Copper-promoted cobalt catalysts for 2,3-dihydrofuran synthesis

The conversion of 1,4-butanediol to 2,3-dihydrofuran in the liquid phase has been studied over novel kaolin-supported Co–Cu catalysts, prepared by means of a simple mechanochemical method. The improvement of the catalytic properties and decrease in the optimum reduction temperature of Co–kaolin catalysts, promoted by copper, has been observed. It was established that a Co:Cu ratio 5:1 is optimum for the specific activity and for the yield in the conversion of 1,4-butanediol to 2,3-dihydrofuran. In the present study, the highest 2,3-dihydrofuran yield (81%) was obtained with the ultrasonically treated catalyst and after reduction pretreatment at 320–350 °C. The existence of an optimum reduction temperature for the catalyst pretreatment was established. In agreement with the results, obtained in our previous studies, the high 2,3-dihydrofuran yield is favoured by the coexistance of cobalt both in the metallic and oxidic state. The increased specific activity of copper-containing catalysts could be related to the lowering of the reduction temperature, which leads to a hexagonal metallic cobalt phase formation. The latter is favourable for 2,3-dihydrofuran synthesis. The advantage of mechanochemical preparation of Co–Cu (5:1) catalyst is that the method prevents penetrating of cobalt ions into the support, thus the whole amount of cobalt loaded is available for the catalyst performance. This is one of the probable reasons for higher specific activity of the 2,3-DHF formation over these catalysts.