Intracrystalline dissolution

Both D1 and D2 dolomite/ankerite types show evidence of partial dissolution, which preferentially affects the Fe-rich zones (Fig. 11B). Some intracrystalline dissolution pores contain authigenic kaolin-ite booklets. In some samples of the middle domain partially dissolved poikilotopic crystals of D1 and D2 are covered, and thus postdated, by thin chlorite rims (Fig. 11C). 

We used desorption of deactivated catalysts in vacuo at reaction temperatures into the ion source of a mass spectrometer as a method of examining desorbable intracrystalline fouling products. The method of dissolution of deactivated catalyst, followed by adsorbate analysis, that was reported by Venuto et al. (3, 4) was also used. The latter method gives composition and quantity of total adsorbate. The vacuum desorption technique provides information on the mobility—i.e., desorption dynamics, of desorbable (rather than total) adsorbed fouling products. 

In a word, the intracrystalline mesopores are developed in the boronation of zeolites p since silicon atoms in the framework are dissolved by base in a large amount. The small atom size and poor stability of boron should be responsible for this dissolution and the modification in porosity. 

I.R. characterisation of the samples is carried out using the KBr technique. U.V. spectroscopy was used for the semi-quantitative determination of the amount of intracrystalline phthallocyanines, after dissolution of the zeolite in concentrated sulfuric acid (0.1 g of catalyst in 10 ml of concentrated H2SO4 for 4 h). The iron content of the samples is determined by chemical analysis. X-ray powder diffraction is used to ensure good crystallinity of the zeolite after the synthesis and purification procedures. 

Other common, though volumetrically minor, feldspar-replacing minerals include titanite, ana-tase, sphalerite, barite, ankerite, siderite, and fluorite. With the exception of replacement driven by force of crystallization, feldspar replacements have intracrystalline distributions that are strongly localized at sites of surface-controlled dissolution. Interestingly, replacement of detrital feldspars by authigenic clays is rarely observed in late diagenesis. 

The amount of intracrystalline complex present in the different catalyst samples was measured by UV spectroscopy after sample dissolution in concentrated sulfuric acid (Table 1). 

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