Two series of Zn-ZSM-5 catalysts were prepared by ion exchanging two commercial zeolites with different Si/Al ratios (40 and 15) with increasing Zn loadings. The nature of the Zn sites in the zeolite was studied by spectroscopy using laboratory and synchrotron techniques. All the evidences suggest that catalytic activity is associated with [Zn(H2O)n(OH)] + species located in the exchange positions of the materials with little or no contribution of ZnO or metallic Zn. The effect of Zn/Al ratio on their catalytic performance in methanol conversion to aromatics has been investigated. In all cases, higher Zn content causes an increase in the yield of aromatics while keeping the production of alkanes low. For similar Zn contents, high densities of Al sites favour the hydrogen transfer reactions and alkane formation whereas in samples with low Al contents, and thus higher Zn/Al ratio, the dehydrogenation reactions in which molecular hydrogen is released are favoured.

In this work, we provide detailed information on the change in product distribution and bio-oil 12 quality during extended feeding of biomass derived fast pyrolysis vapors over ZSM-5. The effect 13 of catalyst deactivation by coking on the resulting oil product characteristics was clarified in order 14 to determine when the vapor upgrading should be stopped and the regeneration initiated. Obtaining 15 a stable catalytic fast pyrolysis (CFP) oil while maintaining good energy recovery is important 16 within the context of potential co-processing these oils with petroleum feedstocks via FCC or 17 hydrotreatment of the whole CFP oil. 18 Wheat straw derived fast pyrolysis vapors were upgraded in an ex-situ fixed bed reactor containing 19 a steamed ZSM-5 catalyst at 500 °C. Oils were collected both for runs starting the upgrading over 20

Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold-titania catalysts can be employed to facilitate the oxidation of amines into amides with high selectivity. Furthermore, we report that pure titania is in fact itself a catalyst for the oxidation of amines with molecular oxygen under very mild conditions. We demonstrate that these new methodologies open up for two new and environmentally benign routes to caprolactam and cyclohexanone oxime, both of which are precursors for nylon-6.

No abstract

No abstract