Nanocomposites and nanomaterials

Structure and catalytic properties of Ni-Co/Silica nanocomposites

Goncharuk O.1, Dyachenko A.2, Ischenko O.2, Shipul O.2, Mischanchuk O. 1,  Sternik D.3
1O.O. Chuiko Institute of Surface Chemistry of NAS of Ukraine, 17 General Naumov str., Kyiv, Ukraine
E-mail: iscgoncharuk@meta.ua
2Taras Shevchenko National University of Kyiv, 64/13 Volodymyrs’ka str., Kyiv, Ukraine
3 Faculty of Chemistry, Maria Curie-Sklodowska University, M.C. Sklodowska Sq.3, 20031 Lublin, Poland
To study the catalytic properties a series of nanocomposites of MxOy/SiO2 (M - Ni, Co in different ratio) was synthesized by two-step method consisting in solvate-stimulated modification of the fumed silica with Ni and Co nitrate hexahydrates and further thermal decomposition. Synthesized nanocomposites have a specific surface (SBET) of more than 200 m2/g (Table) and size of MxOy crystallite of 14-15nm. The catalytic performance of nanocomposites was investigated in the reaction of hydrogenation of CO2. Before to the evaluation of catalytic test the samples were reduced with a supply of 50 vol.% H2-50 vol.% He gas mixture. The temperature dependence of catalytic performance was examined with a supply of 2% CO2-55% H2- 43% He/ The composition of outlet gas was analyzed by an on-line gas chromatograph with a thermal conductivity detector. The highest catalytic activity at low temperature (300 0C) was shown by samples with a high cobalt content (Table). 
Table. SBET and catalityc activity of MxOy/SiO2nanocomposites 
Catalyst	SBET, m2/g
initial	SBET, m2/g
reduced	CH4/CO, yield, %	
			300 °C	350 °C	400°C	
Ni100/SiO2	212.4	215.0	26/4	75/7	98/1	
Сo100/SiO2	204.6	217.5	73/3	90/2	96/1	
Ni50Co50/SiO2	208.4	215.3	32/6	79/9	98/1	
Ni20Co80/SiO2	229.3	216.2	73/5	97/2	98/1	
Ni80Co20/SiO2	214.8	217.0	46/2	100/0	100/0