Preparation method and application of bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation

Abstract

The application discloses a preparation method and application of a bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation, specifically, a metal oxide with acid-base dual sites is prepared by using a corresponding precipitant as a carrier, metal Ni is loaded on the carrier through steps of impregnation, aging, drying, calcination and activation, an auxiliary agent Mo is used to further improve the catalyst activity, and finally, the bifunctional catalyst capable of simultaneously dechlorinating and deoxygenating is obtained, and the bifunctional catalyst can be applied to a plastic pyrolysis oil hydrogenation upgrading process. The bifunctional catalyst preparation process is simple, and the catalytic activity is high. When the bifunctional catalyst is used for hydrogenation upgrading of waste plastic pyrolysis oil containing chlorine and oxygen, the main advantage is that, compared with a single dechlorination and deoxygenation catalyst, the bifunctional catalyst is more suitable for upgrading of complex component pyrolysis oil, and a hydrogenation upgrading process flow is simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial catalysts, in particular to a preparation method and application of a bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation. BACKGROUND

[0002] Pyrolysis is an effective way for recycling of polymer waste such as waste plastics. In the pyrolysis process, chlorine, oxygen and other elements in waste plastics will be removed from the polymer chain and exist in the form of chlorinated hydrocarbons or oxygen-containing compounds. However, the presence of dichloroethane, chlorobenzene and other chlorinated hydrocarbons will cause certain harm to the processing device, such as corrosion of the oil refining device, pipe blockage and catalyst poisoning. The presence of furfural, phenol and other oxygen-containing substances makes the oil acidic and reduces the calorific value of the pyrolysis oil.

[0003] Traditional methods for treating chlorinated hydrocarbons and oxygen-containing substances include plasma treatment, supercritical water method, catalytic decomposition method, catalytic hydrolysis method, etc. However, the first few methods are prone to secondary pollution, the technology is not mature, or the processing cost is too high. Catalytic hydrogenation upgrading technology, i.e. under the action of pressurized hydrogen atmosphere and catalyst, selectively catalyzing the conversion of chlorinated hydrocarbons, converting chlorine into hydrogen chloride small molecule gas, and converting oxygen into H2O molecules, thereby achieving the elimination of chlorinated hydrocarbons and oxygen-containing substances in pyrolysis oil and improving the quality. However, current hydrogenation dechlorination and deoxygenation usually use different catalysts separately, which is complex and has large loss, and in the step-by-step removal process, the dechlorination effect significantly affects the oxygen removal efficiency. Therefore, one-step dechlorination and deoxygenation can improve the hydrogenation upgrading efficiency, and the key is to develop a bifunctional catalyst that takes into account the dechlorination and deoxygenation effects.

[0004] Current hydrogenation dechlorination catalysts mainly include metal active components supported on basic carriers, such as Ni / Al2O3, Ni / CaO, etc. The presence of basic sites can effectively solidify the HCl generated during hydrogenation, avoiding chlorine poisoning of the metal active sites and improving the stability and activity of the catalyst. Studies have shown that after adding basic substances to metal Ni-based catalysts, the active metal can be well dispersed during the hydrogenation dechlorination process, and the hydrogenation activity is enhanced. Hydrodeoxygenation catalysts mainly use metal active components supported on acidic carriers, such as Ni / ZSM-5, Pt / ZSM-5, etc. Studies have shown that acidic sites are essential for dehydration and alkylation reactions during HDO, and the deoxygenation effect of Ni catalysts with a certain amount of acidic sites is significantly improved. The hydrogenation catalysts used in current patent documents are mainly for single substance removal and upgrading, and cannot effectively remove both chlorine-containing and oxygen-containing substances. There is also no treatment for complex chlorinated and oxygenated pyrolysis oil. Therefore, a catalyst with both dechlorination and deoxygenation functions is needed to remove chlorine and oxygen from oil in one step. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide a preparation method and application of a bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation, for efficient removal of 1-2 dichloroethane and chlorobenzene, and efficient removal of furfural and phenol at the same time, realizing simultaneous and efficient removal of chlorohydrocarbon and oxygen-containing substances.

[0006] In order to achieve the above purpose, the technical scheme of the present application is as follows: a preparation method of a bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation, the preparation method specifically being: loading metal Ni on a metal oxide with acid-base dual sites, so that the loading amount of Ni is 10%, to obtain a bifunctional catalyst;

[0007] The metal oxide with acid-base dual sites is prepared by the following steps:

[0008] 10-50g of ZrOCl2 is added to 100-200ml of water, stirred uniformly, a precipitating agent is added until the PH value of the obtained solution is 9-10, and aging is carried out at 40-50℃ for 3h; water at 40-60℃ is used for washing multiple times until the PH value of the solution is neutral, filtration is carried out, and solid precipitate is obtained, which is dried, water is removed (placed in a drying oven at 105℃ overnight), ground into powder, placed in a muffle furnace for calcination for 2-4h, and a metal oxide with acid-base dual sites is obtained.

[0009] Further, the metal oxide with acid-base dual sites includes t-ZrO2, a-ZrO2 and m-ZrO2, the t-ZrO2 is prepared by using a mixed solution of NaHCO3 and Na2CO3 as a precipitating agent and calcination at a temperature of 500-600℃, the a-ZrO2 is prepared by using ammonia as a precipitating agent and calcination at a temperature of 350℃, and the m-ZrO2 is prepared by using Na2CO3 as a precipitating agent and calcination at a temperature of 500-600℃.

[0010] Further, the loading of metal Ni on the metal oxide with acid-base dual sites is specifically: water is added to the nickel nitrate hexahydrate until it is fully dissolved, a compound containing Mo is added to the solution as an additive after sufficient stirring, so that the mass ratio of elements Ni and Mo is 1:2, aging treatment is carried out at 50-60℃ for 10-14h, the metal oxide with acid-base dual sites is added as a carrier, so that the loading amount of element Ni is 10%, and sufficient stirring is carried out; vacuum rotary evaporation is carried out to remove water, drying is carried out, the obtained solid material is calcined for 2-4h; the obtained solid after calcination is ground into powder, and reduction is carried out in an atmosphere of 90% H2 / N2 with a flow rate of 100ml / min, the temperature is maintained at 350-400℃ for 3-4h, and the bifunctional catalyst is obtained.

[0011] Further, the vacuum rotary evaporation is carried out at a vacuum degree of-0.1-0.2 MPa and a temperature of 60-75 DEG C, and the rotation speed is 50-60 rpm.

[0012] Further, the calcination is carried out in a muffle furnace at a temperature increasing rate of 5 DEG C / min, and the calcination temperature is 500-600 DEG C when the t-ZrO2 is used to prepare the bifunctional catalyst, is 350 DEG C when the a-ZrO2 is used to prepare the bifunctional catalyst, and is 500-600 DEG C when the m-ZrO2 is used to prepare the bifunctional catalyst; and the drying is carried out in a drying box at 120 DEG C for 6 h.

[0013] The application further provides a bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation, which is prepared by the preparation method.

[0014] The application further provides an application of the bifunctional catalyst based on catalytic hydrogenation dechlorination and deoxygenation in deoxygenation and dechlorination of oxygen-containing and chlorine-containing pyrolysis oil.

[0015] Further, the application is specifically: the application is carried out in a continuous micro fixed bed, the bifunctional catalyst is fixed in a reaction tube, quartz wool is used to fix both ends, a high-pressure pump is used to add the reactant into the reaction tube at a rate of 0.2 ml / min, and the continuous reaction is carried out at a temperature of 350 DEG C-400 DEG C, a hydrogen pressure of 1-2 MPa, a hydrogen flow rate of 50-100 sccm, and a mass space velocity of 30-60 h / 1 for 1-4 hours, a constant-temperature cooling box is used to condense at 4-8 DEG C, and the condensed liquid product is collected.

[0016] The application has the following beneficial effects:

[0017] The application selects an effective catalyst carrier and an auxiliary agent, and the active substance Ni and the auxiliary agent such as Mo are loaded on the t-ZrO2 carrier through co-precipitation, calcination and activation, the auxiliary agent and the t-ZrO2 carrier can improve the hydrogenation dechlorination and deoxygenation activity of Ni, and the main reason why the catalyst has the dechlorination and deoxygenation performance is that the catalyst has acid and alkali active sites, and the t-ZrO2 has acid and alkali active sites. The alkali active site can effectively absorb the by-product hydrogen chloride generated in the chlorination removal reaction, avoid the reaction of the by-product hydrogen chloride with Ni to cause catalyst poisoning, and thus improve the stability of the catalyst as a whole; the existence of the acid active site can act as an active site to crack the C-O bond, and thus help to improve the hydrogenation deoxygenation effect. The main advantages of the catalyst in the application in the hydrogenation upgrading of chlorine-containing and oxygen-containing waste plastic pyrolysis oil are low cost, simple preparation process, high catalytic activity, and the ability to adapt to the hydrogenation upgrading of complex component pyrolysis oil, compared with traditional hydrogenation upgrading catalysts. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The catalyst effect comparison chart of each catalyst in Comparative Examples 1, 2, 3, and 4.

[0019] Figure 2 The catalyst effect comparison chart of each catalyst in Comparative Examples 5, 6, 7, and 8.

[0020] Figure 3 The catalyst effect comparison chart of each catalyst in Comparative Example 9.

[0021] Figure 4 The XRD pattern of the catalytic absorbent Ni / Mo / ZrO2 prepared in Example 1.

[0022] Figure 5 The CO2-TPD result of the Ni / Mo / ZrO2 prepared in Example 1.

[0023] Figure 6 The NH3-TPD result of the Ni / Mo / ZrO2 prepared in Example 1. DETAILED DESCRIPTION

[0024] The present application first prepares a metal oxide with acid-base dual sites, including obtaining different morphologies t-ZrO2, a-ZrO2, and m-ZrO2 by selecting different precipitants and under different calcination conditions, including the following steps:

[0025] (1) Dissolve 10-50 g of ZrOCl2 into 100-200 ml of deionized water (preferably 150 ml), stir until uniform, add the corresponding precipitant so that the solution PH value is maintained between 9-10, and age at 40-50°C for 3 h.

[0026] Among them, the corresponding precipitant is: for preparing t-ZrO2, a mixed solution of 20-30 ml of NaHCO3 (mass fraction of 5-10%, preferably 5%) and Na2CO3 (mass fraction of 10-20%, preferably 10%) is used; for preparing a-ZrO2, 30-60 ml of ammonia water (mass fraction of 28-30%) is used; for preparing m-ZrO2, 20-50 ml of Na2CO3 (10 wt%) is used.

[0027] (2) Wash the aged solution with 40-60°C deionized water multiple times until the solution PH value is neutral, filter to obtain a solid precipitate, dry in a drying oven to remove water, grind into powder, and place in a muffle furnace to obtain the corresponding metal oxide with acid-base dual sites.

[0028] The calcination temperature is 500-600℃ for preparing t-ZrO2, 350℃ for preparing a-ZrO2, and 500-600℃ for preparing m-ZrO2.

[0029] The metal oxide with acid-base dual sites prepared by the method is used to further prepare a bifunctional catalyst, and the bifunctional catalyst can effectively realize one-step dechlorination and deoxygenation synthesis.

[0030] (1) 2-5 g of nickel nitrate hexahydrate containing Ni is fully dissolved in deionized water, and 1-3 g of a compound containing an auxiliary element is added to the solution after sufficient stirring to form solution A, which is aged at 50-60℃ for 10-14 h.

[0031] The auxiliary element can be Mo, and the compound thereof can be ammonium molybdate.

[0032] (2) 1-3 g of the metal oxide carrier with acid-base dual sites prepared above is added to the aged solution A in step (1) and stirred thoroughly.

[0033] (3) The aged solution is subjected to vacuum rotary evaporation to remove water substances, and the obtained solid material is calcined in a muffle furnace for 2-4 h after drying.

[0034] The optimal conditions for vacuum rotary evaporation are as follows: the vacuum degree is maintained at -0.1-0.2 MPa, the temperature is maintained at 60-75℃, and the rotation speed is 50-60 rpm. The calcination temperature is 500-600℃ for preparing a bifunctional catalyst using t-ZrO2, 350℃ for preparing a bifunctional catalyst using a-ZrO2, and 500-600℃ for preparing a bifunctional catalyst using m-ZrO2.

[0035] (4) The obtained solid after calcination is ground into powder and reduced under an atmosphere of 90% H2 / N2 (100 ml / min) at a temperature of 350-400℃ for 3-4 h, and the bifunctional catalyst is finally obtained.

[0036] In steps (1) and (2), the amount of each component added is such that the mass ratio of Ni to Mo is 1:2, and the final Ni loading of the obtained catalyst is 10%.

[0037] The application will be further described in conjunction with the drawings and examples in the specification, but the protection scope of the application is not limited thereto.

[0038] Example 1

[0039] Take 10 g of zirconium oxychloride into 150 ml of deionized water to make an aqueous solution, add 20-30 ml of 5% (w) NaHCO3 and 10% (w) Na2CO3 solution as precipitant, so that the PH of the resulting solution is kept at 9-10, and the resulting precipitate is placed in the mother liquor at 40°C for 3h aging treatment.

[0040] Wash the precipitate with 50°C deionized water through a filter device until the PH value of the mother liquor reaches neutral, and obtain the precipitate and place it in a drying oven at 105°C overnight.

[0041] Grind the dried solid into powder and place it in a muffle furnace at a heating rate of 5°C / min to 550°C for 3h calcination, and finally obtain white solid t-ZrO2.

[0042] Take 3g of nickel nitrate hexahydrate and add it to 200ml of deionized water to prepare a nickel nitrate solution, add 1.5g of ammonium molybdate to the solution and stir well, and place it in a 50°C oven for 12h aging.

[0043] Add 1.56g of t-ZrO2 to the above resulting solution, stir well and place it in a round-bottom flask, use a vacuum rotary evaporator, maintain a vacuum degree of -0.1MPa, a temperature of 65°C, and a rotation speed of 60rpm to remove surface moisture. Then place it in a drying oven at 120°C for 6h to remove internal moisture.

[0044] Place the resulting dried solid in a muffle furnace and maintain a heating rate of 5°C / min to 550°C for 4h calcination.

[0045] After calcination, grind the resulting solid into powder and activate it under an atmosphere of 90% H2 / N2 (100ml / min) at 400°C for 3h to obtain the final Ni / Mo / ZrO2 bifunctional catalyst with a Ni loading of 10%.

[0046] Example 2-3

[0047] Use the method of preparing the Ni-based catalyst in Example 1, except that different morphologies of ZrO2 (a-ZrO2, m-ZrO2) are prepared. The specific differences are shown in Table 1:

[0048] Table 1 Comparison of catalyst preparation in Examples 1-3

[0049]

[0050]

[0051] Among them, only the differences from the examples are shown, and the precipitant selected in Examples 2, 3 is 30-60ml of ammonia water (28-30%), 20-50ml of Na2CO3 (10wt%).

[0052] Example 4: Application of the hydrodechlorination-deoxygenation catalyst

[0053] The hydrodechlorination-deoxygenation experiments of the chloro-oxygenated mixed oil containing 1,2-dichloroethane, chlorobenzene, furfural and phenol were carried out using the catalyst prepared in Examples 1-3. The reaction was carried out in a continuous feeding fixed bed, with chlorobenzene (8 wt.%) and 1,2-dichloroethane (2 wt.%) as the representative chlorinated hydrocarbon, and furfural (6 wt.%) and phenol (4 wt.%) as the oxygen-containing organic matter. Octane (10 wt.%), octene (20 wt.%) and p-xylene (50 wt.%) were added to prepare 100 ml of chloro-oxygenated pyrolysis oil. The feeding rate was 0.2 ml / min, the temperature was maintained at 350°C, the pressure was 2 MPa, the gas flow rate was 100 sccm, the mass space velocity was 30 h-1, the continuous reaction time was 4 hours, and a constant temperature cooling box was used to maintain a 6°C circulating water condenser. The liquid product obtained after the reaction was collected. -1

[0054] The composition of the liquid phase product was quantitatively detected by gas chromatography-mass spectrometry (Agilent 8860-5977C / MS). The quantitative analysis method used an external standard method for determination. First, standard substances were prepared, and the raw materials mainly included dichloroethane (chromatographic grade, >99%), chlorobenzene (chromatographic grade, >99%), octane (chromatographic grade, >99%), octene (chromatographic grade, >99%) and p-xylene (chromatographic grade, >99%). The standard mixed organic solution was prepared according to the volume ratio of 1:4:5:10:30. The standard mixed solution was diluted by 10 times step by step to obtain 4 groups of concentration gradient standard mixed solutions. The characteristic ions and peak time of the calibration substances were determined according to the qualitative data, and the specific parameters are shown in Table 2. The standard mixed solution was injected in order according to the concentration from high to low to obtain the calibration curve, and then the quantitative detection of the sample was carried out.

[0055] Table 2: Characteristic ions and peak time of each compound

[0056]

[0057]

[0058] wherein the GC parameters are set as follows: injection port temperature 350°C, chromatographic column type HP-5MS

[0059] ​(30m*0.25mm*0.25um), temperature program was 50°C for 3 min, then 20°C / min to 150°C for 1 min, finally 50°C / min to 300°C, total time 12 min. Solvent was n-hexane, solvent ratio was 10:1, split ratio was 80. MS part parameters were set as, solvent delay was 2.4 min, mass to charge ratio range was 30-300. Table 3 was the results of catalysts prepared in each example.

[0060] Table 3 Catalyst experimental results table of examples 1-3

[0061]

[0062] Comparative examples 1-4

[0063] Molecular sieve (HY, ZSM-5) or basic hydrotalcite (Ca-HTLCs, Zn-HTLCs) was added to the aging solution of Ni-based as a carrier, dried, calcined and activated. The prepared Ni-based catalyst only has acidic or basic sites.

[0064] Comparative examples 5-8

[0065] Molecular sieve (HY, ZSM-5) and basic hydrotalcite (Ca-HTLCs, Zn-HTLCs) were mixed in a mass ratio of 1:1 and then added to the aging solution of Ni-based as a carrier, dried, calcined and activated. The prepared Ni-based catalyst has acidic or basic sites.

[0066] Comparative example 9

[0067] Pd / C was selected as a noble metal-based catalyst.

[0068] Table 4 Catalyst parameter table of comparative examples 1-9

[0069]

[0070]

[0071] Ca-HTLCs and Zn-HTLCs are hydrotalcite carriers prepared.

[0072] Table 5 is the results of the catalysts prepared in comparative examples 1-9 in example 4.

[0073] Table 5 Catalyst experimental results table of comparative examples 1-9

[0074]

[0075] Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs.

[0076] Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs. Figure 1 Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs.

[0077] Comparative Examples 5-8: Ni / Mo / HY / Ca-HTLCs; Ni / Mo / ZSM-5 / Ca-HTLCs;

[0078] Ni / Mo / HY / Zn-HTLCs; Ni / Mo / ZSM-5 / Zn-HTLCs.

[0079] Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs. Figure 2 Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs.

[0080] Comparative Example 9: Pd / C

[0081] Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs. Figure 3 Comparative Examples 1-4: Ni / Mo / HY; Ni / Mo / ZSM-5; Ni / Mo / Ca-HTLCs; Ni / Mo / Zn-HTLCs.

[0082] It should be noted that the above-mentioned only is the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Without making creative labor, any modification, equivalent replacement, improvement, etc. should be included in the protection scope of the present application.

Claims

1. The application of a bifunctional catalyst based on catalytic hydrodechlorination and deoxygenation in oxygen- and chlorine-containing pyrolysis oils for deoxygenation and dechlorination, characterized in that, The oxygen- and chlorine-containing pyrolysis oil contains 1,2-dichloroethane, chlorobenzene, furfural, and phenol; The specific preparation method of the bifunctional catalyst is as follows: supporting metallic Ni on a metal oxide with acid-base amphoteric sites, so that the Ni loading is 10%, to obtain the bifunctional catalyst. The metal oxide with acid-base amphoteric sites is prepared through the following steps: Add 10-50 g of ZrOCl2 to 100-200 ml of water, stir well, add precipitant until the pH of the resulting solution is 9-10, age at 40-50℃ for 3 hours; wash several times with water at 40-60℃ until the pH of the solution is neutral, filter to obtain a solid precipitate, dry, remove water, grind into powder, and calcine in a muffle furnace for 2-4 hours to obtain a metal oxide with acid-base amphoteric sites; The metal oxides with amphoteric acid-base sites include t-ZrO2, a-ZrO2, and m-ZrO2. The precipitant for t-ZrO2 is a mixed solution of NaHCO3 and Na2CO3, and the calcination temperature is 500-600℃. The precipitant for a-ZrO2 is ammonia, and the calcination temperature is 350℃. The precipitant for m-ZrO2 is Na2CO3, and the calcination temperature is 500-600℃. The process of loading metallic Ni onto a metal oxide with acid-base amphoteric sites specifically involves: adding water to nickel nitrate hexahydrate until fully dissolved, stirring thoroughly, adding a Mo-containing compound as an additive to the solution to achieve a Ni:Mo mass ratio of 1:2, and aging at 50-60°C for 10-14 hours; adding the metal oxide with acid-base amphoteric sites as a support to achieve a Ni loading of 10%, and stirring thoroughly; removing moisture by vacuum rotary evaporation, drying, and calcining the resulting solid for 2-4 hours; grinding the solid obtained after calcination into powder and reducing it in an atmosphere of 90% H2 / N2 at a flow rate of 100 ml / min at a temperature of 350-400°C for 3-4 hours to obtain the bifunctional catalyst.

2. The application according to claim 1, characterized in that, The vacuum rotary evaporation is performed with a vacuum level maintained at -0.1~0.2MPa, a temperature maintained at 60-75℃, and a rotation speed of 50-60rpm.

3. The application according to claim 1, characterized in that, The calcination is carried out in a muffle furnace at a heating rate of 5℃ / min. The calcination temperature is 500-600℃ when using t-ZrO2 to prepare the bifunctional catalyst, 350℃ when using a-ZrO2, and 500-600℃ when using m-ZrO2. The drying is carried out in a drying oven at 120℃ for 6 hours.

4. The application according to claim 1, characterized in that, The specific application involves fixing the bifunctional catalyst in a reaction tube, adding the oxygen- and chlorine-containing pyrolysis oil to the reaction tube at a rate of 0.2 ml / min, and maintaining the reaction at 350℃-400℃, hydrogen pressure of 1-2 MPa, hydrogen flow rate of 50-100 sccm, and mass hourly space velocity of 30-60 h⁻¹. -1 Under these conditions, the reaction is carried out continuously for 1-4 hours, and the product is condensed in a constant temperature cooling box at 4-8℃. The condensed liquid product is then collected.

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