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Abstract

Two heterogeneously catalyzed gas phase reaction were investigated: The selective hydrogenation of concentrated acetylene and the synthesis of oxymethylene ether (OME). The first was studied for uncommon conditions of equal concentrated acetylene and ethylene as reactants. For this PdAg/α-Al₂O₃ catalysts with various PdAg ratios prepared by the classical wet impregnation technique as well as by the alternative approach of ball milling were tested and compared. Catalysts prepared by both methods were selective towards ethylene when containing a higher Ag loading than Pd. However, the ball-milled catalysts exhibited a higher stability as they were stable for as long as tested (up to 15 h). In addition, PdAu/α-Al₂O₃ and PdCu/α-Al₂O₃ catalysts were prepared by ball milling and tested. These bimetallic PdAu and PdCu catalysts were significantly less selective than the PdAg catalysts independent of their metal ratio. This project demonstrates that selective hydrogenation of concentrated acetylene is feasible and PdAg catalysts are well suitable. The gas phase synthesis of the potential diesel alternative OME was investigated using sulfonated polyether ether ketone (S-PEEK) as a catalyst. A highly active and selective blind activity in the setup was observed after testing the commercial catalyst Amberlyst and a search for the cause followed. This resulted in the finding that leaking sulfonyl groups reacted with a part of the backpressure regulator made of PEEK. S-PEEK was then synthesized and investigated in detail as a catalyst for the conversion of formaldehyde and methanol to OME. It was shown that with S-PEEK an OME_1-2 selectivity of 92% can be obtained, while being stable for more than 60 h.