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The selective oxidation of 5‐(Hydroxymethyl)furfural (HMF) to 2,5‐Furandicarboxylic acid (FDCA) is highly attractive for the production of renewable monomers as substitute for fossil‐based monomers. To achieve a sustainable synthesis, we report on advances for a base‐free approach, reducing waste from the process, using air as oxidant and heterogeneous catalysts. Various Carbon‐based supports, which can be bio‐sourced and cost‐efficient, for Pt particles were investigated as they allow for an easy reuse and at the end‐of‐life Pt can be recycled to enable a closed cycle. Commercially available supports with varying properties, which might replace the base, were studied with Pt particles of similar size and loading. Significant differences in the catalytic activity were observed, which were correlated with the O‐functionalities and graphitization degree of the supports derived from Raman spectroscopy, temperature‐programmed desorption, and X‐ray photoelectron spectroscopy. An activated carbon (Norit ROX) rich in quinone/pyrone‐type groups and a carbon black‐based catalyst with graphene‐layers pushed the efficiency with enhanced FDCA‐yields enabling the complete substitution of the homogeneous base. This allows to circumvent the base in this process which together with high selectivity, air as oxidant, a reusable catalyst, and the use of bio‐based feedstock contributes to the sustainability of the production of renewable monomers. [ABSTRACT FROM AUTHOR]

Metal‐free catalytic systems (MFCS) have emerged as sustainable and cost‐efficient heterogeneous catalysts, particularly in the case of carbonaceous materials with oxygen, nitrogen, boron, sulfur or phosphorus functionalities. This contribution aims to provide a general overview of the recent advances on the design of such materials, with emphasis on those derived from biomass waste and on the relationship between their structure and their activity. The opportunities of using MFCS in different areas of catalysis, including thermo‐, electro‐, and photo‐catalysis, will be addressed for applications towards the upgrading of renewable feedstocks. This analysis will describe sustainable approaches not only with respect to the nature of catalyst but also for the employment of non‐toxic and sustainable precursors, and for the efficiency of the synthetic protocol and its carbon footprint. [ABSTRACT FROM AUTHOR]

The reduction of esters and aldehydes to alcohols is an important reaction in the chemical industry to produce a wide range of bulk and fine chemicals. Herein, the unexpected behavior of three state‐of‐the‐art, commercially available Ru‐catalysts for the hydrogenation of these feedstocks is reported. For ester and aldehydes containing a C=C bond, it was possible to carry out the selective hydrogenation of the ester or aldehyde functionality while keeping the C=C double‐bond essentially untouched. Furthermore, it is demonstrated that these substrates can be reduced under very mild reaction conditions (as low as 40 °C and 5 bar of H2) and that anisole, a solvent with a high sustainability rank, is suitable for these catalytic hydrogenations. [ABSTRACT FROM AUTHOR]

The transformation of chemical production processes to a sustainable feedstock from renewable sources requires a careful assessment of current thermodynamic data, reaction mechanisms and kinetics. The Pd‐catalyzed alkoxycarbonylation of the long chain olefin methyl 10‐undecenoate (10‐UME) from castor oil with methanol yields the building blocks for a renewable polyamide. The mechanism for the complex multi‐step reaction cycle including active catalyst formation was elucidated. The experimental catalyst selectivity with 1,2‐bis(di‐tert‐butylphosphino‐methyl)benzene (1,2‐DTBPMB) as a ligand towards the desired linear diester product can be reproduced and rationalized. The mechanisms of possible side reactions and well as catalyst inhibition by carbon monoxide were also investigated. Solvent effects have an influence on reaction equilibria and transition barriers. These were considered in polar (methanol) and nonpolar (dodecane) media using implicit or mixed cluster/continuum solvation models when explicit solvent coordination was critical. [ABSTRACT FROM AUTHOR]

Aiming to reduce anthropogenic CO2 emissions, there is an urgent demand to develop more efficient and affordable technologies which convert CO2 into valuable feedstock molecules. The use of renewable electricity is a promising and sustainable approach to overcome this environmental issue, while producing valuable chemicals and clean fuels. However, the CO2 electroreduction reaction (CO2RR) still shows two main gaps: poor selectivity and required large overpotentials make the process not profitable enough. To overcome these challenges, model studies on single‐crystalline surfaces aiming to find the relations between surface structure/electrolyte interactions and activity/selectivity are necessary. In these model studies, tuning the electrolyte composition is also key for the fundamental understanding of the CO2RR. In this review, we first discuss the structure‐activity‐selectivity relations from studies on well‐ordered surfaces, i. e., single crystalline electrodes, for the CO2RR. We then summarise the role of the electrolyte, presenting work on classical aqueous solvents as well as non‐aqueous electrolytes such as ionic liquids. We illustrate the importance of carrying out studies on well‐defined electrified interfaces in order to get deep fundamental insights on the mechanism of the CO2RR, as well as scaling the process for real applications. Ultimately, this knowledge will be essential to rationally design the catalyst with tailored activity and selectivity for CO2 reduction. [ABSTRACT FROM AUTHOR]

In this work, we describe a simple, heterogeneous catalytic system for the hydrodeoxygenation (HDO) of 5-nonanone and 2,5-hexanedione, which we use as model compounds for more complex biomass-derived molecules. We present the stepwise reduction of ketones by using supported metal and solid acid catalysts to identify the intermediates en route to hydrocarbons. Although monoketone HDO can be achieved rapidly using moderate conditions (Ni/SiO2.Al2O3, HZSM-5, 200 8C, 1.38 MPa H2, 1h), quantitative g-polyketone HDO requires higher pressures and longer reaction times (Pd/Al2O3, HZSM-5, 2.76 MPa H2, 5 h), although these are more facile conditions than have been reported previously for g-polyketone HDO. Stepwise HDO of the g-polyketone shows the reaction pathway occurs through ring-closure to a saturated tetrahydrofuran species intermediate, which requires increased H2 pressure to ring-open and subsequently to fully HDO. This work allows for further understanding of bio-derived molecule defunctionalization mechanisms, and ultimately aids in the promotion of biomass as a feedstock for fuels and chemicals. [ABSTRACT FROM AUTHOR]

The Pd-catalysed synthesis of sodium acrylate from ethylene and CO2 in the presence of alcoholate bases has been improved significantly. We used amide solvents such as N-cyclohexylpyrrolidone or N, N-dibutylformamide to achieve turnover numbers greater than 500 in one run, which is significantly higher than that of systems for this reaction reported previously. For the first time, we were able to recycle the catalyst without any additional regeneration step. With this system, it is possible to use the simple and easily recycled alcoholate base sodium isopropoxide to achieve good turnover numbers up to 200. [ABSTRACT FROM AUTHOR]

Isoquinolines (IQs) are an abundant feedstock, and N-formyl-1,2,3,4-tetrahydroisoquinolines (FTHIQs) are valuable fine chemicals and key intermediates. Herein, we report for the first time the Co0/ZnCl2-catalyzed direct N-formylation of IQs by using CO2 with H2 to produce FTHIQs. It was discovered that the Co catalyst and ZnCl2 worked synergistically in catalyzing the N-formylation reactions, and moderate to high yields of the desired products could be obtained, depending on the nature of the substrates. The Co0 catalyst could be reused at least five times without a notable decrease in activity. A possible reaction mechanism is proposed on the basis of control experiments. [ABSTRACT FROM AUTHOR]

Saturates, aromatics, resin, and C7 asphaltene (SARA) fractions of feedstock were analyzed systematically, and molecular models were constructed. The Monte Carlo method was utilized to investigate the intermolecular interactions between SARA fractions and the ligands absorbed on nickel sulfide nanocatalysts. Additionally, the structural characteristics of the hydrocracked products were analyzed by using elemental analysis, 1H NMR spectroscopy, and FTIR spectroscopy to study the effect of surface modification on the catalytic performances of nickel sulfide nanocatalysts. Simulation results reveal that oleic acid and 1-dodecanethiol have a better miscibility with aromatic fractions of residue than cetyltrimethyl ammonium bromide and that oleic acid has a high affinity and selectivity to C7 asphaltene. Adsorption experiments show that nickel sulfide nanocatalysts modified with oleic acid and 1-dodecanethiol present a certain 'core affinity' in the diffusion of residue colloid, which leads to a higher catalyst concentration in C7 asphaltene than the average value in the feedstock. Subsequently, experimental data demonstrate that surface modification with oleic acid and 1-dodecanethiol enhances the catalytic activity of nickel sulfide nanocatalysts, which also facilitates the hydrogenation of C7 asphaltene. Furthermore, nickel sulfide nanocatalysts modified with oleic acid show the best hydrogenation and anticoke activity because of the affinity between oleic acid and C7 asphaltene. [ABSTRACT FROM AUTHOR]

Operando UV/Vis spectroscopy with on-line mass spectrometry was used to study the effect of different types of impurities on the hydrocarbon pool species and the activity of H-SAPO-34 as a methanol-to-olefins (MTO) catalyst. Successive reaction cycles with different purity feedstocks were studied, with an intermittent regeneration step. The combined study of two distinct impurity types (i.e., feed and internal impurities) leads to new insights into MTO catalyst activation and deactivation mechanisms. In the presence of low amounts of feed impurities, the induction and active periods of the process are prolonged. Feed impurities are thus beneficial in the formation of the initial hydrocarbon pool, but also aid in the unwanted formation of deactivating coke species by a separate, competing mechanism favoring coke species over olefins. Further, feedstock impurities strongly influence the location of coke deposits, and thus influence the deactivation mechanism, whereas a study of the organic impurities retained after calcination reveals that these species are less relevant for catalyst activity and function as 'seeds' for coke formation only. [ABSTRACT FROM AUTHOR]

Metal oxides such as Nb2O5, Cr2O3, and especially a ZnIICrIII mixed oxide are demonstrated to be highly active and recyclable heterogeneous catalysts for Prins condensation, which provides a clean, high-yielding route for the synthesis of nopol through the condensation of biorenewable β-pinene with paraformaldehyde. ZnCr mixed oxide with an optimum Zn/Cr atomic ratio of 1:6 gave 100 % nopol selectivity at 97 % β-pinene conversion, with the catalyst easily recovered and recycled. The acid properties of Nb2O5 and ZnCr mixed oxide were characterized by the diffuse reflectance IR Fourier transform spectroscopy of adsorbed pyridine and ammonia adsorption microcalorimetry. An appropriate combination of acid-base properties of ZnCr mixed oxide is believed to be responsible for its efficiency. [ABSTRACT FROM AUTHOR]

The increasing demand for light olefins and the changing nature of basic feedstock has stimulated substantial research activity into the development of new process routes. Steam cracking remains the most industrially relevant pathway, but other routes for light-olefin production have emerged. Fluid catalytic cracking only produces ethene in minor concentrations. Challenged by marked catalyst deactivation, in contrast, catalytic dehydrogenation ethane up opens a more selective route to ethene. The oxidative dehydrogenation (ODH) of ethane, which couples the endothermic dehydration of ethane with the strongly exothermic oxidation of hydrogen, would potentially be the most attractive alternative route because it avoids the need for excessive internal heat input, but also consumes valuable hydrogen. In this Review, the current state of the ODH of ethane is compared with other routes for light-olefin production, with a focus on the catalyst and reactor system variants. New catalyst systems and reactor designs have been developed to improve the industrial competitiveness of the ODH reaction of ethane. The current state of our fundamental understanding of the ODH of light alkanes, in particular in terms of catalyst and reactor development, is critically reviewed. The proposed mechanisms and the nature of the active site for the ODH reaction are described and discussed in detail for selected promising catalysts. The reported catalytic performance and the possible limitations of these ODH catalysts will be examined and the performance of the emerging approaches is compared to the currently practiced methods. [ABSTRACT FROM AUTHOR]

Using phenolic bio-oil as feedstock for sustainable production of alkane fuels is of great significance. Here, the hydrodeoxygenation of phenol and its derivatives has been systematically investigated in aqueous media with a dual-functional catalyst system consisting of water-soluble, ionic liquid-like copolymer A-stabilized nanocatalysts and the mineral acid H3PO4. The developed Ru/ A-H3PO4 catalyst system achieved a complete phenol conversion with cyclohexane selectivity higher than 99 %, making it by far one of the most efficient systems for phenol hydrodeoxygenation. Mercury poisoning experiments revealed that the in situ generated Ru nanoparticles are true a heterogeneous catalyst for hydrogenation. The catalytic activity of metal site for phenol hydrodeoxygenation to cyclohexane decreased with the order of Ru>Rh>Pt≫Pd. Our findings also demonstrated the delicate balance between activity and stability of ionic liquid-like copolymer-stabilized nanocatalysts. The research highlights an efficient catalyst system of transforming phenols into alkanes. [ABSTRACT FROM AUTHOR]

The front cover artwork for Issue 22/2019 is provided by researchers from the Catalytic Processes and Waste Valorization Group of the University of the Basque Country (Spain) and Multiscale Reaction Engineering of the King Abdullah University of Science and Technology (Saudi Arabia). The image shows a Cerberus lying down on the floor of a Gothic tower with each of its three heads watching out the scenario of each feedstock through the windows. See the Full Paper itself athttps://doi.org/10.1002/cctc.201901204. [ABSTRACT FROM AUTHOR]