Pier Luigi Beltrame

Crystallization and thermal behaviour of poly(D(-) 3-hydroxybutyrate)/poly(epichlorohydrin) blends

Abstract Atactic poly(epichlorohydrin) (PECH) was blended in a wide range of ratios with poly(D(−)3-hydroxybutyrate) (PHB) isolated from Alcaligenes eutrophus cultures. The crystallization and thermal behaviour of PHB/PECH blends were analysed by d.s.c. and microscopy. All blends show a single glass transition temperature, whose value is dependent on composition, in good agreement with the theoretical values calculated by the Fox equation. The influence of blend composition on the overall crystallization rate and on the spherulite growth rate suggests that the two components form a miscible blend in the amorphous phase. The equilibrium melting temperature decreases with blending; the negative value of the χ12 parameter of the PHB/PECH system suggests that the two components can form a miscible mixture which is thermodynamically stable above the equilibrium melting temperature. The reorganization phenomenon of PHB crystals after first melting was also observed.

Thermal cracking of petroleum residues: 1. Kinetic analysis of the reaction

Abstract In order to define a kinetic scheme and to calculate the kinetic parameters of the thermal cracking of petroleum residues, a vacuum residue of Belaym crude was thermally cracked at 410, 430, 450 and 470 °C for reaction times up to 120 min. The concentration of three pseudo-components, namely vacuum residue, distillate and coke, was detected during conversion and the data from these experiments were used for the definition of the kinetic model. Distillate production can be described as a simple first-order reaction while coke formation seems to be the consequence of consecutive reactions, in particular involving asphaltenes. A study of the structural changes of asphaltenes as a function of severity was also performed and the variations of the average molecular parameters with conversion were correlated. The results of this work have been used as reference data for a subsequent study of residue conversion in the presence of hydrogen-donor solvents.

Alkylation of phenol with methanol over zeolites

Abstract The reaction of phenol with methanol was carried out over five X-, six Y- and three ZSM-zeolites, in a fixed-bed continuous reactor at 250°C. Alkylation products were cresols (o>p>m), anisole, xylenols and methylanisoles. The highest conversion and the highest yields of o- and p-cresols were obtained within the initial 5 h on-stream. Selectivity to o,p-cresols in the range 40-50% at phenol conversion 40-50% was reached on some X- and Y-zeolites, the best catalyst being HY.

Catalytic thermal degradation of polymers: Degradation of polypropylene

Silica, alumina, silica—alumina and zeolites were screened as catalysts for polypropylene degradation in the range 200–600 ° C. The more efficient catalysts for oil production yielded C5—C12 olefins. Gas chromatographic—mass spectrometric analysis of the reaction products gave information on the nature of the products and on the mechanism of the degradation.

Dyeing of Cotton in Supercritical Carbon Dioxide

Abstract The dyeing of cellulosic fibers with disperse and natural dyes was attempted using supercritical carbon dioxide (CO2SCF) as solvent system. The dye uptake was strongly increased if cotton was pretreated with polyethylene glycol (PEG), a known plasticizing agent of cellulose, while reasonable wet-washing and light fastness properties were achieved if PEG-treated cotton was dyed in CO2SCF with disperse dyes included in benzamide crystals. This might be a consequence of partial occlusion of cellulose pores by benzamide, forming hydrogen bonds with cotton and PEG.

Alkylation of phenol with anisole over zeolites or γ-alumina

Abstract The reaction of phenol with anisole was carried out over three X-, six Y-, a ZSM-5 and a ZSM-11 zeolites, and over γ-Al 2 O 3 , in a fixed-bed continuous reactor. Alkylation products were cresols (o>p>m), xylenols and methylanisoles; also some dealkylation of anisole to phenol occurred. Selectivity to cresols and xylenols in the range 45–60% and 25–30%, respectively, at anisole conversions of around 90%, were reached with HY and HNaY zeolites, and with γ-Al 2 O 3 , when operating over fresh catalysts. Alkylations were particularly ortho-selective over γ-Al 2 O 3 .

Inhibiting action of chloro- and nitro-phenols on biodegradation of phenol: A structure-toxicity relationship

Abstract All chlorophenols and six mono- and di-nitrophenols were tested, by discontinuous kinetic measurements, as inhibitors of the phenol degradation by activated sludge. The measured values of pI50 were correlated with structural properties (logP, ϵσ) of the substituted phenols, developing a QSAR.

Fractionation and bioconversion of steam-exploded wheat straw

Abstract Wheat straw was pretreated by steam explosion under various conditions. The capability of the process in inducing a high fractionation of the lignocellulosic material in its major components and the influence of the explosion conditions on the substrate susceptibility to the attack of cellulolytic enzymes have been investigated. Bioconversion was studied considering the cellulose-rich fraction obtained from product fractionation as well as the product directly obtained from the explosion treatment. Quantitative data in terms of rate and yield of hydrolysis have been obtained for the different conditions.

Kinetics of biodegradation of mixtures containing 2,4-dichlorophenol in a continuous stirred reactor

A solution containing 2,4-dichlorophenol (DCP) and phenol (or glucose), in the ratio 1:1 in terms of carbon, was fed to a completely mixed continuous flow reactor with recycle and controlled wasting of the activated sludge, operated at steady-state conditions at 20°C. A carefully adapted sludge was able to degrade DCP, besides the accompanying substrate, with no evidence of substrate inhibition in the concentration range covered (156 mg l−1 in the influent). The reactivity order was found to be glucose ⪢ phenol > DCP. The results of a series of kinetic runs with phenol + DCP were interpreted by a first-order equation for phenol and by the Monod model for DCP.

Thermal degradation of kerogen by hydrous pyrolysis. A kinetic study

Abstract Several hydrous pyrolysis kinetic runs have been carried out on a source rock sample from Northern Italy (type II kerogen) under isothermal conditions in the range 260–330°C and at 15–17 MPa in an argon atmosphere. The products have been quantified and grouped into four classes: light (gas + volatile liquids), saturate, aromatic, and heavy (asphaltenes + resins). The distribution of these classes as well as the bulk composition of the overall product was found to be fairly constant during the whole reaction course, suggesting that primary cracking prevails in the temperature range explored. The kinetic results have been interpreted regarding the degradation as the result of numerous simultaneous independent first-order reactions. The number, the relative importance and the Arrhenius parameters for such reactions have been evaluated using an optimization procedure. The best fitting of the experimental data was achieved considering three simultaneous reactions.