HIGH-PRESSURE FLOW REACTOR DESIGNED FOR AN ULTRAHIGH-VACUUM ANALYSIS SYSTEM

A novel high-pressure flow reactor designed to operate with real powde r catalysts at pressures up to 10 bar and temperatures up to 400 degre es C is described. The gas flow is regulated by mass flow controllers, and the temperature is adjusted by a proportional integral derivative control. Using a heatable capillary along with strong differential pu mping allows the gas composition to be monitored on-line. The high-pre ssure volume is kept small in order to ensure rapid evacuation after t he reaction. All parts of the system exposed to gas pressure and tempe rature are made of metal or ceramic. The reactor is attached to an ult ra-high-vacuum system equipped with x-ray photoelectron spectroscopy a nd secondary ion mass spectrometry for surface and reaction studies. T he performance of the system is demonstrated by CO-hydrogenation exper iments with promoted Pd/SiO2 catalysts. (C) 1997 American Vacuum Socie ty.