UV- and visible-light photocatalysis using Ni-Co bimetallic and monometallic hydrotalcite-like materials for enhanced CO2 methanation in sabatier reaction

The CO2 catalytic reduction activities of four different Co-modified Ni-based catalysts derived from hydrotalcite-like materials (HTCs) prepared by co-precipitation method were investigated under thermal and photocatalytic conditions. All catalysts were tested from 473 to 723 K at 10 bar (abs). The light intensity for photocatalytic reactions was 2.4 W cm-2. The samples were characterized to determine the effect of morphological and physicochemical properties of mono-bimetallic active phases on their methanation activity. The activity toward CO2 methanation followed the next order: Ni > Co-Ni > Co. For the monometallic Ni catalyst an increase of a 72% was achieved in the photo-catalytic activity under UV and vis light irradiation at temperatures lower by > 100 K than those in a conventional reaction. Co-modified Ni based hydrotalcite catalysts performed with stability and no deactivation for the 16 h studied under visible light for methanation at 523 K due to the presence of basic sites.

Catalytic Reforming of Oxygenates: State of the Art and Future Prospects

This Review describes recent advances in the design, synthesis, reactivity, selectivity, structural, and electronic properties of the catalysts for reforming of a variety of oxygenates (e.g., from simple monoalcohols to higher polyols, then to sugars, phenols, and finally complicated mixtures like bio-oil). A comprehensive exploration of the structure-activity relationship in catalytic reforming of oxygenates is carried out, assisted by state-of-the-art characterization techniques and computational tools. Critical emphasis has been given on the mechanisms of these heterogeneous-catalyzed reactions and especially on the nature of the active catalytic sites and reaction pathways. Similarities and differences (reaction mechanisms, design and synthesis of catalysts, as well as catalytic systems) in the reforming process of these oxygenates will also be discussed. A critical overview is then provided regarding the challenges and opportunities for research in this area with a focus on the roles that systems of heterogeneous catalysis, reaction engineering, and materials science can play in the near future. This Review aims to present insights into the intrinsic mechanism involved in catalytic reforming and provides guidance to the development of novel catalysts and processes for the efficient utilization of oxygenates for energy and environmental purposes.

Bimetallic synergistic degradation of chlorophenols by CuCoOx–LDH catalyst in bicarbonate-activated hydrogen peroxide system

A CuCoO_x–LDH-based catalyst demonstrated high activity for chlorophenol degradation with low leaching in a bicarbonate-activated hydrogen peroxide system.

Sustainable hydrogen production by ethanol steam reforming using a partially reduced copper-nickel oxide catalyst

Hydrogen production through the use of renewable raw materials and renewable energy is crucial for advancing its applications as an energy carrier. In this study, we fabricated a solid oxide solution of Cu and Ni within a confined pore space, followed by a partial reduction, to produce a highly efficient catalyst for ethanol steam reforming (ESR). At 300 °C, EtOH is completely converted, a H2 yield of approximately 5 mol per mol is achieved, and CO2 is the main carbon-containing product. This demonstrates that H2 production from bioethanol is an efficient and sustainable approach. Such a highly efficient ESR catalyst is attributed to the ability of the metal-oxide interface to facilitate the transformation of CHx adspecies from acetaldehyde decomposition into methoxy-like adspecies, which are reformed readily to produce H2 and consequently reduce CH4 formation.

Preparation of platy Co/Al hydrotalcites using aluminum hydroxide and investigation of their tribological properties in base oil

In this study, the synthesis of Co/Al hydrotalcite (layered double hydroxides: LDHs) using insoluble Al(OH)3 by a hydrothermal method is described. The syntheses were conducted under various conditions. The as-prepared Co/Al-CO32–-LDH was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The tribological properties of the products were evaluated in base oil using four-ball and Plint friction testers. The LDH thus synthesized displays perfect hexagonal platelike morphology having a disk diameter in the range of 0.2–1.5 μm with a thickness of 40 nm. The addition of the product Co/Al-CO32–-LDH, as an additive to the base oil, significantly reduces the friction coefficient (22.3%) and wear (26.1%) compared to base oil alone. The morphology and chemistry of the worn surface were characterized by SEM, atomic force microscopy (AFM), and X-ray absorption near-edge structure (XANES) spectroscopy. The results show that the structural distortion of LDH induced by mechanochemical processes during friction consumes the friction force between the rubbed surfaces, and as a result, the friction and the wear is reduced. Thus, our results show that the LDH sheets absorbed on the worn surface can prevent direct contact between the friction pairs (surfaces) and decreases the roughness of the worn surface.

Nano bimetallic alloy of Ni–Co obtained from LaCoxNi1−xO3 and its catalytic performance for steam reforming of ethanol

Bimetallic alloy nanoparticles of Ni–Co were obtained from reducing LaCo_xNi_1−xO₃ and this method should be extended to prepare various bimetallic or polymetallic nanoparticles.