Structure sensitivity of Cu supported on manganese oxide catalysts in levulinic acid hydrogenation

Different synthesis methods were used to prepare a series of size-controlled copper nanoparticles supported on manganese oxide octahedral molecular sieve (OMS-2) catalysts. All Cu/OMS-2 catalysts, with average Cu nanoparticle sizes prepared in the range of 2–22 nm, were thoroughly characterised using X-ray diffraction (XRD), N2 sorption, H2 temperature programmed reduction (TPR), transmission electron microscopy (TEM), and ICP-OES elemental analyses. The catalytic activity of the size-controlled Cu/OMS-2 catalysts was investigated in liquid phase hydrogenation of levulinic acid as a model reaction to evaluate the nanoparticle size dependance and structure–activity relationship. The catalytic activity studies showed that the catalyst performance depends greatly on the catalyst preparation methodology and Cu nanoparticle size. Complete conversion of levulinic acid with a high γ-valerolactone yield, >99%, was observed using Cu/OMS-2 catalysts prepared by the precipitation–deposition (Cu nanoparticle size 2–3 nm) method. In comparison to wet-impregnated catalysts (Cu particle size 20–22 nm), the improved performance of precipitation–deposition catalysts was mainly attributed to the well-distributed, smaller Cu nanoparticles. The influence of Cu nanoparticle size is correlated with the turnover frequency (TOF, h−1) for levulinic acid conversion, indicating the structure sensitivity of the levulinic acid hydrogenation reaction

Novel Ionic Liquid Synthesis of Bimetallic Fe–Ru Catalysts for the Direct Hydrogenation of CO₂to Short Chain Hydrocarbons

The selective hydrogenation of CO2 for the production of net-zero fuels and essential chemical building blocks is a promising approach to combat climate change. Key to this endeavor is the development of catalysts with high activity and selectivity for desired hydrocarbon products in the C2–C5 range. The process involves a two-step reaction, starting with the reverse water–gas shift (RWGS) reaction and proceeding to the Fischer–Tropsch reactions under high pressure. Understanding the catalyst features that control the selectivity of these pathways is crucial for product formation, as well as identifying morphological changes in the catalysts during the reaction to optimize their performance. In this study, an innovative method for synthesizing iron–ruthenium bimetallic catalysts is introduced, capitalizing on the synergistic effects of these metals as active phases. This method leverages ionic liquids as solvents, allowing for the precise and uniform distribution of active metal phases. Advanced characterizations and extensive catalytic tests have demonstrated that the use of ionic liquids outperformed traditional colloid-based techniques, resulting in superior selectivity for target hydrocarbons. The success of this inventive approach not only advances the field of CO2 hydrogenation catalysis, but also represents a significant stride towards sustainable e-fuel production

Recent advances in catalyst design for carboxylation using CO₂ as the C1 feedstock

Carbon dioxide is ideal for carboxylation reactions as a renewable and sustainable C1 feedstock and has significant recognition owing to its low cost, non-toxicity, and high abundance. To depreciate the environmental concentration of CO2, which causes the greenhouse gas effect, developing new catalytic protocols for organic synthesis in CO2 utilization is of great importance. This review focuses on carboxylation reactions using CO2 as a C1 feedstock to synthesize value-added functionalized carboxylic acids and their corresponding derivatives via catalytically generated allyl metal intermediates, photoredox catalysis, and electrocatalysis with a focus on recent developments and opportunities in catalyst design for carboxylation reactions. In this article, we describe recent developments in the carboxylation of C–H bonds, alkenes, and alkynes using CO2 as the C1 source for various reactions under different conditions, as well as the potential direction for the further development of CO2 utilization in organic synthesis