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CN-122006791-A - Composite catalyst, preparation method and application thereof, and method for synthesizing dimethyl ether by one-step synthesis gas

CN122006791ACN 122006791 ACN122006791 ACN 122006791ACN-122006791-A

Abstract

The invention relates to a composite catalyst, a preparation method and application thereof, and a method for synthesizing dimethyl ether by a synthesis gas one-step method, wherein the composite catalyst comprises a component A and a component B, the component A is a coral copper-zinc-aluminum catalyst, constituent elements of the coral copper-zinc-aluminum catalyst comprise copper, zinc and aluminum, the microcosmic appearance of the coral catalyst is a coral formed by thin-sheet nanorods, and the component B is an HZSM-5 molecular sieve. The composite catalyst provided by the invention is applied to synthesis of dimethyl ether from synthesis gas, can effectively reduce the temperature in the process of conversion of synthesis gas, reduce the generation of byproducts, and improve the conversion rate of raw materials and the selectivity of dimethyl ether.

Inventors

  • LV JIANGANG
  • SHAO YI
  • LIU BO
  • DING HONGXIN
  • ZHOU HAICHUN
  • CHEN LONG

Assignees

  • 中国石油化工股份有限公司
  • 中石化（上海）石油化工研究院有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. A composite catalyst is characterized by comprising a component A and a component B, wherein the component A is a coralloid copper-zinc-aluminum catalyst, constituent elements of the coralloid copper-zinc-aluminum catalyst comprise copper, zinc and aluminum, the microcosmic appearance is coralloid formed by thin-sheet nanorods, and the component B is an HZSM-5 molecular sieve.
  2. 2. The composite catalyst according to claim 1, wherein, The weight ratio of component A to component B is 4-1:1, and/or The molar ratio of SiO 2 :Al 2 O 3 of the HZSM-5 molecular sieve is 150-400:1.
  3. 3. A composite catalyst as claimed in claim 1 or claim 2 wherein the properties of the coral-like copper zinc aluminium based catalyst of component a include: The thin nano-rods have a width of 30-40nm, and/or Specific surface area of 85-110m 2 /g, and/or The molar ratio of aluminum to zinc is 0.3-1.
  4. 4. A composite catalyst as claimed in any one of claims 1 to 3 wherein the properties of the coral-like copper zinc aluminium based catalyst of component a include: Copper in an amount of 50 to 70 wt.%, preferably 54 to 64 wt.%, based on the total weight of the catalyst, copper in an amount of 30 to 50 wt.%, preferably 35 to 46 wt.%, based on the total weight of the catalyst, aluminum in an amount of 30 to 50 wt.%, and zinc in an amount of 35 to 46 wt.%, and/or When the catalyst is stored, one or more of copper, zinc and aluminum exist in the form of oxide, preferably copper, zinc and aluminum exist in the form of oxide, and/or When the catalyst is used, copper exists in a reduced form, and the rest exists in an oxide form.
  5. 5. A composite catalyst as in any one of claims 1-4, wherein the properties of the coral-like copper zinc aluminum-based catalyst of component a include: the composition element also comprises a metal M element, wherein the metal M element is selected from one or more of zirconium, tin, lead, lanthanum and cerium, and preferably lanthanum and/or cerium; preferably, the metal M element is present in an amount of 0.01 to 20wt%, preferably 1 to 5wt%, calculated as oxide, based on the total weight of the catalyst; preferably, the metal element M is present in the form of an oxide during the storage of the catalyst, and/or When the catalyst is used, the metal element M exists in the form of oxide.
  6. 6. A composite catalyst as claimed in any one of claims 1 to 5, wherein the coral-like copper-zinc-aluminum catalyst of component A is prepared by co-precipitating a copper source, an aluminum source and a zinc source in contact under a solution under a pressure condition, and drying and calcining the obtained solid under a pressure higher than normal pressure.
  7. 7. A composite catalyst as claimed in claim 6, wherein the coral copper zinc aluminum catalyst of component a is prepared by: the pressure is 1-3MPa; And/or The conditions for coprecipitation include: the temperature is 50-80 ℃, and/or the time is 0.5-2h, and/or the pH value of the material after the coprecipitation is 6-8, and/or the process is carried out in a dynamic environment; And/or The drying conditions include a temperature of 60-80deg.C and/or a time of 12-36 hr; And/or The roasting conditions include a temperature of 290-330 ℃ and/or a time of 2-6 hours.
  8. 8. The composite catalyst according to any one of claims 6 to 7, wherein, The copper source is one or more selected from copper sulfate, copper chloride, copper nitrate, copper acetate, copper oxalate, and/or The aluminum source is one or more selected from aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate and aluminum oxalate; the zinc source is selected from one or more of zinc sulfate, zinc chloride, zinc nitrate, zinc acetate, zinc oxalate, and/or The coprecipitate is one or more selected from alkali metal hydroxide, alkali metal carbonate and alkali metal bicarbonate, preferably alkali metal carbonate, and more preferably sodium carbonate.
  9. 9. Use of a composite catalyst according to any one of claims 1 to 8 in the preparation of dimethyl ether in a one-step process of synthesis gas.
  10. 10. A method for synthesizing dimethyl ether by a one-step synthesis gas method, which is characterized by comprising the following steps: carrying out catalytic conversion on synthesis gas in the presence of the composite catalyst of any one of claims 1-8 to synthesize dimethyl ether; preferably, the conditions of catalytic conversion include: The synthesis gas comprises CO, CO 2 and H 2 , and/or The reaction temperature is 240-280℃, and/or The reaction pressure is 3-6MPa, and/or In a slurry bed reactor, and/or Preferably in the presence of a liquid solvent, preferably liquid paraffin.

Description

Composite catalyst, preparation method and application thereof, and method for synthesizing dimethyl ether by one-step synthesis gas Technical Field The invention relates to a composite catalyst, a preparation method and application thereof, and a method for synthesizing dimethyl ether by a one-step synthesis gas. Background Dimethyl ether has become an important chemical intermediate for developing competitive research in various countries since the eighties of the last century, has very important roles in the chemical industries of pharmacy, fuel, pesticide and the like, can replace freon as a refrigerant, reduces the damage to an ozone layer, and can be used as a substitute for urban gas and liquefied petroleum gas. At present, two processes for synthesizing dimethyl ether mainly exist, namely, a two-step method is adopted to synthesize the gas first into methanol and then dehydrate to generate the dimethyl ether, and a compound catalyst is adopted to synthesize the dimethyl ether by the gas. The one-step method adopts the composite catalyst system to lead the synthesis gas to be dehydrated on the dehydration component to generate the dimethyl enzyme immediately after the methanol is generated by synthesizing the methanol catalyst soil, thereby breaking through the thermodynamic equilibrium limit of synthesizing the methanol and obviously increasing the conversion rate of carbon monoxide. CN1356163a discloses a bifunctional catalyst compounded by using composite oxides of copper, zinc and the like as methanol synthesis components and alumina as methanol dehydration active components. Under the reaction conditions that the molar ratio of H 2 to CO is 3.85, the reaction temperature is 300 ℃, the reaction pressure is 4MPa and the space velocity of raw material gas is 1490H -1, the conversion rate of carbon monoxide is 81.75%, and the selectivity of dimethyl ether is 93.56%. The reaction temperature of the catalyst is higher, and the conversion rate of carbon monoxide is lower. Since the optimal activation temperature of active Al 2O3 as a methanol dehydration catalyst is high (about 300 ℃) and does not match the optimal activation temperature of copper-based catalysts of methanol synthesis components (about 250 ℃), the performance of the bifunctional catalyst is reduced. Various molecular sieve catalysts have been studied as active components for methanol dehydration. US6638892 discloses a bifunctional catalyst with a type H Y zeolite as active component for methanol dehydration. The catalyst has a carbon monoxide conversion of 79.2% and a dimethyl ether selectivity of 87.7% in the organic products under the reaction conditions of a synthesis gas composition of H 2/CO/CO2 = 74.8/20.1/5.1, a reaction temperature of 270 ℃, a reaction pressure of 500psig and a feed gas space velocity of 1140H -1. Under the same conditions, the conversion rate of carbon monoxide and the selectivity of dimethyl ether are respectively 68.5% and 55.4% when alumina is used as a methanol dehydration component, and the conversion rate of CO and the selectivity of dimethyl ether can be simultaneously improved by using a Y molecular sieve to replace Al 2O3. Disclosure of Invention The invention provides a novel composite catalyst mainly aiming at the problems of high reaction temperature, low carbon monoxide conversion rate and/or low dimethyl ether selectivity of a composite catalyst for synthesizing dimethyl ether by a one-step method of synthesis gas in the prior art. The composite catalyst is used for the reaction of preparing dimethyl ether from synthetic gas, and has the characteristics of low reaction temperature, high carbon monoxide conversion rate and high dimethyl ether selectivity. The invention provides a composite catalyst which comprises a component A and a component B, wherein the component A is a coralloid copper-zinc-aluminum catalyst, constituent elements of the coralloid copper-zinc-aluminum catalyst comprise copper, zinc and aluminum, the microcosmic appearance is coralloid formed by thin-sheet nanorods, and the component B is an HZSM-5 molecular sieve. The weight ratio of component a to component B in the composite catalyst of the present invention may be in a wide range of choices, and may be specifically determined as desired, and according to a preferred embodiment of the present invention, the weight ratio of component a to component B is 4-1:1. In the composite catalyst of the present invention, the HZSM-5 molecular sieve is not particularly required, and all the commonly used HZSM-5 molecular sieves can be used in the present invention, and according to a preferred embodiment of the present invention, the HZSM-5 molecular sieve with a high silica-alumina ratio is preferably used in the present invention, and preferably, the SiO 2:Al2O3 molar ratio of the HZSM-5 molecular sieve is 150-400:1. In the invention, the coralloid copper-zinc-aluminum catalyst with the composition and the microstructure is applied to