Supercritical carbon dioxide morphologically modified acid-based halloysite catalyst

A process for producing poly(tetramethylene ether) diacetate comprising the steps of:

• making a morphologically modified acid-based halloysite catalyst comprising,
• subjecting a halloysite catalyst to a supercritical carbon dioxide treatment;
• wherein the supercritical treatment temperature is from about 200° C. to about 290° C.;
• wherein the supercritical treatment pressure is from about 1200 to about 3000 psi;
• wherein said halloysite catalyst has the formula Al2Si2O5(OH)4.2H2O wherein the ratio of SiO2 to Al2O3 is from about 1.7 to about 3.0;
• wherein the amount of any zeolite compound is about 10% by weight or less based upon the total weight of said halloysite catalyst;
• said modified halloysite catalysts having an average pore diameter of from about 50 Å to about 500 Å;
• and
• polymerizing tetrahydrofuran or 3-methyl tetrahydrofuran with acetic anhydride in the presence of said modified halloysite catalysts to produce said poly(tetramethylene ether) diacetate.

A process for producing poly(tetramethylene ether) diacetate comprising the steps of:

• making a morphologically modified acid-based halloysite catalyst comprising,
• subjecting a halloysite catalyst to a supercritical carbon dioxide treatment;
• wherein the supercritical treatment temperature is from about 250° C. to about 290° C.;
• wherein the supercritical treatment pressure is from about 1,400 to about 1,700 psi;
• wherein said halloysite catalyst has the formula Al2Si2O5(OH)4.2H2O wherein the ratio of SiO2 to Al2O3 is from about 1.8 to about 2.3;
• wherein the amount of any zeolite compound is about 2% by weight or less based upon the total weight of said halloysite catalyst;
• wherein the average pore diameter of said halloysite catalysts is from about 125 to about 250 angstroms;
• and
• polymerizing tetrahydrofuran or 3-methyl tetrahydrofuran with acetic anhydride in the presence of said modified halloysite catalysts to produce said poly(tetramethylene ether) diacetate.