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Cobalt(I1) 2,9,16,23-tetrasulphophthalocyanine and cobalt(I1) of the samples was characterized by electron microscopy and 2,9,16,23-tetra(chlorosulphonyl)phthalocyanine were sup-electron diffraction. The morphology of the matrix strongly ported on TiOz by reaction of the phthalocyanines with depends on the cobalt phthalocyanine derivative. The phthaTi(OR), followed by sol-gel synthesis. The thus obtained so-locyanines in the titania matrices are monomeric or dimeric lid materials are stable in sulfide-containing media and are depending both on the type of substituents of the CoPc derivtherefore suitable as catalysts for HS oxidation. The structure ative and on the titanium alkoxide used as precursors.Phthalocyanines of cobalt and particularly its soluble derivatives are among the most effective catalysts for HS oxidation,['l[21 There were several efforts to support these compounds on various inorpnic supports to combine the advantages of homogeneous and heterogeneous catalysts. For example, C O P C (~-S O~H )~ supported on charcoal is industrially applied because of the technological advantages of heterogeneous catalysts, although the catalytic activity is much lower than in the homogeneous phase. [31[41 Cobalt phthalocyanine (CoPc) derivatives were immobilized by covalent bonding to surface-modified silica gels with high surface coverages. For this purpuse, carboxy-or amino-substituted phthalocyanines were reacted with aminopropyl-or chloropropyl-modified silica. respectively. [51[61 Alternatively, several cobalt phthalocyaninc derivatives were coordinatively bonded to aminopropyl-or imidazolylpropyl-modified silicas via Co -N bonds. Although only one axial position at the cobalt atom is available for the substrate in these supported derivatives, they exhibit high catalytic acitivity in the oxidation of 2-mercaptoethanol, being comparable to or even higher than that of the dissolved tetracarboxy-and tetrasulphophthalocyanines.L71 Substituents influence the catalytic activity: electronwithdrawing substituents enhance and electron-donating substituents decrease the activity of both ~upported [~] [~'[~][~] and homogeneous cobalt phthalocyanines. L8]Another possibility of heterogenization is to polymerize cobalt phthalocyanines. The polymers exhibit a much higher activity in sulfide oxidation than their monomeric couterparts due to the disproportionation of Co(I1) to Co(1) and Co(I1I) followed by energy compensation in the rate determining reaction step, i.e. dioxygen and SH coordination.Sol-gel processing is an alternative route for the heterogenization of homogeneous catalysts. Ll"] Since the catalysts are located inside the gel matrix instead of being anchored to the surface, the stability usually is higher. There is no loss of activity if the porosity of the gel is properly tailored. C O P C (~-S O~H )~ was heterogenized by sol-gel processing starting from Si(OEt),, (EtO)$iMe and (EtO),Si-(CH2)3NH2 as precursors. The aminopropylsilane was used to covalently bond the catalyst to the silicate matrix by reaction o...