Catalytic role of pre-adsorbed CO in platinum-based catalysts : the reduction of SO 2 by CO on Pt l Au m (CO) n

Using density functional theory, we have investigated the catalytic properties of bimetallic complex catalysts PtlAum(CO)n (l + m = 2, n = 1–3) in the reduction of SO2 by CO. Due to the strong coupling between the C-2p and metal 5d orbitals, pre-adsorption of CO molecules on the PtlAum is found to be very effective in not only reducing the activation energy, but also preventing poisoning by sulfur. As result of the coupling, the metal 5d band is broadened and down-shifted, and charge is transferred from the CO molecules to the PtlAum. As SO2 is adsorbed on the catalyst, partial charge moves to the anti-σ bonding orbitals between S and O in SO2, weakening the S–O bond strength. This effect is enhanced by pre-adsorbing up to three CO molecules, therefore the S–O bonds become vulnerable. Our results revealed the mechanism of the excellent catalytic properties of the bimetallic complex catalysts.

Co-and Ca-phosphate-based catalysts for the depolymerization of organosolv eucalytpus lignin

Depolymerization of purified organosolv eucalyptus wood lignin by the heterogeneous catalysts, cobalt polyphosphate (CoP2O6) and calcium phosphate (β-CaP2O6) was investigated. A total syringol yield of 16.7% was achieved with β-CaP2O6 in a methanol/water (50/50, wt/wt) solvent system after depolymerization at 300 ºC for 1 h, showing selectivity of the catalyst.

Carbohydrate-based liquid crystals

The carbohydrate based mesogens have gained an importance in the field of liquid crystals, primarily through the amphiphilic nature of many sugar derivatives. A constitutional requirement for the amphiphilic mesogen is that the molecule consists of distinct regions within the molecule that separately would have different responses to changes in thermal energies and/or solvations. Such molecules can be synthesized by linking one or more alkyl chains of appropriate length to both cyclic and acyclic sugars. A driving force for the mesophase formation in these molecules is the phase segregation, leading to aggregates, possessing distinct lyophilic and hydrophilic regions. In this review, we discuss the thermotropic behavior of the carbohydrate amphiphiles. We discuss the relationship between constitutions, configurations, functionalities of the sugar component and the length of the hydrophobic chains necessary to form the various types of thermotropic phases. The influence of the linking group between the hydrophilic sugar head groups and lyophilic alkyl chains on the transition temperatures and mesophase stabilities are also presented.