Acid catalysts prepared by impregnation of tungstophosphoric acid solutions on different supports

Keggin heteropolyacid H3PW12O40 supported on different oxides for catalytic and catalytic photo-assisted propene hydration

“…1) correspond roughly to those of the bare supports. No significant changes in the diffraction patterns occurred after the deposition of POM, indicating that POM species are highly dispersed on the support in agreement with previous works 23, 35 and also with SEM and EDAX observations. In the POM supported samples on TiO 2 Merck, WO 3 and ZrO 2 new peaks appeared, with respect to the corresponding bare powders.…”

“…3. A wide band can be observed for the bare heteropolyacid in the range 300-360 nm, in agreement with Pizzio et al 23 This wide band, observed only for the optical characterization of the solid POM material, is responsible for the location of the band edge of the bare POM at wavelengths higher than those expected (260 nm Paper PCCP…”

“…5,22 The dispersion of POMs on solid supports with a high surface area, is, moreover, generally useful because the accessibility to their acid sites, and consequently the catalytic activity, increase. Several supports, such as SiO 2 , [23][24][25][26][27] 23,33 have been used to disperse POM. Silica has been widely favoured as supporting material because it interacts weakly with the Keggin anions preserving their structure.…”

Electrochemical study of H3PMo12 retention on Vulcan carbon grafted with NH2 and OH groups

“…The dispersion of heteropolyacids in solid matrices is another method of increasing the surface area and adjusting the porosity, both of which are important in potential solidstate applications. Molecular oxides have been incorporated in different solid matrices, such as zirconia [18], silica [19], alumina [20], TiO 2 [21], and zeolites [3], exhibiting desorption problems due to weak bonding with the matrix. POM particles have also been deposited on electrode surfaces and immobilized into or within conducting polymers to modify their properties [11,[22][23][24][25][26].…”

Impregnação do ácido 12-fosfotúngstico em sílica - parte I: determinação de parâmetros de impregnação, caracterização e avaliação da atividade catalítica

“…15 Outros trabalhos ainda relatam diversas formas de impregnações/ imobilizações de diversos HPAs em vários suportes e uso em reações variadas. [16][17][18][19][20][21] Diante do exposto, este trabalho teve o objetivo de desenvolver e avaliar a aplicação de um catalisador à base de ácido 12-fosfotún-gstico suportado em sílica em reações de esterificação metílica do ácido esteárico.…”