Conversion of Biomass into Chemicals over Metal Catalysts

One-dimensional (1D) ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications. This article gives a comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods. We will cover the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronic, and energy harvesting devices.

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One-dimensional ZnO nanostructures: Solution growth and functional properties

Lignocellulosic biomass is the most abundant and bio-renewable resource with great potential for sustainable production of chemicals and fuels. This critical review provides insights into the state-of the-art accomplishments in the chemocatalytic technologies to generate fuels and value-added chemicals from lignocellulosic biomass, with an emphasis on its major component, cellulose. Catalytic hydrolysis, solvolysis, liquefaction, pyrolysis, gasification, hydrogenolysis and hydrogenation are the major processes presently studied. Regarding catalytic hydrolysis, the acid catalysts cover inorganic or organic acids and various solid acids such as sulfonated carbon, zeolites, heteropolyacids and oxides. Liquefaction and fast pyrolysis of cellulose are primarily conducted over catalysts with proper acidity/basicity. Gasification is typically conducted over supported noble metal catalysts. Reaction conditions, solvents and catalysts are the prime factors that affect the yield and composition of the target products. Most of processes yield a complex mixture, leading to problematic upgrading and separation. An emerging technique is to integrate hydrolysis, liquefaction or pyrolysis with hydrogenation over multifunctional solid catalysts to convert lignocellulosic biomass to value-added fine chemicals and bio-hydrocarbon fuels. And the promising catalysts might be supported transition metal catalysts and zeolite-related materials. There still exist technological barriers that need to be overcome (229 references).

http://www.chtf.stuba.sk/~szolcsanyi/education/files/Chemia%20heterocyklickych%20zlucenin/Prednaska%207/Doplnkove%20studijne%20materialy/Hydroxymethylfurfural/Catalytic%20conversion%20of%20lignocellulosic%20biomass%20to%20fine%20chemicals%20and%20fuels.pdf

Catalytic conversion of lignocellulosic biomass to fine chemicals and fuels

Recent development in 2D materials beyond graphene

Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the...

Green and Sustainable Solvents in Chemical Processes

Selective hydrolysis of cellulose into glucose over solid acid catalysts

In this work, the catalytic conversion of monosaccharides, such as d -glucose, d -fructose, d -mannose, d -galactose, and d -xylose, into lactic acid and aldonic acid in an alkaline media using supported noble metal catalysts under flowing air was investigated. Thus far, the conventional chemical conversions of d -glucose into lactic acid, such as alkaline degradations and hot water reactions, involved large amounts of by-products including unidentified compounds. To improve the atom economy for the d -glucose conversion, we examined a one-pot reaction of d -glucose into lactic acid and gluconic acid with the alkaline degradation and the air oxidation using supported metal catalysts. It succeeded in yielding about 45 C-% of lactic acid and about 45 C-% of gluconic acid from d -glucose using Pt/C catalysts with a 1.0 mol L −1 of sodium hydroxide aqueous solution at 353 K under flowing air.

A new chemical process for catalytic conversion of D-glucose into lactic acid and gluconic acid

We report for the first time on the controlled hydrothermal synthesis of barium titanate nanostructures using Na2Ti3O7 nanotubes and nanowires as synthetic precursors. A variety of nanostructured BaTiO3 have been prepared, exhibiting either simple shapes of nanowires, nanosheets, nanocubes, and hexagonal nanoparticles or ordered architectures of coral-like nanostructures of assembled nanorods, starfish-like nanostructures, and sword-like nanostructures. The shapes of the various BaTiO3 products are found to be dependent on the concentration of Ba(OH)2, the temperature, and the nature of the precursors. The synthesis route exploits the differences in the hydrothermal stability of the Na2Ti3O7 nanotubes and nanowires and the temperature-dependent crystal structure of barium titanate. Various nanoblocks, including nanosheets and nanorods formed from the Na2Ti3O7 nanotubes and nanowires, respectively, grow and assemble to form the ordered BaTiO3 nanostructures. This represents a new approach that is capable o...

Shape-Controlled Monocrystalline Ferroelectric Barium Titanate Nanostructures: From Nanotubes and Nanowires to Ordered Nanostructures

This paper presents a study on the synthesis and characterization of ZnO nanoparticles by a two-step synthesis procedure. The first step is the solution-free mechanochemical synthesis of ZnC2O4?2H2O nanoparticles by grinding a powder mixture of Zn(CH3COO)2 and H2C2O4?2H2O at room temperature for a certain time. The second step is the thermal decomposition of ZnC2O4?2H2O nanoparticles at 450??C to form ZnO nanoparticles. The obtained ZnO nanoparticles have been structurally characterized by x-ray diffraction, indicating a wurtzite structure (hexagonal phase, space group P63mc) with high crystallinity. The average grain size of the ZnO nanoparticles is in the range of 24?40?nm, depending on the mechanical grinding time. The UV?vis diffuse reflectance spectrum of the ZnO nanoparticles indicates a band gap of about 3.3?eV with an onset of absorption at about 3.1?eV, showing a weak red shift compared to 3.37?eV for the bulk ZnO. X-ray photoelectron spectroscopy and Raman spectra showed a nonadsorption on the surface and a very low concentration of oxygen vacancies, respectively, indicating a high quality of the prepared ZnO nanoparticles. The formation process of the ZnC2O4?2H2O nanoparticles by?the solution-free mechanochemical reaction is discussed.

https://iopscience.iop.org/article/10.1088/0957-4484/17/20/013/pdf

Direct synthesis of ZnO nanoparticles by a solution-free mechanochemical reaction

The solid solutions in the systems of Ca-Cd HAp [Ca 10− x Cd x HAp ( x  = 0–10)], Ca-Sr HAp [Ca 10− x Sr x HAp ( x  = 0–10)] and Ca-Pb HAp [Ca 10− x Pb x HAp ( x  = 0–10)], were successfully synthesized at 200 °C for 12 h under hydrothermal conditions. The site of the metal ions in the solid solutions was analyzed by the Rietveld method. The results of the Rietveld analysis indicated that the metal ions of Pb 2+ , Sr 2+ , and Cd 2+ all preferentially occupied M (2) sites in the apatite structure. The preferential occupancy of the metal ions in M (2) sites were explained mainly by their ionic radius and electronegativity.

Kazumichi Yanagisawa

Papers

Selective hydrolysis of cellulose into glucose over solid acid catalysts

A new chemical process for catalytic conversion of D-glucose into lactic acid and gluconic acid

Shape-Controlled Monocrystalline Ferroelectric Barium Titanate Nanostructures: From Nanotubes and Nanowires to Ordered Nanostructures

Direct synthesis of ZnO nanoparticles by a solution-free mechanochemical reaction

Preferential occupancy of metal ions in the hydroxyapatite solid solutions synthesized by hydrothermal method