A quantitative investigation of the structure of Raney-Ni catalyst material using both computer simulation and experimental measurements

• Published in: Journal of catalysis Vol. 281; no. 2; pp. 300 - 308
• Main Authors: Barnard, N.C., Brown, S.G.R., Devred, F., Bakker, J.W., Nieuwenhuys, B.E., Adkins, N.J.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 25.07.2011; Elsevier; Elsevier BV
• Subjects: Alloys; aluminum; Catalysis; Catalysts; Chemistry; Computer simulation; Exact sciences and technology; General and physical chemistry; leaching; mathematical models; Molecular structure; Monte Carlo method; Monte Carlo simulation; nickel; nitrogen; powders; Raney-nickel catalysts; Spray-atomisation; surface area; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; X-ray photoelectron spectroscopy; Raney-nickel catalysts; Spray-atomisation; Monte Carlo simulation; Monte Carlo method; Computer simulation; Alloys; Raney nickel; Aluminium; X ray; Nitrogen; Physisorption; Precursor; Powder; Heterogeneous catalysis; Kinetic model; Distribution; Photoelectron spectrometry; Kinetics; Surface area; Structure; Catalyst; Surface conditions
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2011.05.010

Monte Carlo modelling is used to simulate the 3D nano-porous structure of leached Raney-nickel catalyst material. Calculated surface areas from the model compare favourably to measured surface areas from BET analysis and also predict surface segregation of residual Al matching X-ray photoelectron spectroscopy results. In the figure, the magnified view at the top left shows a region (A), which is an exposed (1 1 1) plane and a region below (B), which is an exposed (1 0 0) plane. Dark atoms are Ni and light atoms are Al. [Display omitted] ► Nature of Raney-Ni catalyst quantified via experimentation and modelling. ► kMC model correctly predicts surface areas of leached Raney-Ni material. ► MMC model predicts surface segregation of Al in accord with XPS data. This paper describes combined experimental techniques and numerical modelling of the surface condition of activated nanoscopic Raney-nickel catalysts produced via leaching of spray-atomised NiAl precursor powders. Results of off-lattice Metropolis and lattice kinetic Monte Carlo models compare favourably to experimentation quantifying the surface of Raney-nickel catalysts in terms of both surface area and the surface distribution of residual aluminium left over from the leaching process. Predicted surface areas from the kinetic Monte Carlo simulations are shown to be in good agreement with BET measurements from nitrogen physisorption for catalyst materials prepared from two different NiAl precursor alloys. Surface aluminium concentrations predicted by Metropolis Monte Carlo simulations are also in agreement with X-ray photoelectron spectroscopy results and in addition predict an absence of Al–Al bonding at the surface.