Carbon multi-recycle system

Global carbon-recycling energy delivery system for CO2 mitigation (I) Carbon one-time recycle system towards carbon multi-recycle system... 

For synthetic purposes hydroxypyruvate 119 can effectively replace the natural donor components [258]. Its covalent activation occurs at a reduced rate of about 4% relative to xylulose 5-phosphate (121) but is accompanied by spontaneous decarboxylation [262]. Thus, loss of carbon dioxide renders synthetic reactions irreversible whereas alternative donors, for example l-erythrulose, require coupling to cofactor recycling to shift the overall equilibrium [263]. The thermodynamic driving force from decarboxylation of 119 is particularly useful with equilibrating multi-enzyme systems such as that used in the gram-scale synthesis of two equivalents of 121 from 42 (Figure 5.54) [264]. 

Abstract Recent advances in the metal-catalyzed one-electron reduction reactions are described in this chapter. One-electron reduction induced by redox of early transition metals including titanium, vanadium, and lanthanide metals provides a variety of synthetic methods for carbon-carbon bond formation via radical species, as observed in the pinacol coupling, dehalogenation, and related radical-like reactions. The reversible catalytic cycle is achieved by a multi-component catalytic system in combination with a co-reductant and additives, which serve for the recycling, activation, and liberation of the real catalyst and the facilitation of the reaction steps. In the catalytic reductive transformations, the high stereoselectivity is attained by the design of the multi-component catalytic system. This article focuses mostly on the pinacol coupling reaction. 

U. Arena and M. L. Mastellone, Production of multi-wall carbon nanotubes by means of fluidized bed pyrolysis of virgin or recycled polymers, in Proceedings of ENS-European Nano Systems 2005, B. Courtois (ed.), ISBN 2-916187-02-2, pp. 7-12 (2005). 

Aldehyde linearity is high (ca. 90%). Sufficient N-methyl-pyrrolidone (NMP ca. 40%w) and some water (1 -2%w) are applied to achieve a one-phase system in the reactors. After reaction, water is added in a mixer (phase ratio 1 1 v/v), followed by efficient phase separation in a settler, with virtually all catalyst in the NMP/water layer. The crude product layer is subjected to a multi-stage water extraction to remove residual NMP and catalyst, and a final treatment over a silica-bed to reduce Rh leach levels from 0.2 ppmw to 0.02 ppmw. The recycle catalyst layer (in NMP/water) is dried in two steps, to evaporate water and achieve the low water concentrations required for one-phase reaction, and then recycled to the reactors. Water is recycled, from evaporators, via water extraction, to the mixer. The flexibility of this process with respect to alkene carbon number seems excellent good performance has been found for Cs-C aUcenes [61]. 

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