Testing of high pressure methanol synthesis catalysts - to determine activity and long term stability

摘要

In the determination of the activity and/or stability of high pressure methanol synthesis catalysts consisting of zinc oxide-chromium oxide mixts. used as moulded bodies or in fragmented and. opt. pre-reduced form, the novelty is that (a) the activity of a catalyst sample is measured by determining the reaction rate constant k(T) of methanol decomposition under normal pressure for one or more temps. T (pref. 350-400 deg.C), simultaneously determining the pore vol. dV of pores with below 7.5 nm. radius and using the produce of k(T).dV as a measure of activity under high pressure synthesis conditions; and (b) the long term stability is measured by dividing a catalyst sample into two portions, subjecting one portion to an initial 1-4 hr. heat treatment in a flowing H2-inert gas mixt. at 600-800 deg.C, subjecting both portions to determination of opt. the methanol decomposition reaction rate constant k(T) and the angular difference d2theta between the position 2theta of the x-ray diffraction line (400) of the distorted cubic ZnO-Cr2O3 mixed phase and that of the ZnCr2O4 line (400), and using the difference of the reciprocal product k(T), d2theta of the heat treated and fresh catalyst samples as a measure of long term stability under high pressure methanol synthesis conditions. ADVANTAGE - The method provides inexpensive, rapid and relaible testing of catalysts, e.g. for quality control in catalyst prodn., prediction of catalyst properties in methanol synthesis reactors and testing of catalyst samples in research and development.