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CN-121972094-A - System and method for preparing composite carbon material and hydrogen by cracking low-carbon hydrocarbon

CN121972094ACN 121972094 ACN121972094 ACN 121972094ACN-121972094-A

Abstract

The invention provides a system and a method for preparing a composite carbon material and hydrogen by low-carbon hydrocarbon pyrolysis, which relate to the technical field of low-carbon hydrocarbon pyrolysis hydrogen production, wherein the system comprises a multi-section bubbling bed reaction device with at least one porous gas distribution plate arranged inside, and a molten alloy catalyst is filled in the device to enable low-carbon hydrocarbon bubbles and the molten alloy catalyst to undergo catalytic pyrolysis reaction; the molten alloy catalyst comprises molten active metal and a molten medium, wherein the molten active metal is selected from at least two of Ni, cu, co, fe, mo, the molten medium is selected from at least one of Sn, bi, ga, zn, al, pb, bi, in, and the molar ratio of the molten active metal to the molten alloy catalyst is 10% -60%. The invention realizes the high-efficiency conversion of the low-carbon hydrocarbon, obviously reduces the reaction temperature of the hydrogen production gas by cracking the low-carbon hydrocarbon while ensuring the catalytic activity, improves the safety of the reaction, and also obtains the nanotube-graphite composite carbon material with high added value.

Inventors

  • SONG PENGFEI
  • LIU BOWEN
  • ZHANG HUIMIN
  • XIAO LI
  • Nie Suofu
  • WANG XIULIN
  • WANG XIUKANG
  • HOU JIANGUO
  • ZHANG YU
  • ZHOU SHUHUI
  • YAO HUICHAO

Assignees

  • 中海石油气电集团有限责任公司

Dates

Publication Date
20260505
Application Date
20251230

Claims (10)

  1. 1. A system for preparing composite carbon material and hydrogen by cracking low-carbon hydrocarbon is characterized by comprising a multi-section bubbling bed reaction device internally provided with at least one porous gas distribution plate, wherein a molten alloy catalyst is filled in the multi-section bubbling bed reaction device, so that low-carbon hydrocarbon bubbles and the molten alloy catalyst are subjected to catalytic cracking reaction; The molten alloy catalyst comprises a molten active metal and a molten medium; at least two of the molten active metals selected from Ni, cu, co, fe, mo; at least one of the melting media is selected from Sn, bi, ga, zn, al, pb, bi, in; The amount of the substance of the molten active metal accounts for 10% -60% of the amount of the substance of the molten alloy catalyst.
  2. 2. The system for preparing composite carbon material and hydrogen by cracking low-carbon hydrocarbon according to claim 1, wherein the number of porous gas distribution plates in the multi-stage bubbling bed reaction device is 1-5, preferably 1-3.
  3. 3. The system for preparing a composite carbon material and hydrogen by cracking a low-carbon hydrocarbon according to claim 1 or 2, wherein the pore diameters of the porous gas distribution plates are uniform or nonuniform and are each independently 1 μm to 10 mm, preferably 10 μm to 1 mm.
  4. 4. A system for preparing a composite carbon material and hydrogen by cracking a low-carbon hydrocarbon according to claim 1 or 3, wherein the open area ratio of the porous gas distribution plate is 0.01% -10%, preferably 0.1% -1%.
  5. 5. The system for preparing a composite carbon material and hydrogen by cracking low-carbon hydrocarbon according to claim 1 or 4, wherein the amount of the substance of the molten active metal is 20% -40% of the amount of the substance of the molten alloy catalyst.
  6. 6. The system for preparing composite carbon material and hydrogen by cracking low-carbon hydrocarbon according to claim 1 or 5, wherein the molten active metal is Ni and Cu, and the molar ratio of Ni and Cu is (0.5-2) 1, and the molten medium is at least one selected from Sn, bi and Ga, preferably Bi and Sn, and/or Bi and Ga; The melting medium is Bi and Sn, and/or when Bi and Ga, the Bi substance accounts for 50% -80% of the melting medium.
  7. 7. A method for preparing a composite carbon material and hydrogen by cracking low-carbon hydrocarbon, which is characterized in that the method is carried out in the system for preparing the composite carbon material and hydrogen by cracking low-carbon hydrocarbon according to any one of claims 1-6; The method comprises the following steps of introducing low-carbon hydrocarbon bubbles and the molten alloy catalyst in the multi-stage bubbling bed reaction device to perform catalytic cracking reaction.
  8. 8. The method for preparing a composite carbon material and hydrogen by cracking low-carbon hydrocarbon according to claim 7, wherein the gas velocity of the low-carbon hydrocarbon passing through the holes of the porous gas distribution plate is 0.01 m/s to 10 m/s, preferably 0.1 to 2.0 m/s, and/or the residence time of the low-carbon hydrocarbon feed bubbles in the molten alloy catalyst is 0.01 min to 10 h, preferably 0.1 min to 1 h.
  9. 9. The method for preparing a composite carbon material and hydrogen by cracking a low-carbon hydrocarbon according to claim 7 or 8, wherein the temperature of the catalytic cracking reaction is 500-1500 ℃, preferably 900-1100 ℃.
  10. 10. The method for preparing a composite carbon material and hydrogen by cracking a low-carbon hydrocarbon according to claim 7 or 9, wherein the pressure of the catalytic cracking reaction is 0.01 atm to 30 atm, preferably 0.1 atm to 5 atm.

Description

System and method for preparing composite carbon material and hydrogen by cracking low-carbon hydrocarbon Technical Field The invention relates to the technical field of low-carbon hydrocarbon pyrolysis hydrogen production, in particular to a system and a method for preparing a composite carbon material and hydrogen by low-carbon hydrocarbon pyrolysis. Background In the context of the rapid increase in global energy demand and the transition of energy structures to low carbonization, cleanliness and high efficiency, the development and utilization of new energy is of paramount importance. Hydrogen energy is considered to be an ideal clean energy source due to its high energy density, wide source, and no carbon emissions during combustion. The prior hydrogen production method mainly comprises the following steps of hydrogen production by electrolysis of water, purification of industrial byproducts and biomass hydrogen production by patent application CN202510180654.5, patent CN202510054902.1 and patent CN202410710941.8, and the problems of low product purity, high energy consumption, cost and resource limitation and the like of the production process are usually existed. Natural gas is used as a clean energy source, high-purity hydrogen and carbon materials with high added value can be prepared by pyrolysis, and the natural gas has an important promoting effect on the conversion of an energy structure to a zero-carbon cleaning direction and also becomes a focus of attention in energy conversion. Methane is regarded as a raw material for producing hydrogen with high efficiency because of its high hydrogen-carbon ratio as a main component of natural gas. Current mainstream technologies for methane production include methane steam reforming, methane thermal pyrolysis hydrogen production, methane catalytic pyrolysis hydrogen production, and molten metal methane pyrolysis hydrogen production. The methane steam reforming technology disclosed in the patent application CN202410499236.8 has the most wide application and relatively high maturity, but has the problems of high reaction temperature (600-900 ℃), deactivation of carbon deposition of a catalyst, high carbon emission and the like. The methane high-temperature pyrolysis disclosed in patent CN201010160179.9 is an emerging hydrogen production technology, and methane is directly cracked to generate hydrogen and solid carbon by a high-temperature reactor at a temperature of more than 1200 ℃ under the condition of no catalyst intervention. Compared with the methane steam reforming technology, the carbon emission in the reaction process is close to zero, in addition, the catalyst is not required to be added in the process, so that the problems of deactivation and replacement of the metal catalyst are avoided, however, the reaction temperature is required to be maintained above 1200 ℃ to cause the rise of energy consumption, the reduction of heat transfer efficiency and the blockage of a pipeline are caused by the carbon deposition phenomenon, and the long-term stable operation of the system is influenced. The technology for producing hydrogen by catalytic pyrolysis of methane disclosed in patent application CN202311420810.8 is a process of directly decomposing methane under the action of a catalyst to generate hydrogen and solid carbon, and the reaction temperature can be reduced to 600-800 ℃ under the auxiliary action of a solid catalyst system such as Ni-based catalyst, fe-based catalyst and the like. However, the lower temperature results in relatively lower methane conversion per pass, and in addition, the catalyst has the problems of fast deactivation of carbon deposition, poor stability, incapability of long-period operation and the like. The catalyst exists in a solid state in the cracking reaction, the generated carbon material is also solid, the carbon material and the catalyst are difficult to separate and recycle after being mixed, the byproduct of the carbon material can not be realized, and the process economy is reduced. Compared with methane pyrolysis and solid catalytic pyrolysis, the molten metal methane pyrolysis hydrogen production disclosed in the patent application CN202410818737.8 is an innovative thermochemical hydrogen production process. Catalytic cracking is achieved by passing methane into a high temperature molten metal medium. The technology utilizes molten metal (such as Sn, bi or alloy thereof) as a reaction medium, and decomposes methane molecules into hydrogen and solid carbon in a metal melt at an operating temperature of 1000-1100 ℃. Compared with traditional thermal cracking, the molten metal system has better heat conductivity and temperature uniformity, and can obviously improve the reaction efficiency. The reaction principle is that methane bubbles can be cracked when passing through a molten metal layer, generated hydrogen escapes from the surface of the melt, and solid carbon floats on the metal liquid surface due to density