Study On The Performance Of Supported Catalysts Based On Layered Double Hydroxides In Heck Reaction And Glaser Reaction

Layered double hydroxides(LDHs) are a class of anion clays which have attracted increasing interest in the fields of catalysis owing to their unique structural properties like intercalation, anionic exchange capacity, acid-base property, and self-assembly with other functional materials. Transition metal loading onto a LDHs-based catalysts are widely used in numerous organic synthesis because of the virtue of their properties such as simple handling, easy separation and recyclability, and efficient. Therefore, LDHs-based catalysts with highly effective, environmentally benign, recyclability and stability are currently receiving considerable attention. Heck reaction and Glaser reaction are both important C-C bond-forming reactions all the time, especially in catalysis chemistry. In this paper, a series of catalysts based on LDH were prepared. The supported Au-Pd/Ni-Al-O catalysts were prepared and used in Heck reaction. Furthermore, the supported catalysts Cu(OH)x/Zn-Al-O were prepared and their photocatalytic performance for Glaser reaction was discussed for the first time.1. Au-Pd/Ni-Al-O catalysts with different supporters and Au/Pd ratios were prepared by impregnation-reduction method. X-ray diffraction, X-ray photoelectron spectroscopy and UV-visible spectra were used to characterize the catalysts. The results indicated that 1wt% Au-2wt% Pd/2Ni-Al-LDO was an excellent catalyst for Heck reaction. The highest yield would be achieved under the optimized conditions: reaction time of 8h, reaction temperature of 100℃, K2CO3 as base and DMF as solvent at the atmosphere. Evidence of the formation of Au-Pd alloy NPs showed that Au-Pd system has an ensemble effect.2. Deposition-precipitation method was utilized for the preparation of supported Cu(OH)x/Zn-Al-O catalysts. The influence of support, Cu-loading percentage and preparation conditions were investigated by XRD、SEM、XPS、TG-DTA、AAS and so on. In Glaser reaction, the light irradiation was firstly introduced into the catalytic system and produced an even more profound enhancement in the catalytic performance of the catalysts. The photocatalytic activity of catalysts were carried out under different conditions, and the results showed that 10wt% Cu(OH)x/Zn-Al-LDH performed excellent and could be recycled for several times.