3.2.3. Hydroformylation 2467 3.2.4. Dimerization 2468 3.2.5. Oxidative Cleavage and Ozonolysis 2469 3.2.6. Metathesis 2470 4. Terpenes 2472 4.1. Pinene 2472 4.1.1. Isomerization: R-Pinene 2472 4.1.2. Epoxidation of R-Pinene 2475 4.1.3. Isomerization of R-Pinene Oxide 2477 4.1.4. Hydration of R-Pinene: R-Terpineol 2478 4.1.5. Dehydroisomerization 2479 4.2. Limonene 2480 4.2.1. Isomerization 2480 4.2.2. Epoxidation: Limonene Oxide 2480 4.2.3. Isomerization of Limonene Oxide 2481 4.2.4. Dehydroisomerization of Limonene and Terpenes To Produce Cymene 2481

Chemical Routes for the Transformation of Biomass into Chemicals

A review on the utilization of fly ash

ion from a primary OH group of glyc-erol. 223,231 A similar mechanism was proposed manyyears ago for alcohol oxidation on Pt/C, involving asecond step, the transfer of a hydride ion to the Ptsurface (Scheme 11). 8,87,237 We consider it more feasible that the rate-deter-mining step is the cleavage of the C-H bond at theR-carbon atom. A similar mechanism is now generallyaccepted for Au electrodes (Scheme 12). 238 Despite thestructural differences between Au nanoparticles andan extended Au electrode surface, there are alsosimilarities, such as the critical role of aqueousalkaline medium and the absence of deactivation dueto decomposition products (CO and C x H y frag-ments). 239,240 An important question is the nature of active siteson Au nanoparticles. Electrooxidation of ethanol onAu nanoparticles supported on glassy carbon re-quired the partial coverage of Au surface by oxides. 241 Another analogy might be the model proposed for COoxidation. 219,242,243 According to this suggestion, theactive site consists of an ensemble of metallic Auatoms and a cationic Au

Oxidation of Alcohols with Molecular Oxygen on Solid Catalysts

Proteolytic enzymes are ubiquitous in occurrence, being found in all living organisms, and are essential for cell growth and differentiation. The extracellular proteases are of commercial value and find multiple applications in various industrial sectors. Although there are many microbial sources available for producing proteases, only a few are recognized as commercial producers. A good number of bacterial alkaline proteases are commercially available, such as subtilisin Carlsberg, subtilisin BPN′ and Savinase, with their major application as detergent enzymes. However, mutations have led to newer protease preparations with improved catalytic efficiency and better stability towards temperature, oxidizing agents and changing wash conditions. Many newer preparations, such as Durazym, Maxapem and Purafect, have been produced, using techniques of site-directed mutagenesis and/or random mutagenesis. Directed evolution has also paved the way to a great variety of subtilisin variants with better specificities and stability. Molecular imprinting through conditional lyophilization is coming up to match molecular approaches in protein engineering. There are many possibilities for modifying biocatalysts through molecular approaches. However, the search for microbial sources of novel alkaline proteases in natural diversity through the "metagenome" approach is targeting a hitherto undiscovered wealth of molecular diversity. This fascinating development will allow the biotechnological exploitation of uncultured microorganisms, which by far outnumber the species accessible by cultivation, regardless of the habitat. In this review, we discuss the types and sources of proteases, protease yield-improvement methods, the use of new methods for developing novel proteases and applications of alkaline proteases in industrial sectors, with an overview on the use of alkaline proteases in the detergent industry.

Bacterial alkaline proteases: molecular approaches and industrial applications

Post-combustion CO2 capture from the flue gas is one of the key technology options to reduce greenhouse gases, because this can be potentially retrofitted to the existing fleet of coal-fired power stations. Adsorption processes using solid sorbents capable of capturing CO2 from flue gas streams have shown many potential advantages, compared to other conventional CO2 capture using aqueous amine solvents. In view of this, in the past few years, several research groups have been involved in the development of new solid sorbents for CO2 capture from flue gas with superior performance and desired economics. A variety of promising sorbents such as activated carbonaceous materials, microporous/mesoporous silica or zeolites, carbonates, and polymeric resins loaded with or without nitrogen functionality for the removal of CO2 from the flue gas streams have been reviewed. Different methods of impregnating functional groups, including grafting techniques and modifying the support materials, have been discussed to en...

Post-Combustion CO2 Capture Using Solid Sorbents: A Review

Hydrothermal treatment of fly ash with alkali gives various types of zeolites such as Na-Pl, Na-A and hydroxysodalite, where the zeolite zone was formed like an egg white, covering the central core of fly ash particles, as evinced in the previous paper. By fusion with sodium hydroxide, most of the fly ash particles were converted into sodium salts such as silicate and aluminate, from which hydrothermal reaction without stirring favourably resulted in the formation of Na-X zeolite. Crystallinity of Na-X zeolite as high as 62% was attained at the optimum condition of NaOH/fly ash = 1.2 and a fusion temperature of 823 K. Fly ash contains 14 wt% mullite (3Al2O3·2SiO2), which was revealed to be a less-active crystalline component for zeolite formation. Aluminium-enriched fly ash gave Na-A in place of Na-X zeolite. Scanning electron microscope images of cubic and octahedral crystals characteristic of Na-A and Na-X zeolite, respectively, obtained from fly ash, are given.

Selective formation of Na-X zeolite from coal fly ash by fusion with sodium hydroxide prior to hydrothermal reaction

Preparation and phosphate ion-exchange properties of a hydrotalcite-like compound

An efficient chemical absorption method capable of cyclic fixed-bed operations under moist conditions for the recovery of carbon dioxide from flue gases has been proposed employing K2CO3-on-carbon. Carbon dioxide was chemically absorbed by the reaction K2CO3 + CO2 + H2O ⇄ 2KHCO3 to form potassium hydrogencarbonate. Moisture, usually contained as high as 8−17% in flue gases, badly affects the capacity of conventional adsorbents such as zeolites, but the present technology has no concern with moisture; water is rather necessary in principle as shown in the equation above. Deliquescent potassium carbonate should be supported on an appropriate porous material to adapt for fixed-bed operations. After breakthrough of carbon dioxide, the entrapped carbon dioxide was released by the decomposition of hydrogencarbonate to shift the reaction in Eq.1 in reverse on flushing with steam, which could be condensed by cooling to afford carbon dioxide in high purity. Among various preparations of alkaline-earth carbonates (...

Hiromu Hayashi

Papers

Selective formation of Na-X zeolite from coal fly ash by fusion with sodium hydroxide prior to hydrothermal reaction

Preparation and phosphate ion-exchange properties of a hydrotalcite-like compound

Efficient Recovery of Carbon Dioxide from Flue Gases of Coal-Fired Power Plants by Cyclic Fixed-Bed Operations over K2CO3-on-Carbon

The properties of heteropoly acids and the conversion of methanol to hydrocarbons

Oxidation of propylene glycol and lactic acid to pyruvic acid in aqueous phase catalyzed by lead-modified palladium-on-carbon and related systems