Aim
Hot–wall reactors are versatile facilities, which can be used to produce various prod-ucts. They are in particular useful for the formation of nanoscaled materials that are accessible by thermal decomposition of precursors. By controlling the reaction pa-rameters like temperature, pressure, concentration and residence time, particle size and –morphology and therefore the material properties can be changed and adjust-ed. Hot–wall reactors require complex measurement instrumentation techniques for a detailed control and adjustment of the experimental parameters. As many materials that can be produced in hot-wall reactors are sensitive to air, an automatic filling pro-cedure under a protecting gas is necessary. Sufficient availability of highly specific nanomaterials accessible via a hot-wall reactor is important for testing new materials for industrial applications. Hot–wall reactors are designed for continuous production and enable for a high production rate.

Approach
Main part of the hot–wall reactor 126 is a vertically mounted tube furnace with a height of 2.4 m and an inner diameter of 126 mm. The heating zone consists of 6 separately controlled heating units with a total power of 16 KW. The maximum work-ing temperature is 1100°C. The apparatus is designed for a wide pressure range and can be operated between 10 and 1500 mbar. The production rate is between some hundred grams and up to several kg per hour. Back purged filter elements and a ni-trogen purged transfer chamber enable an automatic filling into gas tight bins during synthesis. The facility is equipped with more than 30 sensors for flow, temperature, pressure, and computerized for data logging. To determine the reaction yield, gase-ous components are analyzed periodically with gas–chromatography. Due to its size, a complex safety system is integrated to enable a safe operation during the use of burnable and hazardous gases. The HWR 126 is mainly used to synthesize silicon made from monosilane.

References
H. Wiggers, R. Starke, P. Roth, "Silicon Particle Formation by Pyrolysis of Silane in a Hot Wall Gasphase Reactor", Chem. Eng. Technol. 24, 261-264 (2001).

Contact
apl. Profl Dr. habil. H. Wiggers, Hartmut Wiggers,Tel: +49 (0)203 - 379 8087, IVG