Influence Of Methanol Addition Research Articles

Influence of methanol addition on bio-oil thermal stability and corrosivity

Bio-oil has been considered to be upgraded via co-processing with petroleum intermediates in existing fluid catalytic cracking (FCC) units to produce drop-in fuels. However, the low stability and high corrosivity of bio-oil are two major obstacles preventing further advances in bio-oil upgrading processes. Previously, efforts have been made to improve bio-oil stability through the use of additives, with methanol as a promising candidate. Yet, the effect of these additives on bio-oil corrosivity has not been fully understood. In this study, both the stability and corrosivity of bio-oil with methanol addition are analyzed. Bio-oil was blended with methanol at concentrations of 5–20 wt%. These mixtures were subject to accelerated aging at 50 and 80 °C for up to 168 hours. Fourier-transform infrared spectroscopy, gas chromatography–mass spectrometry, and thermogravimetric analysis were conducted to identify functional groups, chemical compounds, and thermal behaviors of bio-oil, respectively. Viscosity, density, water content, and pH were also measured to track the physical and chemical property changes of bio-oil and bio-oil/methanol mixtures during aging. Alongside, immersion experiments with common FCC structural materials such as carbon steel (CS) and stainless steels (SS) 304L and 316L were conducted in bio-oil and bio-oil/methanol mixtures, at 50 and 80 °C for 168 hours. The result of aging experiments showed that the viscosity increasing rate of bio-oil was dramatically lowered by adding methanol, especially at 80 °C, indicating that adding methanol was effective in stabilizing bio-oil. For corrosivity investigation, CS corroded severely in tested bio-oil mixtures. At 50 °C, it was found that CS immersed in bio-oil mixtures with higher methanol concentration corroded at a more significant rate; whereas at 80 °C, the corrosion rate of CS initially increased with methanol concentration in bio-oil and then declined. 304L SS exhibited moderate corrosion rates at 80 °C, while 316L SS showed minimal corrosion at the tested conditions. It has also been observed that CS accelerated the viscosity increasing rate of bio-oil, especially after being aged at 80 °C for 168 hours. After immersion experiments, abnormally high carbon, oxygen, and nitrogen contents were identified on rigorously cleaned metal coupon surfaces. A combination of viscosity measurements and surface characterization suggested that chelation between organic compounds and metal atoms/ions played a significant role in the corrosion of steels in bio-oil. A mechanism was proposed to justify the corrosion behavior of steels in bio-oil/methanol mixtures.

On the influence of methanol addition on the performances of PEM fuel cells operated at subzero temperatures

The storage and the operation of proton exchange membrane fuel cells (PEM FCs) at subzero temperatures result in the ageing and degradation of membrane-electrode assemblies (MEAs). In this study, we investigated the effect of a freeze-thaw temperature cycles (from ambient down to −80 °C) on various properties of PFSA membranes and on the performance level of MEAs. The beneficial effects resulting from the addition of methanol vapor to the hydrogen have been put into evidence. Small angle x-ray scattering (SAXS) data have been measured on membranes swollen with water and water-methanol mixtures, to identify possible microstructure differences. It was found that the addition of methanol tends to increase the ionic resistivity of the membranes but has a protective effect on the catalytic layers during the freeze-thaw cycles. The degradation rate of the catalytic layer was reduced by almost a factor of two as a result of optimal methanol addition.

The influence of methanol addition during the film growth of SnO 2 by atmospheric pressure chemical vapor deposition

Undoped tin oxide (SnO 2) thin films have been deposited in a stagnant point flow chemical vapor deposition reactor from a water/tin tetrachloride mixture. By adding methanol during the deposition process the film electrical properties change significantly: ten times more conductive SnO 2 films are obtained, with remarkably high mobility values of up to 55 cm 2/V s. The investigations on the morphological and structural properties indicate that the main effect of methanol is the densification of the SnO 2 films, which probably causes the improvement in the electrical properties. In all conditions the nucleation and coalescence phases take place very early in the growth. Below 10 nm the films are already very conductive, which is very beneficial to applications that have strict requirements in terms of film transparency.

Influence of Methanol Addition on the Two Stage Combustion of a Dimethyl Ether/Air Mixture

A numerical study was performed to determine the effects of methanol addition on the two stage oxidation of a dimethyl ether/air mixture and on the production of formaldehyde and formic acid in a micro-flow reactor with a fixed temperature profile. The results indicate that methanol addition influences the reaction pathway for dimethyl ether oxidation at low velocity and this results in the low temperature reactions of dimethyl ether being suppressed. The low temperature reactions of dimethyl ether nearly vanish when methanol is added in the same mass fraction as dimethyl ether. The major cause of this is a decrease in the OH radical concentration. With increasing the amount of methanol the emission index of formic acid decreases sharply but the emission index of formaldehyde increases slightly at first, and then it decreases gradually. Therefore, appropriate methanol addition can result in the reduction of the emission indexes of formic acid and formaldehyde.

Capillary zone electrophoresis for U(VI) and short chain carboxylic acid sorption studies on silica and rutile

Capillary zone electrophoresis was used to study the uranyl and short chain carboxylic acid sorption on silica and rutile. The separation and the simultaneous determination (in a single run) of a number of short chain carboxylic acids (oxalic, formic, acetic and propionic) and U(VI) with direct UV detection is developed for the analysis of solutions after the sorption experiments. The reverse polarity mode is used (the injection is performed at the negative end). The matrix effect of Si(IV) (possible silica dissolution product) and perchlorate (added for constant ionic strength in sorption experiments) on the separation of U(VI) and organic acids is investigated. The influence of methanol addition in carrier electrolyte on the separation selectivity of given analytes is also studied. Under the chosen conditions (carbonate buffer (ionic strength of 0.1M), pH 9.8, 0.15mM of tetradecyltrimethylammonium bromide, 25% (v/v) of methanol) the calibration curves are plotted. They are linear in two ranges of concentration from ∼1×10−5 to ∼1×10−3M for oxalate, acetate, propionate, U(VI) and ∼1×10−4 to ∼1×10−3 for formate. The accuracy of the procedure is checked by the “added-found” method in simulation solutions. The relative standard deviations of the concentrations found are within the range of 1–10% and the recovery is in the range of 90–115%. This method is applied for the analysis of aqueous samples issued from sorption experiments on silica and rutile. The obtained results indicate that the given organic acids decrease uranium sorption both on silica and rutile. These experiments demonstrate that short chain carboxylic acids can influence the mobility and the chemistry of U(VI) in the environment.

Submerged Citric Acid Fermentation on Orange Peel Autohydrolysate

The citrus-processing industry generates in the Mediterranean area huge amounts of orange peel as a byproduct from the industrial extraction of citrus juices. To reduce its environmental impact as well as to provide an extra profit, this residue was investigated in this study as an alternative substrate for the fermentative production of citric acid. Orange peel contained 16.9% soluble sugars, 9.21% cellulose, 10.5% hemicellulose, and 42.5% pectin as the most important components. To get solutions rich in soluble and starchy sugars to be used as a carbon source for citric acid fermentation, this raw material was submitted to autohydrolysis, a process that does not make use of any acidic catalyst. Liquors obtained by this process under optimum conditions (temperature of 130 degrees C and a liquid/solid ratio of 8.0 g/g) contained 38.2 g/L free sugars (8.3 g/L sucrose, 13.7 g/L glucose, and 16.2 g/L fructose) and significant amounts of metals, particularly Mg, Ca, Zn, and K. Without additional nutrients, these liquors were employed for citric acid production by Aspergillus niger CECT 2090 (ATCC 9142, NRRL 599). Addition of calcium carbonate enhanced citric acid production because it prevented progressive acidification of the medium. Moreover, the influence of methanol addition on citric acid formation was investigated. Under the best conditions (40 mL of methanol/kg of medium), an effective conversion of sugars into citric acid was ensured (maximum citric acid concentration of 9.2 g/L, volumetric productivity of 0.128 g/(L.h), and yield of product on consumed sugars of 0.53 g/g), hence demonstrating the potential of orange peel wastes as an alternative raw material for citric acid fermentation.

Influence of methanol addition during selective hydrogenation of benzene to cyclohexene

The addition of a certain methanol concentration during benzene hydrogenation on Ru/Al2O3 improves the selectivity to cyclohexene because of a preferential adsorption of methanol on the most active Ru sites.