Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-IV-18contains phases of NiO and MgO with lattice parameter 4.218 Å. It was found that during theformation of MgO the introduction of Ni 2+ -cations from oxide layer to support MgO takesplace. In supports I and II, nickel is detected by EDX spectra of MgO as spectral lines ofweak intensity corresponding to a nickel concentration of ∼ 2 at.%. In reaction conditions orreduction conditions these Ni 2+ -cations form dispersal nickel crystals.The reduced supported catalysts exhibit phases of nickel and solid solution NiO in MgOwhich disappeared in reaction condition. In the supported nickel catalysts, dispersal nickelparticles are epitaxially bonded with support MgO, which is evidenced by the Moire picture.The conversion value for support MgO I is 52 % and for MgO II - 65 %. The additionaldeposition of nickel results in the increasing of conversion value. Note that the preparednickel catalysts on supports I and II are characterized by comparable conversion values.9590Conversion CH 4,%8580757065605512345500 5 10 15 20 25 30 35 40 45 50 55 60t, hFig. Influence of reaction time on methane conversion in steam reforming reaction: 1 – 5.0 % Ni/pNi + 5.0 %MgO (I) (plate, V=0.7 сm 3 , m=3.29 g); 2 – 5,7 % Ni/pNi + 5.0 % MgO (II) (plate, V=0.7 сm 3 , m=3.28 g);3 – 7,2% Ni/pNi + 5,0% MgOII (plate, m=3.07g, V=0.7 сm 3 ); 4 – NIAP-18 (fraction 0,25–0,5 mm, m=0,80g);5 – NIAP-18 (1/2 of grain, m=1,46 g, V=0,7 сm 3 ).The catalyst activity was stable during 50 hour tests (Fig.). From TEM it was shown thatthere are not any carbon deposits in the tested catalyst samples. We suppose that formed fromsolid solution NiO-MgO or from surface combination dispersal nickel crystals are interactedwith support and so they have increased stability to carbon deposition. The fact of interactionbetween nickel and support is confirmed by TEM HR data which do not show oxide layer indispersal nickel particles (∼20 Å) after additional calcinations (Ar, 550 °C, 2 h).Thus, the nickel catalysts supported on the plate-like porous nickel with the MgO precoatare characterized by high and stable activity in the reaction of methane steam reforming andresistance to carbonization.References1. Kirillov V.A., Kuzin N.A., Kulikov A.V. et al. // Theor.Bases Chem.Techn. 2003, v. 37, No 3, p.300.2. Y.H. Hu, E. Ruckenstein // Catal. Lett., 36 (1996) 145.3. G.C. Bond, S.P. Sarsam // Appl. Catal.A:, General 38 (1988) 365.429