Search

CN-121972148-A - Silver-based dearsenifying agent for ethylene device and preparation method thereof

CN121972148ACN 121972148 ACN121972148 ACN 121972148ACN-121972148-A

Abstract

The invention discloses a silver-based dearsenization agent for an ethylene device and a preparation method thereof, wherein the dearsenization agent comprises, by taking the total mass of the dearsenization agent as 100%, 0.3-0.8wt% of active component silver, 5.0-8.0wt% of bimetallic auxiliary agent (composed of 3.0-5.0wt% of indium oxide and 2.0-3.0wt% of tin oxide), 1.2-2.0wt% of modifier (composed of 0.8-1.2wt% of cerium oxide and 0.4-0.8wt% of polydopamine carbon skeleton) and the balance of modified alumina, and the dearsenization agent has the advantages of low cost, high activity and high safety, realizes the synchronous depth removal of arsenic, mercury and sulfur under ultra-low silver load (< 1%), effectively inhibits the generation and carbon deposition of acetylene silver, does not need to be additionally provided with a mercury/sulfur removal bed layer, remarkably reduces investment, and ensures the long-period stable operation of the ethylene device.

Inventors

  • WANG CAIFENG
  • XIA YUCHEN
  • XU CHUNYI
  • REN JIAJUN
  • YU HONGJIE
  • LI CHUNGUANG
  • LI TIANSHU
  • HE YUMEI
  • MAO MANYI
  • DENG GUOWEI
  • XU LIWEN
  • WANG LIN
  • BAI XUEQIN
  • CHANG HEFEI
  • HUANG RUI

Assignees

  • 湖北华邦化学有限公司
  • 湖北益邦新材料有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. The silver-based dearsenization agent for the ethylene device is characterized by comprising, by taking the total mass of the dearsenization agent as 100%, 0.3-0.8% of active component silver, 5.0-8.0% of bimetallic auxiliary agent, 1.2-2.0% of modifier, 0.8-1.2% of cerium oxide and 0.4-0.8% of polydopamine, and the balance of modified aluminum oxide.
  2. 2. The silver-based dearsenifying agent according to claim 1, wherein said modified alumina is prepared by the following method steps: (1) Mixing pseudo-boehmite with a boron source, adding an acidic binder, kneading, forming, roasting, and performing hydrothermal treatment to obtain pretreated alumina; (2) Dispersing pretreated alumina into ethanol/water mixed solution, adding KH560, carrying out reflux reaction, centrifuging, washing and drying the product to obtain functionalized alumina; (3) Dispersing the functionalized alumina into ethanol, then adding triethylamine and cystamine dihydrochloride, sealing, stirring for reaction, filtering, washing and drying the product to obtain the modified alumina.
  3. 3. The silver-based dearsenifying agent according to claim 2, wherein in the step (1), the boron source is one or more of boric acid, boron oxide, sodium borate, potassium borate and ammonium borate, the addition amount of the boron source is 0.5-1.0wt% of the pseudo-boehmite by weight calculated by B 2 O 3 , the acidic binder is 3-10wt% of nitric acid aqueous solution, the roasting condition is 550-600 ℃ for 3-4 hours, the hydrothermal treatment condition is 180-220 ℃ and the treatment condition is 0.8-1.2 MPa for 2-3 hours under the steam atmosphere.
  4. 4. The silver-based dearsenifying agent according to claim 2, wherein in the step (2), the pretreated alumina, the ethanol/water mixture and the KH560 are used in a volume ratio of 5g to 80-160 mL to 2-5 mL, and the ethanol/water mixture has a volume ratio of 90-95:5-10.
  5. 5. The silver-based dearsenifying agent according to claim 2, wherein in the step (2), the reflux reaction is performed under the condition of stirring at 66-78 ℃ for 4-7 hours, the product is washed with absolute ethyl alcohol for 2-5 times, and then the product is placed in an oven at 105-115 ℃ for heat treatment for 1-2 hours.
  6. 6. The silver-based dearsenifying agent according to claim 2, wherein in the step (3), the dosage ratio of the functionalized alumina, the ethanol, the triethylamine and the cystamine dihydrochloride is 5g to 60-120 mL to 2-5 mL to 1-3 g, the stirring reaction is carried out for 12-24 h under 50-65 ℃, and the product is alternately washed by absolute ethanol and deionized water for 3 times in an ultrasonic manner.
  7. 7. A method for preparing the silver-based dearsenicating agent according to any one of claims 1 to 6, comprising the steps of: (a) Preparing silver precursor into silver solution, vacuum impregnating modified alumina, drying, and carrying out reduction treatment under a reducing atmosphere to obtain a silver-containing carrier; (b) Preparing a mixed solution of indium salt and tin salt, dipping a silver-containing carrier, drying and roasting to obtain an intermediate loaded with silver, indium oxide and tin oxide; (c) And (3) coating cerium oxide sol on the intermediate, roasting, then modifying by using a dopamine solution, and finally drying in vacuum to obtain the silver-based dearsenifying agent for the ethylene device.
  8. 8. The preparation method of the silver oxide film according to claim 7, wherein in the step (a), the silver precursor is silver nitrate, the reducing atmosphere is a mixed gas of hydrogen and nitrogen, the volume percentage of the hydrogen is 5-15%, the reducing temperature is 200-220 ℃, and the reducing time is 2-4 hours.
  9. 9. The method according to claim 7, wherein in the step (b), the indium salt is indium nitrate, the tin salt is tin chloride, the molar ratio of the indium nitrate to the tin chloride is 1-3:1, and the roasting condition is 380-420 ℃ for 2-4 hours.
  10. 10. The preparation method according to claim 7, wherein in the step (C), the roasting condition is 350-400 ℃ for 2-4 hours, the concentration of the dopamine solution is 2-8 g/L, the pH value is 8-9, and the temperature of the vacuum drying is 100-110 ℃.

Description

Silver-based dearsenifying agent for ethylene device and preparation method thereof Technical Field The invention relates to the technical field of dearsenization agents, in particular to a silver-based dearsenization agent for an ethylene device and a preparation method thereof. Background Ethylene is a basic raw material for petrochemical industry, and the yield and the technical level thereof are important marks for measuring the national petrochemical industry development level. In the ethylene production process, the carbon two fraction (the main components are ethylene and acetylene) obtained by compressing and separating the pyrolysis gas usually contains trace amounts of impurities such as arsine, phosphine, hydrogen sulfide, mercury and the like. Although the levels of these impurities are typically in the ppb level, the hazard is significant. In particular arsine, as a highly toxic substance, is a "permanent poison" of downstream acetylene selective hydrogenation catalysts (typically palladium-based or silver-based catalysts). Arsenic forms stable metal arsenides with active sites on the catalyst surface, resulting in rapid loss of catalyst activity, severely shortened catalyst life, and even unplanned plant downtime. In addition, if mercury in the raw materials is not removed, the mercury not only can poison a hydrogenation catalyst, but also can carry out amalgamation reaction with aluminum equipment (such as a cold box of a cryogenic system), so that serious intergranular corrosion is caused, and equipment leakage and even explosion accidents are caused. Therefore, deep dearsenification and mercury removal is necessary before the carbon two fraction enters the hydrogenation reactor. Currently, the dearsenifying agents commonly used in industry mainly comprise copper oxide-zinc oxide series, lead oxide series and silver-carrying series. The copper oxide dearsenifying agent has low dearsenifying precision at normal temperature and is easy to generate a temperature runaway accident of reduced heat release, and the lead oxide has good activity but serious heavy metal pollution risk and is gradually eliminated. In contrast, silver-based dearsenifying agents are considered to be the most effective purification materials for protecting downstream noble metal catalysts because of their extremely high reactivity and removal accuracy at low temperatures. However, the existing silver-based dearsenization agent still has the following technical problems to be solved in practical application: The raw material cost is high, limited by the surface properties of the carrier and the preparation process, and the existing commercial silver dearsenicating agents generally need extremely high silver loading in order to ensure enough active sites and service life. This makes the adsorbent very expensive to manufacture, greatly increasing the operating costs of the ethylene plant. There is a serious potential safety hazard that under the environment of high-concentration acetylene (usually 1.0% -2.0%) in the carbon two-fraction, high-content active silver is easy to react with acetylene to generate silver acetylene. Silver acetylene is an extremely sensitive explosive compound that is extremely prone to decomposition and explosion by heat or friction, which presents a significant safety risk for the handling of the adsorbent and the operation of the device. The carrier is easy to coke and side reaction, and the surface of the common alumina carrier is generally distributed with more strongly acidic sites. Under the reaction conditions, these acidic sites catalyze the polymerization of acetylene and ethylene (i.e., the formation of "green oil") and coking and carbon deposition. Carbon deposition not only covers active centers to reduce arsenic capacity, but also plugs pore channels to increase bed pressure drop. The existing silver-based dearsenifying agent has a good removal effect on arsine, and has extremely weak capability of capturing impurities such as mercury, hydrogen sulfide and the like. In order to meet the purification requirements, ethylene units often require a dedicated mercury removal bed (e.g., sulfur-loaded activated carbon) in series, which not only increases equipment investment and floor space, but also makes the process flow more complex. Therefore, the development of the multifunctional integrated novel dearsenifying agent which has ultralow silver content (low cost), can inhibit the generation of acetylene silver (high safety) and has strong coking resistance and can realize deep dearsenification, mercury removal and desulfurization simultaneously is a key technical problem to be broken through in the current ethylene purification field. Disclosure of Invention In order to solve the defects existing in the prior art, the invention aims to provide the silver-based dearsenization agent for the ethylene device and the preparation method thereof, and the dearsenization agent has low cost, high acti