Catalysts comprising zeolite ZSM-5 impregnated with precious metals including Ag, Cu, Ni, Pd, Ir and Ru, have been tested for the methanol to hydrocarbons reaction in a continuous flow fixed bed reactor. Comparison with the activity of unmodified ZSM-5 showed that Ag, Cu and Ni enhanced the selectivity to C 6 -C 11 aromatic products by a factor of two or higher. Moreover, Ag/ ZSM-5 showed improved selectivity for the C 6 -C 7 fraction of aromatic products. Ni/ZSM-5 was found to be selective to naphthalene, while Cu/ZSM-5 was selective for C 9 -C 11 aromatic products. It was ascertained that all the impregnated metals were present as metal oxides in the starting materials. It is therefore proposed that the enhanced selectivity to aromatic products is due to the interaction of the acid sites of the zeolite with the basic sites of the metal oxide at the edge of the zeolite crystals, as well as the possible coordination of propene molecules formed during the reaction, that are likely to be the building blocks for the formation of aromatics.

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The activation and use of oxygen for the oxidation and functionalization of organic substrates is among the most important reactions in a chemist's toolbox. Nevertheless, despite the vast literature on catalytic oxidation, the phenomenon of autoxidation, an ever-present background reaction that occurs in virtually every oxidation process, is often neglected. In contrast, autoxidation can affect the selectivity to a desired product, to those dictated by pure freeradical chain pathways, thus affecting the activity of any catalyst used to carry out a reaction.This critical review compares catalytic oxidation routes by transition metals versus autoxidation, particularly focusing on the industrial context, where highly selective and "green" processes are needed. Furthermore, the application of useful tests to discriminate between different oxygen activation routes, especially in the area of hydrocarbon oxidation, with the aim of an enhanced catalyst design, is described and discussed. In fact, one of the major targets of selective oxidation is the use of molecular oxygen as ultimate oxidant, combined with the development of catalysts capable to perform the catalytic cycle in a real energy and cost effective manner on a large scale. To achieve this goal, insights from metallo-proteins that could find application in some areas of industrial catalysis are presented, as well as considering the physicochemical principles that are at the fundament of oxidation and autoxidation processes.3

The aerobic oxidation of 1,2-propanediol in alkaline aqueous solvent over bimetallic AuPt/C catalysts has been studied and catalyst reusability has been assessed.

Nanocrystalline hydroxyapatite (nanoHA) is the main hard component of bone and has the potential to be used to promote osseointegration of implants and to treat bone defects. Here, using active pharmaceutical ingredients (APIs) such as ibuprofen, we report on the prospects of combining nanoHA with biologically active compounds to improve the clinical performance of these treatments. In this study, we designed and investigated the possibility of API attachment to the surface of nanoHA crystals via the formation of a hydrogen-bonded complex. The mechanistic studies of an ibuprofen/nanoHA complex formation have been performed using a holistic approach encompassing spectroscopic (Fourier transform infrared (FTIR) and Raman) and X-ray diffraction techniques, as well as quantum chemistry calculations, while comparing the behavior of the ibuprofen/nanoHA complex with that of a physical mixture of the two components. Whereas ibuprofen exists in dimeric form both in solid and liquid state, our study showed that the formation of the ibuprofen/nanoHA complex most likely occurs via the dissociation of the ibuprofen dimer into monomeric species promoted by ethanol, with subsequent attachment of a monomer to the HA surface. An adsorption mode for this process is proposed; this includes hydrogen bonding of the hydroxyl group of ibuprofen to the hydroxyl group of the apatite, together with the interaction of the ibuprofen carbonyl group to an HA Ca center. Overall, this mechanistic study provides new insights into the molecular interactions between APIs and the surfaces of bioactive inorganic solids and sheds light on the relationship between the noncovalent bonding and drug release properties.

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Nanocrystalline hydroxyapatite (HA) has good biocompatibility and the potential to support bone formation. It represents a promising alternative to autologous bone grafting, which is considered the current gold standard for the treatment of low weight bearing bone defects. The purpose of this study was to compare three bone substitute pastes of different HA content and particle size with autologous bone and empty defects, at two time points (6 and 12 months) in an ovine scapula drillhole model using micro-CT, histology and histomorphometry evaluation. The nHA-LC (38% HA content) paste supported bone formation with a high defect bridging-rate. Compared to nHA-LC, Ostim® (35% HA content) showed less and smaller particle agglomerates but also a reduced defect bridging-rate due to its fast degradation The highly concentrated nHA-HC paste (48% HA content) formed oversized particle agglomerates which supported the defect bridging but left little space for bone formation in the defect site. Interestingly, the gold standard treatment of the defect site with autologous bone tissue did not improve bone formation or defect bridging compared to the empty control. We concluded that the material resorption and bone formation was highly impacted by the particle-specific agglomeration behaviour in this study.