Method for preparing acetic acid by catalyst

A method for preparing acetic acid by a catalyst, comprising:

• S1:
• preparing a hydrotalcite carrier by a hydrothermal method, comprising:
• mixing MgCl2·6H2O, AlCl3·6H2O, and urea according to a molar ratio of (1-5):(1-5):(1-7) to obtain a resulting mixture and dissolving the resulting mixture in methanol to obtain a resulting solution, after stirring the resulting solution evenly, sealing a stirred solution in a polytetrafluoroethylene lining for a hydrothermal reaction, centrifuging a white precipitate obtained by the hydrothermal reaction, washing a centrifuged white precipitate with a first deionized water and a first ethanol, drying a washed white precipitate at 50-120° C. for 10-24 h to obtain a hydrotalcite carrier MgAl-LDH;
• S2:
• an ion exchange process, comprising:
• dispersing the hydrotalcite carrier MgAl-LDH obtained in S1 in a deionized water containing a metal salt including a cobalt salt and a palladium salt stirring and performing ion exchange with the cobalt salt and the palladium salt to obtain an exchange solution, then centrifuging the exchange solution to obtain a centrifuged precipitate, collecting the centrifuged precipitate and washing the centrifuged precipitate with water to obtain a washed precipitate;
• S3:
• a liquid phase reduction process, comprising:
• dispersing the washed precipitate obtained in S2 in a NaBH4 aqueous solution, after stirring and reducing for 0.1-2 h to obtain a reduced solution, performing washing the reduced solution with a second deionized water and a second ethanol respectively to obtain a washed product, after drying the washed product to obtain a dried product, roasting the dried product in an inert atmosphere for 1-5 h to obtain a CoPd-supported MgAl-LDH catalyst;
• and
• S4:
• placing the CoPd-supported MgAl-LDH catalyst obtained in S3 in a two-channel fixed bed step-by-step continuous reactor, carrying out a reaction at 100-400° C. and 0.1-20 MPa, synthesizing the acetic acid by an alternating feeding of CH4+H2+H2O and CO2+H2+H2O, with an alternating time of 50-300 s.