Showing papers by "Gongying Wang published in 2012"

Functionalized IRMOF-3 as efficient heterogeneous catalyst for the synthesis of cyclic carbonates

Abstract: Functionalized isoreticular metal–organic framework-3 (IRMOF-3) was developed as a novel heterogeneous catalyst for the solventless synthesis of cyclic carbonates without any co-catalyst. The results showed that functionalized IRMOF-3 performed excellent activity, selectivity and reusability. The effects of reaction temperature, pressure, and time on the yield of propylene carbonate were tested. And the reaction mechanism was also discussed.

A highly efficient catalyst for direct synthesis of methyl acrylate via methoxycarbonylation of acetylene

Abstract: A non-petroleum approach for the catalytic synthesis of methyl acrylate via methoxycarbonylation of acetylene with carbon monoxide and methanol as nucleophilic reagent has been studied under various conditions. Pd(OAc)2/2-PyPPh2/p-tsa was found to be a highly efficient catalytic system. The types of phosphorus ligands and their concentration was a determinative factor for catalytic activity. Mono-dentate phosphorus ligand such as triphenylphosphine has no activity while 2-(diphenylphosphino)pyridine with a mixed N-P bidentate structure has an excellent activity. Catalytic performance of acids depends on their acidic strength and coordinative property. Among all acidic promoters, p-toluenesulfonic acid displayed an excellent performance. Other parameters such as solvent polarity and initial pressure of carbon monoxide have also important influences on the hydroesterification of acetylene. It is beneficial for the reaction that the solvents have a high polarity. At low pressure of carbon monoxide, to high active palladium catalyst, the reaction easily proceeded. However, at high pressure of carbon monoxide, acetylene will transfer from solution to gas phase, resulting in lower conversion of acetylene. In addition, due to steric hindrance of alcohols, methanol has a highest activity in hydroesterification of acetylene in low carbon alcohols. Under the optimal reaction conditions, 99.5% of acetylene conversion and 99.7% of selectivity toward methyl acrylate as well as 2,502 h−1 TOF were achieved.

Photolysis kinetics and influencing factors of bisphenol S in aqueous solutions.

Abstract: The photodegradation of bisphenol S (BPS) in aqueous solutions was studied under different conditions. Photolysis and kinetics were investigated, as were the photolysis mechanism and the influences of initial pH value, light source, and environmental substances in water. The results showed that the photolysis of BPS occurred under UV light, and the rate increased with light source intensity. The photolysis of 5.0–50.0 mg/L BPS in water followed first-order kinetics: the rate was γ = 0.0161C BPS under a 40-W UV-lamp, and the degradation half-life was 43.1 min. Due to its absorption of light, direct photolysis of BPS was a predominant pathway for BPS but was not obviously affected by reactive oxygen species. The results confirmed that the photolysis rates of BPS in alkaline water solution were faster than those in acidic and neutral water solution because of the ionization of BPS. The photodegradation rate of BPS increased in the presence of chloride and ferric ions, while the rate was inhibited by nitrate and phosphate in aqueous solution.

Structure and Properties of Poly(Diphenylsiloxane-Co-Dimethylsiloxane) Modified MQ Silicone Resin

Abstract: A novel kind of poly(diphenylsiloxane-co-dimethylsiloxane)s modified MQ silicone resin were synthesised by the hydrolysis and condensation of diphenyldimethyloxysilane, dimethyldimethyloxy- silane, tetraethyloxysilane and hexamethyldisiloxane. The structure of the copolymers was confirmed by 1H and 29Si NMR. Their molecular weights were determined by GPC. Thermal transitions were characterized by DSC. In addition, the thermal stabilities were evaluated by TGA. Results indicated that the increasing content of phenyl mol% in copolymer enhances the optical and thermal properties of the copolymers. Moreover, it can be used as a potential vinyl terminated component in hydrosilylation materials in PSA and LED encapsulation.