Microstructure and catalytic performances of chitosan intercalated montmorillonite supported palladium (0) and copper (II) catalysts for Sonogashira reactions.

Title Microstructure and catalytic performances of chitosan intercalated montmorillonite supported palladium (0) and copper (II) catalysts for Sonogashira reactions.
Authors Q. Liu; M. Xu; J. Zhao; Z. Yang; C. Qi; M. Zeng; R. Xia; X. Cao; B. Wang
Journal Int J Biol Macromol
DOI 10.1016/j.ijbiomac.2018.03.066
Abstract

In this study, an efficient heterogeneous catalytic material including Pd nanoparticles and Cu cations supported on montmorillonite/chitosan (MMT/CS) composite was prepared by solution intercalation and complexion methods. The valence states of Pd (both Pd(0) and Pd(II) coexisting) and Cu (mainly Cu(II)) of the Pd/Cu@MMT/CS catalyst were confirmed by the X-ray photoelectron spectroscopy (XPS) characterization. The d spacing was enlarged from 1.25nm (MMT) to 1.94nm (Pd/Cu@MMT/CS). Pd/Cu@MMT/CS catalyst had obviously bigger specific surface area (S) and total pore volume (V) than pure MMT. High resolution transmission electron microscopy (HR-TEM) observation of the Pd/Cu@MMT/CS catalyst showed that separated Pd nanoparticles sized below 3nm dispersed well both in the interlayer space and surface of MMT layers. The positron annihilation lifetime spectroscopy (PALS) was very sensitive to the microstructure changes caused by the formation of nano particles Pd after reduction of Pd/Cu@MMT/CS to Pd/Cu@MMT/CS. The prepared Pd/Cu@MMT/CS catalysts are highly active for the Sonogashira reactions of aromatic halides and alkynes in HO/ether solution, and can be recycled 6 times. The leaching of Cu species is much quicker than Pd species during recycling, which should be the main reason for the decrease in efficiency of the recycled Pd/Cu@MMT/CS catalysts.

Citation Q. Liu; M. Xu; J. Zhao; Z. Yang; C. Qi; M. Zeng; R. Xia; X. Cao; B. Wang.Microstructure and catalytic performances of chitosan intercalated montmorillonite supported palladium (0) and copper (II) catalysts for Sonogashira reactions.. Int J Biol Macromol. 2018;113:13081315. doi:10.1016/j.ijbiomac.2018.03.066

Related Elements

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29 Cu 63.546000000 Copper

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Palladium

46 Pd 106.420000000 Palladium

Palladium Bohr ModelSee more Palladium products. Palladium (atomic symbol: Pd, atomic number: 46) is a Block D, Group 10, Period 5 element with an atomic weight of 106.42. The number of electrons in each of palladium's shells is 2, 8, 18, 18 and its electron configuration is [Kr] 4d10. The palladium atom has a radius of 137 pm and a Van der Waals radius of 202 pm. In its elemental form, palladium has a silvery white appearance. Palladium is a member of the platinum group of metals (along with platinum, rhodium, ruthenium, iridium and osmium). Elemental PalladiumPalladium has the lowest melting point and is the least dense of the group. Palladium can be found as a free metal and alloyed with other platinum-group metals. Nickel-copper deposits are the main commercial source of palladium. Palladium was discovered and first isolated by William Hyde Wollaston in 1803. Its name is derived from the asteroid Pallas.

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