JPS6135239B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to arsenic oxidation treatment of an arsenic-containing petroleum fraction when the petroleum fraction containing arsenic is used in a reaction step using a noble metal as a catalyst. The purpose is to provide a new reaction process in which the poisonous effect of arsenic contained in the petroleum fraction on the noble metal catalyst is reduced. The petroleum fractions described in this specification include petroleum, straight-run naphtha, kerosene, light oil, vacuum distillate, atmospheric residual oil, etc., as well as pyrolysis gasoline by-produced in the pyrolysis equipment of an ethylene plant, and coker. It refers to a wide range of hydrocarbon oils, including hydrocarbon oils that have been heat-treated using vis-breakers, naphtha fractions produced in catalytic crackers, and recycled oils. Furthermore, the term "arsenic" as used herein refers to a compound containing elemental arsenic as one of its constituent elements. However, the arsenic in the following phrases, i.e., arsenic element, arsenic compound, arsenic concentration, and arsenic adhesion amount described in this specification, of course means arsenic itself and does not mean an arsenic compound. Many petroleum distillates contain trace amounts of arsenic. Although its form differs depending on the fraction, arsine and organic arsenic compounds can be considered. In the process of manufacturing various petrochemical raw materials or petrochemical products from petroleum fractions, this trace amount of arsenic may act as a poison to the catalyst, depending on its content.
Alternatively, it often interferes with various processes, such as promoting coking during steam pyrolysis. For example, in the process of producing aromatic compounds benzene, toluene, and xylene from straight-run naphtha or kerosene byproduct gasoline (hereinafter referred to as cracked gasoline), arsenic is contained in the cracked gasoline.
It appears to act as a poison to the palladium catalyst used in the hydrogenation process of diolefin to olefin, rapidly reducing its activity. Generally, arsenic is highly toxic to catalysts, and in particular it significantly reduces the activity of noble metal catalysts such as Pt and Pd used for hydrogenation, dehydrogenation, etc. Therefore, it has been essential to remove arsenic from the raw materials in advance, especially in treatment processes using noble metal catalysts. Conventionally, various techniques as described below have been disclosed regarding methods for removing arsenic from petroleum fractions. (1) A method of removing arsenic along with sulfur through hydrodesulfurization treatment. (2) Method of contact with basic compounds (USP
2779715). In this method, an alkali metal or alkaline earth metal compound is used as the basic compound. (3) Method of contacting copper and/or salts of metals with lower electromotive force than copper (USP 2781297) (4) Nitrogen compounds containing three additional groups and one unpaired electron (e.g., aqueous Ammonia, Hydrazine, Alkanolamines) (USP)
2867577) (5) Method of contact with acid-impregnated carrier (USP 3093574) (6) Method of contact with activated carbon (USP 3542669) As a result of conducting research, the following facts were discovered and the present invention was completed. That is, if the arsenic contained in the petroleum fraction is oxidized by an appropriate method, even if it is not removed, when the arsenic-containing petroleum fraction is used in a reaction process that uses a precious metal catalyst, it will be surprisingly effective against the precious metal catalyst. The toxic effect is significantly reduced. The means of oxidation in the present invention is firstly a method using a gas containing oxygen, such as air. This method will be explained below using arsenic-containing decomposed gasoline as an example. First, the cracked gasoline is brought into contact with air in a suitable container, and the oxygen in the air converts the arsenic directly into oxidation products. At the same time, oxygen reacts with olefins, diolefins, etc. contained in the cracked gasoline, producing peroxide as a by-product, and the by-product peroxide may contribute to the oxidation of arsenic. In addition, the oxidation process can be further facilitated by adding a very small amount of a radical initiator, such as azobisisobutyronitrile, or a substance that easily reacts with oxygen to easily generate peroxides, such as acetaldehyde or acetone. Proceed to. Reaction temperature is room temperature to 150℃
It may be adjusted according to the arsenic removal rate. After oxidation, it is preferable to degas the air dissolved in the petroleum fraction. A second means of oxidizing arsenic in petroleum fractions is the use of organic peroxides. The organic peroxide referred to here is a general term for organic compounds having an -O-O- bond, and includes hydroperoxides, percarboxylic acids, dialkyl peroxides, diacyl peroxides,
Refers to peroxide esters, etc. These organic peroxides can also be used after being diluted with an appropriate solvent depending on their physical properties. Examples of organic peroxides include cumene hydroperoxide (hereinafter abbreviated as CHP), lauroyl peroxide, diisopropylbenzene hydroperoxide,
Examples include P-menthane hydroperoxide. When these are used, the formation of a polymer called gum is also reduced. Therefore, oxidation using an organic peroxide is a preferred method. Especially CHP
It is easily available as an intermediate for the production of phenol using the cumene process, and is also a relatively thermally stable compound and is a preferred oxidizing agent. Another method for oxidizing arsenic in petroleum fractions is to use a common inorganic oxidizing agent and treat the arsenic at room temperature to 200°C. As an inorganic oxidizing agent,
Examples include H ₂ O ₂ , hypochlorous acid, KMnO ₄ , and inorganic peroxides. The method of reducing the poisonous effect of arsenic-containing petroleum fractions on noble metal catalysts according to the present invention can be said to be a much more economical and innovative method than the method of removing arsenic. The present invention will be explained below with reference to its embodiments. Model Experiment A series of model experiments (Experiments 1 to 3) are described below to examine the toxicity of oxidized arsenic to the catalyst.
The reaction mechanism of the present invention was confirmed. In Experiment 1, 100ml of pyrolyzed gasoline produced from an ethylene plant (diene value DV18, bromine value Br.No.41, total sulfur 100wt ppm, no arsenic detected) was used as SUS.
Palladium catalyst prepared in autoclave
Using 1 g of (Pd0.3wt%, carrier γ-Al ₂ O ₃ ), the reaction temperature was 50°C, the reaction pressure was 50 Kg/cm ² -G (under pressure of H ₂ ),
Hydrogenation was performed under conditions of a reaction time of 20 minutes, and the diene value of the hydrogenated oil was measured. (The diene value was measured by the maleic anhydride method. The same applies hereinafter.) In Experiment 2, triphenylarsine (Asφ ₃ )
Prepare 100 ml of a toluene solution with a concentration of 300 wt ppm, charge this solution into the autoclave used in Experiment 1, and use this solution to heat 1 g of paraladium catalyst at 60°C.
It was poisoned with 50Kg/cm ² -G (under pressure of H ₂ ) for 2 hours. Next, the toluene solution of triphenylarsine used for catalyst poisoning was completely extracted from the autoclave (however, the poisoned catalyst remained in the autoclave), and 100 ml of the same pyrolysis gasoline used in Experiment 1 was charged into the experiment. Hydrogenation treatment was performed under the same conditions as in Example 1, and the diene value of the hydrogenated oil and the arsenic content adsorbed on the catalyst were measured. In experiment 3, triphenylarsine (Asφ ₃ )
Add cumene hydroperoxide to a flask containing 100 ml of toluene solution with a concentration of 300 wt ppm.
Triphenylarsine and cumene hydroperoxide were added to give a concentration of 750 wtppm (CHP/As = 5 mol/mol), and reacted with triphenylarsine in a H ₂ stream at 60° C. for 2 hours at normal pressure. Next, experiment 2 using this solution
After the catalyst was poisoned in the same manner as above, the pyrolyzed gasoline was hydrogenated, and the diene value of the hydrogenated oil and the amount of arsenic adsorbed on the catalyst were measured. In Experiments 2 and 3, liquid charging and extraction operations and catalyst handling were performed using argon or argon gas.
The test was carried out in a H ₂ stream, and care was taken not to expose it to air. Table 1 shows the diene value of hydrogenated oil obtained in each experiment, the amount of arsenic detected in the catalyst used, and the reduction rate of diene value (DV ₀
-DV)/DV ₀ (DV ₀ is the diene value of the feedstock oil, DV is the diene value of the hydrogenated oil).

[Table] Combining the above model experiment results, organic arsenic compounds contained in petroleum fractions are reduced by oxidation treatment.
It is clear that its poisonous effect on noble metal hydrogenation catalysts is significantly weakened. The structure and effects of the present invention will be further clarified by the following comparative examples and examples. Comparative example Pyrolysis gasoline produced from an ethylene plant with an arsenic concentration of 1.2 wt ppm (diene value 20, bromine value 42, benzene 32 wt%, toluene 23 wt%, C ₈
Aromatic 18.5%, _C9 aromatic 2.5wt%, total sulfur content
150 wtppm, actual gum amount 12 mg/100 ml) was subjected to a continuous hydrogenation reaction treatment with a palladium catalyst using a flow type high pressure reactor (made of SUS). The conditions were as follows. Catalyst: Palladium catalyst (Pd0.3wt%, support γ-Al ₂ O ₃ ) Reaction temperature: 90℃ Reaction pressure: 50Kg/cm ² -G (in H ₂ gas flow) LHSV: 3hr ^-1 Oil passage time: 30 days Operation Changes in catalyst activity over time from the start to the end were determined from the diene value reduction rate (DV ₀ - DV)/DV ₀ , which was determined from the diene value DV ₀ of the raw material pyrolysis gasoline and the diene value DV of the hydrogenated oil. . Example The pyrolysis gasoline used in the comparative example was oxidized as described below, and the resulting treated oil was used to conduct a continuous hydrogenation reaction experiment under the same reaction conditions as in the comparative example. The oxidation treatment of pyrolysis gasoline is carried out in a cylindrical container.
Pyrolyzed gasoline is charged, and while stirring, air is pumped in from the bottom of the container at a flow rate of 10/Hr at room temperature and normal pressure.
This was done by injecting time. The actual gum content of the pyrolyzed gasoline increased to 17mg/100ml oil through oxidation treatment, but no other changes were observed in the properties. Table 2 shows the reduction rate of diene value (DV ₀ - DV)/DV ₀ on the 5th day, 10th day, 15th day, and 30th day from the start of operation determined in the comparative example and the example.
shows.

[Table] The results of the comparative example show that the activity of the catalyst decreases over time. The results of the examples show that a slight decrease in catalyst activity is observed at the beginning of operation, but after the 10th day, the activity remains almost constant and no decrease in activity is observed. The amount of arsenic deposited on the catalysts used in the comparative examples and examples was measured, and the amount of arsenic deposited on the catalysts was 890 wt ppm in the former and 890 wt ppm in the latter.
It was 1030wt ppm. 〓〓〓〓〓

Claims (1)

[Scope of Claims] 1. A method of oxidizing arsenic in a petroleum fraction and then using the arsenic petroleum fraction in a reaction step using a noble metal as a catalyst. 2. The method according to claim 1, wherein a gas containing oxygen is used for oxidation. 3. The method according to claim 1, wherein an organic peroxide is used for the oxidation. 4. The method according to claim 1, wherein an inorganic oxidizing agent is used for the oxidation.