This short review documents some examples of recent innovations in the field of catalytic selective oxidation. The processes that are currently being developed for propene oxide are described, ...highlighting innovative aspects that contribute to a better sustainability of the chemical industry. The target of closing the chlorine cycle, one of the main problems in the modern chemical industry, is also discussed, with the aim of highlighting the important role of catalytic oxidation.
Catalytic oxidation provides several examples of the remarkable steps made forward towards a more sustainable chemical industry: use of alternative reactants, the design of new catalysts, new ...reactions, and new reactor technologies. The recent developments described in this Review clearly show that better sustainabily and improved economics often go hand in hand.
This Review documents some examples of recent innovations in the field of catalytic selective oxidation from an industrial point of view. The use of alkanes as building blocks for the synthesis of bulk chemicals and intermediates is discussed, along with the main properties that catalysts should possess in order to efficiently catalyse the selective oxidation of these hydrocarbons. The currently developed processes for propene oxide and new processes under investigation for the synthesis of adipic acid are also described, highlighting innovative aspects for a better sustainability of the chemical industry.
Catalytic oxidation provides several examples of the remarkable steps made forward towards a more sustainable chemical industry: use of alternative reactants, the design of new catalysts, new reactions, and new reactor technologies. The recent developments described in this Review clearly show that better sustainabily and improved economics often go hand in hand.
Methyl methacrylate (MMA) is a specialty monomer for poly methyl methacrylate (PMMA) and the increasing demand for this monomer has motivated industry to develop clean technologies based on renewable ...resources. The dominant commercial process reacts acetone and hydrogen cyanide to MMA (ACH route) but the intermediates (hydrogen cyanide, and acetone cyanohydrin) are toxic and represent an environmental hazard. Esterification of methacrylic acid (MAA) to MMA is a compelling alternative together with ethylene, propylene, and isobutene/t-butanol as feedstocks. Partially oxidizing isobutane or 2-methyl-1,3-propanediol (2MPDO) over heteropolycompounds to MAA in a single-step is nascent technology to replace current processes. The focus of this review is on catalysts and their role in the development of processes herein described. Indeed, in some cases remarkable catalysts were studied that enabled considerable steps forward in both the advancement of catalysis science and establishing the basis for new technologies. An emblematic example is represented by Keggin-type heteropolycompounds with cesium and vanadium, which are promising catalysts to convert isobutane and 2MPDO to MAA. Renewable sources for the MMA or MAA route include acetone, isobutanol, ethanol, lactic, itaconic, and citric acids. End-of-life PMMA is expected to grow as a future source of MMA.
A common way to convert ethanol into chemicals is by upgrading it over oxide catalysts with basic features; this method makes it possible to obtain important chemicals such as 1‐butanol (Guerbet ...reaction) and 1,3‐butadiene (Lebedev reaction). Despite their long history in chemistry, the details of the close inter‐relationship of these reactions have yet to be discussed properly. Our present study focuses on reactivity tests, in situ diffuse reflectance infrared Fourier transform spectroscopy, MS analysis, and theoretical modeling. We used MgO as a reference catalyst with pure basic features to explore ethanol conversion from its very early stages. Based on the obtained results, we formulate a new mechanistic theory able to explain not only our results but also most of the scientific literature on Lebedev and Guerbet chemistry. This provides a rational description of the intermediates shared by the two reaction pathways as well as an innovative perspective on the catalyst requirements to direct the reaction pathway toward 1‐butanol or butadiene.
Lebedev and Guerbet: what's the difference? The multifaceted approach used to study the mechanism of the Lebedev and Guerbet reactions indicates that the two processes share the same anionic intermediate but evolve along different reaction pathways, which avoid the thermodynamically hampered aldolic route.
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•The MPV reduction of aromatic aldehydes with methanol was catalyzed by MgO.•The mechanism of the reaction was elucidated by means of DFT calculations.•The mechanism was fully ...consistent with results of catalytic experiments.•The reaction was of general validity for the reduction of aromatic aldehydes.•Furfural was reduced to furfuryl alcohol with 100% yield.
The previously unexplored use of methanol as a H-transfer agent for the Meerwein–Ponndorf–Verley reduction of aromatic aldehydes and aryl ketones is described. Furfural, 5-hydroxymethylfurfural, benzaldehyde, and acetophenone were selectively reduced to the corresponding alcohols in mild conditions. The reaction mechanism was elucidated by means of reactivity tests and DFT calculations. It was found to include the highly efficient H-transfer with the formation of formaldehyde, which further reacted with excess methanol to generate the adsorbed hemiacetal. In turn, the latter reduced carbonyl, with the formation of methylformate, which further decomposed into CO, CH4, and CO2. Compared to the alcohols typically used for carbonyl reductions, methanol showed the advantage of producing gaseous components as the only co-products, which are easily separated from the reaction medium. In the case of furfural, a 100% yield to furfuryl alcohol was obtained, using the high-surface area MgO as the easily recoverable and reusable catalyst.
Biomass is an interesting candidate raw material for the production of renewable hydrogen. The conversion of biomass into hydrogen can be achieved by several processes. In particular, this short ...review focuses on the recent advances in glycerol reforming to hydrogen, highlighting the development of new and active catalysts, the optimization of reaction conditions, and the use of non-innocent supports as advanced materials for supported catalysts. Different processes for hydrogen production from glycerol, especially aqueous phase reforming (APR) and steam reforming (SR), are described in brief. Thermodynamic analyses, which enable comparison with experimental studies, are also considered. In addition, research advances in terms of life cycle perspective applied to support R&D activities in the synthesis of renewable H2 from biomass are presented. Lastly, also featured is an evaluation of the studies published, as evidence of the increased interest of both academic research and the industrial community in biomass conversion to energy sources.
Au-Based catalysts supported on nanosized NiO (nNiO) were synthesized and were investigated in the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) under base-free ...conditions using molecular oxygen as the oxidant, at 90 °C. By choosing the optimal composition of Au-Pd nanoparticles (6 : 4 Au/Pd atomic ratio), we report an efficient and stable nNiO-supported Au-Pd alloy catalyst. The presence of nNiO and Au-Pd nanoparticles on the surface was essential to achieve high conversion (95%) and high activity, high yield of FDCA (70%) and good level of stability. Significant synergistic effects were observed between Au and Pd in the alloy as well as on NiO. The present work provides mechanistic insights into the alloying effect and support-metal interaction in terms of understanding better the role of the alloy and support in affecting specific reaction pathways. Finally, the outcome of this knowledge can help develop efficient catalysts for the aerobic oxidation of biomass-derived molecules under base-free conditions in water and under mild reaction conditions.
AuPd nanoparticles supported on NiO exhibit high activity and stability in the base free oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA).
This title offers a comprehensive overview of the most recent developments in both total oxidation and combustion and also in selective oxidation. For each topic, fundamental aspects are paralleled ...with industrial applications.
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