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AlSBA-15 catalysts possessing Br?nsted acid and Lewis acid–base bifunctionalities catalyze the direct arylation of benzyl alcohols to diarylmethanes with an 85% product yield through C–O bond activation. 2 and 4wt%AlSBA-15 catalysts have been synthesised by adopting a simple and efficient post-synthetic metal implantation route. The synthesised catalysts were characterized using XRD, N 2 adsorption and desorption, 27 Al MAS NMR, XPS, HR-TEM, NH 3 and CO 2 -temperature-programmed desorption (TPD) and pyridine-transmission-FTIR spectroscopy techniques to confirm the existence of Br?nsted acid and Lewis acid–base bifunctionalities. Through various control experiments, it is verified that Br?nsted acid sites activate the benzyl alcohol and Lewis base sites interact with phenylboronic acid concurrently to accomplish the coupling reaction. In the recyclability study, 4wt%AlSBA-15 preserves its activity and stability up to 5 cycles. The 4wt%AlSBA-15 catalyst unlike homogeneous catalysts does not require additives, long reaction time and expensive metals.

The current perspective will present the use of amidinate group 4 complexes in α-olefin polymerizations. We will present the structural studies of the complexes bearing various numbers of amidinates as spectator ligands, with a special emphasis on the bis(amidinate) group 4 systems. The mechanistic studies elucidate the influence of various reaction conditions on the behaviour of the reactive species. Additionally, the study of the active species by techniques such as EPR spectroscopy and MALDI-TOF spectrometry are presented. We will also demonstrate how, based on such techniques, highly stereospecific bis(amidinate) titanium complexes may be designed and applied in the polymerization of propylene.

Linear α-olefins (LAOs) and linear internal olefins (LIOs) are essential intermediates in the synthesis of surfactants, lubricants, and polymers. Concurrently with petroleum-based industrial processes, the production of LAOs and LIOs from renewable feedstocks has gained increasing interest in recent years. Organometallic catalysts have been developed designedly, especially Pd, Fe and Ir catalysts. However, such catalysts are mostly stabilized by phosphanes, ligands sometimes difficult to handle especially on large scales. Alternatives to phosphanes would thus be highly desirable. In the present study, we demonstrate that Ir catalysts coordinated by amines are suitable to decarbonylate a wide range of biosourced substrates under mild conditions. The resulting LAOs and LIOs are obtained with good conversion provided that the nature and the quantity of the amines are controlled accurately. The LAO/LIO selectivity can also be tuned by a judicious choice of experimental conditions. Interestingly, the Ir-based catalytic system is applicable to the decarbonylative dehydration of saturated, unsaturated and polyunsaturated fatty acids.

The heterogeneous SCR reaction dynamics, the well-known Eley–Rideal mechanism and the Langmuir–Hinshelwood mechanism are well-understood by most researchers, all involving the adsorption of ammonia as the premise of the whole redox reaction. Alkali species prevent the collision between the acidic V-site and gaseous NH 3 molecules and result in serious reactivity losses to the commercial V 2 O 5 –WO 3 /TiO 2 catalyst. Yet, in fast SCR reactions, alkali species provide additional basic sites for NO 2 adsorption. In contrast to the accepted mechanism, gaseous NH 3 molecules were shown to participate in the reaction and react with other adsorbed substances. The active site is transformed and the mechanism shifts to a fast SCR over the poisoned catalyst. This study presents a new strategy to design catalysts for fast SCR processes and deal with alkali metal poisoning issues.

Owing to the high-volume production of the silicone industry, in which hydrosilylation products are polluted by Pt, it is of major interest to develop alternative catalysts that would be based on non-noble metals and that would be easy to separate from the reaction products. In this context, we explore here the preparation of catalysts based on non-noble metal nanoparticles as alternatives to Pt complexes or non-noble metal complexes (main trend in academic research). We demonstrate here that isolated nickel nanoparticles in solution or deposited on silica can be used as catalysts for alkene hydrosilylation. The composition of the nickel nanoparticles (nickel silicide, metallic nickel or nickel oxide) is key for selectivity and activity. These catalysts which exhibited similar Ni particle sizes were tested in the challenging reaction of triethoxysilane with triethoxyvinylsilane. The heterogeneous catalyst based on metallic nickel nanoparticles was found to be the most promising and could be filtered off, leading to pure reaction products (no metal pollution). This result suggests that the exploration of non-noble metal nanoparticles and particularly diverse nickel (0) phases may be a key to the development of highly selective heterogeneous catalysts.

The structural, textural and acidic characteristics of hierarchical ZSM-5 (Si/Al = 18–32), obtained with two desilication approaches, and the effect of these treatments on the reactivity in various cracking reactions of variable feedstock size and severity have been investigated. Emphasis is given to understanding the accessibility of acid sites; this was investigated by textural analysis, FTIR probe molecules (pyridine, trimethylacetonitrile and 2,4,6-trimethylpyridine) and reactions involving n -decane, 1,3,5-triisopropylbenzene (TIPB), and low and high-density polyethylene, LDPE and HDPE, respectively. Higher surface areas and a narrower pore size distribution were obtained for NaOH both parameters are linearly dependent on the pivalonitrile and collidine accessibility factors, for LDPE and HDPE. The T 5% for HDPE is more influenced by the accessibility factors than it is for the LDPE. This is interpreted to be the result of the branching degree of HDPE and LDPE; linear HDPE is more sensitive to the enhanced number of pore mouths of ZSM-5 channels on the mesopores. At high conversion, the influence on the T 50% of the accessibility factors for HDPE and LDPE is weaker, suggesting that the cracking at this stage involves intermediate molecules of smaller size with fewer diffusional limitations. With respect to our own prior work, the chosen zeolite and the cracking of polyolefins gave more pronounced differences for the hierarchical ZSM-5.

A water-soluble β-cyclodextrin polymer synthesized by crosslinking β-cyclodextrin with epichlorohydrin and glycidyltrimethylammonium chloride allowed the stabilization of ruthenium nanoparticles not only in basic aqueous medium but also in acidic medium. The aqueous ruthenium colloidal suspensions obtained with this polymer were active as catalysts for the hydrogenation of a large variety of unsaturated compounds including aromatic or fatty acids. The recycling of this catalytic system was attested through ten consecutive runs without loss of stability and activity, demonstrating its robustness.

Detailed study of the synthesis parameters of silver doped with the organic dye Congo-red (CR@Ag) have led to an understanding of the origins of the superior performance of this novel-type methanol-oxidation catalyst (compared to pure silver) as demonstrated by the significant lowering of the temperature needed to reach maximal conversion by more than 100 °C. The origins of the effect of the organic dopant on the catalytic properties of silver are suggested and discussed in terms of its effects on morphology, on oxygen chemisorption properties, on the surface area, on the thermal behavior and on the sinterability of the silver aggregated crystallites. For instance, the organic dopant affects the surface area dramatically, increasing it from 600–3000 cm 2 g ?1 for undoped silver to 46?000 cm 2 g ?1 for CR@Ag; and oxygen chemisorption, crucial for this catalytic process, increases from 32 cm 2 g ?1 for Ag to 893 cm 2 g ?1 for CR@Ag. Preliminary work with CR@copper provides a positive outlook for the general use of organic dopants to improve catalytic properties of other metals.

IR spectroscopic studies of NH 3 and CO adsorption were applied to establish the status of Ag 0 and Ag + in silver loaded zeolites Y and USY. The nature of the silver particles and ions and their dispersion were found to be influenced by the type of support. Application of zeolite USY as support allowed to operate such catalysts at low temperatures with high selectivity to nitrogen (95%). Zeolite USY as support guaranteed a high concentration of uniformly dispersed metallic silver species and Ag + cations with strong electron acceptor properties. The silver species of defined nature together with the highly acidic centres in AgUSY protected NH 4 + ions against oxidation thus high selectivity to nitrogen was observed.

We recently reported biomass-derived tetrahydrofuran-2,5-dicarboxylic acid (THFDCA) as a potential renewable feedstock for adipic acid (AA) production by combining HI and molecular H 2 in organic acid solvents. However, the volatile and corrosive nature of HI, the catalyst, presents challenges in industrial implementation. In this work, we demonstrate an improved, less corrosive system with comparable AA yields (～87%) using Nafion and an iodide salt, e.g. , LiI, NaI and KI. Kinetic and reactivity studies indicate that the activation of THFDCA's etheric C–O bond proceeds either by direct protonation at the surface of the solid acid or by liquid-phase protons which are transported from the surface of the solid acid to the bulk solvent through an ion-exchange process. The combination of a solid acid and an iodide salt functions as a controlled release mechanism for protons without sacrificing the effectiveness of HI, while significantly reducing the corrosiveness of the reaction mixture. Further, the spent Nafion can easily be separated from the reaction mixture and regenerated by ion-exchange with minimal loss in reactivity.