Effects of nano-TiO2 on combustion and desulfurization

• The burn-off rate of coals was raised and the combustible contents were reduced by adding nano-TiO2.
• The desulfurization in combustion can be achieved by adding CaO， but the combustion efficiency was inhibited.
• Nano-TiO2 can promote the transfer rate of oxygen from gas phase to the surface of char.

Nanosized titanium oxide powder was prepared via the sol–gel process and characterized by transmission electron microscope. The effects of nano-TiO2 on combustion characteristics of lignite, desulfurization in combustion and the properties of ashes were investigated. The calorific value of coals and the fusion point of the coal ashes were measured by calorimeter and ash fusion point determination meter; the components of coal ashes and the contents of combustible matters in ash were determined by chemical methods; the pore-size distribution and specific surface area of the coal ash were analyzed by surface area analyzer. A thermogravimetric analyzer was used to investigate the effect of nano-TiO2 on combustion. The results showed that the calorific value of the coal and the fusion temperature of the coal ash were lowered by adding CaO, while on the other hand adding nano-TiO2 to coal increased the calorific value and the melting temperature effectively. Meanwhile, the coal combustion efficiency and desulfurization in combustion could be effectively improved by the co-action of TiO2.