Silica/titania composite-supported Ni catalysts for CO methanation: Effects of Ti species on the activity, anti-sintering, and anti-coking properties

Autor: Shusen Liu, Zhong Li, Jiyu Zhu, Haidong Li, Yong-Yong Jin, Jianying Lin, Jun Ren
Rok vydání: 2017
Předmět:
Zdroj: Applied Catalysis B: Environmental. 201:561-572
ISSN: 0926-3373
DOI: 10.1016/j.apcatb.2016.08.061
Popis: Catalysts composed of Ni supported on SiO 2 /TiO 2 composite oxides (ST) with different Si/Ti molar ratios have been prepared by an ultrasonic impregnation method and used in CO methanation. Experimental results show that the ST systems have large specific surface area, large pore volume, and offer suitable metal–support interactions, thereby facilitating the dispersion of Ni. Indeed, these catalysts have more suitable Ni active sites for methanation, and the composite oxides show good support and synergistic effects. Thus, Ni/ST x ( x = 50, 10, 5, 1) with a Ni loading of 10 wt% displayed higher catalytic performances relative to catalysts composed of Ni supported on individual oxides (SiO 2 , TiO 2 , and γ-Al 2 O 3 ). Among the catalysts, 10Ni/ST5 displayed the best catalytic activity (370 °C, CO conversion: 99.9%, CH 4 selectivity: 95.6%). Furthermore, 10Ni/ST5 showed better CH 4 yield (290 °C, CH 4 yield: 92.4%), anti-sintering properties (smaller Ni particles), and anti-coking properties (lower amount of deposited carbon) after a stability test of duration 144 h at 600 °C than those of a typical 10Ni/γ-Al 2 O 3 catalyst (290 °C, CH 4 yield: 80.0%). This can be attributed to the optimal amount of TiO 2 separating/separated from the ST5 and playing the role of an electronic promoter. It not only effectively facilitated the dispersion of Ni during sintering, but also triggered electron transfer and enhanced the electron cloud density of Ni 00 (Ni 00 → Ni δ− ), thereby weakening the C O bond of Ni-C O and enhancing the dissociation of CO.
Databáze: OpenAIRE
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