JPH0417698B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for demetallizing and regenerating a deteriorated zeolite-based fluid catalytic cracking catalyst by treating raw oil containing metal compounds. and a method for removing contaminant metals from vanadium. Nickel and vanacidium exist as organometallic compounds in heavy fractions of crude oil, and when raw oil containing these components is catalytically decomposed, they adhere to the catalyst surface and have a detrimental effect on the decomposition reaction. In other words, the cracking activity of the catalyst decreases and the yield of gasoline, the main product, decreases, the amount of hydrogen produced increases and additional equipment is required for compressing lean gas, and the amount of coke produced increases and the liquid Yields are reduced and additional operations are required in the catalyst regeneration step to remove coke. In the case of catalytic cracking of raw oil with such a large metal content, the metal concentration in the catalyst quickly reaches a limit value determined by operational constraints. Therefore, in order to maintain a constant activity level, it is necessary to extract the used equilibrium catalyst and replace it with new catalyst, which increases the amount of expensive catalyst consumed. It is well known to those skilled in the art that as a method of reducing the adverse effects of these metal contaminants, a method of inactivating the attached contaminant metals is also employed. However, its application range is limited to a range where the amount of metal deposited is relatively low concentration, and there are restrictions on the use of certain passivating agents due to environmental regulations. If metal-contaminated fluid catalytic cracking catalysts can be demetallized and their unfavorable cracking behavior suppressed, relatively abundant low-grade feedstock oils can be converted into high-value gasoline and other light hydrocarbons. The development of new and improved demetalization methods for metal-contaminated fluid catalytic cracking catalysts is desired. Several treatment methods have already been devised for amorphous silica-alumina catalysts as demetallization regeneration methods for fluid catalytic cracking catalysts contaminated with metals (for example, US Pat. No. 3,222,293). In the demetallization regeneration treatment of zeraolite-based catalysts, it is necessary to devise ways to remove metals without damaging the crystals of zeolite, which is a crystalline aluminosilicate. U.S. Patent No. 3985639 and U.S. Pat.
A method disclosed in No. 4013546 is known. These patents regenerate the contaminated catalyst by removing coke and reducing it, contacting it with carbon monoxide under pressure to separate the nickel as a carbonyl compound, and then contacting it with chlorine gas to separate the vanadium as a chlorine compound. The method is disclosed. However, in this method, the catalyst is treated with carbon monoxide, which is a toxic gas, and highly toxic nickel carbonyl is produced, so consideration must be taken when putting it into practical use. It is not clear whether the crystals will remain intact. The demetal treatment according to the present invention consists of the following steps. The fluidized catalytic cracking catalyst, which has deteriorated due to the adhesion of nickel and vanadium in the feedstock oil during catalytic cracking, is partially bypassed from the plant's regenerator and taken out at 650℃.
Air oxidation is performed at 800℃ to remove residual coke,
Next, hydrogen reduction is performed at 650℃ to 800℃. or
Oxidize with air or oxygen at 650℃ to 800℃,
Reduction treatment is performed by an alternating process of repeating hydrogen reduction treatment at 650°C to 800°C. In this process, nickel is reduced and vanadium changes to a lower oxidation state. A chemical treatment is carried out in which the reduced catalyst is contacted with a mixture with carbon tetrachloride or hexachloroethane at 300° C. to 450° C. under a hydrogen atmosphere. Vanadium is separated as a gas at about 200°C as vanadium chloride or vanadium oxychloride, and nickel is converted to chloride. Next, the chemically treated catalyst is treated with at least one member selected from the group consisting of methanol, water, chloroform, acetone, and carbon tetrachloride.
Elution treatment is carried out using a different solvent at a pressure of normal pressure to 10 kg/cm ² and a temperature of room temperature to 200°C. Nickel chloride and residual vanadium compounds are dissolved and separated from the catalyst. The solvent of the eluted catalyst is removed by heating and drying or by purging with dry nitrogen gas, and the demetallization process is completed. The demetalized catalyst is returned to the fluid catalytic cracking plant regenerator and used again for catalytic cracking. According to the present invention, by selecting the conditions of oxidation treatment, reduction treatment, chemical treatment and elution treatment,
It is possible to carry out demetallization regeneration treatment without damaging the zeolite, which is the active component in the catalyst. The present invention will be explained below with reference to Examples. Demetallization is carried out in a flow-through quartz tube reactor with oxidation, reduction, and chemical treatments. A reactor with an inner diameter of 28 mm is filled with 20 g of catalyst, and the H ₂ /chlorine compound molar ratio is 10 in a hydrogen stream with a gas flow rate (at room temperature) of 150 mm/min for oxidation or reduction treatment, and a flow rate of 150 ml/min for chemical treatment. A mixture of carbon tetrachloride or hexachloroethane was supplied through a microfeeder in an amount of 1 to 15%. The elution treatment was carried out using a Soxthlet type extractor or an autoclave equipped with a Soxthlet type extractor inside the reactor. Catalyst activity evaluation is performed using a fixed bed microreactor test method (MAT, ASTM D3907-
A microactivity test (according to 80) was conducted. The reaction conditions are catalyst amount 5g, reaction temperature 482.2
℃, the oil flow rate was 2 ml/75 sec, and the weight liquid space velocity was 17.2 per hour. The zeolite-based fluid catalytic cracking catalyst subjected to the metal removal treatment was characterized by the properties listed in Table 1. Zeolite cations (RE ₂ O ₃ ) were determined by fluorescent X-ray method, and zeolite content was determined by X-ray diffraction method (111) and (533) of Y-type zeolite.

[Table] Quantified from the diffraction lines attributed to the plane. Analysis of other components was performed using conventional methods. Example 1 The catalyst was calcined in an oxygen stream at 750°C for 3 hours, the residual oxygen was purged with nitrogen gas, the switch was switched to hydrogen gas, and the alternating process of reducing at 750°C for 3 hours was repeated three times, and then the catalyst was calcined at 750°C in a hydrogen stream for 3 hours. Chemical treatment was carried out by catalyzing with carbon tetrachloride for 0.2 h at ℃. Next, the catalyst was transferred into a paper cylinder, placed in a Soxley extractor, and subjected to elution treatment using water at about 50° C. for 5 hours under normal pressure. After taking it out, it was dried in a dryer at 105°C for 5 hours, filled into a glass reaction tube, and purged with nitrogen at 250°C for 1 hour to complete the demetal treatment. The thus regenerated catalyst was subjected to MAT experiments and the above-mentioned analysis.
Table 2 summarizes the products of the MAT experiment and the analysis results of metals and zeolites. The metal removal rate is 31% based on nickel equivalent (Ni + 1/4V),
There is almost no change in the zeolite content and RE ₂ O ₃ content due to the demetallization treatment. In the MAT experiment, the amount of hydrogen and coke produced decreased, and a C ₅ fraction with a boiling point of 204.4℃ corresponding to the gasoline yield and a C ₁ fraction with a boiling point of 204.4℃ corresponding to the total cracking activity.
Distillate is increasing. Therefore, it can be seen that the metal is removed by this demetalization treatment, the zeolite and substituted cations are kept intact, and the catalytic activity and selectivity are clearly restored. Example 2 The catalyst was reduced with hydrogen at 750°C for 3 hours and placed in a hydrogen stream.
Chemical treatment was carried out by catalyzing with carbon tetrachloride at 380℃ for 0.2 hours. Elution treatment was performed in the same manner as in Example 1 using methanol at about 50° C. for 5 hours under normal pressure. The solvent was removed in the same manner as in Example 1, and the sample was subjected to analysis and MAT experiment. As can be seen from Table 3, the metal removal rate is 30%.
The zeolite and substituted cations are kept intact,
Hydrogen and coke are reduced to _C5 fraction or boiling point 204.4
℃ yield and the yield of C ₁ fraction or boiling point 204.4℃ are increasing. Therefore, it is clear that the active components of the catalyst are not impaired by this demetallization treatment and the catalyst performance is restored.

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[Table] Example 3 A catalyst was reduced with hydrogen at 750°C for 3 hours, and then chemically treated with carbon tetrachloride at 375°C for 0.2 hours in a hydrogen stream. After taking it out, it was transferred to a cylindrical paper, placed in an autoclave equipped with a Soxle type extractor, and subjected to elution treatment using methanol at 120° C. and 7 kg/cm ² for 3 hours. Almost similar metal analysis values were obtained using chloroform, acetone, and carbon tetrachloride instead of methanol. It was dried in the same manner as in Example 1 and subjected to analysis and MAT experiment. As shown in Table 4, at a demetalization rate of 54%, zeolite and substituted cations are kept as they are, hydrogen and coke are reduced, and the _C5 fraction has a boiling point of 204.4℃ and the _C1 fraction has a boiling point of 204.4℃. yield is increasing. It is clear that the decomposition activity and selectivity are restored without destroying the zeolite crystals. Example 4 A catalyst was reduced in the same manner as in Example 1 and treated with carbon tetrachloride containing 10% hexachloroethane in a hydrogen stream.
Chemical treatment was performed by contacting at 400°C for 0.3 hours. Next, the remaining solvent was removed in the same manner as in Example 2, and the sample was subjected to MAT experiment and analysis. As shown in Table 5, at a demetalization rate of 57%, the zeolite and substituted cations are kept as they are, and the yield of hydrogen and coke decreases, resulting in a C ₅ fraction with a boiling point of 204.4°C and a C ₁ fraction with a boiling point of 204.4°C. °C yield is increasing. Therefore, it is clear that even under these treatment conditions, the active components are maintained as they are by the demetallization treatment, the harmful contact effects of metals are suppressed, and the decomposition activity is restored.

Claims (1)

[Claims] 1. A zeolite-based fluid catalytic cracking catalyst whose activity has deteriorated due to the adhesion of nickel and vanadium is reduced, then chemically treated with a chlorine-based reagent, and then washed with a polar solvent to remove metals and increase the catalytic activity. How to play. 2 Remove residual coke from the deteriorated catalyst and reduce it with hydrogen at 650℃ to 800℃, or reduce it with hydrogen at 650℃ to 800℃
After firing in air or oxygen atmosphere at 800℃
The method according to claim 1, wherein alternating hydrogen reduction treatment is carried out at 650°C to 800°C. 3. Claim 1 above, in which vanadium is separated as a gas by chemical treatment at 300°C to 450°C in a hydrogen atmosphere under normal pressure using a reagent that is a mixture of carbon tetrachloride or hexachloroethane as a chlorinated reagent. The method described in section. 4 Using at least one solvent selected from the group consisting of methanol, water, chloroform, acetone, and carbon tetrachloride as a polar solvent, under normal pressure or
The method according to claim 1, wherein the elution treatment is carried out at a pressure of 10 Kg/cm ² and a temperature of room temperature to 200°C. 5. The method according to claim 1, which is carried out using a fluid catalytic cracking equilibrium catalyst having a total of 3000 parts by weight of nickel and vanadium deposited in at least 1 million parts by weight of the catalyst.