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CN-115869947-B - M (M)1Manganese oxide carrier catalyst, preparation and application for catalyzing ethylene epoxidation

CN115869947BCN 115869947 BCN115869947 BCN 115869947BCN-115869947-B

Abstract

The application relates to an M 1 /manganese oxide carrier catalyst, a preparation method and application thereof in catalyzing ethylene epoxidation. Wherein M is selected from noble metals, preferably Ag, ir, ru, rh, pd, pt and Au, and M is supported on a carrier in a single-atom site state, and the carrier is manganese oxide MnO x or a substance converted into manganese oxide, preferably alpha-MnO 2 . Compared with a catalyst system of silver nano particles widely used in industry, the single-atom noble metal catalytic system of the application has excellent catalytic activity and selectivity in the reaction of preparing ethylene oxide by ethylene selective oxidation, and has higher industrial application prospect.

Inventors

  • DENG MINGLIANG

Assignees

  • 北京单原子催化科技有限公司

Dates

Publication Date
20260512
Application Date
20210926

Claims (8)

  1. 1. A method for epoxidation of C 2-8 olefin comprises the steps of reacting C 2-8 olefin with oxygen, and reacting under the conditions of 20-350 ℃ and 0.01-10.0 MPa in the presence of a catalyst of M 1 /manganese oxide carrier, wherein the reaction time is 0.1-1000 hours, and C 2-8 olefin is selected from C 2-8 olefin or C 2-8 naphthene olefin; The catalyst of the M 1 /manganese oxide carrier comprises noble metal M which is Ir and is loaded on the carrier in a single atom site state, wherein the manganese oxide carrier is alpha-MnO 2 , the average pore size of the manganese oxide carrier is 1-20nm, and the loading amount of the noble metal M is 0.01-10 wt percent based on the total weight of the catalyst.
  2. 2. The process according to claim 1, wherein the catalyst is Ir 1 /α-MnO 2 and the manganese oxide support has an average pore size of 1 to 8nm.
  3. 3. The method of claim 1, wherein the catalyst is prepared by a process comprising: S1, adding water into manganese oxide powder to prepare a first dispersion liquid; S2, mixing a soluble noble metal salt compound with a solvent to prepare a second solution containing noble metals; s3, mixing the first dispersion liquid and the second solution, continuously stirring, and carrying out solid-liquid separation; S4, heating the obtained solid powder in oxygen or oxygen-containing atmosphere; In the step S1, manganese oxide is commercially available or prepared, and when the manganese oxide powder is prepared, the preparation method comprises the steps of heating a mixed solution of potassium permanganate and manganese sulfate, evaporating to remove water to obtain brown powder, and calcining at a high temperature to obtain the manganese oxide powder, wherein the high temperature is 400-550 ℃ and the calcining time is 2-6 hours; In the step S2, the soluble noble metal salt compound is soluble salt in nitrate, chloride, chlorate or acetylacetonate of noble metal, the total molar concentration of the noble metal salt is 0.001-0.3 mol/L, and the solvent is deionized water or ammonia water; S3, in the step, the solid-liquid separation is filtration or centrifugal separation; in the step S4, the temperature of the heating treatment is 200-600 ℃.
  4. 4. The process of claim 3, wherein in step S2, the noble metal salt is selected from the group consisting of H 2 IrCl 6 and aqueous ammonia as a solvent.
  5. 5. The method according to claim 3, wherein the solid obtained after the solid-liquid separation of S3 is further washed and dried to obtain dry solid powder, and the washing is carried out in a suspension centrifugal washing mode, and the solvents used in the washing are ethanol and water respectively.
  6. 6. A method according to claim 3, wherein the oxygen or oxygen-containing gas is a flowable atmosphere.
  7. 7. The method of claim 6, wherein the oxygen-containing gas is selected from the group consisting of air.
  8. 8. The method of any of claims 1-7, wherein the C 2-8 olefin is ethylene and the molar ratio of C 2-8 olefin to oxygen is 1:2-1000.

Description

M 1/manganese oxide carrier catalyst, preparation and application in catalyzing ethylene epoxidation Technical Field The invention relates to noble metal monoatomic catalysis and application of catalyzing ethylene epoxidation to prepare ethylene oxide, and belongs to the field of industrial catalysis. Background Monoatomic catalysts (SAC) are a new class of heterogeneous catalysts that have recently received widespread attention. SAC generally exhibits unexpected chemical and reaction pathways compared to conventional nanocatalysts, probably due to its unique local chemical environment determining the SAC's electronic structure, oxidation state and charge distribution, which in turn affects their catalytic activity and selectivity. More notably, spatially uniform metal active sites in SACs provide an ideal platform for identifying the exact structure of individual sites, determining the catalytically active sites under practical reaction conditions, and elucidating the underlying reaction mechanism at the molecular level. The selective oxidation of ethylene to Ethylene Oxide (EO) is one of the most important industrial processes, since EO is an irreplaceable chemical intermediate, and has been widely used in synthetic pharmaceuticals, antifreeze, detergents and plastics. Silver has been considered to date as the most effective catalyst for ethylene epoxidation and has been widely studied. The EO selectivity can only reach 90% with the aid of promoters (Cs, re, C 2H4 Cl, cu). The most common route for ethylene epoxidation follows the E-R mechanism. Despite the great efforts, many of the key problems related to this reaction remain unsolved, and in addition, few studies have been conducted on the use of quantum chemistry and in situ spectroscopy during ethylene epoxidation reactions due to the lack of novel well-defined catalytic systems of excellent performance. Manganese oxide has been used in the fields of industrial catalysis and energy storage, with an ordered array of MnO 6 units sharing edges and vertices. Mn (IV) in manganese oxide has a unique d-electron structure (with at least one pair of unpaired electrons) so that oxygen more easily interacts with externally adsorbed metal atoms and forms a structure that facilitates catalytic reactions. Thus, the combination of a single metal atom with manganese oxide may provide a significant breakthrough in the field of ethylene epoxidation. There is a need in the industry for a more excellent catalyst for the production of ethylene oxide. Disclosure of Invention The invention provides a catalyst with an M 1/manganese oxide carrier structure, wherein M is selected from noble metals, preferably Ag, ir, ru, rh, pd, pt and Au, M metal is loaded on a carrier in a single-atom site state, the manganese oxide carrier is manganese oxide or a substance converted into manganese oxide, the manganese oxide has a chemical formula of MnO x, x=1-4, the average pore size of the manganese oxide is 1-20nm, more preferably 1-8nm, and the loading amount of the noble metal M is 0.01-10 wt percent based on the total weight of the catalyst. The manganese oxide or MnO x comprises pyrolusite (MnO 2), pyrolusite (MnO.MnO 2·nH2 O), manganite (MnO 2·nH2 O), manganite (MnO 2·Mn(OH)2), limonite (Mn 2O3) and pyrolusite, wherein the substance converted into manganese oxide refers to a compound or a mixture which is converted into manganese oxide through heating or chemical reaction, such as MnCO 3、 KMnO4、MnSO4, basic manganese carbonate or a mixture of potassium permanganate and manganese sulfate. More preferably x=2, still more preferably MnO x is α -MnO 2, and M is selected from Ag or Ir. The invention also discloses a preparation method of the M 1/manganese oxide catalyst, which comprises the following steps: S1, adding water into the obtained or prepared manganese oxide powder to prepare a first dispersion liquid; S2, mixing a soluble noble metal salt compound with a solvent to prepare a second solution containing noble metals; s3, mixing the first dispersion liquid and the second solution, continuously stirring, and carrying out solid-liquid separation; S4, heating the obtained solid powder in oxygen or oxygen-containing atmosphere; Wherein, the The manganese oxide powder in the step S1 can be obtained commercially or prepared according to the following method, wherein the mixed solution of potassium permanganate and manganese sulfate is heated, water is removed by evaporation, brown powder is obtained, and the brown powder is obtained by high-temperature calcination. The elevated temperature is 300-900 ℃, preferably 400-550 ℃, and the calcination time is preferably 2-6 hours. In step S1, the water is preferably deionized water. In the step S2, the soluble noble metal salt compound is soluble salt or soluble complex of noble metal, preferably soluble salt in nitrate, chloride, chlorate or acetylacetonate of noble metal, the total molar concentration of AgNO 3、 H2IrCl6、H2PtCl6、HAuCl4、PdC