Characterization of sepiolite as a support of silver catalyst in soot combustion

• Published in: Applied clay science Vol. 32; no. 3-4; pp. 291 - 296
• Main Authors: Güngör, Nurfer, Işçi, Sevim, Günister, Ebru, Miśta, Włodzimierz, Teterycz, Helena, Klimkiewicz, Roman
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-05-2006; Amsterdam Elsevier Science; New York, NY
• Subjects: Catalyst; Earth sciences; Earth, ocean, space; Exact sciences and technology; Mineralogy; Sepiolite; Silicates; Silver; Soot combustion; Support; Zirconium oxide; Soot combustion; Silver; Zirconium oxide; Support; Sepiolite; Catalyst; oxides; degradation; specific surface; BASIC; sheet silicates; silicates; zirconium; oxygen; scanning electron microscopy; adsorption; morphology; low temperature; carbonates; high temperature; combustion; materials; differential thermal analysis; sepiolite; clay minerals; silver; desorption
• ISSN: 0169-1317; 1872-9053
• DOI: 10.1016/j.clay.2006.03.005

Turkish sepiolite–zirconium oxide mixtures were applied as a support for the silver catalyst in a soot combustion. Sepiolite–Zr–K–Ag–O catalyst was characterized by XRD, N2 adsorption, SEM, TPR-H2 and EGA-MS. The combustion of soot was studied with a thermobalance (TG-DTA). The modification resulted in a partial degradation of the sepiolite structure, however, the morphology was preserved. The adsorption of N2 of the modified sepiolite is a characteristic for mesoporous materials with a wide distribution of pores. The specific surface area SBET equals 83 m2/g and the pores volume is 0.23 cm3/g. The basic character of the surface centers of sepiolite is indicated by CO2 desorption (TPD-MS) at 170 °C and at about 620 °C due to a surface carbonates decomposition. The thermodesorption of oxygen at 650–850 °C indicates the decomposition of AgOx phases at the surface. The presence of AgOx phases is also confirmed by TPR-H2 spectrum (low temperature reduction peak at 130 and 180 °C). The high-temperature reduction at about 570 °C is probably related to Ag–O–M phases on the support.
The soot combustion takes place at T50=575 °C. Without silver (sepiolite–Zr–K–O) T50=560 °C but sepiolite modified with silver (sepiolite–Zr–K–Ag–O) undergoes the same process at T50=490 °C.