Unraveling the Electrocatalytic Activity in HMF Oxidation to FDCA by Fine-Tuning the Degree of NiOOH Phase Over Ni Nanoparticles Supported on Graphene Oxide.

The development of an efficient electrocatalyst for HMF oxidation to FDCA has been in the early stages. Herein, the NiNPs/GO-Ni-foam is fabricated as an electrocatalyst for FDCA production. However, the electrocatalytic performance of the untreated NiNPs/GO-Ni-foam is observed with moderate Faradaic efficiency (FE) (73.0%) and FDCA yield (80.2%). By electrochemically treating the NiNPs/GO-Ni-foam in an alkaline solution with positive potential at different treatment durations, the degree of NiOOH on metal surfaces is changed. The distinctive electrocatalytic activity obtained when using the different NiOOH degrees allows to understand the crucial impact of NiOOH species in HMF electrooxidation. Enhancing the portion of the NiOOH phase on the electrocatalyst surface improves electrocatalytic activity in terms of FE and FDCA yield up to 94.8±4.8% and 86.9±4.1%, respectively. Interestingly, as long as the NiOOH portion on the electrocatalyst surface is preserved or regenerated, the electrocatalyst performance can be intact even after several catalytic cycles. The theoretical study via density functional theory (DFT) also agrees with the experimental observations and confirms that the NiOOH phase facilitates the electrochemical transformation of HMF to FDCA through the HMFCA pathway, and the potential limiting step of the overall reaction is the oxidation of FFCA to FDCA.

Highly Enantioselective Synthesis of Pharmaceuticals at Chiral-Encoded Metal Surfaces.

Invited for the cover of this issue are the groups of Chularat Wattanakit and Alexander Kuhn at the Vidyasirimedhi Institute of Science and Technology and the University of Bordeaux. The two tunnels in the image illustrate the entrance into a porous heterogeneous catalyst for the stereoselective transformation of adrenalone into the desired epinephrine stereoisomer. Read the full text of the article at 10.1002/chem.202302054.

Highly Enantioselective Synthesis of Pharmaceuticals at Chiral-Encoded Metal Surfaces.

Enantioselective catalysis is of crucial importance in modern chemistry and pharmaceutical science. Although various concepts have been used for the development of enantioselective catalysts to obtain highly pure chiral compounds, most of them are based on homogeneous catalytic systems. Recently, we successfully developed nanostructured metal layers imprinted with chiral information, which were applied as electrocatalysts for the enantioselective synthesis of chiral model compounds. However, so far such materials have not been employed as heterogeneous catalysts for the enantioselective synthesis of real pharmaceutical products. In this contribution, we report the asymmetric synthesis of chiral pharmaceuticals (CPs) with chiral imprinted Pt-Ir surfaces as a simple hydrogenation catalyst. By fine-tuning the experimental parameters, a very high enantioselectivity (up to 95 % enantiomeric excess) with good catalyst stability can be achieved. The designed materials were also successfully used as catalytically active stationary phases for the continuous asymmetric flow synthesis of pharmaceutical compounds. This illustrates the possibility of producing real chiral pharmaceuticals at such nanostructured metal surfaces for the first time.

Rational design of isolated tetrahedrally coordinated Ti(IV) sites in zeolite frameworks for methyl oleate epoxidation.

The rational design of isolated metals containing zeolites is crucial for the catalytic conversion of biomass-derived compounds. Herein, we explored the insertion behavior of the isomorphic substitution of Ti(IV) in different zeolite frameworks, including ZSM-35 (FER), ZSM-5, and BEA. The different aluminium topological densities of each zeolite framework lead to the creation of different degrees of vacant sites for hosting the tetrahedrally coordinated Ti(IV) active sites. These observations show the precise control of the degree of four-coordinated Ti(IV) sites in a zeolite framework, especially in BEA topology, by tuning the degree of unoccupied sites in the host zeolite structure via dealumination. Interestingly, the more vacancies in the host zeolite structure, the more isolated tetrahedrally coordinated Ti(IV) can be increased, eventually enhancing the catalytic performance in methyl oleate (MO) epoxidation for producing methyl-9,10-epoxystearate (EP). The engineered Ti-ß exhibits outstanding performances in bulky MO epoxidation with the amount of produced EP per number of Ti sites up to 17.1 ± 1.8 mol mol-1. This observation discloses an alternative strategy for optimizing catalyst efficiency in the rational design of the Ti-embedding zeolite catalyst, endeavoring to reach highly efficient catalytic performance.

Bifunctional Pt/Au Janus electrocatalysts for simultaneous oxidation/reduction of furfural with bipolar electrochemistry.

The sustainable conversion of biomass-derived compounds into high added-value products is a very important contemporary scientific challenge. In this context, we report here the simultaneous electro-oxidation/-reduction of a biomass-derived compound in a one-pot approach using bipolar electrochemistry. Bifunctional Pt/Au Janus electrocatalysts are employed for a selective conversion of furfural into both, furfuryl alcohol and furoic acid, which can't be achieved when using non-Janus particles. The results emphasize the benefits of bipolar electrochemistry in the frame of electrosynthesis processes.

Binder-free hierarchical zeolite pellets and monoliths derived from ZSM-5@LDHs composites for bioethanol dehydration to ethylene.

The development of industrial catalysts is of crucial importance for practical uses. However, the use of extruded catalysts in industry is still limited because of a remarkably decreased catalytic activity when combining them with binders. This contribution illustrates the rational design of binder-free hierarchical ZSM-5 pellets and monoliths derived from zeolite@LDHs composites via extrusion and 3D printing technologies, respectively. The designed catalyst applied in bioethanol dehydration boosts the ethylene yield by over 93.4 ± 2.2% due to the synergistic effect of zeolites and LDHs.

Fine-tuning the chemical state and acidity of ceria incorporated in hierarchical zeolites for ethanol dehydration.

The chemical state and acidity of ceria incorporated in hierarchical zeolites have been successfully tuned due to the presence of hierarchical structures of zeolite nanosheets and interaction between ceria and zeolite supports with different Si/Al ratios. The Ce reactivity of the designed materials for ethanol dehydration is remarkably improved due to the improvement of the metal-support interaction, acidity, and reducibility of Ce species, eventually facilitating an unprecedented yield of ethylene close to 100%. This finding opens up a new perspective for the development of ceria based hierarchical zeolite catalysts for ethanol dehydration applications.