MgO Modified by X, HX, or Alkyl Halide (X = Cl, Br, or I) Catalytic Systems and Their Activity in Chemoselective Transfer Hydrogenation of Acrolein into Allyl Alcohol.

A new type of catalyst containing magnesium oxide modified with various modifiers ranging from bromine and iodine, to interhalogen compounds, hydrohalogenic acids, and alkyl halides have been prepared using chemical vapor deposition (CVD) and wet impregnation methods. The obtained systems were characterized using a number of methods: determination of the concentration of X ions, surface area determination, powder X-ray diffraction (PXRD), surface acid-base strength measurements, TPD of probe molecules (acetonitrile, pivalonitrile, triethylamine, and -butylamine), TPD-MS of reaction products of methyl iodide with MgO, and Fourier transform infrared spectroscopy (FTIR). The catalysts' activity and chemoselectivity during transfer hydrogenation from ethanol to acrolein to allyl alcohol was measured.

Sonocatalytic Activity of Porous Carbonaceous Materials for the Selective Oxidation of 4-Hydroxy-3,5-dimethoxybenzyl Alcohol.

Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts.

Selective (sono)photocatalytic cleavage of lignin-inspired β-O-4 linkages to phenolics by ultrasound derived 1-D titania nanomaterials.

Catalytic conversion of lignin to value-added aromatic compounds is still an open challenge, since the selective cleavage of the linkages interconnecting the aromatic molecules, especially the β-O-4 ones, is not efficiently achieved yet. Herein, novel titania-based nanostructured materials were synthesized using low-power-low-frequency ultrasound that demonstrated high efficiency for the selective cleavage of C-C bond of β-O-4 linkages of lignin-inspired model compounds. Going a step ahead, experiments of sonophotocatalytic valorization of 2-phenoxy-1-phenylethanol were contacted for the first time, where the exposure to ultrasound leading to better conversion and selectivity towards the desired products in the case of the novel ultrasound-synthesized nano-photocatalyst.

Catalytic Ketonization over Oxide Catalysts (Part XIV): The Ketonization and Cross-Ketonization of Anhydrides, Substituted Acids and Esters.

A series of 20 wt.% MO/S catalysts (where M = Ce, Mn or Zr and S = SiO or AlO) were prepared using various precursors of the active phases. The resulting catalysts were characterized using different methods (XRD, TPR and S).

Tuning the physicochemical features of titanium oxide nanomaterials by ultrasound: Elevating photocatalytic selective partial oxidation of lignin-inspired aromatic alcohols.

The research for "green" and economically feasible approaches such as (photo)catalysis especially for biomass valorization such as selective oxidation of biomass derived compounds like aromatic alcohols to corresponding aldehyde by avoiding the harsh reaction conditions and the addition of reagents concentrate the focus of attention the last years. Hence, design and development of novel photocatalyst for the partial selective oxidation is highly desirable. In this research work, ultrasonication of different frequencies (22, 40, 80 kHz) and different amplitudes was utilized as synthesis tool in order to obtain novel materials by precipitation method.

Bimetallic TiO Nanoparticles for Lignin-Based Model Compounds Valorization by Integrating an Optocatalytic Flow-Microreactor.

The challenge of improving the activity of TiO by modifying it with metals and using it for targeted applications in microreactor environments is an active area of research. Recently, microreactors have emerged as successful candidates for many photocatalytic reactions, especially for the selective oxidation process. The current work introduces ultrasound-assisted catalyst deposition on the inner walls of a perfluoro-alkoxy alkane (PFA) microtube under mild conditions.

Titania/chitosan-lignin nanocomposite as an efficient photocatalyst for the selective oxidation of benzyl alcohol under UV and visible light.

Developing functional materials from biomass is a significant research subject due to its unique structure, abundant availability, biodegradability and low cost. A series of chitosan-lignin (CL) composites were prepared through a hydrothermal method by varying the weight ratio of chitosan and lignin. Subsequently, these CL composites were combined with titania (T) to form a nanocomposite (T/CL) using sol-gel and hydrothermal based methods.

Correction: Titania/chitosan-lignin nanocomposite as an efficient photocatalyst for the selective oxidation of benzyl alcohol under UV and visible light.

[This corrects the article DOI: 10.1039/D1RA06500A.].

Selective Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran by Visible Light-Driven Photocatalysis over In Situ Substrate-Sensitized Titania.

Solar energy-driven processes for biomass valorization are priority for the growing industrialized society. To address this challenge, efficient visible light-active photocatalyst for the selective oxidation of biomass-derived platform chemical is highly desirable. Herein, selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) was achieved by visible light-driven photocatalysis over titania.

Correction: A novel biomass-based support (Starbon) for TiO hybrid photocatalysts: a versatile green tool for water purification.

[This corrects the article DOI: 10.1039/C3RA43673J.].

Development of photocatalyst coated fluoropolymer based microreactor using ultrasound for water remediation.

Formation of thin layers of photocatalyst in photo-microreactor is a challenging work considering the properties of both catalyst and the microchannel material. The deposition of semiconductor materials on fluoropolymer based microcapillary requires the use of economical methods which are also less energy dependent. The current work introduces a new method for depositing nanoparticles of TiO on the inner walls of a hexafluoropropylene tetrafluoroethylene microtube under mild conditions using ultrasound technique.

Self-diffusion in nanocrystalline alloys.

We report an operando XRD/MS experiment on a nanocrystalline Pd(70%)Ag(30%) alloy supported on silica (10 wt% of metal) monitoring slow reversible Pd (in CO) and subsequently Ag (in He) surface segregation at 673 K. XRD data following CO and He flow show structural changes that can be modeled and interpreted in terms of the diffusion phenomena within a typical metal nanocluster. Qualitative differences in the rate of both segregation processes suggest different diffusion mechanisms as the Pd segregation involves vacancy depletion.

Sonophotodeposition of bimetallic photocatalysts Pd-Au/TiO2 : application to selective oxidation of methanol to methyl formate.

The aim of this work is to develop bimetallic Pd-Au/TiO2 P90 systems, which are highly active and selective for the photocatalytic oxidation of methanol to form methyl formate. Modification of commercial TiO2 P90 with Pd-Au nanoparticles was successfully achieved for the first time by means of a sonophotodeposition (SPD) method. The prepared materials were characterized by TEM, UV/Vis spectroscopy, X-ray photoelectron spectroscopy, and powder XRD.