.

[0005] Chinese patent document CN101962559A discloses a method for producing light fuel oil from oil shale. The catalyst used comprises the following raw materials by weight: 20-35% cobalt naphthenate, 30-40% ethylene glycol monomethyl ether, 3-5% acidified activated clay, 10-20% glycerol stearate, and 20-37% chlorinated paraffin. Chinese patent document CN103464179A provides a catalyst for extracting shale oil from oil shale, comprising a divalent cobalt manganese salt, water, and a surfactant. Chinese patent document CN103878031A discloses a catalyst for pyrolysis of oil shale, comprising the following raw materials by weight: 2-8% molecular sieve, 1-5% activated clay, 10-60% organic cobaltate, 5-20% metal sulfide, 8-30% glycerate, and 15-35% paraffin. The oil shale catalysts described above all use a single active ingredient combination, resulting in relatively low catalytic activity. Chinese patent document CN109985627A provides a catalyst for increasing oil shale pyrolysis oil production, comprising a carrier, an active ingredient, and an additive. The catalyst comprises acidified bentonite as the carrier, a cobalt salt as the active ingredient, and nickel oxide as the additive. However, the catalyst preparation method is complex and costly, and the reduction in oil shale pyrolysis temperature is low.

[0006] Therefore, it is of great significance to develop a low-cost, highly active and stable supported catalyst for oil shale pyrolysis. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention provides a catalyst for reducing the oil production temperature during pyrolysis of oil shale, as well as its preparation method and application. The catalyst of the present invention features high activity, ease of preparation, and excellent thermal stability. Its application in the pyrolysis of oil shale can reduce the oil production temperature and increase the oil yield of the shale.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis comprises the following steps:

[0010] Zinc salt and chlorella are added into deionized water, stirred evenly, dried and calcined to obtain a catalyst for reducing the oil production temperature of oil shale pyrolysis.

[0011] According to the present invention, preferably, the zinc salt is zinc chloride, zinc sulfate or zinc nitrate, more preferably zinc chloride.

[0012] According to the present invention, preferably, the mass of the zinc salt is 3-15% of the mass of Chlorella, and more preferably 5-10%.

[0013] According to the present invention, preferably, the chlorella is at least one of Chlorella pyrenoidosa, Chlorella ellipsoidea, and Chlorella vulgaris, and the chlorella is dried at 100-105° C. for 10-15 hours before use.

[0014] Preferably according to the present invention, the ratio of the mass of the Chlorella to the volume of deionized water is 1 g:50-100 mL.

[0015] Preferably, according to the present invention, the stirring temperature is 55-65° C., and the stirring time is 4-6 hours.

[0016] According to the preferred embodiment of the present invention, the drying temperature is 100-105° C. and the drying time is 10-15 hours.

[0017] Preferably, according to the present invention, the calcination temperature is 500-600° C., the calcination time is 3-5 h, the heating rate during the calcination process is 5-10° C. / min, and the calcination atmosphere is air.

[0018] The present invention also provides a catalyst prepared by the above preparation method and used for reducing the oil production temperature of oil shale pyrolysis.

[0019] According to the present invention, the above-mentioned catalyst for reducing the oil production temperature of oil shale pyrolysis is used in the pyrolysis of oil shale.

[0020] According to the preferred embodiment of the present invention, the specific application method is as follows:

[0021] The oil shale particles and a catalyst for reducing the oil production temperature of the oil shale pyrolysis are mixed, stirred evenly and then pyrolyzed. The mass ratio of the catalyst for reducing the oil production temperature of the oil shale pyrolysis to the oil shale particles is 1:10.

[0022] The technical features and beneficial effects of the present invention are as follows:

[0023] The catalyst of the present invention is a supported catalyst, using nitrogen- and phosphorus-doped biochar obtained by calcining Chlorella vulgaris as a carrier and zinc oxide as an active ingredient. Both the carrier and the active ingredient themselves affect pyrolysis, and through loading, the carrier and active ingredient act synergistically. Chlorella vulgaris is a type of microscopic single-celled phytoplankton. They have spherical or disc-shaped calcareous plates covering their cell surfaces. Chlorella vulgaris is widely distributed and can be found in oceans and freshwater lakes, and is abundant. Chlorella vulgaris has a spherical structure with a large specific surface area, typically ranging from 3 to 5 microns in diameter. After high-temperature calcination, it produces nitrogen- and phosphorus-doped biochar, which can serve as a catalyst support. Zn, as a transition metal, accelerates the breaking of chemical bonds in the organic matter kerogen in oil shale during pyrolysis. Loading zinc oxide increases the specific surface area of the Chlorella vulgaris, increasing the contact between Zn and oil shale, improving catalytic performance. Zn also disrupts the molecular structure of oil shale, accelerating its decomposition and increasing pyrolysis efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 TG curves of pyrolysis of oil shale and pyrolysis of the catalysts of Comparative Examples 1-2 and Example 1 mixed with oil shale.

[0025] Figure 2 TG curves of pyrolysis of oil shale and pyrolysis of the catalyst of Example 2-4 mixed with oil shale.

[0026] Figure 3 TG curves of pyrolysis of oil shale and pyrolysis of the mixture of catalysts of Examples 5-7 and oil shale.

[0027] Figure 4 TG curves of pyrolysis of oil shale and pyrolysis of the mixture of Example 8 catalyst and oil shale.

[0028] Figure 5 These are the DTG curves for the pyrolysis of oil shale and the pyrolysis of the catalysts of Comparative Examples 1-2 and Example 1 mixed with oil shale.

[0029] Figure 6 These are the DTG curves for the pyrolysis of oil shale and the pyrolysis of the mixture of the catalyst of Example 2-4 and oil shale.

[0030] Figure 7 These are the DTG curves for the pyrolysis of oil shale and the pyrolysis of the mixture of the catalysts of Examples 5-7 and oil shale.

[0031] Figure 8 These are the DTG curves for the pyrolysis of oil shale and the pyrolysis of a mixture of the catalyst of Example 8 and oil shale. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto.

[0033] The chlorella used in the examples is Chlorella vulgaris, a common commercial product, which was dried at 105° C. for 12 h before use.

[0034] Example 1

[0035] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis comprises the following steps:

[0036] ZnCl2 and Chlorella vulgaris are added to deionized water, with the mass of ZnCl2 being 3% of the mass of Chlorella vulgaris, and the volume ratio of the mass of Chlorella vulgaris to the deionized water being 1 g:80 mL; the mixture is then stirred at 60°C for 5 hours, and the resulting mixture is dried at 100°C for 12 hours. The resulting solid is then placed in a muffle furnace, heated to 550°C at a heating rate of 5°C / min, calcined in air at 550°C for 4 hours, and naturally cooled to room temperature to obtain a catalyst for reducing the oil production temperature of oil shale pyrolysis.

[0037] Example 2

[0038] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 4% of the mass of Chlorella.

[0039] Example 3

[0040] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 5% of the mass of Chlorella.

[0041] Example 4

[0042] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 6% of the mass of Chlorella.

[0043] Example 5

[0044] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 7% of the mass of Chlorella.

[0045] Example 6

[0046] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 8% of the mass of Chlorella.

[0047] Example 7

[0048] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 9% of the mass of Chlorella.

[0049] Example 8

[0050] A method for preparing a catalyst for reducing the oil production temperature of oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 10% of the mass of Chlorella.

[0051] Comparative Example 1

[0052] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 1% of the mass of Chlorella.

[0053] Comparative Example 2

[0054] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 2% of the mass of Chlorella.

[0055] Comparative Example 3

[0056] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that ZnCl2 is not added.

[0057] Comparative Example 4

[0058] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that the mass of ZnCl2 is 20% of the mass of Chlorella.

[0059] Comparative Example 5

[0060] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that corn straw powder is used instead of Chlorella.

[0061] Comparative Example 6

[0062] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that bentonite is used instead of Chlorella.

[0063] Comparative Example 7

[0064] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that NiCl2 is used instead of ZnCl2.

[0065] Comparative Example 8

[0066] A method for preparing a catalyst for oil shale pyrolysis is as described in Example 1, except that CoCl2 is used instead of ZnCl2.

[0067] Test Example 1

[0068] The catalysts prepared in Examples 1-8 and Comparative Examples 1-2 were mixed with oil shale in a mass ratio of 1:10, and the resulting samples were subjected to thermogravimetric analysis experiments. The instrument used was a US TGA550 thermogravimetric analyzer. High-purity nitrogen was purged for 30 minutes before the experiment, and subsequent experiments were conducted to ensure that no other gases affected the pyrolysis process. The nitrogen flow rate was 50 mL / min, and the instrument heating rate was set to 10°C / min. The temperature was heated from room temperature to 600°C. During the experiment, the computer detected the percentage of weight loss of the oil shale in real time, and the pyrolysis of oil shale without catalyst was used as a control. The comparison graphs of its thermal weight loss curve and pyrolysis rate comparison curve are shown as follows: Figure 1-4 , Figure 5-8 shown.

[0069] Depend on Figure 1-4 The TG curve and Figure 5-8 From the DTG curve, it can be seen that the TG curve has no change before 200℃, and the thermal weight loss rate is 0%·℃ -1 In the temperature range of 200℃ to 400℃, the mass loss of the original oil shale is small, and the weight loss rate is maintained at 0.01%·℃. -1 At this temperature stage, only the weak chemical bonds of organic matter in the oil shale are broken, releasing a small amount of compounds; in the temperature range of 400℃ to 500℃, the mass loss of the original oil shale continues to increase, and the weight loss rate reaches a maximum of 0.15%·℃ at 496℃. -1 This temperature range represents the primary decomposition stage of organic matter in oil shale. Kerogen molecules in the oil shale decompose to form asphaltene, which then decomposes to form various aromatic and aliphatic hydrocarbons. These volatiles escape and diffuse from the oil shale, rapidly increasing mass loss. Shale oil and shale gas begin to form in this temperature range. The decomposition rate of oil shale gradually decreases between 500°C and 600°C. This is because the thermal decomposition of most of the organic matter in the oil shale completes between 200°C and 400°C, resulting in fewer chemical reactions within this temperature range.

[0070] Comparing the TG and DTG curves of the catalyst-added oil shale samples revealed that, compared to the TG curve of the oil shale, as the amount of zinc salt in the catalyst increased, the TG curve of the sample showed a trend of shifting to the left, that is, moving towards a lower temperature pyrolysis range, indicating that the catalyst can prematurely decompose the organic matter in the oil shale. The temperature corresponding to the maximum weight loss rate represents the average stability of the oil shale's macromolecular structure. The higher the temperature, the less likely the organic matter in the oil shale is to be destroyed during pyrolysis. The catalyst-added sample reached its maximum thermal weight loss rate at around 450°C, and the temperature corresponding to the maximum weight loss rate decreased with the amount of zinc chloride added. The temperature corresponding to the maximum weight loss rate of the oil shale sample was 496°C, while the temperature corresponding to the maximum weight loss rate of the oil shale with the catalyst prepared in Example 8 was 443°C, indicating that the catalyst can disrupt the molecular structure of the oil shale's organic matter, accelerating its decomposition.

[0071] Test Example 2

[0072] 30g of oil shale was mixed with 3g of the catalysts prepared in Examples 1-8 and Comparative Examples 1-8, respectively. The resulting samples were placed in an autoclave reactor and subjected to catalytic pyrolysis experiments. After three N2 purges, the temperature was raised to 300°C, and the product was collected every two hours. The temperature was then raised by 50°C, and the product was collected every two hours. The experiment ended after the product at 500°C was collected. The results are shown in Table 1-2.

[0073] Table 1 Comparison of oil production of oil shale samples with catalysts from Examples 1-8 added at different temperatures

[0074]

[0075] Table 2 Comparison of oil production of oil shale samples with catalysts from Comparative Examples 1-8 added at different temperatures

[0076]

[0077] As can be seen from the analysis of Table 1, after being treated with the synthetic catalyst of the present invention, the oil yield of the sample gradually increases as the amount of ZnCl2 in the catalyst increases. The higher the content of ZnCl2, the higher the oil yield in the low temperature range. When the content of ZnCl2 in the catalyst exceeds 20%, the oil yield decreases significantly, indicating that the optimal addition amount of ZnCl2 helps to promote production. After the spherical algae in the catalyst are replaced with straw and bentonite, the oil yield decreases, indicating that the active metals in the spherical algae have specific catalytic activity for organic matter in oil shale. NiCl2 and CoCl2 have certain catalytic activity for the pyrolysis of oil shale, but are significantly lower than the ZnCl2 of the present invention.

Claims

1. A catalyst for reducing the oil production temperature of oil shale pyrolysis in oil shale pyrolysis, characterized in that: The method for preparing the catalyst for reducing the oil production temperature by pyrolysis of oil shale comprises the following steps: Zinc salt and Chlorella vulgaris are added to deionized water, stirred evenly, dried, and calcined to obtain a catalyst for reducing the oil production temperature of oil shale pyrolysis; The zinc salt is zinc chloride, zinc sulfate or zinc nitrate; the mass of the zinc salt is 3-15% of the mass of Chlorella; the calcination temperature is 500-600° C., the calcination time is 3-5 hours, and the calcination atmosphere is air.

2. The use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The zinc salt is zinc chloride.

3. The use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The mass of the zinc salt is 5-10% of the mass of Chlorella.

4. The use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The chlorella is at least one of chlorella pyrenoidosa, chlorella ellipsoidea, and chlorella vulgaris. The chlorella is dried at 100-105° C. for 10-15 hours before use.

5. Use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The ratio of the mass of the Chlorella to the volume of deionized water is 1 g:50-100 mL.

6. Use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The stirring temperature is 55-65° C., and the stirring time is 4-6 hours; the drying temperature is 100-105° C., and the drying time is 10-15 hours.

7. Use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The heating rate during the calcination process is 5-10°C / min.

8. Use of the catalyst for reducing the oil production temperature of oil shale pyrolysis according to claim 1 in oil shale pyrolysis, characterized in that: The specific application methods are as follows: The oil shale particles and a catalyst for reducing the oil production temperature of the oil shale pyrolysis are mixed, stirred evenly and then pyrolyzed. The mass ratio of the catalyst for reducing the oil production temperature of the oil shale pyrolysis to the oil shale particles is 1:10.

Images