Methods for preparing biodiesel by directional regulating hydrodeoxygenation of biological oils

A method for preparing biodiesel by directional regulating hydrodeoxygenation of biological oils, the method comprising:

• dissolving the biological oils in a solvent to obtain an oil mixed solution with a mass concentration of 1.0% to 20%;
• mixing the oil mixed solution with hydrogen gas to obtain a mixture and injecting the mixture into a fixed-bed reactor;
• performing a hydrodeoxygenation reaction using an atom-substituted zirconia supported Ni catalyst;
• controlling the biological oils to directionally generate alkanes having corresponding carbon numbers or alkanes having one less carbon atom by changing a coordination structure of a support and heteroatoms in the atom-substituted zirconia supported Ni catalyst;
• and obtaining the biodiesel;
• wherein
• a chemical formula of the atom-substituted zirconia supported Ni catalyst is Ni/xMZrO2, where x is a molar percentage of M in the support and has a value of 1% to 20%;
• M is at least one of Ce or Ti;
• and a loading amount of Ni is 5 wt. % to 50 wt. %;
• and
• the atom-substituted zirconia supported Ni catalyst is prepared by a process including:
• 1) mixing and dissolving at least one of a zirconium salt, a cerium salt, or a titanium salt in deionized water to obtain a metal precursor salt solution;
• adding urea to the metal precursor salt solution and stirring thoroughly until dissolution is completed to obtain a metal precursor mixed solution;
• placing the metal precursor mixed solution in an autoclave for heating, and filtering to obtain a precipitate;
• washing and drying the precipitate;
• and calcining the precipitate in an O2/Ar mixed atmosphere to obtain an atom-substituted zirconia support;
• and
• 2) adding the atom-substituted zirconia support and a nickel salt to the deionized water, stirring uniformly, performing rotary evaporation and drying, and then calcining in the O2/Ar mixed atmosphere to obtain the atom-substituted zirconia supported Ni catalyst.