Bestimmung von Palladium in Katalysatoren durch potentiometrische Titration mit ionensensitiver Endpunktsanzeige

Zusammenfassung Zur Bestimmung von Milligramm-Mengen Palladium in Katalysatormassen wird die Fällungstitration mit Jodid herangezogen. Zur Indikation des Titrationsendpunktes wird eine Meßkette aus einer Silberjodid/Sulfidelektrode und einer Referenzelektrode mit Zwischenelektrolyten verwendet. Die potentio-metrische Indikation vereinfacht das Verfahren bezüglich der üblichen Trübungsmessung und bringt gegenüber der Redoxindikation eine weitgehende Unabhängigkeit von der Säurekonzentration. Palladiummengen von 1–20 mg können so mit einer relativen Standardabweichung von 0,4% bestimmt werden.

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Determination of palladium in catalysts by means of potentiometric titration with ion-sensitive endpoint indication

The determination of milligram amounts of palladium in catalysts is performed by iodide titration. The endpoint of the titration is indicated by a silver iodide — silver sulphide electrode together with a double junction reference electrode. Potentiometric indication facilitates the procedure considerably in comparison to the turbidimetric endpoint method. The indication is independent of the acid concentration of the solution, which gives also a major advantage over the redox indication technique. Palladium amounts of 1–20 mg can be determined with a relative standard deviation of 0.4 %.

     

A Versatile Metalloporphyrinic Framework Platform for Highly Efficient Bioinspired,Photo‐ and Asymmetric Catalysis

Even though numerous bioinspired catalysts have been developed, there remain huge gaps between the artificial and natural catalysts, because it is very difficult to imitate simultaneously the complicated constituents, structures, and synergistic effect of enzymes. We report herein a versatile metalloporphyrinic framework platform, which exhibits high efficiency in bioinspired catalysis, photocatalysis, and asymmetric catalysis. The catalytic properties are highly dependent on the tunable constituents and their cooperation, and are significantly superior to the corresponding molecular catalyst systems which lack the synergistic effects. Since there are numerous functional moieties that can readily be incorporated into the metalloporphyrinic framework platform, a myriad of applications can be simply realized by embedding different functional moieties.