Method for preparing biogenic guanidine complex, method for preparing polyethylene terephthalate (pet), and method for preparing poly (ethylene isophthalate-co-terephthalate) (peit)

A method, comprising:

• adding to a reactor, terephthalic acid (TA), ethylene glycol (EG), and guanidine complex GMX2/G2X2 in a molar ratio TA:EG:GMX2/G2MX2=1.0:1.3:(2.0-3.0)×10−5, wherein G represents arginine (Arg), guanidinoacetic acid (Gaa), creatine (Cra), creatinine (Cran), guanine (Gua), or agmatine (Agm);
• M represents Fe2+, Mg2+, or Zn2+;
• and X represents Cl−, CH3COO−, or CH3CH(OH)COO−;
• purging the reactor with nitrogen until a pressure of the reactor is 150 kPa;
• holding the pressure at 220-244° C. for 2.0-2.5 hours;
• reducing the pressure to 10 kPa, and holding the pressure at 245-257° C. for 40-45 min;
• further reducing the pressure to 1 kPa, and holding the pressure at 258-264° C. for 30-35 min;
• reducing the pressure to 5 Pa, and holding the pressure at 265-268° C. for 40-45 min;
• and
• collecting a product in the reactor, pelleting the product, and drying to yield polyethylene terephthalate (PET);
• a process chart of the method being as follows:

A method, comprising:

• adding to a reactor terephthalic acid (TA), isophthalic acid (IPA), ethylene glycol (EG), and guanidine complex GMX2/G2MX2 in a molar ratio of 0.98:0.02:1.30:(2.0-3.0)×10−5, wherein G represents arginine (Arg), guanidinoacetic acid (Gaa), creatine (Cra), creatinine (Cran), guanine (Gua), or agmatine (Agm);
• M represents Fe2+, Mg2+, or Zn2+;
• and X represents Cl−, CH3COO−, or CH3CH(OH)COO−;
• purging the reactor with nitrogen until a pressure of the reactor is 150 kPa;
• holding the pressure at 220-244° C. for 2.0-2.5 hours;
• reducing the pressure to 10 kPa, and holding the pressure at 245-257° C. for 40-45 min;
• further reducing the pressure to 1 kPa, and holding the pressure at 258-264° C. for 30-35 min;
• reducing the pressure to 5 Pa, and holding the pressure at 265-268° C. for 40-45 min;
• and
• collecting a product in the reactor, pelleting the product, and drying to yield poly(ethylene isophthalate-co-terephthalate) (PEIT);
• a process chart of the method being as follows, wherein Ph represents 1,4-phenylene, and mPh represent 1,3-phenylene: