Oxygen consumption, measurement instrumentation

The instrumentation for TP investigations is relatively simple the set-ups for TP reduction (TPR) and TP oxidation (TPO) studies of catalysts are shown in Figure 2.1. The reactor, charged with catalyst, is controlled by a processor, which heats the reactor at a rate of typically 0.1 to 20 °C min-1. A thermal conductivity detector measures the hydrogen or oxygen content of the gas mixture before and after reaction. For TPR, one uses a mixture of typically 5% H2 in Ar, or for TPO 5% 02 in He, to optimize the thermal conductivity difference between reactant and carrier gas. With this type of apparatus, a TPR (TPO) spectrum is a plot of the hydrogen (oxygen) consumption of a catalyst as a function of temperature. 

Initial velocity measurements in kinetic experiments were carried out by following the oxygen consumption with an oxygen electrode (Yellow Spring Instruments 1 mL chamber). 

The recent development of rate of heat release tests in a form that can be routinely used by test houses represents a major step forward. Probably the best known instrument is the cone calorimeter (ISO 5660-1), which determines the rate of heat release using the oxygen consumption technique. The OSU calorimeter (ASTM E906) uses a direct heat measuring system and is used in regulations by the FAA. 

Instrumentation for the measurement of the flammability characteristics of polymers intended for use in mining, electrical, transport, furniture, construction materials is discussed in Chapter 17, including methods of identifying combustion products and the measurement of oxygen consumption by oxygen cone calorimetry. New methods based on pyrolysis - gas chromatography - mass spectrometry and laser pyrolysis time of flight mass spectrometry are also discussed. 

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