Physicochemical and catalytic properties of glass crystal catalysts for the oxidation of methane

Variations in fly ash composition with sampling location: Case study from a Portuguese power plant

“…All these Fe minerals occur, in most cases, embedded in a Fe-rich aluminosilicate glass and are the main components of ferrospheres (Lauf et al, 1982;Anshits et al, 1998). Therefore, density and magnetic properties (Anshits et al, 2000) may be responsible for capture and segregation at the sampling locations.…”

“…Since fly ash is a heterogeneous and complex anthropogenic material, and, like coal, includes organic and crystalline and amorphous inorganic phases, a large number of techniques may be applied in fly ash characterization (French et al, 2007;Vassilev & Vassileva, 2005), to study FA mineralogy (Raask, 1982;Vassilev & Vassileva, 1996a;Ward & French, 2006), morphotypes (Anshits et al, 1998;Bailey et al, 1990;Fomenko et al, 1998a,b;Hower & Mastalerz, 2001;Hower et al, 2005;Sokol et al, 2002;SuarezRuiz & Valentim, 2007;Vassilev & Vassileva, 2007), Hg capture by carbon (Hower et al, 2000;Senior & Johnson, 2005), magnetic properties (Anshits et al, 2000;Hansen et al, 1981), the environmental and technological behavior of trace elements, the mechanisms for concentration enhancement, the relation between trace elements and fly ashes (Block & Dams, 1979;Clark, 1993;Conzemius et al, 1984;Danihelka et al, 2003;Donahoe et al, 2007;Finkelman et al, 1990;Haynes et al, 1982;Meij, 1994;Meij & Winkel, 2009;Swaine, 1990Swaine, , 2000Valkovic, 1983;Yan et al, 2001), and chemical classification of fly ashes (Roy & Griffin, 1982;Vassilev & Vassileva, 2007), among others. Therefore, a case study of FA from a TPP was conducted using several characterization techniques in order to see if FA variations inside a TPP are exclusive of some properties or if they cover a wide range of situations: granulometry, carbon content, major oxides and chemical classification, mineralogy and phase-mineral classification, and trace elements (Cr, Cu, Mn, Ni, ...…”

Composition, Structure, and Formation Routes of Blocklike Ferrospheres Separated from Coal and Lignite Fly Ashes

“…The use of process flow diagrams for separation and deep purification of FSs concentrates, which include granulometric, hydrodynamic, dry, and wet magnetic separation stages, enables classification of four known ash types, sialic (S), ferrisialic (FS), ferricalsialic (FCS), and calsialic (CS), into narrow FSs fractions of constant composition with the Fe 2 O 3 content in a range of 30–92 wt % and globule size in a range of 50–250 μm , and with reproducible magnetic properties. , The produced FSs fractions have the common composition–morphology–microstructure relationship for iron-containing phases, which, in turn, suggests their application areas as functional materials. FSs of constant composition can be used as effective catalysts for deep oxidation, oxidative coupling of methane, − thermolysis of heavy oils and oil residues, and magnetic carriers for affinity sorbents in protein separation …”

“…27,28 The produced FSs fractions have the common composition−morphology−microstructure relationship for iron-containing phases, 25 which, in turn, suggests their application areas as functional materials. FSs of constant composition can be used as effective catalysts for deep oxidation, 29 oxidative coupling of methane, 30−32 thermolysis of heavy oils and oil residues, 33 and magnetic carriers for affinity sorbents in protein separation. 34 The differences in chemical and phase compositions and functional properties of FSs from different ashes are explained by the presence of several morphological globule types with their different contents in narrow fractions.…”

Catalytic properties and nature of active centers of ferrospheres in oxidative coupling of methane

“…Contrarily, ferrospheres and magnetic cenospheres with a lower iron content oxidized methane to carbon oxides [14,15]. In order to elucidate possible fundamental reasons for the different OCM performance, we thoroughly characterized ferrospheres with the content of Fe 2 O 3 in the range of 30-92 wt% to determine their composition, morphology, microstructure of iron-containing phases, and catalytic properties [16][17][18].…”