1. PPGE3M, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970, Brazil
2. Laboratory of Technological Processes and Catalysis, Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970, Brazil
3. Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul 91501-970, Brazil