Abstract
The presence of co-operative adsorption behaviour, operating between neighbouring pores within a disordered, void-space network, such as advanced adsorption effects, can significantly complicate the interpretation of gas adsorption data for complex porous solids, such as coked heterogeneous catalysts. The novel integrated gas sorption and mercury porosimetry method can be used to abstract the specific adsorption and desorption behaviour for particular, small sub-sets of similarly-sized pores contained within the complex network of a disordered porous solid. It will be shown in this work how, for ink-bottle geometries, the integrated experiments also allow the deconvolution of the gas sorption behaviour in pore necks, as well as pore bodies, and therefore enable the mechanism of desorption from the pore bodies to be determined. However, proper interpretation of the adsorption data from integrated experiments can be problematic using classical adsorption theories. In this work, it has been demonstrated that the experimental observations can be better understood in the light of mean-field DFT simulations of adsorption in representative pore models. Hence, a better description of the particular physical mechanisms underlying adsorption isotherms in disordered porous solids has been obtained. In addition, the new method allows more detail of the void space geometry to be obtained, such as the ratio of pore neck length relative to pore body length.
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Barrett, E.P., Joyner, L.G., Halenda, P.H.: The determination of pore volume and area distributions in porous substances-I. Computations from nitrogen isotherms. J. Am. Chem. Soc. 73, 373–380 (1951)
Cohan, L.H.: Sorption hysteresis and the vapor pressure of concave surfaces. J. Am. Chem. Soc. 60, 433 (1938)
De Boer, J.H.: The shapes of capillaries. In: Everett, D.H., Stone, F.S. (eds.) The Structure and Properties of Porous Solids, pp. 68–94. Butterworths, London (1958)
Elias-Kohav, T., Sheintuch, M., Avnir, D.: Steady-state diffusion and reaction in catalytic fractal porous media, Chem. Eng. Sci. 46, 2787–2798 (1991)
Esparza, J.M., Ojeda, M.L., Campero, A., Dominguez, A., Kornhauser, I., Rojas, F., Vidales, A.M., López, R.H., Zgrablich, G.: N2 sorption scanning behaviour of SBA-15 porous substrates, Colloids Surf. A: Physicochem. Eng. Asp. 241, 35–45 (2004)
Gregg, S.J., Sing, K.S.W.: Adsorption, Surface Area and Porosity. Academic Press, London (1982)
Hollewand, M.P., Gladden, L.F.: Transport heterogeneity in porous pellets-II. NMR imaging studies under transient and steady-state conditions. Chem. Eng. Sci. 50, 309–326 (1995)
Kierlik, E., Monson, P.A., Rosinberg, M.L., Tarjus, G.: Adsorption hysteresis and capillary condensation in disordered porous solids: a density functional study. J. Phys.: Condens. Mater. 14, 9295–9315 (2002)
Libby, B., Monson, P.A.: Adsorption/desorption hysteresis in ink-bottle pores: a density functional theory and Monte Carlo simulation study. Langmuir 20, 4289–4294 (2004)
Morishige, K., Nakamura, Y.: Nature of adsorption and desorption branches in cylindrical pores. Langmuir 20, 4503–4506 (2004)
Morishige, K., Tarui, N.: Capillary condensation of nitrogen in ordered mesoporous silica with bicontinuous gyroid structure. J. Phys. Chem. C 111, 280–285 (2007)
Morishige, K., Tateishi, N.: Adsorption hysteresis in ink-bottle pore. J. Chem. Phys. 119, 2301–2306 (2003)
Neimark, A.V., Ravikovitch, P.I.: Capillary condensation in MMS and pore structure characterization. Microporous Mesoporous Mater. 44–45, 697–707 (2001)
Rigby, S.P.: A unified model for the effects of surface heterogeneity on gas absorption and surface diffusion on silica surfaces. In: Fong, P.A. (ed.) Colloid and Surface Research Trends, pp. 147–167. Nova Science Publishers, New York (2007)
Rigby, S.P., Edler, K.J.: The influence of mercury contact angle, surface tension and retraction mechanism on the interpretation of mercury porosimetry data. J. Colloid Interface Sci. 250, 175–190 (2002)
Rigby, S.P., Fletcher, R.S.: Experimental evidence for pore blocking as the mechanism for nitrogen sorption hysteresis in a mesoporous material. J. Phys. Chem. B 108, 4690–4695 (2004)
Rigby, S.P., Barwick, D., Fletcher, R.S., Riley, S.N.: Interpreting mercury porosimetry data for catalyst supports using semi-empirical alternatives to the Washburn equation. Appl. Catal. A 238, 303–318 (2003)
Rigby, S.P., Chigada, P.I., Perkins, E.L., Lowe, J., Edler, K.J.: Fundamental studies of gas sorption within mesopores situated amidst an inter-connected, irregular network. Adsorption (2008). doi:10.1007/s10450-007-9091-8
Rouquerol, F., Rouquerol, J., Sing, K.: Adsorption by Powders and Porous Solids: Principles, Methodology and Applications. Academic Press, London (1999)
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Rigby, S.P., Chigada, P.I. Interpretation of integrated gas sorption and mercury porosimetry studies of adsorption in disordered networks using mean-field DFT. Adsorption 15, 31–41 (2009). https://doi.org/10.1007/s10450-008-9147-4
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DOI: https://doi.org/10.1007/s10450-008-9147-4