AMT/SiO2 Catalyst on Orthortho-Hydroxy Anisole Production II

Ammonium metatungstate, also known as AMT, is a tungsten chemical in the form of highly soluble hydrated crystals. Global Tungsten & Powders AMT is produced as minus 10-mesh powder to meet stringent demands in the catalyst, medical, semiconductor and other high-technology industries. GTP AMT is also used in materials research and in analytical chemistry. At room temperature, aqueous solutions can be saturated up to 70% by weight of contained WO3. This equates to 1.6 kilograms per liter or 13.3 pounds per gallon.

AMT / SiO2 catalyst calcined at different temperatures has different degrees of AMT decomposition, resulting in different properties of the catalyst surface pH center, resulting in catalyst performance vary. The activity and stability of catalyst prepared at low firing temperature calcination is much better than a catalyst prepared at high firing temperature. Weak acid-weak alkali centers on the catalyst surface is the main activity center of catechol and methanol monoetherification reaction to produce ortho-hydroxy anisoles. the main reason for the reduced activity is coke on the catalyst surface during the reaction. the catalyst after inactivation was calcined at a higher temperature and regeneration treatment then the reactivity partially restored, but still significantly lower than the fresh catalyst, and the stability of the catalyst after regeneration process is poor. This may be the high temperature regeneration properties of the active center of the catalyst surface (including pH properties) has changed, so that the regenerated catalyst is more easily inactivated.