Experimental Considerations Relating to Catalyst Preparation or Sample-Handling Procedures

Experimental Considerations Relating to Catalyst Preparation or Sample-Handling Procedures 

The performance of a catalyst is well known to be sensitive to its preparation procedure. For this reason, ideally an oxide-supported metal catalyst should be subjected to a number of characterization procedures. These may include measurements of the metal loading within the overall catalyst (usually expressed in wt%), the degree of metal dispersion (the proportion of metal atoms in the particle surfaces), the mean value and the distribution of metal particle diameters, and qualitative assessments of morphology including the particle shapes and evidence for crystallinity. These properties in turn can depend on experimental variables used in the preparation, such as the choice and amounts of originating metal salts, prereduction, calcination or oxygen treatments, and the temperature and duration of hydrogen reduction procedures. 

Characteristics of the Different Vibrational Spectroscopies Used to Obtain Results from Species Adsorbed on Finely Divided or Single-Crystal Metal Surfaces 

Technique Wavenumber range (cm-1) Working resolution (cm 1) General sensitivity Type of sample Applicability to moderate gas-phase pressures Conditions for most intense bands Degree of usage 

IR transmission 4000-co. 1100 1 High Finely divided metals Yes Dipole change perpendicular to surface Very great 

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