JPH0417699B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for demetallizing and regenerating catalysts contaminated with metals during fluid catalytic cracking of heavy petroleum feedstocks.More specifically, the present invention relates to a method for demetallizing catalysts contaminated with metals during fluid catalytic cracking of heavy petroleum feedstocks. The present invention relates to a method for extracting, removing, and regenerating zeolite, which is an active component of a fluid catalytic cracking catalyst, without damaging it. Fluid catalytic cracking involves cracking petroleum-based feedstocks by contacting them with a catalyst to obtain gasoline and other valuable light fractions. Conventionally, fluid catalytic cracking has processed feedstock oils mainly consisting of gas oil or a mixture with vacuum gas oil, but as the crude oil produced tends to become heavier, demand for light oils such as kerosene and diesel oil is increasing. , Fluid catalytic cracking of raw oil containing residual oil is an effective means of dealing with heavy oil. The residual oil contains organic metal compounds such as nickel and vanadium, which are decomposed during catalytic cracking and these metals adhere to the catalyst. Since the deposited metal partially covers the catalyst surface and has dehydrogenation ability, it decreases the conversion rate from feedstock to cracked products, decreases the yield of gasoline as the main product, and increases the amount of hydrogen and coke produced. and has a negative effect on catalytic cracking. In other words, as the yield of the main product decreases and at the same time the amount of hydrogen produced increases, additional equipment is required for compressing lean gas, and as the amount of coke produced increases, the liquid yield decreases and it becomes difficult to burn off the coke. Additional equipment will be required. When raw oil with a large metal content is subjected to catalytic cracking, the metal concentration in the catalyst increases and quickly reaches a limit value determined by operational constraints. Therefore, in order to maintain a constant level of catalyst activity and selectivity, it is necessary to extract the equilibrium catalyst circulating in the fluid catalytic cracker and replace it with new catalyst, which increases the consumption of expensive catalyst. It turns out. However, if it is possible to suppress unfavorable catalytic cracking behavior by demetallizing and regenerating fluid catalytic cracking catalysts that have deteriorated due to adhesion of metals, it is possible to convert relatively abundant low-grade heavy feedstocks into valuable light distillates such as gasoline and other high-value oils. It is desired to develop a new and improved demetallization regeneration method that can be stably and continuously converted in minutes. Several treatment methods have been devised for amorphous silica-alumina catalysts as demetallization regeneration methods for fluid catalytic cracking catalysts contaminated with metals (for example, U.S. Pat. No. 322,229); In metal removal treatment, it is necessary to devise ways to remove contaminant metals without damaging the crystals of zeolite, which is a crystalline aluminosilicate. US Patent No.
No. 3985639 and No. 4013546. These patents involve burning off and reducing the coke on the contaminated catalyst, contacting it with carbon monoxide under pressure to separate the nickel on the catalyst as a nickel carbonyl compound, and then contacting it with chlorine gas to reduce the vanadium as chloride. Discloses a method for separating and regenerating. However, in this method, the catalyst is treated with carbon monocarbon, which is a poisonous gas, and highly toxic nickel carbonyl is produced, so consideration must be given when putting it into practical use. Not specified. The vanadium removal treatment according to the present invention consists of the following steps. In catalytic cracking, the metal-attached catalyst in the feed oil is extracted from the regeneration tower of the fluid catalytic cracker by partially bypassing it, and is heated under relatively mild conditions, i.e., 600°C to 700°C, at approximately the same temperature as the internal temperature of the regeneration tower with air or In an oxygen stream, remaining coke is burnt and removed while adhering metals are oxidized. This process transforms vanadium into a highly oxidized state. The oxidized catalyst is oxidized using at least one catalyst selected from the group consisting of methanol, ethanol, and water.
The vanadium is extracted by washing at a pressure of 10 kg/cm ² at room temperature to 200°C. The solvent of the extracted catalyst is removed by heat drying or purging with dry nitrogen gas, and the vanadium removal process is completed. The devanadated catalyst is returned to the regeneration tower of the fluid catalytic cracker and used again for catalytic cracking. According to the present invention, by selecting the oxidation treatment and extraction treatment conditions, the devanadium-free regeneration treatment can be performed without damaging the zeolite in the catalyst. Furthermore, the extraction solvent is recovered by evaporation and the vanadium is extracted as an oxide, so no waste liquid is generated that requires reprocessing. Further, if the vanadium removal treatment method of the present invention is performed as a pretreatment for passivation treatment of contaminated metals, a great effect can be obtained in improving the performance of a deteriorated catalyst. That is, the catalyst may be treated with a metal passivating agent after the vanadium removal treatment, or the catalyst may be returned to the fluid catalytic cracker after the vanadation treatment and the treatment agent may be added to the feedstock oil. The metal passivating agent is a substance that inactivates metals such as nickel and vanadium attached to the catalyst and reduces harmful catalytic decomposition behavior caused by the attachment of contaminant metals, and is well known in the industry and has already been disclosed in the patent application. Showa 52-
68002, 53-26801, 53-104588, 53-
No. 142406, No. 56-144749, Japanese Patent Publications No. 56-158149 and No. 57-39186. Although oil-soluble antimony compounds or inorganic antimony compounds dissolved in oil are known as typical examples of metal passivating agents, the pretreatment method of the present invention is effective for both. The present invention will be explained in detail below with reference to Examples. The devanadation treatment was carried out by oxidizing an equilibrium catalyst for fluid catalytic cracking that had been processed from raw oil containing residual oil in a laboratory-scale flow-through reactor, and then washing it in a Soxhlet type extractor. Oxidation treatment has an inner diameter of 48
200g of catalyst was placed in a quartz reactor with a flow rate of 300mm.
This was carried out by firing at 650°C for 3 hours in an air or oxygen stream at a flow rate of ml/min. After cooling, the catalyst is taken out and washed for 5 hours under specified conditions using methanol or water as a solvent in an autoclave equipped with a Soxhlet type extractor in the case of normal pressure extraction or a Soxhlet type extractor in the case of pressure extraction. I processed it. After the extraction process, the catalyst was transferred to a dryer kept at 150°C and dried in a nitrogen stream for 5 hours to remove the solvent and complete the regeneration process. When performing vanadium removal treatment as a pretreatment for passivation treatment, after the above treatment, apply a passivating agent to the catalyst using an impregnation method to a concentration of 0.1% by weight in terms of antimony metal, and place it in the same quartz reactor as above. Transfer the catalyst
Similarly, calcination treatment was carried out at 650°C for 1 hour in an air stream. Table 1 shows the properties of the equilibrium catalyst for fluid catalytic cracking used in the experiment. As can be seen from the table, this catalyst is a zeolite catalyst with a matrix of clay minerals, and the total amount of nickel and vanadium attached is
It was 8000ppm, which is a high concentration of contamination for this type of catalyst. The zeolite catalyst was quantitatively determined by X-ray diffraction, the zeolite cation species (RE ₂ O ₃ ) was determined by fluorescent X-ray method, and other components were analyzed and physical properties were determined by conventional methods. Catalyst performance was evaluated using a bench-scale fluidized catalytic cracker (catalyst inventory 2.3 kg) using desulfurized vacuum decompressor as feedstock oil.

【table】

[Table] Using oil, reactor temperature is 500℃, regenerator temperature is 600℃,
It was conducted at a catalyst to oil ratio of 10 w/w and a WHSV of 15 w/w/time. Example 1 A metal-contaminated catalyst was calcined and oxidized in an air stream under predetermined conditions, and extracted using a Soxhlet extractor with water as a solvent at normal pressure. A comparison is shown in Table 2. This treatment removed 12% of vanadium, and the zeolite content and amount of zeolite cation species remained unchanged, maintaining the active components of the catalyst.
As for the performance of the catalyst, the conversion rate increased by 3.5% by volume, the main product sasorin fraction (C ₅ ~CCG) increased by 4.5% by weight, the LPG yield also increased, and the cracking activity was obviously improved. In addition, the H ₂ /CH ₄ ratio, which indicates the amount of hydrogen produced, decreased by about 19%, the amount of coke produced also decreased, and the selectivity of the catalyst improved, so the effect of the vanadium removal treatment was remarkable. Almost the same effect was observed even when the oxidation treatment was performed under the same conditions in an oxygen stream.

[Table] Example 2 A catalyst was oxidized by being calcined under specified conditions in an air flow, and extracted under pressure in an autoclave using methanol as a solvent. The properties and activity test results of the catalyst were compared with the untreated catalyst. A comparison is shown in Table 3. This treatment removed 14% of vanadium, while maintaining the zeolite content and amount of zeolite cation species. The performance of the catalyst is that the conversion rate is 4% by volume and the yield of gasoline (C ₅ - CCG) is 4% by weight.

[Table] It is clear that the activity is improved as the LPG yield increases, the H ₂ /CH ₄ ratio decreases by 21%, and the amount of coke produced decreases, indicating that the selectivity is greatly improved. Almost similar results were obtained under the same conditions using ethanol as the extraction solvent. Example 3 Table 4 shows the activity test results of a catalyst treated with an antimony-based passivation agent after oxidation treatment by air calcination and atmospheric pressure extraction treatment using ethanol as a solvent.
As can be seen from Table 4, 12% of the adhering vanadium was removed by the pre-vanadium removal treatment, and the active components of the catalyst were maintained as they were. Passivation treatment of untreated catalyst increases conversion by 5% by volume, gasoline yield by 3.5% by weight, and H ₂ /
The CH ₄ ratio decreases by 19%, but removing vanadium as a pretreatment increases the conversion by 5.5% by volume, the gasoline yield by 4.5% by weight, and reduces the H ₂ /CH ₄ ratio by 33%.
Considering the results shown in Tables 2 and 3, devanadation treatment mainly recovers the activity of the catalyst, and passivation treatment further increases the amount of hydrogen produced.

[Table] It is clear that the amount of metal-contaminated catalysts produced is suppressed, and the devanadium treatment of the present invention as a pretreatment for passivation was recognized to be extremely effective in restoring the performance of metal-contaminated catalysts.

Claims (1)

[Claims] 1. In fluid catalytic cracking of heavy petroleum feedstock,
A method for demetallizing a deteriorated fluid catalytic cracking catalyst, which comprises oxidizing a fluid catalytic cracking catalyst whose performance has deteriorated due to adhesion of nickel and vanadium, and then removing vanadium by extraction with a polar solvent. 2. The method for demetallizing a deteriorated fluid catalytic cracking catalyst according to claim 1, wherein the oxidation treatment is carried out by firing in air or oxygen atmosphere at 600°C to 700°C. 3. Claim 1 in which the extraction process is carried out using at least one solvent selected from the group consisting of methanol, ethanol, and water as a solvent, at a pressure of normal pressure to 10 Kg/cm ² and at room temperature to 200°C. A demetallization regeneration method for a deteriorated fluid catalytic cracking catalyst as described in Section 3. 4 Vanadium in at least 1 million parts by weight of catalyst
A method for demetallizing a deteriorated fluid catalytic cracking catalyst according to claim 1, which is carried out using 2500 parts by weight of fluid catalytic cracking catalyst attached. 5. A method for demetallizing a deteriorated fluid catalytic cracking catalyst according to claim 1, which is carried out as a pretreatment for a passivation method for metals attached to the catalyst. 6 At least nickel in 1 million parts by weight of catalyst
A method for demetallizing a deteriorated fluid catalytic cracking catalyst according to claims 1 and 5, which is carried out using a fluid catalytic cracking catalyst on which 1500 parts by weight and 2500 parts by weight of vanadium are attached.