Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

/pdf/the-surface-chemistry-of-amorphous-silica-zhuravlev-model-4kfs2lx66q.pdf

The surface chemistry of amorphous silica. Zhuravlev model

Lewis Acids: From Conventional Homogeneous to Green Homogeneous and Heterogeneous Catalysis

Chemical modification of silica surface by immobilization of functional groups for extractive concentration of metal ions.

Sulfated zirconia and its modified versions as promising catalysts for industrial processes

https://pure.tue.nl/ws/files/2267329/590935.pdf

Acid Sites in Sulfated and Metal-Promoted Zirconium Dioxide Catalysts

13C NMR (CMR) spectra of a number of di- and trisubstituted ethylenes have been measured. Very consistent values are found for the differential shieldings of allylic carbons in a number of linear, (Z)- and (E)-disubstituted ethylenes. The discrepancies between the several structural elements are explained tentatively by assuming different rotational preferences in the (Z)-isomers, the (E)-isomers, or both. The results obtained for some branched olefins are qualitatively in agreement with conclusions reached in previous 1H NMR (PMR) investigations, with the possible exception of 2,5-diMe-3-hexene. Differential shieldings in trisubstituted ethylenes are larger than in disubstituted ethylenes, probably as a consequence of steric interaction between geminal substituents. It is confirmed, that API's recent relabelling of the isomers of 3-Me-2-hexene was justified. Furthermore, the (E)-configuration is assigned to the high-boiling isomer of 3,4,4-triMe-2-pentene. On the other hand, the high-boiling isomer of 3-Et-4-Me-2-pentene is shown to be the (Z)-isomer. For the isomeric pair of geraniol and nerol, the (E)-configuration is assigned to the former and the (Z)-configuration to the latter, in agreement with our recent PMR investigations.

Configurations and conformations in acyclic, unsaturated hydrocarbons. A 13C NMR study

https://pure.tue.nl/ws/files/1740000/620016.pdf

Characterization of modified silica powders by fourier transform infrared spectroscopy and cross-polarization magic angle spinning NMR

The rate of silica gel dissolution in aqueous alkaline media was investigated using 29Si nuclear magnetic resonance spectroscopy. A profound difference of alkali metal hydroxides on the dissolution rate of amorphous silica gel was observed. The dissolution rate increases in order LiOH ≈ CsaOH) < (RbOH ≈ NaOH) < KOH, as was confirmed by the β = silicomolybdate complexation method. Silica gel dissolution involved formation of monomeric silicic acid, Q0. The monomeric anions oligomerise into dimer species, which in turn form cyclic and lineartrimer species. The structure of highly polymerised silicate species depends on the alkali metal cation, i.e. low pH silicate solutions have structurally different silicate species as a function of alkali metal hydroxide, as is shown by 29Si-NMR spectroscopy. Potassium cations gave rise to more polymerised silica species compared with other alkali metal cations studied. On the contrary, when lithium hydroxide and silica gel are mixed in a molar SiO2/Li2O = 1:1, a microcrystalline phase is formed which consists of lithium silicate crystals. Crystallisation of the lithium silicate proceeds via monomeric silica being in solution.

/pdf/silica-gel-dissolution-in-aqueous-alkali-metal-hydroxides-3bgl3pn1yd.pdf

Silica gel dissolution in aqueous alkali metal hydroxides studied by 29SiNMR

The 71Ga and 129Si magic angle spinning(MAS) NMR and some 1H NMR (CRAMPS) investigations were carried out on H(Ga)ZSM5 zeolites. Quantification of the 71Ga NMR responses, obtained for the acid form of the zeolite, showed that .apprx.70 +- 2% of the theor. signal intensity was measured, based on the total Ga content of the samples. Only signals from tetrahedral Ga were obsd. in a reproducible manner. The lack of Ga NMR response, which is ascribed to the presence of large elec. field gradients on part of the Ga nuclei, was found to depend on the nature of the counter ion in the zeolite. Max. NMR signal intensities were obtained for Rb+- and Cs+-exchanged zeolites. A model to explain these phenomena is presented. The gallosilicates were thermally stable up as ?600 Deg but in the presence of steam a loss of framework Ga was obsd. at >550 Deg. [on SciFinder (R)]

/pdf/determination-of-gallium-in-h-ga-zsm5-zeolites-by-71ga-mas-5farpigycj.pdf

J.W. de Haan

Papers

Acid Sites in Sulfated and Metal-Promoted Zirconium Dioxide Catalysts

Configurations and conformations in acyclic, unsaturated hydrocarbons. A 13C NMR study

Characterization of modified silica powders by fourier transform infrared spectroscopy and cross-polarization magic angle spinning NMR

Silica gel dissolution in aqueous alkali metal hydroxides studied by 29SiNMR

Determination of gallium in H(Ga)ZSM5 zeolites by 71Ga MAS NMR spectroscopy