Synthesis and characterisation of MCM-41 supported nickel oxide catalysts

Nickel ions were deposited onto hydrothermally synthesised all-silica MCM-4 1 by means of incipient wetness impregnation with different nickel precurso r solutions, viz, nickel nitrate and nickel citrate. The calcined nickel ca talysts (10 wt.% Ni) were characterised using nitrogen physisorption, tempe rature programmed reduction, transmission electron microscopy. X-ray diffra ction and X-ray photo-electron spectroscopy. With nickel citrate the highes t nickel oxide dispersion was obtained. The nickel oxide particle size was inferred to be very small with this precursor, allowing the particles to be located mainly inside the mesopores of MCM-41. With nickel nitrate a bimod al particle size distribution was obtained and next to small nickel oxide p articles inside the mesopores relatively large particles (i.e. > 10 nm) wer e present on the external surface of the support, thus lowering the dispers ion of this catalyst. Textural analysis showed that with both preparation m ethods neither pore-blocking nor structural collapse of the support occurre d. From these results it is concluded that incipient wetness impregnation w ith a nickel citrate precursor solution is an excellent method to prepare M CM-41 supported nickel catalysts combining both a high metal loading and a high dispersion of the active phase. (C) 2001 Elsevier Science B.V. All rig hts reserved.