Battegazzore D.,Polytechnic University of Turin |
Salvetti O.,Polytechnic University of Turin |
Frache A.,Polytechnic University of Turin |
Peduto N.,Radici Chimica SpA |
And 2 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2016
Composites consisting of fully (PA10.10) and partially (PA6.10) bio-based polyamides and 10-20 wt.% rice husk ash (RHA) was prepared by melt compounding. The mechanical analysis data showed that RHA induced significant improvement in Young's modulus, a slight reduction in the tensile strength and a large decrease in the deformation at break. Pukanszky's model was used to evaluate the filler-matrix interactions. The two PAs exhibited similar filler-matrix load transfer with RHA and better performance than polylactic acid (PLA). The addition of modified clay (Cloisite 30B) to the systems with 10 wt.% of RHA gave the best mechanical properties and filler-matrix interactions, notwithstanding the matrix used. Finally, DMT analyses demonstrated that the addition of RHA caused an increase in the heat deflection temperature (HDT) compared to the neat PA matrices. Furthermore, the simultaneous presence of RHA and clay provided the best results. © 2015 Elsevier Ltd.
Radici Chimica S.p.A. | Date: 2011-04-15
It is described a process for the production of hexamethylenediamine by hydrogenation of adiponitrile, comprising an improved step of regeneration of the catalyst. Also described are an equipment for the production of hexamethylenediamine, and a washing apparatus (
Antonetti C.,University of Pisa |
Galletti A.M.R.,University of Pisa |
Accorinti P.,Radici Chimica SpA |
Alini S.,Radici Chimica SpA |
And 8 more authors.
Applied Catalysis A: General | Year: 2013
In this paper we compare two different reactions, aimed at the synthesis of 1,2-cyclohexanediol. Specifically: (a) the direct epoxidation and hydrolysis (dihydroxylation) of cyclohexene to trans-1,2-cyclohexanediol, with an aqueous solution of hydrogen peroxide, and (b) the hydrogenation of catechol to a mixture of cis and trans-1,2-cyclohexanediol, in an attempt to establish green protocols for the synthesis of diols. Both reactions, the dihydroxylation of cyclohexene and the hydrogenation of catechol, were carried out without organic solvents. In the former case, an unprecedented 97.4% yield to the glycol was obtained, by selecting proper reaction conditions and using a tungstic acid/phosphoric acid catalyst, in a biphasic system with a phase-transfer agent. In the second approach, a heterogeneous alumina-supported Ru(OH)x catalyst was used, and a 90% yield to the glycol was obtained. A comparison of the two processes allowed to show the lower environmental impact of the catechol hydrogenation route. © 2013 Elsevier B.V. All rights reserved.
Cavani F.,University of Bologna |
Ferroni L.,University of Bologna |
Frattini A.,University of Bologna |
Lucarelli C.,University of Bologna |
And 5 more authors.
Applied Catalysis A: General | Year: 2011
This report deals with the results of a study on the oxidation of cyclohexanone to adipic acid with air, catalysed by Keggin-type polyoxometalates of composition H3+xPMo12-xVxO40 (x = 1 and 2), which was carried out in a semi-continuous stirred-tank reactor. It was found that when conducted in the presence of a water-only solvent, the reaction proceeds with a redox mechanism, in which the step of reoxidation of the reduced POM by oxygen is rate limiting. When, however, the reaction was carried out with an acetic acid co-solvent, a radical-chain autoxidation mechanism prevailed, especially when very low amounts of catalyst were used. Autoxidation overlapped with the redox mechanism when the catalyst-to- cyclohexanone ratio was increased. Moreover, the composition of the polyoxometalate, that is, the number of V atoms per Keggin unit, affected the relative importance of the two mechanisms. The selectivity to adipic acid achieved was a function of the reaction mechanism, but also was affected by cyclohexanone conversion, due to the presence of a complex reaction network. © 2010 Elsevier B.V. All rights reserved.
Rozhko E.,University of Bologna |
Raabova K.,University of Bologna |
Macchia F.,University of Bologna |
Malmusi A.,University of Bologna |
And 7 more authors.
ChemCatChem | Year: 2013
The aerobic oxidation of trans-1,2-cyclohexanediol in the synthesis of adipic acid was studied. Two classes of catalysts are compared, 1)alumina-supported Ru(OH)3, and 2)Keggin type P/Mo/V polyoxometalates. These two classes are representative examples because they are active in alcohol oxidation under quite different reaction conditions. In the former case, basic conditions are needed in order to activate the substrate, whereas with polyoxometalates, acidic conditions are used. Their catalytic behavior showed remarkable differences; in basic conditions, the reaction network was very complex, and several side reactions led to a number of by-products, with a low selectivity to adipic acid in the end. The supported Ru(OH)3 catalyst was very efficient in 1,2-cyclohexanediol oxidative dehydrogenation to 1,2-cyclohexanedione, but several undesired reactions occurred starting from this key intermediate under basic conditions: rearrangement into 6-hydroxycaprolactone and 1-hydroxycyclopentanecarboxylic acid, and formation of the product of aldol condensation. The former compound was also an intermediate for adipic acid formation, but this reaction gave only a minor contribution to the reactant conversion. Polyoxometalates were extremely selective in 1,2-cyclohexanediol conversion into adipic acid, but under acidic conditions the product reacted with the unconverted reactant to yield the corresponding ester. © 2013 WILEY-VCH Verlag GmbH & Co.