3363a.     ---------------.  [TEICHNER, S., AND PERNOUX, E.]  Texture and Surface Area of Kieselguhrs After Various Treatments.  Clay Minerals Bull., vol. 1, 1951, pp. 145-150; Fuel Abs., 1952, abs. 4949.

        Properties of raw and acid-treated Filter-Cel and Hyflo-Super-Cel characterize their ability to combine with the other constituents of catalysts.  Their degree of “reactivity” was determined and compared with specific surface and appearance in the electron microscope.  Densities and adsorption isotherms of N at -195° were determined experimentally and surfaces calculated by the methods of Brunauer, Emmett and Teller.  Attack by hot 5% Na₂CO₃ solution, which was used to measure the “reactivity,” had not the same effect for all samples.  Loss of silica, brought about by a small part of the kieselguhr dissolving in the carbonate solution, was nearly proportional to the initial specific surface of the samples.  The specific surface of acid-treated Filter-Cel fell from 27-14 m.² per gm. but after alkaline attack, that of crude Filter-Cel was only slightly reduced.  In the 1^st case, the treatment had caused departure of a “reactive” silica with large surface formed by the acid treatment; in the 2d case, the “reactive” but low surface silica removed by alkaline treatment probably owed its solubility only to its finely divided state.  Photographs of Filter-Cel treated with mineral acids and then by Na₂CO₃ are very different from those of Filter-Cel treated with mineral acids alone.  The appearance of Filter-Cel treated by Na₂CO₃ alone is little different from that of the initial Filter-Cel.  Thus acid treatment of crude kieselguhr causes the formation of a large surface silica gel which increases the total specific surface of the carrier.  This gel is eliminated during alkaline treatment and the specific surface of the substance diminishes by 50% and approaches that of the crude product.  Formation of a hydrosilicate with flaky structure similar to that of montmorillonite is related to the possibility of combination of this “reactive” fraction of the kieselguhr which is used as a carrier.  The conditions of formation of hydrosilicates in the catalyst mass of the Fischer process are different from the ordinary conditions of hydrothermal synthesis; hydrosilicate appears at atmospheric pressure and temperatures as low as 200° in the almost dry catalyst.

        TEJIMA, T.  See abs. 1918, 1919, 1920, 1921, 1922, 1923, 1924, 1925, 1926.

        TELEGIN, V. G.  See abs. 2030, 2033, 2034.