Solid acid-catalyzed dehydration/Beckmann rearrangement of aldoximes: towards high atom efficiency green processes

Rare earth metal ion exchanged (La3+, Ce3+, RE3+) KFAU-Y zeolites were prepared by simple ion-exchange methods and have been characterized using different physico-chemical techniques. In this paper a novel application of solid acid catalysts in the dehydration/ Beckmann rearrangement of aldoximes; benzaldoxime and 4-methoxybenzaldoxime is reported. Dehydration/Beckmann rearrangement reactions of benzaldoxime and 4-methoxybenzaldoxime is carried out in a continuous down flow reactor at 473K. 4-Methoxybenzaldoxime gave both Beckmann rearrangement product (4-methoxyphenylformamide) and dehydration product (4-methoxybenzonitrile) in high overall yields. The difference in behavior of the aldoximes is explained in terms of electronic effects. The production of benzonitrile was near quantitative under heterogeneous reaction conditions. The optimal protocol allows nitriles to be synthesized in good yields through the dehydration of aldoximes. Time on stream studies show a fast decline in the activity of the catalyst due to neutralization of acid sites by the basic reactant and product molecules.

Development of integrated separation processes with green solvents

Dissertação para obtenção do Grau de Doutor em Química Sustentável

Electrochemistry and green chemical processes: electrochemical ozone production

After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

Preparazione di una resina epossidica bio-based e studio delle relative proprietà

Epoxy resins are very diffused materials due to their high added value deriving from high mechanical proprieties and thermal resistance; for this reason they are widely used both as metallic coatings in aerospace and in food packaging. However, their preparation uses dangerous reagents like bisphenol A and epichlorohydrin respectively classified as suspected of causing damage to fertility and to be carcinogen. Therefore, to satisfy the ever-growing attention to environmental problems and human safeness, we are considering alternative “green” processes through the use of reagents obtained as by-products from other processes and mild experimental conditions, and also economically sustainable and attractive for industries. Following previous results, we carried out the reaction leading to the formation of diphenolic acid (DPA), its allylation and the following epoxidation of the double bonds, all in aqueous solvent. In a second step the obtained product were cross-linked at high temperature with and without the use of hardeners. Then, on the obtained resin, some tests were performed like release in aqueous solution, scratch test and DSC analysis.

Catalysts study of adipic acid synthesis from 1,6-hexanediol

Sustainable chemicals currently have a very limited market share due to current low production but biomass is expected to become one of the major renewable energy and fine chemicals sources in the coming years. Bearing in mind the compromise of all nations to climatic change remediation, the industries will need to use efficient catalysts and green processes to meet the requirements of emissions and efficiency. This project is expected to develop new catalysts to convert 1,6-hexanediol to adipic acid through a green approach based on the “nano-catalysis” and “green chemistry” concepts. Supported Au and Pd nanoparticles were used to study one-pot reaction of HDO oxidation to AA using O2 as a final oxidant and H2O as a solvent. Catalytic results showed that under low pressure O2 atmosphere and low temperature (< 120°C) AuNPs supported on basic-supports are more active than acid and amphoteric oxides. The effect of basic oxide (MgO) addition to MgF2 was studied. The study showed that doping of MgF2 with MgO increased significantly the activity of the catalyst. The best results were obtained with the Au/0.4MgF2-0.6MgO sample, which gave the selectivity to AA of 33% at HDO conversion of 62%.

Supported metal nanoparticles for sustainable green catalytic processes

Preformed Au nanoparticles supported on activated carbon and TiO2 were synthesised by sol-immobilisation. Polyethylene glycol, polyvinyl pyrrolidone and polyvinyl alcohol were used as stabilisers for the gold nanoparticles at different polymer/Au wt/wt ratios for each polymer. The effect of polymer/Au wt/wt ratios was investigated on (i) the average nanoparticle size, (ii) catalytic activity for two reactions, 4-nitrophenol reduction and glucose oxidation to glucaric acid. 4-nitrophenol reduction is recognised as a model reaction for nanomaterial catalytic activity tests; glucose oxidation to glucaric acid is a reaction that is traditionally carried out with concentrated nitric acid, for which alternative reaction pathways are looked for in an effort to reduce its environmental impact. The catalysts were characterised from the nanoparticle synthesis by colloidal method by means of UV-vis spectroscopy and DLS analysis, to the immobilisation step by XRD and TEM. The effect of the polymer:Au wt/wt ratio on nanoparticle size depends on the polymer nature, and point out the need to optimise supported nanoparticle synthesis protocols in the future depending on the type of stabiliser. The catalytic tests revealed that the polymers interact with Au nanoparticles through different active sites. Activated carbon (AC) and TiO2 were compared as supports for Au nanoparticles stabilised by PVA at PVA/Au 0,65 wt/wt. AC-supported Au NPs were the most active for glucose oxidation while TiO2-stabilised Au NPs were five times more active in 4-nitrophenol reduction that AC-supported NPs. Hence support and stabiliser are important parameters that should be optimised in order to achieve high catalytic activity for a given reaction.

Green production of zero-valent iron nanoparticles using tree leaf extracts

The interest in zero-valent iron nanoparticles has been increasing significantly since the development of a green production method in which extracts from natural products or wastes are used. However, this field of application is yet poorly studied and lacks knowledge that allows the full understanding of the production and application processes. The aim of the present work was to evaluate the viability of the utilization of several tree leaves to produce extracts which are capable of reducing iron(III) in aqueous solution to form nZVIs. The quality of the extracts was evaluated concerning their antioxidant capacity. The results show that: i) dried leaves produce extracts with higher antioxidant capacities than non-dried leaves, ii) the most favorable extraction conditions (temperature, contact time, and volume:mass ratio) were identified for each leaf, iii) with the aim of developing a green, but also low-cost,method waterwas chosen as solvent, iv) the extracts can be classified in three categories according to their antioxidant capacity (expressed as Fe(II) concentration): >40 mmol L−1; 20–40 mmol L−1; and 2–10 mmol L−1; with oak, pomegranate and green tea leaves producing the richest extracts, and v) TEManalysis proves that nZVIs (d=10–20 nm) can be produced using the tree leaf extracts.

Development of biocompatible and “smart” porous structures using CO2-assisted processes

Dissertação apresentada para a obtenção do grau de Doutor em Engenharia Química, especialidade Engenharia da Reacção Química, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Development of thermoresponsive (polysulfone/polyacrylonitrile) - based membranes for bioseparation processes

Mestrado integrado em Engenharia Química e Bioquímica

An information model for lean, agile, resilient and green supply chain management

Dissertação para a obtenção de Grau de Mestre em Engenharia e Gestão Industrial

Continuous catalyst free production of biodiesel from agro industrial waste with green solvents

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

Alternative solvents in separation processes

Dissertation presented to obtain the Ph.D degree in Sustainable Chemistry

Synthesis, characterization and applications of new schiff base fluorescent chemosensors for metal and DNA interactions: conventional and "green" approaches

Dissertação apresentada para a obtenção do Grau de Doutor em Química Sustentável, especialidade de Química-Física Inorgânica, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

One-pot enzymatic resolution/separation of enantiomers using green solvents

Dissertação para obtenção do Grau de Mestre em Biotecnologia

Modelling lean and green supply chain

Dissertação para obtenção do Grau de Doutor em Engenharia Industrial