Core shell silica particles with a hydrodynamic diameter of 28nm, an IEP of 7.1 and a zeta potential of +35mV at pH 4.0 were synthesised. The role of freeze-drying for the conservation of zwitterionic nanoparticles and the usefulness of different lyoprotective agents (LPA) for the minimisation of particle aggregation were studied. The activity of the nanoparticles was measured as DNA-binding capacity and transfection efficiency in Cos-1 cells before and after lyophilisation. It was found that massive aggregation occurred in the absence of LPA. Of the various LPAs screened in the present investigations, trehalose and glycerol were found to be well suited for conservation of cationically modified silica nanoparticles with simultaneous preservation of their DNA-binding and transfection activity in Cos-1 cells.

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The development of a suitable tar reforming catalyst for integration in a ceramic hot gas filter element is presented. Calcined dolomite, CaO-Al 2 O 3 mixed oxide, and MgO were used as catalyst supports with a grain size fraction between 0.1 and 0.3 mm for Ni doping. The activity of the catalysts with regard to the benzene and naphthalene conversion with and without additional Ru doping was examined. A MgO supported Ni catalyst with a NiO loading of 6% was found to be the most active catalyst in naphthalene reforming in the presence of 100 ppmv H 2 S at 800°C and a filtration velocity of 90 m/h using model biomass gasification gas containing 5 g/N m 3 naphthalene. Complete naphthalene conversion was still achieved after 100 h. After integration of the MgO-Ni catalyst in the ceramic filter element, a differential pressure increase of 6.8 mbar at 25°C was measured, thus indicating the technical relevance of the developed catalyst for use in hot gas cleaning of biomass gasification gas.

Six crystalline titanodiphenylsiloxanes have been synthesised by reaction of diphenylsilanediol (DPSD) with titanium tetraisopropoxide or its complexes with acetylacetonate (acac) as ligand. Two of them show a spirocyclic structure with the formula TiO] 2 B which have already been described in the literature. Two compounds C and D were identified by X ray analysis to have the same bicyclic structure but different coordinating solvent molecules. Tetrahydrofuran acts as a non bridging ligand at the Ti atoms in [Ti(acac) acts as a bridging ligand between the Ti atoms of neighbouring molecules of [TiThe titanodiphenylsiloxanes E and F were identified by a cyclotetrameric structure and the formulas [] 3 , respectively. The titanodiphenylsiloxanes A E were characterised by 29Si and 17O NMR spectroscopy, IR and time of flight mass spectrometry measurements. The hydrolytic stabilities of the SiMOMTi bonds in the titanodiphenylsiloxanes A E have been examined mainly by means of 29Si NMR spectroscopy. The results reveal a strong influence of the structure type of the titanodiphenylsiloxanes on the hydrolytic stability of their SiMOMTi bonds apart from the hydrolytic conditions (amount of water, Si, Ti and H+ concentration). The hydrolytic stability of the titanodiphenylsiloxanes A E decreases in the order cyclotetramer ( E)>spirocyclo (A, B)>bicyclo (C, D). Reasons for the different hydrolytic stability are discussed. The results on the different hydrolytic stabilities of SiMOMTi bonds can contribute to a better understanding of the synthesis of homogeneous heterometal materials on a molecular scale via the sol gel process.