Pore corrugation

To measure structures with corrugated pores [i.e., to measure the true pore size function, which is not influenced by pore corrugation, in particular to measure the statistical distribution of the volume of the trapped (blocked) pores Vtr versus both their radii rn and the radii of the blocking pores... 

Very recently, Kruk et al. (1997a) have analysed their detailed nitrogen isotherms determined on a series of siliceous MCM-41 samples of different pore size. The low-pressure data were used to calculate the adsorption energy distribution, which in general appeared to show little variation from one sample to another. However, it was found that the adsorption at the lowest accessible pressures (5 x 10"7 < p/pa < 1CT3) was significantly enhanced by the decrease in pore size. This may have been due to either corrugations in the pore walls or an overall increased curvature of the pore wall. 

Many applications of AFM to pillared clays or zeolites have not specifically addressed the porosity characteristics, but rather the occurrence of adsorbed surface Al species in, e.g., pillared montmorillonite [41], or the crystal growth processes, adsorption on porous surfaces and the surface structure of natural zeolites [42]. Sugiyama et al. [43] succeeded to reveal the ordered pore structure of the (001) surface of mordenite after removal of impurities that clogged the pores. The authors indicated that resolution in AFM imaging of zeolites is significantly affected by the magnitude of the periodical corrugation on the crystal surface, so that if the surface contains deep pores only the pore structure, but not the atomic structure, can be resolved. 

A New Method for Microporosity Detection Based on the Use of the Corrugated Pore Structnre Model (CPSM). 

The Corrugated Pore Structure Model (CPSM), [8,9] was used to simulate the sorption data of both types of materials under consideration and the results are presented in Fig. 1 (continuous lines through the points). It is obvious from the plots of Fig. 1 that in all cases an excellent fit was achieved for the set of CPSM parameters reported in Table 1. 

Nominal Pore Length (Frequency of Corrugated Pore Cross Sectional Area Variation, [8]). 

Simulation of Nitrogen Sorption Data Using the Corrugated Pore Structure Model -CPSM... 

Additionally to the above, the so-called Corrugated Pore Structure Model CPSM [13,15,16] was employed to simulate the N2 adsorption - desorption experimental data. The intention is to work out true PSD curves based on a simulation of the entire hysteresis loop and to a single PSD prediction and thus to overcome the difficulty of choosing either one or the other branch of hysteresis loops, which result in di-similar predictions. The PSD predicted by the CPSM model (i.e. solid line PSDs in Fig. 2) indicate Dmax values that approach those... 

Figure 12 Variations on a regular 2-D stochastic pore network, (a) Random configuration (b) subordering of corrugations between nodes (c) random node displacement with subordering. (From Ref. 11.)...

Here, we extend the investigations on iodine insertion compounds of zeosils to host compounds with larger pore diameters (see Fig. 1) ITQ-4, CIT-5, SSZ-24 and UTD-l, with twelve- or fourteen-membered ring windows and channel diameters between 6 and 10 A. All the pore systems consist of uni-dimensional channels. In lTQ-4, the channel walls are corrugated, and a channel may be described as a series of large cages. 

Relationship between intrinsic pore-wall corrugation and adsorption hysteresis of Ng, O2, and Ar on regular mesopores... 

The effects of the pore width on the hysteresis of the adsorption isotherm of N2, O2, and Ar on mesoporous silica at 77 K were examined. A new analysis for the adsorption hysteresis was developed using the Saam-Cole theory. The critical thickness difference AJ (= 4 - /J for adsorbed film, which was derived from this analysis, was associated with the intrinsic mesopore width distribution due to the surface corrugation, giving the theoretical dependence of the adsorption hysteresis on the pore width and adsorbate the critical pore width for N2 is about 4 nm and those for O2 and Ar are about 3 nm, agreeing with the experimental results. 

In this work, we measured the dependence of the adsorption hysteresis on the pore width of mesoporous silica for N, O., and Ar at 77 K. The Saam-Cole analysis was extended to the examination of the hysteresis problem and the cause for the difference of the pore-width dependence of the hysteresis was associated with the corrugation of the pore-walls. 

Adsorption hysteresis disappearance due to the pore-wall corrugation... 

Salamacha and coworkers304 306 have carried out a series of studies on Lennard-Jones fluids confined to nanoscopic slit pores made from parallel planes of face centred cubic crystals. Grand canonical and canonical ensemble MC simulations have been used to determine the structure and phase behaviour as the width of the pore and the strength of the fluid-wall interactions were varied. The pore widths were small accommodating 2 to 5 layers of fluid molecules.304,305 The strength of the fluid-wall interaction is linked to the degree of corrugation of the surface, and it is found that the structure of the... 

DON), all of them containing a 14-ring channel system. While UTD-1 has pores bound by smooth 6-ring nets, both SSZ-53 and SSZ-59 possess pores with corrugated surfaces. In SSZ-53, these corrugations are centered about the vertices (of the major axis) of the elliptical pore, while in SSZ-59 the corrugations are positioned on the sides (i.e., near the vertices of the minor axis) of the elliptical pore. 

---