Temperature Programmed Techniques

TPO- Temperature Programmed Oxidation

The TPO system is typically used to quantify coke deposits in heterogeneous catalysts and also let us perform an on-line analysis of the SWNT yield in the reaction. It consists of a quartz tube containing the sample that is placed in an electric furnace while an Oxygen/He stream flows through the sample. The temperature of the oven is then linearly increased. The exit gas is sent through a catalytic methane reactor where all the CO is converted to CH4 that is finally detected by an FID detector.

 

 

 

 

 

 

 

TPR- Temperature Programmed Reduction

This technique determines the number of reducible species present in the catalyst and the temperature at which the reduction of each species occurs .The system consists of a quartz tube containing a calcined catalyst that is placed in an electric furnace while a Hydrogen/Ar stream flows through the sample. The temperature of the oven is then linearly increased. The hydrogen uptake as a function of temperature is monitored using a thermal conductivity detector.

 

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Role of water on the surface-guided growth of horizontally aligned
single-walled carbon nanotubes on quartz

The role of water in carbon feed on the surface-guided growth of horizontally aligned single-walled carbon
nanotubes (HA-SWCNTs) was investigated. It is shown that the amount of water can be optimized to favor HA-SWCNT growth, which is proposed to be due to selective etching of carbon deposits at carbon–metal interface. Without water, nanotube–nanotube interaction and carbon accumulation at the interface are disproportionately large compared to the rate of nanotube growth, leading to catalyst deactivation. With excess water, suppression of nanotube growth occurs, resulting in reduced carbon yield on the surface.
Intermediate carbon/water feed ratios achieve cleaner growth with high efficiency.

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