A Mo-based catalyst, a preparation method thereof, and its application in catalytic pyrolysis of oily sludge and oil products

Abstract

The present invention relates to a Mo-based catalyst, a preparation method thereof, and its use in the catalytic pyrolysis reaction of oil products in oily sludge. The Mo-based catalyst comprises a carbon cloth loaded with a ZSM-5 molecular sieve adsorbed with the active component Mo. The Mo-based catalyst is intended to improve the high-resource conversion and utilization of oil products during the treatment of oily sludge; the Mo-based catalyst can increase the yield of high-value-added aromatic hydrocarbons in the product.

Description

Technical Field

[0001] The present invention belongs to the field of catalysis technology, and particularly relates to a Mo-based catalyst, a preparation method thereof, and an application thereof in catalytic pyrolysis reaction of oily sludge and oil products. Background Art

[0002] Oily sludge is a significant solid waste generated by the petroleum industry. It comes from a wide range of sources and has a complex composition, typically consisting of petroleum hydrocarbons, water, heavy metals, and solid particles. While oily sludge has significant recycling value, improper handling can also cause severe environmental pollution due to its toxic substances. Catalytic pyrolysis technology for treating oily sludge offers high treatment efficiency and low secondary pollution, making it an emerging technology for resource utilization and environmental sustainability. Summary of the Invention

[0003] In view of this, the main purpose of the present invention is to provide a catalyst for the catalytic pyrolysis and aromatization reaction of oil products in oily sludge and a preparation method thereof, so as to convert the oil phase of oily sludge into high-value aromatic hydrocarbons through catalytic pyrolysis reaction, thereby realizing the resource treatment and high-value recycling of oily sludge waste.

[0004] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions: According to the present invention, a Mo-based catalyst is provided, which includes a carbon cloth loaded with a molecular sieve ZSM-5, and the molecular sieve ZSM-5 adsorbs the active component MoO3.

[0005] Furthermore, the Mo loading is 10% to 50% based on the mass of the Mo-based catalyst; the mass ratio of the molecular sieve ZSM-5 to Mo is (2 to 10):1, preferably 5:1. In this way, the active component loading is moderate, the molecular sieve pores will not be blocked, and the catalytic activity is the best.

[0006] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to the present invention, a method for preparing a catalyst for catalytic pyrolysis and aromatization of oily sludge oil products comprises the following steps:

[0007] Step 1: adding cetyltrimethylammonium bromide to a 0.01-0.5 mol / L aqueous solution of ammonium molybdate to obtain a coprecipitation emulsion of ammonium molybdate-cetyltrimethylammonium bromide;

[0008] Step 2: adding carbon cloth and molecular sieve ZSM-5 to the co-precipitation emulsion of ammonium molybdate and hexadecyltrimethylammonium bromide obtained in step 1, stirring uniformly at a constant temperature, and performing supramolecular self-assembly of molecular sieve ZSM-5 and Mo at a constant temperature of 150-300° C., reacting for 12-24 hours, and then naturally cooling and completely drying to obtain a catalyst precursor;

[0009] Step 3: The catalyst precursor obtained in step 2 is heated to 600-1000° C. under a nitrogen atmosphere, calcined for 4-8 hours, and naturally cooled to room temperature to obtain a Mo-based catalyst.

[0010] Furthermore, in step 1, the amount of cetyltrimethylammonium bromide (CTAB) added is 0 to 50% by mass of the ammonium molybdate aqueous solution, preferably 40%. The surface activity of the carbon cloth is better and the molecular sieve loading is more uniform. More preferably, when the concentration of the ammonium molybdate solution is 0.075 mol / L and the amount of CTAB added is 40%, the active components are fully loaded and the catalytic activity is the highest.

[0011] Furthermore, step 1 specifically includes: adding a certain amount of ammonium molybdate ((NH4)6Mo7O 24 ·4H2O)) is dissolved in 40 mL of deionized water to obtain an aqueous ammonium molybdate solution with a concentration of 0.01-0.5 mol / L; then, cetyltrimethylammonium bromide (CTAB) accounting for 0-50% (preferably 40%) of the mass of the ammonium molybdate solution is dissolved in the ammonium molybdate solution to immediately generate a white microemulsion. The mixture is allowed to stand at room temperature for 12-14 hours, and the white microemulsion settles to the bottom of the beaker. The supernatant is discarded to obtain a co-precipitation emulsion of ammonium molybdate and CTAB.

[0012] Furthermore, in step 2, the constant temperature stirring temperature is 50°C to 100°C, and the time is 1 to 2 hours; the drying temperature is 50-70°C.

[0013] Furthermore, step 2 specifically includes: transferring the precipitated emulsion of ammonium molybdate and CTAB into a 50mL polytetrafluoroethylene reactor, adding a piece of carbon cloth and 0.5-3g ZSM-5 molecular sieve at the same time, stirring at a constant temperature of 50°C to 100°C for 1-2h, transferring it into a blast drying oven, and performing supramolecular self-assembly of the molecular sieve and metal Mo at a constant temperature of 150-300°C. After reacting for 12-24h, naturally cooling it, and completely drying it at 50-70°C in a blast drying oven to obtain a catalyst precursor.

[0014] Furthermore, in step three, the heating rate is 6-10°C / min.

[0015] Furthermore, step three specifically includes: transferring the obtained catalyst precursor into a quartz boat and placing it in a tubular heating furnace, heating it to 600-1000°C at a heating rate of 6-10°C / min under a nitrogen atmosphere, calcining it for 4-8 hours, and then taking it out after naturally cooling it to room temperature to obtain a Mo-based catalyst.

[0016] Furthermore, the method further includes a carbon cloth pretreatment step before step one.

[0017] Furthermore, the carbon cloth pretreatment specifically includes: the carbon cloth must be pretreated to remove surface oil stains before use, first cutting the carbon cloth into suitable sizes (0.5-2) cm×(0.5-2) cm for standby use, then soaking and heating it in 65-68wt% concentrated nitric acid at 60-100°C for 1-3 hours to enhance its hydrophilicity, then rinsing the carbon cloth with deionized water for more than 3 times, then rinsing it twice with anhydrous ethanol to remove residual liquid on the surface, and then drying it naturally.

[0018] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions: The present invention provides an application of a Mo-based catalyst in the catalytic pyrolysis aromatization reaction of oily sludge.

[0019] Furthermore, the application includes the following steps: mixing the catalyst and the oil phase of the oil-containing sludge at 400-500°C, and conducting a catalytic pyrolysis reaction for 1-2 hours in an N2 atmosphere, with the oil phase boiling range being 200-450°C and the aromatic hydrocarbon yield being 19.3-22.4%; compared with conventional pyrolysis, the oil phase boiling range is reduced by 50-300°C, and the yield of value-added aromatic hydrocarbons is increased by 3-10%, which indicates that the Mo-based catalyst can promote the decomposition of heavy oil.

[0020] Furthermore, the mass ratio of the catalyst to the oily sludge oil is 1:20-1:100, preferably 1:25, so that the catalyst can function most effectively.

[0021] The objectives of the present invention and the technical problems solved therein are achieved by adopting the following technical solutions. According to the present invention, a catalytic pyrolysis reaction device for oily sludge using a Mo-based catalyst is provided, comprising a nitrogen tank, a quartz reactor, a tubular heating furnace, a three-necked flask, a condenser, and a condensate water tank; the nitrogen tank is connected to the inlet of the quartz reactor, the quartz reactor is vertically fixed in the vertical tubular heating furnace, the outlet of the quartz reactor is connected to the inlet of the condenser, the outlet of the condenser is connected to the inlet of the three-necked flask, and the upper and lower ends of one side of the condenser are respectively connected to the condensate water tank.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a catalyst for the catalytic pyrolysis aromatization reaction of oil products from oily sludge, which uses ZSM-5 molecular sieve and carbon cloth as carriers and Mo metal as the active component. The Mo metal oxide (MoO3) in the catalyst has excellent catalytic pyrolysis activity for long-chain saturated hydrocarbons in petroleum, can promote the aromatization of the oil phase of the oily sludge, and increase the yield of aromatic hydrocarbons in the product; the ZSM-5 molecular sieve can provide a large specific surface area, and loading it on the carbon cloth can easily separate the catalyst from the oil phase of the oily sludge after the reaction is completed. In addition, the addition of the surfactant CTAB during the preparation process improves the uniformity of the ZSM-5 molecular sieve loading on the carbon cloth and the activity of the carbon cloth, thereby significantly increasing the adsorption of MoO3 / ZSM-5 and the catalytic activity.

[0024] In summary, the catalyst for the catalytic pyrolysis and aromatization of oily sludge products can be prepared under mild operating conditions, can increase the yield of high-value-added aromatic hydrocarbons in the catalytic pyrolysis reaction products of oily sludge products, and facilitates separation of the reactants after the reaction. Therefore, the catalyst for the catalytic pyrolysis and aromatization of oily sludge products provided by the present invention can simultaneously harmlessly treat oily sludge and provide an effective and reliable method for the high-value conversion and utilization of oily sludge.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of an oil-phase catalytic pyrolysis reaction device for oil-containing sludge according to the present invention;

[0027] Among them, a. nitrogen tank, b. quartz reactor, c. tubular heating furnace, d. three-necked flask, e. condenser, f. condensing water tank.

[0028] Figure 2 This is an electron microscope image of the catalyst involved in the present invention;

[0029] Figure 3 This is a graph showing the full distillation range test results of the crude oil containing oily sludge and its aromatic hydrocarbons (column chromatography separation) and the catalytic pyrolysis reaction products under different reaction conditions of Comparative Examples 1-3;

[0030] Figure 4 1. This is a graph showing the full distillation range test results of catalytic pyrolysis products of the catalysts prepared with different CTAB addition amounts for the oily sludge of Examples 1-4; Specific implementation plan

[0031] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with preferred embodiments, details the specific implementation methods, features, and effectiveness of a Mo-based catalyst, its preparation method, and its application in the catalytic pyrolysis of oily sludge and oil products. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features or characteristics of one or more embodiments may be combined in any suitable manner.

[0032] The following materials or reagents, unless otherwise specified, were commercially available.

[0033] like Figure 1 As shown, the embodiments of the present invention provide a catalytic pyrolysis reaction device for oily sludge using a Mo-based catalyst for use in the following comparative examples 1-3 and embodiments 1-3, comprising a nitrogen tank a, a quartz reactor b, a tubular heating furnace c, a three-necked flask d, a condenser e, and a condensation water tank f; the nitrogen tank a is connected to the inlet of the quartz reactor b, the quartz reactor b is vertically fixed in the vertical tubular heating furnace c, the outlet of the quartz reactor b is connected to the inlet 2 of the condenser e, the outlet of the condenser e is connected to the inlet 1 of the three-necked flask d, and the upper and lower ends of one side of the condenser e are respectively connected to the condensation water tank f; wherein the inlet 3 of the three-necked flask d is sealed; nitrogen is used as a carrier gas, and the reaction products condensed and refluxed by the condenser e are collected in the three-necked flask d, and the condensed water in the condenser e comes from the condensation water tank f. The quartz reactor b is a fixed-bed batch reactor

[0034] The oily sludge oil phase used in the following Comparative Examples 1-3 and Examples 1-3 was prepared by the following steps:

[0035] A 546.39 g oily sludge sample from Yanchang Petroleum Engineering Technology Research Institute was extracted with conventional petroleum ether and distilled to remove water;

[0036] The oily sludge after dewatering was then subjected to conventional Soxhlet extraction to obtain the oil phase of the oily sludge, wherein the results of the mass of each phase of the oily sludge are shown in Table 1.

[0037] Table 1 Mass distribution of each phase of oily sludge

[0038]

[0039] Table 1 shows that the sum of the three phases separated from the oily sludge sample is similar to the initial mass, within the acceptable error range. Furthermore, the water phase in this oily sludge sample has the highest content, reaching 77.7%, followed by the oil phase at 15.5%. The solid residue accounts for 6.8% of the mass, indicating that this oily sludge has a high water content.

[0040] Comparative Example 1

[0041] 30 mL of the oil phase of the oily sludge extracted above was added separately to the quartz reactor b ( Figure 1 ). Then fix it vertically in the vertical tubular heating furnace c ( Figure 1 ), the inlet of one end of the quartz reactor b is fed with N2 from the nitrogen tank a at a flow rate of 50 mL / min, and the outlet of the other end is connected to the condenser e for recovering light oil products and the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask d was collected. The obtained oil phase product was subjected to full distillation test. The results are as follows Figure 3 As shown in the figure, compared with crude oil, the overall boiling range of oil products in ordinary pyrolysis products is 200-650℃, and the high-boiling point asphaltenes and char are partially pyrolyzed into small molecular saturated hydrocarbons with a boiling point of about 200℃.

[0042] Comparative Example 2

[0043] 1 g ZSM-5 molecular sieve and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. ( Figure 1 ). It was then fixed vertically in a vertical tubular heating furnace c, and N2 ( Figure 1 ), the outlet at the other end is connected to the condenser e for recovering light oil products, the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask was collected. The obtained oil phase product was subjected to full distillation test. The results are as follows Figure 3 As shown. Figure 3 It can be seen that after adding ZSM-5 as a catalyst for catalytic pyrolysis reaction, all the upstream and midstream components are decomposed at 600°C, and the saturated hydrocarbons at around 200°C decrease by 3% compared with crude oil and decrease by 5.9% compared with the saturated hydrocarbons in Comparative Example 1, indicating that this part of the saturated hydrocarbons undergoes catalytic reforming and generates aromatic hydrocarbons.

[0044] Comparative Example 3

[0045] This comparative example provides a method for preparing a Mo-based catalyst, comprising the following steps:

[0046] Step 1: 1.236 g of ammonium molybdate ((NH4)6Mo7O 244H2O) was dissolved in 40 mL of deionized water, and 1 g of ZSM-5 molecular sieve was added. After stirring evenly, the mixture was poured into a 50 mL polytetrafluoroethylene reactor and stirred at 80°C for 2 h. The mixture was then transferred to a forced air drying oven and reacted at 200°C for 12 h, followed by natural cooling. After complete drying at 60°C in a forced air drying oven, the catalyst precursor was obtained.

[0047] Step 2: The catalyst precursor obtained in step 1 was transferred into a quartz boat and placed in a tubular heating furnace. The temperature was raised to 900°C at a heating rate of 6°C / min under a nitrogen atmosphere and maintained for 6 hours. After the temperature was naturally cooled to room temperature, it was taken out to obtain a Mo-based catalyst named MoO3 / ZSM-5. Figure 2 (a). Figure 2 As can be seen in (a), the MoO3 / ZSM-5 catalyst powder is a three-dimensional structure formed by the accumulation of numerous small particles. This porous structure and large specific surface area allow for ample contact with the oil product during the reaction. Consequently, after the reaction, the powdered MoO3 / ZSM-5 catalyst cannot be separated from the product.

[0048] 1 g of the catalyst obtained in this comparative example and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. ( Figure 1 ). Then fix it vertically in the vertical tubular heating furnace c ( Figure 1 ), N2 with a flow rate of 50 mL / min was introduced from the inlet of one end of the quartz reactor b, and the outlet of the other end was connected to the condenser e for recovering light oil products and the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask was collected. The obtained oil phase product was subjected to full distillation test. The results are as follows Figure 3 As shown. Figure 3 It can be seen that, compared with the ordinary pyrolysis of Comparative Example 1 and the catalytic pyrolysis (ZSM-5 as catalyst) of Comparative Example 2, after adding the catalyst described in Comparative Example 3, the asphaltene and char in the oil phase of the oily sludge are all pyrolyzed into small molecular saturated hydrocarbons with lower boiling points, the overall boiling range of the oil product decreases by 300°C, and the mass fraction of high value-added aromatic hydrocarbons increases by more than 10.9%. This shows that the Mo metal oxide (MoO3) in the catalyst of Comparative Example 3 has good catalytic pyrolysis activity for long-chain saturated hydrocarbons in petroleum, can promote the aromatization of the oil phase of the oily sludge, and increase the yield of aromatic hydrocarbons in the product.

[0049] Example 1

[0050] This embodiment provides a method for preparing a catalyst, comprising the following steps:

[0051] Step 1: Pretreatment of the carbon cloth. First, cut the carbon cloth into appropriate sizes (0.5 cm x 0.5 cm) and soak it in concentrated nitric acid (65-68 wt%) at 80°C for 1-3 hours to remove surface oil and enhance its hydrophilicity. Rinse the carbon cloth three times with deionized water and twice with anhydrous ethanol to remove residual surface liquid, then air dry.

[0052] Step 2: 1.236 g of ammonium molybdate ((NH4)6Mo7O 24 ·4H2O)) was dissolved in 40 mL of deionized water, stirred evenly, and poured into a 50 mL polytetrafluoroethylene reactor. A piece of treated carbon cloth and 1 g of ZSM-5 molecular sieve were added at the same time. The mixture was stirred at a constant temperature of 80°C for 2 h, transferred to a blast drying oven, reacted at a constant temperature of 200°C for 12 h, cooled naturally, and completely dried at 60°C in a blast drying oven to obtain a catalyst precursor.

[0053] Step 4: The catalyst precursor obtained in step 3 was transferred into a quartz boat and placed in a tubular heating furnace. The temperature was raised to 900°C at a heating rate of 6°C / min under a nitrogen atmosphere and maintained for 6 hours. After the temperature was naturally cooled to room temperature, it was taken out to obtain a Mo-based catalyst named MoO3 / ZSM-5 / CC. The electron microscopy results of the relevant catalyst are shown in the figure below. Figure 2 (b) From Figure 2 As can be seen in (b), when ZSM-5 molecular sieve and carbon cloth are used as carriers at the same time, the MoO3 / ZSM-5 catalyst particles are distributed and adsorbed on the carbon cloth. The surface of the carbon cloth is rough and the molecular sieve adsorption amount is very small.

[0054] 1 g of the catalyst obtained in this example and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. ( Figure 1 ). It was then fixed vertically in a vertical tubular heating furnace, and N2 from nitrogen tank a was introduced at a flow rate of 50 mL / min from the inlet at one end of the quartz reactor b. The outlet at the other end was connected to the condenser e for recovering light oil products and the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask d was collected. The obtained oil phase product was subjected to full distillation test. The results are as follows Figure 4 As shown. Figure 4 It can be seen that after adding the above-mentioned catalyst of this embodiment, the asphaltenes and char in the oil phase of the oily sludge are completely pyrolyzed into small molecular saturated hydrocarbons with lower boiling points, the overall boiling range of the oil product is reduced to 200°C to 450°C, and the mass fraction of high value-added aromatic hydrocarbons is above 10.9%.

[0055] Example 2

[0056] This embodiment provides a method for preparing a catalyst for catalytic pyrolysis and aromatization of oil products from oily sludge, comprising the following steps:

[0057] Step 1: Pre-treat the carbon cloth. First, cut the carbon cloth into appropriate sizes (0.5 cm x 0.5 cm) for later use. Soak and heat the carbon cloth in concentrated nitric acid (65-68 wt%) at 80°C for 1-3 hours to remove surface oil and enhance its hydrophilicity. Rinse the carbon cloth three times with deionized water and twice with anhydrous ethanol to remove any residual surface liquid. Allow to air dry.

[0058] Step 2: 1.236 g of ammonium molybdate ((NH4)6Mo7O 24 4H2O) was dissolved in 40 mL of deionized water. CTAB (40% by weight of the ammonium molybdate aqueous solution) was then added to the ammonium molybdate solution. Mixing and stirring immediately produced a white microemulsion. The mixture was allowed to stand at room temperature for 12 hours, and the white microemulsion settled to the bottom of the beaker. The supernatant was discarded to obtain a coprecipitated emulsion of ammonium molybdate and CTAB.

[0059] Step 3: The thick co-precipitation emulsion of ammonium molybdate and CTAB obtained in step 2 is transferred to a 50 mL polytetrafluoroethylene reactor, and a piece of treated carbon cloth and 1 g of ZSM-5 molecular sieve are added. The mixture is stirred at a constant temperature of 80 ° C for 2 h, transferred to a blast drying oven, reacted at a constant temperature of 200 ° C for 12 h, cooled naturally, and completely dried at 60 ° C in a blast drying oven to obtain a catalyst precursor.

[0060] Step 4: The catalyst precursor obtained in step 3 was transferred into a quartz boat and placed in a tubular heating furnace. The temperature was raised to 900°C at a heating rate of 6°C / min under a nitrogen atmosphere and maintained for 6 hours. After the temperature was naturally cooled to room temperature, it was taken out to obtain a Mo-based catalyst named MoO3 / ZSM-5 / CC / 4-CTAB. Figure 2 (c) is shown. Figure 2 It can be seen from (c) that when ZSM-5 molecular sieve and carbon cloth are used as carriers at the same time, the MoO3 / ZSM-5 catalyst particles are distributed and adsorbed on the carbon cloth. Due to the addition of surfactant CTAB, the activity of the carbon cloth surface is enhanced and the carbon fiber surface becomes smooth, so that the adsorption of MoO3 / ZSM-5 is significantly increased, which is beneficial to the improvement of catalytic activity.

[0061] 1 g of the catalyst obtained in this example and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. ( Figure 1 ). Then fix it vertically in the vertical tubular heating furnace c ( Figure 3) was introduced into the inlet of one end of the quartz reactor b at a flow rate of 50 mL / min from nitrogen tank a. The outlet at the other end was connected to a condenser e for recovering light oil products and a three-necked flask d. After purging under N2 for 10 minutes, the temperature was programmed to 500°C at a rate of 10°C / min and held for 2 hours. After the reaction was completed, the temperature was cooled to room temperature, and the condensed oil phase product in the three-necked flask d was collected. The reaction product was tested over the entire distillation range, and the results were as follows. Figure 4 As shown. Figure 4 It can be seen that compared with the MoO3 / ZSM-5 / CC catalyst without CTAB in Example 1, the carbon cloth of this embodiment has a smooth surface and is more likely to adsorb the active components of MoO3 / ZSM-5. After the reaction, the overall boiling range of the oil product is 190-450°C, and the aromatic hydrocarbon yield is 22.4%. At the same time, through experimental observation and analysis, during the oil-phase catalytic pyrolysis of oily sludge, the catalyst supported on the carbon cloth can be clearly separated from the oil product after the reaction, while the powdered MoO3 / ZSM-5 catalyst of Comparative Example 3 cannot be separated. Therefore, the MoO3 / ZSM-5 / CC / 4-CTAB catalyst has a longer lifespan and recycling value.

[0062] Example 3

[0063] This embodiment provides a method for preparing a catalyst for catalytic pyrolysis and aromatization of oil products from oily sludge, comprising the following steps:

[0064] Step 1: Pretreatment of the carbon cloth. First, cut the carbon cloth into appropriate sizes (0.5 cm x 0.5 cm) for later use. Soak and heat the carbon cloth in concentrated nitric acid (65-68 wt%) at 80°C for 1-3 hours to remove surface oil and enhance its hydrophilicity. Rinse the carbon cloth three times with deionized water and twice with anhydrous ethanol to remove any residual surface liquid. Allow to air dry.

[0065] Step 2: 1.236 g of ammonium molybdate ((NH4)6Mo7O 24 4H2O) was dissolved in 40 mL of deionized water. CTAB (10% by weight of the ammonium molybdate aqueous solution) was then added to the ammonium molybdate solution. Mixing and stirring immediately produced a white microemulsion. After standing at room temperature for 12 hours, the white microemulsion settled to the bottom of the beaker. The supernatant was discarded, yielding a thick co-precipitation emulsion of ammonium molybdate and CTAB.

[0066] Step 3: The co-precipitated emulsion of ammonium molybdate and CTAB obtained in step 2 is transferred to a 50 mL polytetrafluoroethylene reactor, and a piece of treated carbon cloth and 1 g of ZSM-5 molecular sieve are added. The mixture is stirred at a constant temperature of 80 ° C for 2 h, and then transferred to a blast drying oven. The mixture is reacted at a constant temperature of 200 ° C for 12 h, cooled naturally, and completely dried at 60 ° C in a blast drying oven to obtain a catalyst precursor.

[0067] Step 4: The catalyst precursor obtained in step 3 was transferred into a quartz boat and placed in a tubular heating furnace. The temperature was raised to 900°C at a heating rate of 6°C / min under a nitrogen atmosphere and maintained for 6 hours. After the temperature was naturally cooled to room temperature, it was taken out to obtain a Mo-based catalyst named MoO3 / ZSM-5 / CC / 1-CTAB.

[0068] 1 g of the catalyst obtained in this example and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. ( Figure 1 ). Then fix it vertically in the vertical tubular heating furnace c ( Figure 3 ), N2 from nitrogen tank a was introduced at a flow rate of 50 mL / min from one end inlet of the quartz reactor b, and the outlet at the other end was connected to the condenser e for recovering light oil products and the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask d was collected. The reaction product was tested for the full distillation range. The results are as follows Figure 4 As shown. Figure 4 As can be seen from the figure, the catalyst prepared with 10 wt% CTAB as an additive achieved an aromatic hydrocarbon yield of 19.6%. Its catalytic activity was comparable to that without CTAB, indicating that a small amount of CTAB did not improve the surface activity of the carbon cloth and did not enhance the adsorption of MoO3 / ZSM-5.

[0069] Example 4

[0070] This embodiment provides a method for preparing a catalyst for catalytic pyrolysis and aromatization of oil products from oily sludge, comprising the following steps:

[0071] Step 1: Pre-treat the carbon cloth. First, cut the carbon cloth into appropriate sizes (0.5 cm x 0.5 cm) for later use. Soak and heat the carbon cloth in concentrated nitric acid (65-68 wt%) at 80°C for 1-3 hours to remove surface oil and enhance its hydrophilicity. Rinse the carbon cloth three times with deionized water and twice with anhydrous ethanol to remove any residual surface liquid. Allow to air dry.

[0072] Step 2: 1.236 g of ammonium molybdate ((NH4)6Mo7O 24 4H2O) was dissolved in 40 mL of deionized water; then, 50% by mass of CTAB was added to the ammonium molybdate solution. Mixing and stirring immediately formed a white microemulsion. After standing at room temperature for 12 hours, the emulsion settled to the bottom of the beaker. The supernatant was discarded to obtain a coprecipitated emulsion of ammonium molybdate and CTAB.

[0073] Step 3: The thick co-precipitation emulsion of ammonium molybdate and CTAB obtained in step 2 is transferred to a 50 mL polytetrafluoroethylene reactor, and a piece of treated carbon cloth and 1 g of ZSM-5 molecular sieve are added. The mixture is stirred at a constant temperature of 80 ° C for 2 h, transferred to a blast drying oven, reacted at a constant temperature of 200 ° C for 12 h, cooled naturally, and completely dried at 60 ° C in a blast drying oven to obtain a catalyst precursor.

[0074] Step 4: The catalyst precursor obtained in step 3 was transferred into a quartz boat and placed in a tubular heating furnace. The temperature was raised to 900°C at a heating rate of 6°C / min under a nitrogen atmosphere and maintained for 6 hours. After the temperature was naturally cooled to room temperature, it was taken out to obtain a Mo-based catalyst named MoO3 / ZSM-5 / CC / 5-CTAB.

[0075] 1 g of the catalyst obtained in this example and 30 mL of the oil phase of the oily sludge extracted above were added to the quartz reactor b in sequence. Then fix it vertically in the vertical tubular heating furnace c ( Figure 3 ), N2 from nitrogen tank a was introduced at a flow rate of 50 mL / min from one end inlet of the quartz reactor b, and the outlet at the other end was connected to the condenser e for recovering light oil products and the three-necked flask d ( Figure 1 After purging under N2 atmosphere for 10 minutes, the temperature was raised to 500℃ at a heating rate of 10℃ / min and maintained for 2h. After the reaction was completed, the temperature was cooled to room temperature and the condensed oil phase product in the three-necked flask d was collected. The reaction product was tested for the full distillation range. The results are as follows Figure 4 When the CTAB addition amount is 10% of the mass of the ammonium molybdate solution, the aromatic hydrocarbon yield is 20.4%, which is lower than the aromatic hydrocarbon yield of the catalyst with 40wt% CTAB addition. This shows that there is a threshold for the addition of CTAB. Excessive CTAB may clog the molecular sieve pores, reduce the specific surface area of ​​the catalyst, and reduce the catalytic activity.

[0076] In the description of the present invention, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some embodiments, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0078] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0079] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a Mo-based catalyst, characterized in that: The following steps are involved: Step 1: adding cetyltrimethylammonium bromide to a 0.01-0.5 mol / L aqueous solution of ammonium molybdate to obtain a coprecipitation emulsion of ammonium molybdate-cetyltrimethylammonium bromide; the amount of cetyltrimethylammonium bromide added is 40% by mass of the aqueous solution of ammonium molybdate; Step 2: adding carbon cloth and molecular sieve ZSM-5 to the co-precipitation emulsion of ammonium molybdate and hexadecyltrimethylammonium bromide obtained in step 1, stirring uniformly at a constant temperature, and performing supramolecular self-assembly of molecular sieve ZSM-5 and Mo at a constant temperature of 150-300° C., reacting for 12-24 hours, and then naturally cooling and completely drying to obtain a catalyst precursor; Step 3: heating the catalyst precursor obtained in step 2 to 600-1000° C. under a nitrogen atmosphere, calcining for 4-8 hours, and naturally cooling to room temperature to obtain a Mo-based catalyst; The catalyst includes carbon cloth, the carbon cloth is loaded with molecular sieve ZSM-5, and the molecular sieve ZSM-5 is adsorbed with active component MoO3; based on the mass of the Mo-based catalyst, the loading amount of the Mo is 10% to 50%.

2. The preparation method according to claim 1, wherein In step 2, the constant temperature stirring temperature is 50°C to 100°C for 1 to 2 hours; the drying temperature is 50-70°C.

3. The preparation method according to claim 1, wherein In step 3, the heating rate is 6-10°C / min.

4. The preparation method according to claim 1, wherein Before step 1, a carbon cloth pretreatment step is also included.

5. Use of a Mo-based catalyst prepared by the method according to any one of claims 1 to 4 in the catalytic pyrolysis and aromatization reaction of oily sludge, characterized in that: At 400~500℃, the catalyst and the oil phase of oily sludge were mixed and catalytic pyrolysis reaction was carried out in N2 atmosphere for 1~2h. The boiling range of the oil phase was 200~450℃, and the yield of aromatic hydrocarbons was 19.3~22.4%.

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