JPH0364166B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field of the Invention The present invention relates to a method for removing arsenic from a fluid, and more particularly, the present invention relates to a method for removing arsenic from a fluid, and more particularly, to remove arsenic such as hydrogen arsenide or its compounds contained in light hydrocarbons produced by-product in a fluidized bed catalytic cracker for petroleum. Concerning how to remove it efficiently. Technical background of the invention and its problems In recent years, with the aim of effectively utilizing heavy fractions of crude oil,
Gasoline production using fluidized bed catalytic crackers (FCC) is increasing. Effective use of the by-product LPG fractions (C ₃ and C ₄ fractions) is extremely important in maintaining cost competitiveness.
However, this LPG fraction, especially the _C3 fraction, contains arsenic compounds such as hydrogen arsenide.
It is known that even trace amounts of arsenic compounds such as hydrogen arsenide can act as catalyst poisons in subsequent reaction steps. Therefore, when using this _C3 fraction as a raw material for various chemical reactions, it is necessary to pre-mix hydrogen arsenide, etc. It is strongly desired to remove the arsenic compounds to a predetermined amount or less. Heretofore, the following methods have been disclosed as methods for removing arsenic or its compounds from fluids. (a) an alkaline aqueous solution containing at least one salt or oxide of zinc or lead; and an alkaline aqueous solution of at least one salt of anthraquinone sulfonic acid or anthraquinone disulfonic acid;
A method for removing volatile arsenic derivatives in a gas phase using a cleaning solution consisting of an organic solvent containing at least one quinone derivative in the presence of an amine or ethanolamine (Japanese Patent Publication No. 33408/1983). (b) A method of reactive adsorption or oxidation treatment of arsenic or its compounds in the gas phase using manganese oxide, copper oxide, and mixtures thereof (Japanese Patent Publication No. 60-17772)
Publication No.). (c) A method of removing hydrogen arsenides in a gas phase using activated carbon supporting copper group and chromium group compounds (Japanese Patent Application Laid-Open No. 60-238144). (d) A method of adsorbing and removing arsenic or its compounds in a liquid phase using activated carbon (Japanese Unexamined Patent Publications Nos. 170-170-1987 and 170-170-88). (e) A method of removing arsenic oxidation products after oxidizing arsenic in a liquid phase (Japanese Patent Publication No. 11714/1983,
Publication No. 60-9549). However, the method for removing arsenic or its compounds disclosed above has a low arsenic removal ability, requires a large amount of arsenic removal agent for a fraction containing a high concentration of arsenic or its compounds, and also requires high equipment costs and operational costs. In addition to being expensive, there are safety issues with introducing oxygen-containing compounds into the process that handles LPG fractions, as well as problems such as the highly reactive olefins in LPG fractions polymerizing. . While investigating various inexpensive and efficient methods for removing arsenic or its compounds from fluids, the present inventors set the copper content, pore radius, pore volume, and specific surface area of the adsorbent within specific ranges. The present inventors have discovered that the removal rate of arsenic and its compounds can be significantly improved by bringing a controlled copper adsorbent into contact with a fluid containing arsenic, leading to the completion of the present invention. Purpose of the Invention The present invention aims to solve the problems associated with the prior art, such as low arsenic removal ability and high equipment and operating costs, when removing arsenic or its compounds from a fluid. The purpose of the present invention is to provide a method for efficiently and inexpensively removing arsenic or its compounds. Summary of the Invention The method for removing arsenic from a fluid according to the present invention comprises
Contains % copper by weight, has a pore volume of 0.12 ml/g or more with a pore radius of 40 to 300 Å, and has a specific surface area of
The method is characterized in that an adsorbent in which copper oxide is supported on a carrier in an amount of 100 m ² /g or more is brought into contact with a fluid containing arsenic. DETAILED DESCRIPTION OF THE INVENTION The method for removing arsenic or its compounds from a fluid according to the present invention will be specifically described below. Fluid The fluid used in the present invention is a liquid or gaseous hydrocarbon, an inert gas such as nitrogen gas, air, or various exhaust gases. In the present invention, the liquid or gaseous hydrocarbons from which arsenic is removed include LPG fraction produced as a by-product from a fluidized bed catalytic cracker,
Distillates such as naphtha, kerosene, and light oil that flow out from crude oil through atmospheric distillation or vacuum distillation, or petroleum fractions such as light fractions produced by heat treatment in ethylene plants, cokers, and visbreakers, etc., may also be used. I can do it. In such hydrocarbons, arsenic is usually present in R _o
It is contained in the form of a hydride or an organic compound represented by AsH _3-o (wherein R is an alkyl group, phenyl group, etc., and n is 0, 1, 2, or 3). Specific examples of such arsenic compounds include arsine, monomethylarsine, dimethylarsine, trimethylarsine, tributylarsine, and triphenylarsine. Arsenic can also be present in the hydrocarbon in the form of halogenated arsenic compounds such as dimethylchloroarsine or oxidized arsenic compounds such as trimethylarsine oxide. Arsenic or its compounds vary depending on the type of hydrocarbon, but in general, arsenic or its compounds are present in a large number in hydrocarbons.
It is often contained in ppb (by weight) to several hundred ppb (by weight). Fluids other than hydrocarbons from which arsenic is removed using the adsorbent according to the present invention include, for example, exhaust gas containing arsenic or arsenic compounds discharged from the semiconductor electronics industry or other chemical industries, or exhaust gases used as raw materials for semiconductors. Examples include crude phosphine gas containing arsenic hydride as an impurity. Adsorbent The adsorbent used in the present invention is an adsorbent in which copper oxide, particularly cupric oxide, is supported on a carrier. Specific examples of the carrier used include silica, alumina, silica-alumina, activated carbon, diatomaceous earth, activated clay, and magnesia, among which alumina is particularly preferred. Such a carrier has a pore volume of 0.20 ml/g or more with a pore radius of 40 to 300 Å, and a specific surface area of 40 to 300 Å.
It is preferable that it is 200 m ² /g or more. In the arsenic removal adsorbent according to the present invention, the copper content is
The content is 30 to 55% by weight, particularly preferably 35 to 50% by weight. If the copper content is less than 30% by weight, the arsenic removal ability will be poor, and if the copper content exceeds 55% by weight,
This is not preferable because not only the pore volume decreases but also the strength of the adsorbent decreases. The arsenic removal adsorbent according to the present invention has a pore radius of 40 to
The pore volume of 300 Å is 0.12 ml/g or more, especially the pore volume of 40 to 300 Å radius is 0.14 ml/g.
It is preferable that it is above. Further, the arsenic removal adsorbent according to the present invention has a specific surface area of 100 m ² /g or more, and preferably 120 m ² /g or more. The pore volume with a pore radius of 40 to 300 Å is less than 0.12 ml/g, and this specific surface area is
If it is less than 100 m ² /g, the arsenic adsorption rate will be poor.
As a result, when this adsorbent is used in a flow system, its arsenic adsorption capacity decreases even if the copper content is high, which is not preferable. Such an adsorbent is produced by, for example, mixing an aqueous solution of copper sulfate and copper nitrate with an aqueous sodium hydroxide solution, adding a carrier, stirring well, recovering by filtration, drying, and pulverizing processes, and then molding it into a predetermined shape using a molding machine. It is prepared by molding it into the shape of. Contact Conditions The contact between the fluid containing arsenic or its compound and the adsorbent can be appropriately selected from conventionally known methods. For example, a method in which the fluid and the adsorbent are brought into contact in a gas phase or a liquid phase using a fixed bed method, a moving bed method, a fluidized bed method, etc. can be employed. In some cases, the fluid and adsorbent can also be brought into contact in a batch manner. The contact time between the fluid and adsorbent is 1 to 1 in gas hourly space velocity (GHSV) when contacting in the gas phase.
1000 hours ^-1 is preferably about 100 to 800 hours ^-1 , and when contact is made in the liquid phase, the liquid hourly space velocity (L.
HSV) from 0.01 to 20 hours ^-1 preferably from 1 to 10 hours
It is about ^-1 . Moreover, the temperature at the time of contact is about 0 to 100°C. Effects of the Invention According to the method of the present invention, highly concentrated arsenic in a fluid can be removed with a high removal rate using a small amount of adsorbent. Moreover, no pre-treatment equipment is particularly required for removal, and furthermore, no post-treatment equipment other than a strainer is required. Furthermore, even if highly reactive olefins are contained in the hydrocarbon from which arsenic or arsenic compounds are removed, problems such as polymerization of these olefins will not occur during the removal of arsenic or arsenic compounds. It will be done. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. Note that the percentages in the examples are based on weight unless otherwise specified. Example 1 The adsorbent has a copper content of 41% and a pore radius of 40~
An arsenic removal adsorbent having a pore volume of 300 Å of 0.140 ml/g and a specific surface area of 140 m ² /g was prepared. The above adsorbent 5 was transferred to a fixed bed reactor (8 mmφ×
100mm), naphtha containing 220ppb arsenic, and tributylarsine as the arsenic amount.
Add 1000ppb and liquid hourly space velocity (LHSV) for 5 hours
^-1 Oil passed at room temperature. After arsenic has been removed in this way, the naphtha has a total oil flow rate of 20,000/-
The adsorbent contained 24 ppb of arsenic, and the arsenic removal rate was 98%. Example 2 The following composition was produced as a by-product from a fluidized bed catalytic cracker.
Hydrogen arsenide was removed using a raw material gas consisting of _C3 fraction. Propylene 69.4 mol% Propane 30.2 C ₂ fraction 0.2 C ₄ fraction 0.2 Hydrogen arsenide 500 ppb 2 ml of the adsorbent used in Example 1 was packed into a fixed bed reactor (7 mmφ x 46 mm). The above raw material gas was circulated at room temperature and pressure at a gas hourly space velocity (GHSV) of 500 hours ^-1 . After hydrogen arsenide has been removed in this way, the total aeration amount in the raw gas is 1×10 ⁷
/- adsorbent contained 10 ppb of hydrogen arsenide, and the removal rate of hydrogen arsenide was 98%. Example 3 Raw material gas is produced as a by-product from a fluidized bed catalytic cracker
Hydrogen arsenide removal treatment was carried out in the same manner as in Example 2, except that nitrogen gas containing 1.07% by volume of hydrogen arsenide was used instead of the C ₃ fraction. When the hydrogen arsenide concentration in the fixed bed reactor outlet gas reached 5 mol ppm, ventilation of the hydrogen arsenide-containing gas was stopped (throughflow breakthrough point), and the arsenic adsorption capacity was determined using the following formula. Arsenic adsorption capacity (%) = Arsenic content in adsorbent (%) x Amount of adsorbent after aeration (%) / Amount of adsorbent before aeration (
%) The results are shown in Table 1. Comparative Example 1 Commercially available adsorbent manufactured by JGC Chemical Co., Ltd., product name N-
Hydrogen arsenide removal treatment was carried out in the same manner as in Example 2 except that 202D was used. After hydrogen arsenide has been removed in this way, the total aeration amount in the raw gas is 5×10 ⁶ /
- The adsorbent contained 10 ppb of hydrogen arsenide, and the removal rate of hydrogen arsenide was 98%. However, when the total aeration amount was 1×10 ⁷ /− adsorbent, 500 ppb of hydrogen arsenide was contained, and hydrogen arsenide breakthrough was observed. Comparative Example 2 Hydrogen arsenide was removed in the same manner as in Example 3, except that commercially available adsorbents (13 types) were used. Table 1 shows the name of the adsorbent, the copper content of the adsorbent, the pore volume with a pore radius of 40 to 300 Å, the specific surface area of the adsorbent,
The adsorbent composition and arsenic adsorption capacity are shown.

Table 1 shows that the arsenic removal method according to the present invention can remove arsenic compounds at low cost and efficiently, and has a long adsorbent life.

Claims (1)

[Claims] 1. Contains 30 to 55% by weight of copper and has a pore radius of 40 to 55% by weight.
A fluid containing arsenic is brought into contact with an adsorbent in which copper oxide is supported on a carrier and has a pore volume of 300 Å of 0.12 ml/g or more and a specific surface area of 100 m ² /g or more. Characteristic methods for removing arsenic from fluids. 2. The method according to claim 1, wherein the copper oxide is cupric oxide. 3. The method according to claim 1 or 2, wherein the support is alumina.