Presence Of Alkaline Catalyst Research Articles

Characterization of isolated lignin from eucalyptus wood chip obtained by liquid hot water process

In this study, we propose a novel optimization for lignin isolation from the eucalyptus wood chip (EWC) under hydrothermal liquid hot water (LWH) process in the presence of alkaline catalyst (NaOH). The optimal conditions were obtained employing response surface methodology (RSM). The optimal condition was 160°C for 30 min in the presence of alkaline catalyst of 0.020 M. This condition demonstrated the highest lignin extraction with solid fraction of 77.3% and 76.1%. In addition, the physicochemical structure of isolated lignin was characterized with diverse techniques. The lignin recovery from liquid phase’s GPC analysis illustrated a high average Mw/Mn (17500/7450 g/mol) while polydispersity index (2.34) was lower in comparison with the commercial organosolv lignin. The TGA analysis showed the maximum decomposition of lignin recovery at 140 to 350oC. Furthermore, the Py/GCMS analysis showed a predominance of 57.63% of syringyl units (S) over 37.37% of guaiacyl units (G) under optimal conditions. The results revealed that the integrated process was a potential approach to add more value in the employment of the agricultural waste material.

Optimization of Biodiesel Production from Used Cooking Oil: Aspen HYSYS Simulation and Experimental Validation

Due to the awareness of adverse effects of conventional fuels to environment and the frequent rise in crude oil price, the need for sustainable and environmentally friendly alternative source of energy has gained importance in recent years. This alternative has been identified to be biofuel, one of which is biodiesel. As such, this work was carried out to contribute to the development of biodiesel. The aim was accomplished by employing Design Expert, based on the chosen operating factors (reaction temperature and methanol-to-oil ratio), to design experiments carried out for the production of biodiesel using used cooking oil and methanol in the presence of alkaline catalyst. After carrying out the experiments using the design parameters generated, the results were analysed, and a model equation was developed for the system. Furthermore, the model equation was used to optimize the process using Excel Solver to obtain a temperature, a methanol-to-oil ratio and a yield of 63.45 °C, 3 and 59.32 as the optimum values, respectively. The optimum parameters estimated were validated experimentally and with the Aspen HYSYS model of the process that was also developed. The results obtained using the design factors showed that the factors considered were having effects on the yield of biodiesel. Also, the results of the experimental validation carried out with the optimum parameters obtained with the aid of Excel Solver were found to compare very well with those obtained from the simulation of the developed Aspen HYSYS model of the biodiesel production because the errors were estimated to be less than 5%. Therefore, the developed Aspen HYSYS model of biodiesel production of this work was able to represent the process very well and can be used for further studies on the process.

CHARACTERIZATION OF FATTY ACID METHYL ESTERS FROM OILS WITH DIFFERENT ORIGINS USING FOURIER TRANSFORM INFRARED SPECTROSCOPY

The fatty acid methyl esters (FAME) of triglycerides obtained by transesterification reaction in the presence of alkaline catalysts became a serious alternative of fossil fuels. In the present research FAME synthesized from five different in their chemical nature and composition vegetable oils were studied. The data for analysis and characterization of FAME was obtained using fourier transform infrared spectroscopy and then basic properties of biodiesel fuels were determined. The confirmation and validation of the results were proved by classical chemical methods of analysis. The ability for express analysis of biodiesel fuels by IR spectroscopy was confirmed and the achieved results are reliable basis for the biofuels stability research.

Catalytic hydrothermal upgradation of wheat husk

Catalytic hydrothermal upgradation of wheat husk was performed at 280°C for 15 min in the presence of alkaline catalysts (KOH and K2CO3). The effect of alkaline catalysts on the yield of bio-oil products and composition of bio-oils obtained were discussed. Total bio-oil yield (31%) comprising of bio-oil1 (ether fraction) and bio-oil2 (acetone fraction) was maximum with K2CO3 solution. Powder XRD (X-ray diffraction) analysis of wheat husk as well as bio-residue samples show that the peaks due to cellulose, hemicellulose and lignin become weak in bio-residue samples which suggest that these components have undergone hydrolytic cleavage/decomposition. The FTIR spectra of bio-oils indicate that the lignin in the wheat husk samples was decomposed to low molecular weight phenolic compounds. (1)H Nuclear Magnetic Resonance (NMR) spectrum of bio-oil1 shows more than 50% of the protons resonate in the up field region from 0.5 ppm to 3.0 ppm.

ChemInform Abstract: Mannich‐Type Reaction for Synthesis of 3‐Methyl‐4‐nitroimino‐tetrahydro‐1,3,5‐oxadiazine.

AbstractMannich reaction of N‐methyl‐N′‐nitroguanidine (I) in the presence of alkaline catalysts provides access to the title oxadiazine (III) and triazine derivative (IV).

Thermal risk analysis of cumene hydroperoxide in the presence of alkaline catalysts

Many studies have been performed to clarify the basic thermal runaway hazards and kinetics of cumene hydroperoxide (CHP) decomposition. However, materials that are incompatible with CHP have not been clearly identified. Alkaline solutions have been used as a catalyst to form dimethylphenyl carbinol (DMPC) and dicumyl peroxide (DCPO); however, these solutions also affect the reaction and storage temperature of CHP. In this study, thermal calorimeters, differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2), were used to compare the effects of various bases on the decomposition of CHP in cumene. Specifically, the exothermic onset temperature, change in pressure over time, self-heating rate and heat of decomposition were evaluated. Moreover, to appraise the degree of hazard associated with the use of CHP, the compatibility of CHP with various substances was analyzed, and a risk matrix for thermal runaway reactions was obtained. The results of the present study could be used to design safety procedures for the production of CHP and its derivatives.

High Functionality Polyether Polyols Based on Polyglycerol

Polyglycerol (PGL) is a polyhydroxyl compound obtained by selfcondensation of glycerol in the presence of alkaline catalysts. It is a very attractive polyol as a starter for the synthesis of polyether polyols for rigid polyurethane foams. It is liquid, easy to handle and has a very high average functionality of 4—20 (or more) hydroxyl groups/mol. By propoxylation of PGL or PGL—sucrose mixtures, we obtained new polyether polyols with very high functionalities, which are very difficult or impossible to obtain by other methods. A new technology for PGL-based polyether polyols preparation was investigated. In the first step the self-polycondensation of glycerol to PGL in the presence of potassium hydroxide or potassium methoxide as a catalyst was carried out. In the second step, the crude alkaline PGL was alkoxylated with PO without removing the catalyst, followed by purification of the resulting polyether polyols. Rigid polyurethane foams prepared from the synthesized PGL-based polyether polyols and crude MDI displayed good physical and mechanical properties, excellent dimensional stability, and low friability.

Application of Neural Network for Estimating Properties of Diesel–Biodieselblends

Soybean oil was transesterified with methanol in the presence of alkaline catalyst to produce methyl esters commonly known as biodiesel. Biodiesel–diesel blends were prepared and tested in laboratory for flash point, fire point, viscosity and density. Seven neural network architectures, three training algorithms along with ten different sets of weight and biases were examined to predict the above-mentioned properties of diesel and biodiesel blends. The best-suited neural network and training algorithm were selected and further generalized to improve its performance by using early stopping technique. The results showed that the neural network having an architecture 2-7-4 with Levenberg–Marquardt algorithm gave the best estimate for the properties of diesel–biodiesel blends.

Synthesis of carboxymethyl cellulose (CMC) and starch-based hybrids and their applications in flocculation and sizing

Starch and hydrolyzed starches along with carboxymethyl cellulose were independently subjected to cationization by reacting them with N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (known commercially as Quat 188) in presence of alkaline catalyst. The cationization reaction was carried out under different conditions Optimal reaction conditions could be achieved at Quat 188 (2 mmol), NaOH (1 mmol) at temperature (70 °C) 60 min for CMC or 120 min for starch. The cationic products were characterized by FTIR spectroscopy, and nitrogen percentage. Application of the cationized products as well as their parent materials in textile sizing was also undertaken. Moreover, hybrids of starch-Quat 188 and CMC-Quat 188 were used as flocculants; flocculation was carried at pH 6 using different flocculant dose. Results obtained indicate that the cationic-based hybrids – under investigation display characteristics, which qualify them to function as an excellent sizing and flocculating agents.

Transesterification of rapeseed oil for the production of biodiesel using homogeneous and heterogeneous catalysis

In the present work, the transesterification reaction of rapeseed oil with methanol, in the presence of alkaline catalysts, either homogeneous (NaOH) or heterogeneous (Mg MCM-41, Mg–Al Hydrotalcite, and K+ impregnated zirconia), using low frequency ultrasonication (24 kHz) and mechanical stirring (600 rpm) for the production of biodiesel fuel was studied. Selection of heterogeneous catalysts was based on a combination of their porosity and surface basicity. Their characterization was carried out using X-ray diffraction (XRD), Nitrogen adsorption–desorption porosimetry and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The activities of the catalysts were related to their basic strength. Mg–Al hydrotalcite showed particularly the highest activity with conversion reaching 97%). The activity of ZrO 2 in the transesterification reaction increased as the catalyst was doped with more potassium cations, becoming thus more basic. Use of ultrasonication significantly accelerated the transesterification reaction compared to the use of mechanical stirring (5 h vs. 24 h). Given the differences in experimental design, it can be concluded that the homogeneous catalyst accelerated significantly the transesterification reaction, as compared to all heterogeneous catalysts, using both mechanical stirring (15 min vs. 24 h) and ultrasonication (10 min vs. 5 h). However, the use of homogeneous base catalysts requires neutralization and separation from the reaction mixture leading to a series of environmental problems related to the use of high amounts of solvents and energy. Heterogeneous solid base catalysts can be easily separated from the reaction mixture by simple filtration, they are easily regenerated and bear a less corrosive nature, leading to safer, cheaper and more environment-friendly operations.

Producing biodiesel from yellow greases with high free fatty acids

Biodiesel is a diesel replacement fuel that is manufactured from vegetable oils recycled cooking greases and oils or animal fats. Biodiesel offers many advantages because it is renewable, nontoxic, biodegradable, and suitable for sensitive environments. It can also be used in most diesel equipments with no or only minor modifications. These yellow greases contain great quantities of free fatty acids which form soaps in the presence of alkaline catalyst. Pretreatments of the raw material with acid catalysts are necessary to avoid the soap formation. The transesterification of yellow greases is supplemented in the presence of an alkaline catalyst. The greatest production of biodiesel corresponds to molar flows of 4.985 kmol.hr-1 of methyl oleate, and 4.658 kmol.hr-1 of methyl butyrate.

Study on the synthesis and composition of polynitroalcohols prepared from butadiene–styrene nitrooligomer and formaldehyde

Oligomeric polynitroalcohols (PNA) containing 1.9–3.6% hydroxyl groups were prepared by reacting butadiene–styrene nitrooligomer (BSNO) with formaldehyde at 40°C for 5 h. The BSNO/formaldehyde mass ratio was 2:1 and the reaction was conducted in the presence of alkaline catalyst. A quantitative determination of the functional groups content and the fragmentary composition of PNA obtained were carried out by using IR spectroscopy (baseline internal standard techniques), elemental analysis and liquid adsorption chromatography. To this purpose, one of the polynitroalcohols prepared was fractionated by a liquid adsorption chromatography on silica and the fractions obtained were characterized by elemental analysis and IR spectroscopy. The specific character of the condensation reaction was also discussed. PNA are considered to serve as starting materials for the preparation of polynitrourethanes.

Co‐condensates of resorcinols and methylol compounds for adhesive resins

AbstractA proton magnetic nuclear resonance study was performed on co‐condensation reactions of resorcinol, 5‐methylresorcinol and 2,5‐dimethylresorcinol with methylol compounds, including ortho‐ and para‐methylolphenol, N‐methylol‐caprolactam, methylol‐N,N‐diethylurea, methylolurea and N,N′‐dimethylolurea. Spectral assignments, reaction kinetics and composition of products are discussed. The reaction in melt (120°C) with methylolphenols occurs as co‐condensation in the presence of all catalysts studied. In resorcinols C4C6 substitution is favored. The rate constants of methylol disappearance clearly indicate the preferable influence of acid and alkaline catalyst (not zinc acetate) on para‐methylol. The reaction with N‐containing methylol compound does not give any co‐condensate in the presence of alkaline catalyst. The optimum conditions for co‐condensation mainly depend on reactivity of co‐reagents with formaldehyde and stability of methylol compound. The quantitative amount of co‐condensate with methylolcaprolactam can be obtained in melt‐condensation (70°C) in the presence of acid catalyst. Because of the higher reactivity of urea, the reaction in melt (100°C) in the presence of acid catalyst does not lead to quantitative co‐condensation. The condensation of methylol compound or resorcinols with formaldehyde can be avoided substantially by performing the reaction in aqueous solution at lower temperature.

Isolation and Characterization of Organosolv Lignin under Alkaline Condition from Wheat Straw

Delignification of wheat straw with aqueous ethanol in the presence of alkaline catalyst has been studied. The use of 60% (v/v) ethanol under alkaline condition (0.5 N NaOH) resulted in increased rate of delignification by 7.1% as compared with the treatment of wheat straw in 0.5 N NaOH medium without ethanol. The chemical composition of the lignin fraction isolated by two steps of precipitation are reported. The characteristics of the lignin were further investigated by gel permeation chromatography (GPC), infrared (IR) and 13C-nuclear magnetic resonance (NMR) spectroscopy.

Reactions of brown coals with COH 2O in the presence of alkaline catalysts in a well-stirred autoclave with hot-charge facility

Victorian brown coals were reacted with COH 2O in the presence of different amounts of NaAlO 2, NaOH, Na 2CO 3 and Ca(AlO 2) 2 in a well-stirred autoclave with a hot-charge facility. The effects of reaction time, temperature, stirrer speed, reactant gas composition, coal structure and reactant ratios were studied and the results were compared with those of reactions using a similar reactor in a less well-mixed system. Efficient mixing led to higher yields of liquid products, at lower water:coal ratios and lower promoter loadings. In addition, the product yields were less sensitive to coal structure in this well-mixed system.

Kinetics of Fatty Acids Polyethoxylation

Fatty acids (C 12 -C 18 ) ethoxylation in the presence of alkaline catalysts is normally performed in industry for the production of nonionic surfactants. The reaction takes place in two steps. In the first one, monoethoxylation occurs with a decelerative behavior. When all the acid has reacted, reaction rates strongly increase as consequence of the alcoholate anion formation. We will show that the first step reaction mainly occurs with a noncatalytic mechanism and that the observed behavior can be described with a first-order kinetic law with respect to the free fatty acid. In the second step of the reaction, that is during propagation reactions, reaction rates are affected from the catalyst concentration. Together with ethoxylation, a transesterification reaction occurs, producing diesters and polyglycols. This reaction is promoted by the alkaline medium; therefore, it mainly occurs during the second reaction step. A kinetic model able to satisfactorily reproduce all the experimental observations has been developed and discussed

Methanopyrolysis of coal

The conversion of coal with methane was studied in the presence of alkaline catalysts and various reactive gases. Best results were obtained with a methane/nitrous oxide mixture as the reactant gas and lithium oxide as the catalyst. The product composition is compared with the results from controlled experiments based on hydrogen (hydroliquefaction) and nitrogen (pyrolysis) in the presence and absence of the catalyst. Strong indications for the conversion of coal with methane are the increase of alkylated aromatics and of general liquid formation in the presence of methane relative to identical reaction conditions in the presence of hydrogen and nitrogen.

Reactions of coals with carbon monoxide/deuterium oxide in the presence of alkaline catalysts. Establishment of mineral matter in the coal as the origin of kinetic isotope effects

Replacement of water by deuterium oxide in reactions of a range of coals with carbon monoxide in the presence of alkaline catalysts has been shown to lead to significant changes in yields, in agreement with previous work. However, these kinetic isotope effects disappear when acid-washed coals are used in the reactions, suggesting that they are probably caused by the presence of inorganic matter in the coal.

A Polish process for pentaerythritol manufacture

Pentaerythritol is a synthetic polyalcohol with the formula C 2OH)4, obtained in the reaction of one acetaldehyde molecule with four molecules of formaldehyde. This reaction takes place in a dilute aqueous solution in the presence of alkaline catalysts. Besides the pentaerythritol a salt of formic acid, most often sodium formate, is the by‐product obtained.

Organic reactions in emulsions—Preparation of glycerol and polyglycerol esters of fatty acids by transesterification reaction

AbstractMonoglycerol and polyglycerol esters of fatty acids have been prepared in an emulsion medium of polyglycerol in esters of fatty acids. Transesterification between glycerol or polyglycerols and methyl esters of fatty acids is made at relatively low temperatures (95–150 C) in the presence of alkaline catalyst and anionic or nonionic emulsifiers. The reaction system consists of two immiscible phases transformed into a “milky” (macro) or transparent (micro) emulsion throughout the heating process. The product obtained using this technology is not a highly substituted ester since the transesterification reaction is selective. The type and the amount of emulsifier have to be carefully selected. Unsuitable emulsifiers which will not stabilize the emulsion are ineffective in enlarging the contact between the reactants; therefore, the conversion of the reactants is very poor. With suitable emulsifiers, the conversions and the yields improved due to a better contact between reactants.