Cerâmicas bioinspiradas recobertas com óxidos perovskíticos para aplicação em catálise por plasma de micro-ondas

Abstract

Climate changes related to global warming are directly associated with greenhouse gases emissions, mostly originated from fossil fuels. To help mitigate these gases emissions, the viability of advanced catalytic techniques, such as microwave plasma catalysis, are evaluated. This thesis aims to produce a bioinspired ceramic by microwave sintering to be used as support for catalytic particles for microwave plasma catalysis. The support was produced by conventional and microwave sintering, achieving a 35% reduction in energy consumption when sintered by the microwave technique. The catalytic ceramics, BaTiO3, SrTiO3, Ba0,5Sr0,5TO3 and MgTiO3, were synthesized by the conventional or microwave assisted Pechini method, followed by analysis of the resulting powder using X-ray diffraction, scanning and transmission electron microscopy, and diffuse reflectance spectroscopy. The particle deposition over the bioinspired support was carried out, investigating their microwave plasma resistance. It was noted that the particles protected the support from plasma ablation and sputtering. The plasma resistance under Argon or Nitrogen microwave plasmas of the bulk titanate ceramics were also investigated, evaluating their microstructural stability, densification and modification of electrical and dielectric properties regarding the sintering technique and type of plasma treatment. The SrTiO3 composition presented the best plasma resistance, while others were also resistant to plasma ablation and sputtering. All compositions presented high values of dielectric constant, foreseeing a decent application as catalytic materials in microwave plasma catalysis.