Production and Characterization of Bio-Chars and Bio-Oils Formed by Pyrolysis of Persian Hogweed (Heracleum persicum Desf.) in A Fixed-Bed Reactor
Pages 205-215
Tevfik Aysu

DOI: http://dx.doi.org/10.6000/1929-5030.2013.02.04.1

Published: 25 November 2013

Abstract: Pyrolysis of Persian Hogweed(Heracleum persicum Desf.) stalks were performed in a fixed-bed tubular reactor with (K₂CO₃, ZnCl₂) and without catalyst at three different temperatures (400, 500 and 600 ^oC) with a constant heating rate of 50 ^oC/min. and with a constant sweeping gas (N₂) flow rate of 100 cm³/min. The amounts of bio-char, bio-oil and gas produced were calculated and the compositions of the obtained bio-oils were characterized by GC-MS. The effects of pyrolysis parameters such as temperature and catalyst on the product yields were investigated. According to the results, both temperature and catalyst had significant effects on the conversion of Heracleum persicum Desf.into bio-chars, bio-oils and gaseous products. The highest bio-oil yield of 41.42% by weight including aqeous phase was achieved with 10% potassium carbonate catalyst at 500 ^oC. 71 different compounds were identified by GC-MS in the bio-oils obtained at 500 ^oC.

Pyrrolidinyl Group as Charge Donor for the Excited State Intramolecular Chargetransferin 3-(4-methoxyphenyl)-1-(4-(pyrrolidin-1-yl) phenyl) Prop-2-en-1-one
Pages 72-82
Nidhi Mishra, Kamal Kumar Chaudhary and Satish Kumar Awasthi

DOI: http://dx.doi.org/10.6000/1929-5030.2015.04.01.6

Published: 25 Feburary 2015

Abstract: The absorption and steady state emission properties of a chemically synthesizedchalcone, 3-(4-methoxyphenyl)-1-(4-(pyrrolidin-1-yl) phenyl) prop-2-en-1-one (MPPP) containingasymmetrical donor and acceptor groups has been investigated both experimentally andtheoretically. The ground state, MPPP has a significant intramolecular charge transfer (ICT) character and a great sensitivity to the hydrogen bond donating ability of the medium as reflected from the absorption spectra in pure non polar, polar and neutral solvents. On the other hand, its excited singlet state exhibits high ICT characters as manifested by the drastic solvatochromic effects. These results are consistent with the data. The absorption spectra of the compound MPPP undergoes minor changes with increasing polarity of the solvents and the fluorescence spectra experiences a distinct bathochromic shifts in the both position and fluorescence quantum yields, increases reaching a maximum before decrease with increasing the solvent effects. The quantum yields decrease with increase in the solvent polarity. The magnitude of change in the dipole moment was also calculated using Austin Model 1 (AM1). These results suggest that the evidence about the intramolecular charge transfer in the emitting singlet state of this compound. The solvent dependence of quantum yields of MPPP was interpreted on the basis of positive and negative solvatokinetic as well as hydrogen bonding effects. Intramolecular charge (ICT) transfer took place from pyrrolidine nitrogen to α, β unsaturated carbonyl in the ground state..

Production and Characterization of Energy Materials with Adsorbent Properties by Hydrothermal Processing of Corn Stover with Subcritical H₂O
Pages 117-130
N.T. Machado, D.A.R. de Castro, L.S. Queiroz, M.C. Santos and C.E.F. da Costa

DOI: http://dx.doi.org/10.6000/1929-5030.2016.05.03.2

Published: 17 October 2016

Abstract: This work aims to investigate the effect of temperature on the process performance of hydrothermal processing (HTC) of corn Stover with subcritical H₂O and on the morphology of solid products. The experiments were carried out at 200, 225 and 250 ºC, reaction time of 240 minutes, heating rate of 2.0 ºC/min, and biomass to water ratio of 1:10, using a pilot scale stirred tank reactor (STR) of 5 gallon, operating in batch mode. The process performance analyzed by computing the yields of solid and liquid reaction products (RLP). The aqueous phase (H₂O + RLP) was physicochemical analyzed for pH and total carboxylic acids, expressed as total acetic acid content. The chemical compositions of carboxylic acids, furfural, and hydroxymethylfurfural (HMF) in the aqueous phase determined by GC-MS and HPLC. The results showed solid yields ranging from 57.39 to 35.82% (wt.), and liquid reaction products (RLP) yields ranging from 39.53 to 54.59% (wt.). The solid phase products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The chemically activated (2.0 M NaOH) solid phase energy material obtained by HTC at 250°C, applied as adsorbent to investigate the capacity and/or efficiency to adsorb acetic acid from 1.0 to 4.0 g/L model solutions at 25 °C. The solid phase yield decreases along with the temperature, showing an inflection region between 200 and 225 °C, whereas a drastic change takes place, while that of liquid phase increases, showing also a drastic change between 200 and 225 °C. The total acetic acid content of aqueous phase varied from 4064 to 5387 mg/L, while the pH from 3.77 to 3.91. The GC analysis identified the presence of volatile carboxylic acids, particularly acetic acid, in concentrations between 4020 and 5040 mg/L. HPLC identified the presence of furfural and hydroxymethylfurfural, whose concentrations decrease exponentially and linearly along with the temperature between 686.7 and 0.0, and 443.9 and 0.0 mg/L, respectively, being both compounds not detectable at 250 °C. The elemental/ultimate analysis of solid products shows that carbon content increases, while the oxygen and hydrogen contents decrease, along with the temperature. The H/C and O/C ratios decrease linearly as process temperature increases, and the high heating value (HHV) of solid reaction products, an energy densified material, changes sharply between 200 and 225 °C, showing an increase with temperature. The SEM, EDX, and XDR indicates a change on the morphology and mineralogical phases present in solid reaction products with temperature, particularly at 250 °C. The activated solid phase has proven to be very selective to adsorb acetic acid, showing that recovery of acetic acid from hydrothermal carbonization/liquefaction aqueous solutions is feasible by using a multistage-stage adsorption process in series.

Recent Advances on Design and Synthesis of Chiral Imidazolium Ionic Liquids and their Applications in Green Asymmetric Synthesis
Pages 3-20
Arijit Saha, Soumen Payra and Subhash Banerjee

DOI: http://dx.doi.org/10.6000/1929-5030.2016.05.01.1

Published: 26 February 2016

Abstract: Over the past decade, catalysis by ionic liquids (ILs) has experienced a tremendous growth in the context of “Green Chemistry”, and there are numerous examples of a variety of catalytic reactions that have been successfully carried out in such neoteric media. The great enthusiasm for catalysis in ILs is not only driven by the curiosity of chemists, but also due to the growing awareness of developing greener reactions or process media in catalytic science and greener catalytic technologies due their advantages of unique physical and chemical properties as compared to traditional volatile organic solvents. Recently, development of chiral ionic liquids and their applications in asymmetric synthesis have attracted much attention as these reactions have widespread applications in the synthesis of chiral drugs and pharmaceutical industries. Asymmetric induction is mainly achieved by the use of chiral substrates or reagents, chiral catalysts or enzymes. Owing to the vast number of structurally different room temperature ILS that have been synthesized, this review focuses on imidazolium ionic liquids that possess chirality either in the imidazolium moiety or in the anion moiety. The aim of this review is to highlight the recent breakthrough of Chiral ILs in chirality transfer or chiral recognition when used as solvent or co-solvent: the case of task specific ionic liquids is beyond the scope of this review. In the first part, the synthesis of of CILs has been presented and the second part of the review has been devoted on the applications of such CILs in green asymmetric synthesis as well as various pharmaceutical industries.