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Gold nanoparticle catalysts are important in many industrial production processes.N evertheless,f or traditional C sp 2 ÀC sp 2 cross-coupling reactions they have been rarely used and Pd catalysts usually give as uperior performance.H erein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form C sp 3 À C sp 3 bonds.Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, whicha llowed for convenient catalyst recovery and reuse.T he present study is ar are case where ag old metal catalyst is superior to Pd catalysts in ac ross-coupling reaction of an organic halide and an organometallic reagent.

We developed a rapid aging method for Ni/Al2O3 methanation catalysts mimicking the real aging in the actual application. The method is based on hydrothermal deactivation of the catalyst at 600 or 700 °C, which leads to a catalyst with nearly constant conversion after a much shorter time period compared to normal aging. The hydrothermally aged catalysts are characterized by N2 adsorption, X-ray powder diffraction, temperature-programmed reduction and H2 chemisorption. The catalytic performance of the aged catalysts is comparable to the one of a catalyst deactivated in a long-term measurement with up to 720 h on stream. The time needed for reaching a stable conversion can be diminished by rapid aging by a factor of 10. The investigations also showed that the long-term deactivation is caused by Ni particle sintering and that the support pores limit the Ni particle size. Graphical Abstract

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Goldnanopartikel sind fürv iele industrielle Prozesse wichtige Katalysatoren. In traditionellen C sp 2 -C sp 2 -Kreuzkupplungen wurden sie jedochs elten eingesetzt, da Pd-Katalysatoren in der Regel überlegen sind. Hier beschreiben wir in situ gebildete Goldmetallnanopartikel als hochaktive Katalysatoren fürdie Kreuzkupplung von Allylstannanen und aktivierten Alkylbromiden zur Bildung von C sp 3 -C sp 3 -Bindungen. In Gegenwart von Aktivkohle als Trägermaterial, was eine einfacheK atalysatorrückgewinnung und -wiederverwendung ermçglichte,k onnten Umsatzzahlen von bis zu 29.000 erreicht werden. Die vorliegende Studie ist ein seltenes Beispiel füre ine Kreuzkupplungsreaktion eines organischen Halogenids mit einem metallorganischen Reagens,b ei der ein Goldmetallkatalysator Pd-Katalysatoren überlegen ist.