Obtenção de dióxido de titânio rutilo em temperaturas inferiores às usadas industrialmente a partir de diferentes precursores

摘要

Titanium dioxide (Ti02.) is a ceramic material, commonly known as titania. The two more common and important phases of the TiO2 are anatase and rutile. In many cases itudwould be desirable to produce the stable rutile phase, but most low temperatures synthesis methods (aqueous route) produces predominantly the metastable anatase phase that reverts to rutile just when heated up to 1000 °C. The calcination for obtaining of the rutile phase is the most intensive by energy demanding step for titanium dioxide manufacture by means of sulphate process responsible for almost 60% of total energy consumption. In this study an innovative technique involving a sonification pre-treatment in acid medium was developed to change the particles reactivity and accelerate the anatase to rutile transformation. Analysis of scanning electron microscopy and surface area measurements checked the alteration in texture and porosity of the powders. Results show to be possible to obtain 100% of the rutile phase at temperatures as low as 430 °C with real possibilities to save time and energy during the calcination stage. The process developed also allowed the thermal stabilization of the pore-structure of the rutile phase. Surprisingly, after the calcination that allowed the obtaining of 100% of the rutile, the titania retained a surface area as high as 52m2/g. A patent requested was submitted to INPI in 03/09/2004, application number PI 0403757-0.