Pilot plant reactor-surface analysis

A Pilot Plant Reactor-Surface Analysis System for Catalyst Studies... 

Furthermore, Identical surfaces were found In postmortem analysis of catalyst samples from the pilot plant reactor and the mlnlreactor. These observations provide assurances that the "working" catalyst surface can be examined with the system described here despite the necessary transfer from high pressure feed gas to ultrahlgh vacuum. 

A system has been constructed which allows combined studies of reaction kinetics and catalyst surface properties. Key elements of the system are a computer-controlled pilot plant with a plug flow reactor coupled In series to a minireactor which Is connected, via a high vacuum sample transfer system, to a surface analysis Instrument equipped with XFS, AES, SAM, and SIMS. When Interesting kinetic data are observed, the reaction Is stopped and the test sample Is transferred from the mlnlreactor to the surface analysis chamber. Unique features and problem areas of this new approach will be discussed. The power of the system will be Illustrated with a study of surface chemical changes of a Cu0/Zn0/Al203 catalyst during activation and methanol synthesis. Metallic Cu was Identified by XFS as the only Cu surface site during methanol synthesis. 

These data taken together suggest that vanadium is deposited on the catalyst in three successive forms. The initial vanadium which appears on the catalyst is primarily an isolated V02+ species, presumably associated with alumina defect sites. This is followed by the diamagnetic vanadium surface phase and finally by the vanadium sulfides. This progression is illustrated by the analysis of catalyst samples taken from different positions in a reactor which had been employed in a pilot-plant treatment of a petroleum residuum (Figure 4). Note that all of... 

Often a catalyst sample has to be analyzed in a condition which is sensitive to atmospheric exposure. For instance, samples taken from pilot or plant reactors can be stored in containers under a protective atmosphere and in.serted into a spectrometer with the help of a glove box [12]. This sounds simple, but a fully controlled realization of this experimental concept is a great challenge for the analyst. Another approach relies on the preparation of a. selected cataly.st state within a special reaction chamber containing heat and gas treatment options, which allows transfer of the sample into the analysis chamber without any air exposure. Some surface analysis instrumentation manufacturers offer this optional chamber on their standard spectrometers. There are many papers... 

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