Preparation method of biobased adipic acid

A preparation method of biobased adipic acid, comprising preparing a nickel-based hydrogenation catalyst, and conducting a hydrogenation reaction on biobased sodium muconate for preparing adipic acid in a microreactor under the action of the nickel-based hydrogenation catalyst;

• wherein
• the preparing the nickel-based hydrogenation catalyst comprises carrier pretreatment and metal nickel loading by a precipitation-deposition method, comprising:
• step A:
• putting a carrier into an aqueous solution consisting of 0.5 M Na2CO3 and water, performing ultrasonic pretreatment for 30 min;
• and after solid-liquid separation, drying the carrier to obtain a pretreated carrier, wherein the carrier is alumina powder;
• step B:
• adding 10 g of the pretreated carrier to 200 ml of water for ultrasonic shaking for 30 min to obtain a carrier suspension with a concentration of 50 g/L;
• step C:
• mixing a nickel source with urea and 50 mL of deionized water to obtain a nickel source-urea mixed solution, wherein a mass ratio of the nickel source to deionized water is 0.05, and a molar ratio of urea to the nickel source is 4;
• step D:
• mixing the carrier suspension with the nickel source-urea mixed solution;
• adding to a jacketed beaker, and sealing and stirring in a water bath at 90° C. for 4 h for impregnating;
• then unsealing, stirring and drying in a water bath at 90° C. until the water completely volatilizes to obtain a dry nickel-based hydrogenation catalyst precursor;
• step E:
• placing the dry nickel-based hydrogenation catalyst precursor in a tube furnace;
• injecting hydrogen for reducing at high temperature of 300° C. for 4 hours to obtain a nickel-based hydrogenation catalyst;
• step F:
• pressing, sieving and filling the nickel-based hydrogenation catalyst in a steel pipe with an inner diameter of 0.635 cm, where both ends of the steel pipe are filled with inert glass microbeads to prevent the catalyst from leaking;
• and injecting hydrogen and a 200 g/L biobased sodium muconate solution into the microreactor, wherein a flow rate of a liquid is controlled by a constant-flux pump, a flow rate of the injected biobased sodium muconate solution is 0.1 mL/min, a gas flow rate is controlled by a gas flowmeter at 10 mL/min, and a pressure of hydrogen in the microreactor is 3 MPa, the microreactor requires a water/oil bath to maintain the reaction temperature, a reaction is conducted at 80° C., an inner diameter of the microreactor is ¼ inch, a height of a catalyst bed is 10 cm, a residence time is 157 s, and the reaction is conducted for 157 s;
• the nickel-based hydrogenation catalyst is composed of carrier loaded metal nickel, wherein the average particle size of the metal nickel is 2.5-4.5 nm obtained by transmission electron microscopy (TEM), and the specific surface area of the nickel-based hydrogenation catalyst is 50-300 m2/g;
• and the load of the metal nickel in the nickel-based hydrogenation catalyst is 2-40 wt %;
• the biobased muconic acid is cis-muconic acid prepared from biomass raw material;
• the biobased adipic acid is adipic acid converted from the biobased muconic acid.