Nanocatalysis: Mature Science Revisited or Something Really New?

Abstract

"Nanomania" has reached the area of heterogeneous catalysis. Nanosized catalyst constituents are important for functions that require structural control over several scales of dimension. Nanocatalysis may be understood as a redefinition of catalyst synthesis: multidimensional structural control is exerted by considering catalysts as inorganic polymers rather than as close-packed crystals. Primary, secondary, and tertiary structural hierarchies translate into molecular building blocks and linkers, the defect structure of crystals, and particle morphology. High-throughput techniques and in situ synthetic analysis are the tools required to arrive at better defined catalytic materials that can fulfil the high expectations created by the incorporation of catalysts into the "nano" research field.

Monitoring Transport Phenomena of Paramagnetic Metal‐Ion Complexes Inside Catalyst Bodies with Magnetic Resonance Imaging

“…Impregnation with a CoA C H T U N G T R E N N U N G (0.2)CA-A C H T U N G T R E N N U N G (0.2)-pH5 solution resulted in formation of a sharp ring of low 1 H NMR signal intensity near the external surface of the extrudates immediately after impregnation. Only slight broadening of this ring was observed after ageing for 15 h. A photograph of an extrudate that was bisected at this time after impregnation (Figure 6) shows that the observed 1 H NMR signal intensity profile indeed corresponds to a [28][29] However, considering its low negative charge, the observed interaction between 3 ] À and the support seems too strong to be explained by purely electrostatic interactions. Exchange of water ligands for support hydroxyl groups can lead to formation of inner-sphere surface complexes, as expressed in Equation (6) …”

“…Formation of 1:1 Co 2 + citrate complexes was observed in Co 2 + /citrate solutions of pH higher than 8, regardless of the amount of citrate available for complexation. 3 ] 2À complexes are formed in which coordination takes place through two carboxylate groups and a deprotonated hydroxyl group. The formation of this complex from 3 ] À is shown in Equation (3).…”

“…3 ] 2À complexes are formed in which coordination takes place through two carboxylate groups and a deprotonated hydroxyl group. The formation of this complex from 3 ] À is shown in Equation (3). For the different Co 2 + complexes that can be present in aqueous solution, the positions of their characteristic UV/Vis/NIR bands are listed in Table 2.…”

“…It proved to be impossible to distinguish 3 ] À complexes by UV/Vis/NIR spectroscopy, since the only difference between these complexes is the protonation state of the free carboxylate group. Since deprotonation of the carboxylate groups is complete at this pH, the CoA…”

“…The dispersion of the active phase and its macrodistribution inside the catalyst bodies are important parameters in this respect. [2][3] A number of studies in this field have led to a basic understanding of the physicochemical processes that take place during the preparation of supported catalyst bodies. [4][5][6][7][8] Models have even been derived that allow one to describe the effect of parameters such as the drying rate and the metal ion/support interaction on the macrodistribution of the metal-ion precursor in the dried catalyst bodies.…”