Showing papers by "Ajay K. Dalai published in 2006"
TL;DR: In this paper, a review of the methods for the transesterification of waste cooking oil and the performance of biodiesel obtained from waste cooking oils in a commercial diesel engine is presented, and the effects of the products formed in the frying process on biodiesel quality are examined.
Abstract: Biodiesel (fatty acid methyl ester) is a nontoxic and biodegradable alternative fuel that is obtained from renewable sources. A major hurdle in the commercialization of biodiesel from virgin oil, in comparison to petroleum-based diesel fuel, is its cost of manufacturing, primarily the raw material cost. Used cooking oil is one of the economical sources for biodiesel production. However, the products formed during frying, such as free fatty acid and some polymerized triglycerides, can affect the transesterification reaction and the biodiesel properties. Apart from this phenomenon, the biodiesel obtained from waste cooking oil gives better engine performance and less emissions when tested on commercial diesel engines. The present paper attempts to review methods for the transesterification of waste cooking oil and the performance of biodiesel obtained from waste cooking oil in a commercial diesel engine. The paper also examines the basic chemistry involved during frying and the effects of the products formed in the frying process on biodiesel quality.
1,166 citations
TL;DR: In this paper, 12-Tungstophosphoric acid (TPA) impregnated on four different supports such as hydrous zirconia, silica, alumina and activated carbon was evaluated as solid acid catalysts for the biodiesel production from low quality canola oil containing upto 20 wt% free fatty acids.
420 citations
TL;DR: In this article, the transesterification of karanja oil with methanol was carried out using solid basic catalysts, and the reaction conditions, such as catalyst concentration, reaction temperature and molar ratio, were optimized with the solid basic Li/CaO catalyst.
Abstract: The transesterification of karanja oil with methanol was carried out using solid basic catalysts. Alkali metal-impregnated calcium oxide catalysts, due to their strong basicity, catalyze the transesterification of triacylglycerols. The alkali metal (Li, Na, K)-doped calcium oxide catalysts were prepared and used for the transesterification of karanja oil containing 0.48-5.75% of free fatty acids (FFA). The reaction conditions, such as catalyst concentration, reaction temperature and molar ratio of methanol/oil, were optimized with the solid basic Li/CaO catalyst. This catalyst, at a concentration of 2 wt-%, resulted in 94.9 wt-% of methyl esters in 8 h at a reaction temperature of 65 °C and a 12 : 1 molar ratio of methanol to oil, during methanolysis of karanja oil having 1.45% FFA. The yield of methyl esters decreased from 94.9 to 90.3 wt-% when the FFA content of karanja oil was increased from 0.48 to 5.75%. The performance of this catalyst was not significantly affected in the presence of a high FFA content up to 5.75%. The catalytic activities of Na/CaO and K/CaO were also studied at the optimized reaction conditions. In these two cases, the reaction initially proceeds slowly, however, leading to similar yields as in the case of Li/CaO after 8 h of reaction time. The purified karanja methyl esters have an acid value of 0.36 mg KOH/g and an ester content of 98.6 wt-%, which satisfy the American as well as the European specifications for biodiesel in terms of acid value and ester content.
196 citations
TL;DR: In this paper, the authors performed a kinetic modeling of the production of hydrogen by the catalytic reforming of crude ethanol over a 15%-Ni/Al 2 O 3 catalyst prepared by the co-precipitation technique.
111 citations
TL;DR: Carbon nanotubes (CNTs) were used as support to Cu-Zn catalysts and tested their feasibility for hydrogen production from partial oxidation of methanol as mentioned in this paper.
Abstract: Carbon nanotubes (CNTs) were used as support to Cu-Zn catalysts and tested their feasibility for hydrogen production from partial oxidation of methanol. The CNTs were synthesized by CVD method using acetylene as carbon source over anodic aluminum oxide template. The structural characteristics of CNTs were analysed by SEM, TEM, XRD, Raman spectroscopy and TGA. Using these CNTs as support, Cu-Zn catalysts with varying metal loading were prepared by co-precipitation method. The reducibility of the catalysts was tested with H 2 -TPR. N 2 adsorption and CO chemisorption were used to monitor the surface area and total CO uptake of catalysts, respectively. The metal particle size of Cu-Zn/CNTs catalysts were measured from XRD and TEM. The nature of copper species and acidity were analysed by DRIFT study of CO adsorption and pyridine adsorption method, respectively. The deposition of Cu on CNTs surface resulted in creation of strong Lewis acid sites. The methanol conversion rate and H 2 selectivity are increased from 0.066 to 0.11 mol/h/g cat and 57 to 70.6%, respectively, when increasing Cu loading from 5 to 12 wt% at 260 °C and further increase shows a fall in activity. The enhanced activity of 12 wt% Cu-9 wt% Zn/CNTs is due to the improved metal dispersion, narrow particle size distribution and almost complete reduction of Cu particles. The XRD analysis of spent catalyst indicates that during the POM reaction, the active Cu 0 species is slowly converted into CuO, which is responsible for fall in activity.
61 citations
TL;DR: In this article, a rigorous numerical model was developed to simulate the production of hydrogen from the reforming of crude ethanol in a packed bed tubular reactor (PBTR), which was based on the coupling of mass and energy balance equations as well as a new kinetic model developed for the process.
60 citations
TL;DR: In this article, high purity multi-walled carbon nanotubes were synthesized from aromatic hydrocarbons (benzene, toluene, xylene and trimethyl benzene) using ferrocene as the source of Fe catalyst.
60 citations
TL;DR: Saskatchewan lignite was used as a precursor to prepare carbonaceous adsorbents for use as SO 2 adsorbent from flue gases as mentioned in this paper, where carbon dioxide and steam were used as activating agents.
51 citations
TL;DR: In this article, an attempt was made to produce high-quality biodiesel from green seed canola oil and methanol, ethanol and various mixtures of methenol and ethanol using KOH as a catalyst.
Abstract: Increasing percentage of green canola seed every year is a serious problem for canola growers. Chlorophyll content of this oil is very high, which makes it more susceptible to photo-oxidation and ultimately the oxidation stability of the oil is very reduced. Hence green seed canola oil is underutilized for edible purposes. The present work is an attempt to produce high-quality biodiesel from green seed canola oil and methanol, ethanol and various mixtures of methanol and ethanol using KOH as a catalyst. A mixture of alcohols improved the rate of reaction. After transesterification of green seed canola oil using KOH, the chlorophyll content of the oil was decreased substantially (from 22.1 ppm to 10.3 ppm). Characteristics of the esters prepared from green seed canola oil were well within the limits of ASTM standards. Lubricity of the green seed oil esters was excellent (20% decrease in wear scar area) when added at 1 vol% to the base fuel. Oxidation stability is crucial for long-term storage of the fuel. Oxidation stability index (OSI) of green seed esters was 4.9 h at 110 °C, which is much less than the European Standard (6 h at 100 °C). The low oxidation stability of green seed esters is attributed to its higher chlorophyll (10.3 ppm) content. An attempt was also made to reduce the chlorophyll content of the oil before transesterification using activated carbon treatment, and it was observed that chlorophyll content was reduced from 22.1 to 2.2 ppm. Copyright © 2006 Society of Chemical Industry
45 citations
TL;DR: In this article, the effects of incorporation of boron in the framework on the structure, crystal parameters, framework vibrations and textural properties of SBA-15 were discussed based on the results from XRD, FT-IR and nitrogen adsorption studies.
38 citations
10 May 2006
TL;DR: In this paper, the authors compared the performance of heterogeneous (CaO, MgO, Ba(OH)2, Li/CaO and Zeolite) and homogeneous (KOH) catalyst for transesterification of vegetable oil.
Abstract: Fatty acid methyl esters (FAME) are produced by transesterification of vegetable oil with methanol usually in presence of an alkaline catalyst The purpose of this work is to compare the performance of heterogeneous (CaO, MgO, Ba(OH)2, Li/CaO, Zeolite) and homogeneous (KOH) catalyst for the transesterification of vegetable oil The effect of stirring speed and addition of ethanol with methanol on ester yield was studied This research showed that stirring speed has substantial effect on the ester yield both in homogeneous and heterogeneous catalyzed reaction Addition of ethanol with methanol has improved the rate of formation of ester, thus helped in reducing the mass transfer limitations Amongst all the heterogeneous catalysts examined, the performance of Ba(OH)2 catalyst was better which produced 99 wt% ester yield in 480 min and its performance was comparable to that of potassium hydroxide Ester obtained from canola oil and methanol and ethanol mixture (3:3) {MEE (3:3)} acted as a good lubricity additive by reducing wear scar area by 16% and improving the lubricity number of base fuel by 20%
TL;DR: In this article, a detailed kinetic study was performed for the reaction under investigation over the best Mn-promoted Cu/Al2O3 catalysts in the temperature range of 448-533 K. The catalysts were characterized suitably by various techniques.
Abstract: Water-gas-shift reaction was carried our over a series of Mn-promoted Cu/Al2O3 catalysts in the temperature range of 448–533 K. The catalysts were characterized suitably by various techniques. The catalyst containing 8.55 wt% Mn was found to be the most active one among five catalysts tested. A maximum CO conversion of 90% was obtained over this catalyst at 513 K with a CO space-time of 5.33 h. The catalysts were found to be structure sensitive for the low-temperature water-gas shift reaction. A detailed kinetic study was performed for the reaction under investigation over the best catalyst. The kinetic data were fitted to two different models and the redox model was found to the better one than the other. From the estimated kinetic constant, the activation energy was determined to be 81 kJ/mol for the water-gas shift reaction in the temperature range of 448–463 K.
TL;DR: In this paper, a non-equilibrium method using fixed bed microreactor was used to measure SO 2 adsorption characteristics of chars and activated carbons derived from Saskatchewan lignite.
TL;DR: In this paper, Nitric oxide removal was investigated over reduced and unreduced Fe, Cu, Co and Ni impregnated activated carbons (AC) in a microreactor system in the presence and absence of oxygen.
Abstract: Adsorption of nitric oxide was studied over reduced and unreduced Fe, Cu, Co and Ni impregnated activated carbons (AC) in a microreactor system in the presence and absence of oxygen. In the absence of oxygen reduced Fe–AC showed an NO removal efficiency of 58% which was higher than that of virgin activated carbon by a factor of 2.5. The removal efficiency of Cu–AC with and without oxygen was in the range of 44–46%.
TL;DR: In this article, controlled laboratory and field experiments were performed to collect volatile organic compounds (VOCs) emitted during drying of alfalfa, and the results showed that the most common VOCs emitted were alcohols, aldehydes, ketone, ester and unsaturated and saturated hydrocarbons.
TL;DR: Permittivity measurements were done using a HP 8510 Vector Network Analyzer and coaxial probe reflection method to study the dielectric properties of naphthenic acid in water and the effects of process variables such as frequency, concentration and temperature on dielectrics were determined.
Abstract: Naphthenic acid (NA) is predominantly a mono-carboxylic acid obtained as a by-product of petroleum refi ning with variable composition and ingredients. It is reported that water affected by processes in the petroleum industries generally contains 40-120 mg /L of naphthenic acid which is considered to be in the range of toxicity to human consumption (Clemente et. al, 2005; McMartin, 2003). This contaminated water needs treatment before its use as drinking water by the remote communities. Recent literature suggests that NAs could be separated from diesel fuel using microwave radiation (Lingzhao et. al, 2004). Removal of naphthenic acid from vacuum cut # 1 distillate oil of Daqing using microwaves has also been reported by Huang et. al (2006). The microwave treatment can be applied to drinking water containing small concentrations of naphthenic acid. In this case permittivity information is useful in designing a microwave applicator and modeling studies. Permittivity measurements were done using a HP 8510 Vector Network Analyzer and coaxial probe refl ection method to study the dielectric properties of naphthenic acid in water. The effects of process variables such as frequency, concentration and temperature on dielectric properties were determined.