Flame-assisted spray pyrolysis using an annular flame nozzle with decoupled velocity control

Abstract

Flame spray pyrolysis, widely used in chemical industries, is a technology to synthesize nanoparticles. While the flame spray pyrolysis uses fuels as a solution liquid, the flame-assisted spray pyrolysis method uses aqueous solutions. Since process parameters such as concentration of precursor, size of droplets, and ratio of the air–gas mixture affect the size of nanoparticles, developing a flexible system to control these parameters is required. This paper proposes a new type of nozzle system to produce nanoparticles using flame-assisted spray pyrolysis. The annular nozzle design allows flexible control of particle flow and temperature, and an ultrasonic nebulizer was used to produce droplets with different size. Experiments were conducted to analyze the relationship between nanoparticle size and process parameters, concentration of precursor, frequency of the atomizer, and flame temperature. A precursor solution consisting of silver nitrate (AgNO3) mixed in deionized water is used. The effects of the process parameters are discussed, and analysis of the nanoparticles shows that silver nanoparticles are deposited with an average size of 25~115 nm.