4 documents found, page 1 of 1
Acetalization of glycerol over silicotungstic acid supported in silica
Castanheiro, J; Pinto, A; Lopes, ME; Santos, FIThe acetalization of glycerol with butanal was carried out in the presence of silicotungstic acid (HSiW) immobilized in silica, by sol-gel technique, at 70ºC. The products of glycerol acetalization with butanal were (Z + E)-(2-propyl-1,3-dioxolan-4-yl) methanol and (Z + E)-2-propyl-1,3-dioxan-5-ol. Catalysts with different amount of HSiW were prepared. The catalysts were characterized by FTIR, XRD, ICP and N2 a...
Zeolites as heterogeneous catalysts to valorization of monoterpenes into flavor...
Castanheiro, J; Pinto, AP; Lopes, MEZeolites are aluminosilicate with high surface area and uniform microporosity. Monoterpenes are renewable resources. The catalytic transformation of terpenes are synthetic routes to valuable compounds. Strong homogeneous acid catalysts have been used in the acid reactions. Due to enviromental problems, homogeneous catalysts have been replaced by heterogeneous catalysts, which are reusable and easy to be separat...
Biological Approaches for Remediation of Metal-Contaminated Sites
Pinto, AP; de Varennes, A; Lopes, ME; Martins Teixeira, DEnvironmental pollution by several heavy metals and metalloids is a severe problem worldwide, as soils became increasingly contaminated, posing a threat to ecosystems and ultimately to human health. Contamination derives from large scale urbanization and industrialization, threatening land ecosystems, surface and groundwater, as well as food safety and human health. Remediation strategies for heavy metal-contam...
Synthesis and electrical properties of nanocrystalline Ca1−xEuxMnO3±δ
Lopes, ME; Silveira, C; Nunes, M R; Melo Jorge, M ENanopowders of Ca1−xEuxMnO3 (0.1≤x≤0.4) manganites were synthesized as a single phase using the auto gel-combustion method. The citrate method shows to be simple and appropriate to obtain single phases avoiding segregation or contamination. The Ca1−xEuxMnO3 system has been synthesized at 800 °C during 18 h, against the conventional method of mixing oxides used to obtain these materials at higher temperatures of...