Preparation of 13C-Poly(p-phenylene). IR, 13C-NMR, and ESR Spectra of the Polymer
13C-Enriched poly(p-phenylene) PPP prepared by dehalogenation polycondensation of 13C-enriched p-diiodobenzene with Ni(0) complex gives basic data for assignment of the IR vibration modes of PPP, reveals the magnitude of magnetic dipole interaction in the NMR spectrum, and indicates considerably small coupling of spin with 13C-nuclei in the ESR spectrum presumably due to rapid movement of electrons.
Coupling conversion of methane with carbon monoxideviacarbonylation over Zn/HZSM-5 catalysts
Efficient direct transformation of methane into value-added chemicals has great significance for long-term sustainability of fuels and chemicals, but remains a major challenge due to its high inertness. Reported here is that methane can be activated effectivelyviacarbonylation with CO over Zn/HZSM-5 catalysts under mild conditions. The selectivity to aromatics alone reaches 80% among all hydrocarbon products at 823 K, whereas as high as 92% ethane selectivity is achieved at a lower temperature of 673 K.13CO isotope labelling experiments demonstrate that approximately 50% of the carbon atoms in all the products originate from carbon monoxide, whereas another half of the carbons come from methane, indicating that the precursors of hydrocarbon products are acyl compounds and/or acetic acid formed by carbonylation of methane with carbon monoxide. This provides potential for transformation of methane into value-added chemicals under mild reaction conditions.
Conversion of methoxy and hydroxyl functionalities of phenolic monomers over zeolites
This study investigates the mechanisms of gas phase anisole and phenol conversion over zeolite catalyst. These monomers contain methoxy and hydroxyl groups, the predominant functionalities of the phenolic products of lignin pyrolysis. The proposed reaction mechanisms for anisole and phenol are distinct, with significant differences in product distributions. The anisole mechanism involves methenium ions in the conversion of phenol and alkylating aromatics inside zeolite pores. Phenol converts primarily to benzene and naphthalene via a ring opening reaction promoted by hydroxyl radicals. The phenol mechanism sheds insights on how reactive bi-radicals generated from fragmented phenol aromatic rings (identified as dominant coke precursors) cyclize rapidly to produce polyaromatic hydrocarbons (PAHs). Resulting coke yields were significantly higher for phenol than anisole (56.4% vs. 36.4%) while carbon yields of aromatic hydrocarbons were lower (29.0% vs. 58.4%). Water enhances formation of hydrogen and hydroxyl radicals, thus promoting phenol conversion and product hydrogenation. From this finding we propose phenol-water-zeolite combination to be a high temperature hydrolysis system that can be used to generate both hydrogen and hydroxyl radicals useful for other kinds of reactions.
Thilakaratne, Rajeeva,Tessonnier, Jean-Philippe,Brown, Robert C.
p. 2231 - 2239
(2016/04/19)
More Articles about upstream products of 32488-44-1