In a typical temperature-programmed desorption (TPD) experiment on a supported metal catalyst, a small amount of catalyst (10–200 mg) is contained in a reactor that can be heated by a furnace. An inert gas, usually helium at atmospheric pressure, flows over the catalyst. Following pretreatment to obtain a reduced catalyst, a gas is adsorbed on the surface, usually by pulse injections of the adsorbate into the carrier gas upstream from the reactor. After the excess gas is flushed out, the catalyst is heated to create a linear rise in temperature with time. A small thermocouple inserted in the catalyst measures the temperature and a detector downstream measures the change in the inert gas stream. The ideal detector is a mass spectrometer which measures the composition of the effluent stream as a function of catalyst temperature. Because of the high carrier-gas flow rate, the detector response is proportional to the rate of desorption if diffusion and readsorption are not limiting.

Temperature-Programmed Desorption and Reaction: Applications to Supported Catalysts

The kinetics of liquid-phase hydrogenation reactions have been reviewed with a special emphasis on α, β-unsaturated aldehydes as reactants. These reactions can be complex and can be influenced by factors such as metal specificity, side reactions, and metal-support interactions as well as reaction parameters. The importance of results in the absence of heat and mass transfer limitations has been emphasized. Hydrogenation reactions are typically assumed to be structure-sensitive, but dependencies on metal crystallite size have been reported; however, this behavior has been attributed to side reactions which can inhibit activity. Finally, solvent effects can exist, but the effect of H2 concentration in the liquid phase has infrequently been isolated. Thermodynamic arguments indicate that a solvent effect can enhance the surface coverage of hydrogen on the catalyst surface at a constant H2 partial pressure, but in the absence of any solvent effects, surface coverage is independent of the liquid-phase H2 concentration.

Kinetics of liquid-phase hydrogenation reactions over supported metal catalysts — a review

Adsorption of atomic hydrogen on alumina by hydrogen spillover

Etude par chimisorption: Cu, Rh, Pt, Pd, Ni, Ru. Etude par chromatographie. Etude par desorption a temperature programmee de H 2 (pour Ni, Ir, Pt). Etude par XPS

Surface Characterization of Supported and Nonsupported Hydrogenation Catalysts

Reaction pathways and poisons—II: The rate controlling step for electrochemical oxidation of hydrogen on Pt in acid and poisoning of the reaction by CO

Y. Amenomiya

Papers

Study of Metal Catalysts by Temperature Programmed Desorption, II. Chemisorption of Hydrogen on Platinum J. Catalysis, 19