Jonas Wuyts

The 10 % Ni@CeOx catalyst exhibits excellent catalytic efficiency in the reduction amination of levulinic acid to prepare 1,5-dimethyl-2-pyrrolidone.

Abstract

1,5-dimethyl-2-pyrrolidone (MNMP), as a highly efficient green solvent, can be obtained from biomass-derived levulinic acid and its esters with 100 % conversion and 96.8 % yield over a 10 % Ni@CeOx catalyst at 140 °C, 2 MPa H₂, 8 h, and with water as the solvent. Structure-property correlation investigations were performed with diverse characterization methods, including BET, XRD, XPS, TEM, HAADF-STEM, H₂-TPR, NH₃-TPD, CO₂-TPD and FT-IR, and the results revealed that the excellent catalytic performance of the 10 % Ni@CeOx catalyst was mainly resulted from the strong interaction between Ni and CeOx, which formed more catalytic active sites and contributed to higher reductive amination efficiency. Besides, the 10 % Ni@CeOx catalyst had a chemisorption effect on LA. This was also the key to the excellent catalytic activity of the 10 % Ni@CeOx catalyst. The 10 % Ni@CeOx catalyst exhibited great stability throughout 6 reaction runs and excellent catalytic efficiency in the kilogram scale preparation of MNMP. This work provides a low-cost, efficient, and environmentally friendly heterogeneous catalytic system for the production of MNMP.

Abstract

A mild photocatalyzed approach to achieve the α-alkylation of esters via formation of an α -radical is disclosed here. Cesium enolates of esters were generated in situ using Cs₂CO₃ as a base. A subsequent photocatalyzed oxidation at the α-carbon of these enolates produced an α-radical that was added into activated alkenes. This is the first example accessing the α-carbon radical of esters in photoredox catalyed transformations.

Nature Catalysis, Published online: 08 June 2023; doi:10.1038/s41929-023-00967-8

Shuttle catalysis is a promising approach to improve traditional hydrofunctionalization reactions, although thermodynamic constraints limit its application. Here the authors show how the properties of zeolites can drive the shuttling equilibrium of such catalytic processes, widening the applicability of reactions such as transfer hydrocyanation and transfer hydroformylation.

Publication date: May 2023

Source: Chemical Engineering Research and Design, Volume 193

Author(s): Mensah S. Brobbey, Jeanne Louw, Johann F. Görgens

Nature Catalysis, Published online: 25 May 2023; doi:10.1038/s41929-023-00965-w

Follow that atom!

Nature Reviews Chemistry, Published online: 19 May 2023; doi:10.1038/s41570-023-00502-0

Large language models such as GPT-4 have been approaching human-level ability across many expert domains. GPT-4 can accomplish complex tasks in chemistry purely from English instructions, which may transform the future of chemistry.

Metal-free catalytic materials, as a sustainable and cost-efficient alternative to traditional metal catalysts, have been here in described, considering their applications in thermocatalytic, electrocatalytic and photocatalytic reactions, specially highlighting the employment of sustainable precursors such as biomass wastes as carbon or heteroatom sources.

Abstract

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.

The inherent formation of salt waste in C-H carboxylations is a key obstacle precluding the utilization of CO2 as C1 building block in the industrial synthesis of base chemicals. This challenge is addressed in a circular process for the production of the C4 base chemical dimethyl succinate from CO2 and acetylene. At moderate CO2 pressures, acetylene is doubly carboxylated in the presence of cesium carbonate. Hydrogenation of the C-C triple bond stabilizes the product against decarboxylation. By increasing the CO2 pressure to 70 bar, the medium is reversibly acidified, allowing an esterification of the succinate salt with methanol. The cesium base and the hydrogenation catalyst are regenerated and can be reused. This provides the proof of concept for a salt-free route to C4 chemicals from biogas (CH4/CO2). The origin of this reversible acidity switch and the critical roles of the cesium base and the NMP/MeOH solvents were elucidated by thermodynamic modeling.

Nature Chemistry, Published online: 06 April 2023; doi:10.1038/s41557-023-01187-0

Polyhydroxyalkanoates are potential substitutes for non-degradable polyolefin plastics. Now, it has been shown that structurally related methylated polyhydroxybutyrates, synthesized from carbon monoxide and 2-butenes, can provide a full suite of polyolefin-like polymers. These materials can be recycled or upcycled, and their properties can be easily tuned by varying the cis/trans ratio of the starting materials.

Nature Communications, Published online: 03 April 2023; doi:10.1038/s41467-023-37039-1

Lack of information on authors’ contribution to specific aspects of a study hampers reproducibility and replicability. Here, the authors propose a new, easily implemented reporting system to clarify contributor roles in the Methods section of an article.

Nature Catalysis, Published online: 27 March 2023; doi:10.1038/s41929-023-00926-3

Microporous zeolites have pores of molecular dimension that can stabilize desired chemical pathways but may also introduce mass-transfer limitations. Now, synthesis protocols allow for greater control of catalyst active-site location via elemental zoning, enabling an alternative strategy to reduce mass-transfer limitations and consequently improve catalyst performance for methanol-to-hydrocarbon reactions.

Publication date: 25 April 2023

Source: Tetrahedron, Volume 136

Author(s): Mohammad Mostafa Tohidi, Behnaz Paymard, Salomon Ramiro Vasquez-García, Daniel Fernández-Quiroz