Biodiesel production by transesterification of duck tallow with methanol on alkali catalysts

Duck tallow was employed as a feedstock for the production of biodiesel by transesterification with methanol. The content of fatty acid methyl ester (FAME) was evaluated on various alkali catalysts during transesterification. The composition and chemical properties of the FAME were investigated in the raw duck tallow and the biodiesel products. The major constituent in the biodiesel product was oleic acid. The FAME content was 97% on KOH catalyst in the reaction. It was acceptable for the limit of European biodiesel qualities for BD100. Acid value, density, and kinematic viscosity of the biodiesel products also came up to the biodiesel qualities.     

Screening,optimization and kinetics of Jatropha curcas oil transesterification with heterogeneous catalysts

This work investigates the production of fatty acid methyl esters (FAME) from Jatropha curcas oil using a variety of heterogeneous catalysts: resins, zeolites, clays, hydrotalcites, aluminas and niobium oxide. For this purpose, a catalyst screening was first conducted in a batch reactor at the following operating conditions: oil to methanol molar ratio of 1:9, 6 h of reaction, 5 wt% catalyst, at 333 and 393 K. From the screening step, KSF clay and Amberlyst 15 catalysts were selected to carry out a 2³ full factorial central composite rotatable design so as to elucidate the effects of process variables on FAME yield. The optimum reaction conditions for both catalysts were found to be oil to methanol molar ratio of 1:12, 5 wt% of catalyst, 433 K and 6 h of reaction with a FAME yield of about 70 wt%. A kinetic study was then experimentally performed and a semi-empirical model was built to represent the experimental data. Finally, catalyst re-utilization in five successive batch experiments was evaluated at the optimized conditions.     

The Kinetics of the transesterification of Simarouba glauca oil for the production of biofuel using zirconia-based catalysts

This study reveals the synthesis of biofuel (BF) from Simarouba glauca (SG) oil through the process of transesterification using honeycomb (HC) coated with modified forms of zirconia as basic catalysts. Zirconia and its modified forms such as zirconia-calcia and zirconia-magnesia were coated on monoliths by the dip-dry method and were characterized for their surface basicity, powder X-ray diffraction, infrared, and scanning electron microscopy (SEM) techniques. The effect of incorporation of calcium/magnesium ions on the basicity, crystallinity, and catalytic activity of zirconia is discussed. Kinetic study reveals that zirconia-calcia coated on the HC exhibits the lowest energy of activation (Ea) in transesterification and hence is an efficient catalyst for BF synthesis.     

Electrooxidations of ethanol,acetaldehyde and acetic acid using PtRuSn/C catalysts prepared by modified alcohol-reduction process

Well-dispersed ternary PtRuSn catalysts of various atomic ratios (60:30:10, 60:20:20 and 60:10:30) were deposited onto carbon using modified alcohol-reduction process for electrochemical oxidation of ethanol. The alloy phase structure and surface morphology for each variation of the PtRuSn/C catalysts were determined by XRD and HRTEM. In order to evaluate the contributions of Ru and Sn in the different stages of ethanol oxidation, electrochemical oxidations of adsorbed CO, ethanol, acetaldehyde and acetic acid were performed on each PtRuSn/C catalyst. The results indicated that the Ru-rich PtRuSn/C catalyst (60:30:10) exhibited the lowest onset potential for the electrooxidations of adsorbed CO, ethanol and acetaldehyde, revealing that the removal through oxidation of the intermediate C₁ and C₂ species from Pt sites is primarily attributed to the Ru and Pt₃Sn alloy structures. However, for the overall oxidation of ethanol, the Sn-rich PtRuSn/C catalyst (60:10:30) containing PtSn phase and SnO₂ structure is favorable for the activation of CC bond breaking, thereby generating higher current density (mass activity) at higher potentials. Moreover, in the electrooxidation of acetic acid, a remarkable improvement for oxidizing acetic acid to C₁ species was observed in the Sn-rich PtRuSn/C catalyst (60:10:30), while the Ru-rich PtRuSn/C catalyst (60:30:10) was almost incapable of breaking the CC bond to further oxidize acetic acid. The possible reasons for the different reactivities on the studied PtRuSn/C catalysts were discussed based on the removal of intermediates and activation of the CC bonds on the different surfaces.     

Optimization of transesterification process parameters of castor oil ethanolysis using response surface methodology-based genetic algorithm

Castor oil is unusual oil that is predominantly composed of ricinoleic acid. In the present study, castor oil biodiesel was produced from castor oil with bio-alcohol (ethanol) via a transesterification process. Also, this study investigates the influence of transesterification process parameters, i.e., reaction temperature, catalyst (sodium ethoxide) concentration, and ethanol:castor oil molar ratio on the yield of castor oil ethyl ester. The experiments are carried our as per a central composite design. A second-order response surface model was developed to predict the yield of castor oil ethyl ester as a function of transesterification process parameters. The developed models indicated that the predicted values are well in agreement with the experimental results. Finally, optimization of transesterification process parameters was carried out using a response surface methodology-based genetic algorithm. The optimization results indicated a reaction temperature of 41°C, catalyst concentration of 1.25% w/w of oil, and ethanol to oil molar ratio of 18.42 for achieving a higher yield of castor oil ethyl ester of 93.9%.     

Experimental study on the coal tar hydrocracking process over different catalysts

In the paper, the results of the study on a laboratory process of hydrocracking of coal tar are presented. High-temperature coal tar was hydrocracked in an autoclave reactor, at 400–413 °C and 7,3–9,6 MPa over 5 different, hydrocracking catalysts to study the yields and characteristics of the products. Liquid products were obtained with a yield of 88–92 wt.% and gas products with a yield of 12–8 wt.%. After dehydration by azeotropic distillation, liquid products were separated on the oil fraction boiling below 360 °C, and pitch fractions boiling above this temperature. In the balance of distillation, it is clear that only the cracking activity of NiW/Al₂O₃ and Y zeolite catalysts is so high that the raw material containing 5 vol.% fraction boiling below 200 °C provides a product comprising approx. 12,5 vol.% of this fraction. The influence of five different catalysts on the yield of 18 poly aromatic hydrocarbons (PAHs) in the hydrocracking products have been investigated by GC/MS. The results indicate that NiW/Al₂O₃ and Y zeolite catalysts have the highest catalytic activity for light aromatic formation (the highest yield of fraction boiling below 200 °C) and aromatic condensed aromatic cracking (PAHs). After the hydrocracking NiW/Al₂O₃ catalyst, the total yields of PAHs decrease 52.7% as that of raw coal tar.     

Effect of reaction parameters on the catalytic transesterification of cottonseed oil using silica sulfuric acid

Transesterification of refined cottonseed oil was studied in the presence of silica sulfuric acid as a new heterogeneous solid acid catalyst to overcome the drawbacks of homogeneous alkali and acid catalysts. The effect of various reaction parameters, such as oil to methanol ratio, reaction temperature, reaction time, and catalyst amount, was investigated. The highest methyl ester conversion was obtained at 373 K using 5% catalyst amount and 1:20 methanol ratio within 8 h. Silica sulfuric acid was found to be a promising catalyst for cleaner biodiesel production without tedious post treatments for the product purification.     

Investigation of hydrogen generation from sodium borohydride using different cobalt catalysts

Effective Co/Cu, CoB/Cu, and CoBM (M = Mo,Zn,Fe)/Cu catalysts were prepared on the copper surface by a simple electroless deposition method using a morpholine borane as a reducing agent in the glycine solution. The activity of the deposited catalysts was investigated for hydrogen generation from an alkaline sodium borohydride solution. It was determined that these synthesized catalysts demonstrated the catalytic activity for the hydrolysis reaction of NaBH₄. The lowest obtained activation energy (E_A) of the hydrolysis reaction of NaBH₄was 27 kJ mol^?1 for the CoBMo/Cu catalyst. The hydrogen generation rate of 15.30 ml min^?1 was achieved using CoBMo/Cu catalysts at 313 K and it increased ~3.5 times with the increase of temperature to 343 K. The highest hydrogen generation rate obtained by CoBMo/Cu films may be related to the hierarchical cauliflower-shaped 3D structures and the high roughness surface area. Moreover, the CoBMo/Cu catalyst showed an excellent reusability.     

Microwave deposition of Pt catalysts on carbon nanotubes with different oxidation levels for formic acid oxidation

Platinum (Pt) nanoparticles are uniformly deposited on carbon nanotubes (CNTs) with different oxidation levels using a pulse microwave-assisted polyol (MP) method. The CNTs are chemically oxidized using nitric acid for different periods of time (1−3 h). The MP route is capable of depositing uniform Pt nanoparticles with grain size of 2.67–2.95 nm over the surface of CNTs, forming Pt@CNT catalysts for formic acid electro-oxidation. The oxygen functionalities assist in the deposition of Pt crystals over the oxidized CNTs. The Pt@CNT catalyst with high oxidation level shows positive effects on the ratio of direct (dehydrogenation) to indirect (dehydration) oxidation, CO tolerance, and long-term stability. The improved anti-poisoning ability is attributed to the facts that the surface oxygen functionalities facilitate the direct pathway of HCOOH oxidation and strip the Pt-CO_ads occupied sites.     

Performance of microwave reactor system in decomposition of ammonia using nickel based catalysts with different supports

In this study, the ammonia decomposition reaction to produce COx-free hydrogen is investigated in a microwave reactor system using nickel-based catalysts supported by different materials. Unlike the activated carbon supported catalyst (Ni@AC), the alumina supported catalyst (Ni@Alumina) is mixed with carbon in a 1:1 ratio to reach the necessary reaction temperature in the microwave reactor. Ni@Alumina gives an overall hydrogen production rate of 73 mmol/min.g_cat with 99% conversion at 400 °C under pure ammonia flow (60 ml/min). Ni@Alumina outperforms Ni@AC under microwave reactor conditions, but underperforms Ni@AC under the conventional testing, which is done for comparison. It is suggested that selective heating of nickel species in Ni@Alumina enables better performance in the microwave reactor in comparison to Ni@AC. On the other hand, high surface area and small nickel particles present in the Ni@AC structure in comparison to the Ni@Alumina structure, causes higher activity in the conventional reactor at temperatures over 550 °C. Between 400 and 550 °C, both Ni@Alumina and Ni@AC have substantially lower activity under conventional heating than microwave heating when compared at the same temperatures. Hot spot formation and microwave selective catalytic effect are considered as possible reasons for the improved performance of microwave reactor system.     

亚临界甲醇中固体催化剂催化酯交换反应的活性比较

对几种固体催化剂用于亚临界甲醇与大豆油的酯交换反应制备生物柴油的催化活性进行了研究。考察在不同催化剂作用下酯交换反应产物中脂肪酸甲酯（FAMEs）含量随反应时间的变化规律。结果表明。在醇油摩尔比为40，反应温度为180℃，反应压力为2～3MPa，催化剂用量为3g及反应时间为10min的条件下，K2O／γ-Al2O3催化酯交换反应的产物中FAMEs含量达90％。     

An experimental study of the effects of catalysts on an ammonium perchlorate based composite propellant using 5 kHz PLIF

The catalytic effect of iron (III) oxide (Fe₂O₃) and copper (II) oxide (CuO) on an ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) propellant was studied. High speed (5 kHz) planar laser induced fluorescence (PLIF) and visible microscopic imaging of the surface was carried out in an effort to determine the mechanisms that account for the effect of catalysts. Diffusion flame lengths, crystal burn times, and ignition delay times for single AP crystals were measured during deflagration of catalyzed propellants at 1 atm. A long distance microscopic lens was also used to image AP crystal behavior in the presence of the catalysts. General trends observed on the surface are discussed. The addition of a transition metal oxide (TMO) catalyst greatly reduces the ignition delay times of the AP crystals while not significantly altering the coarse AP crystal burn times. The diffusion flame length was found to increase proportionally with the propellant’s burning rate. The findings of this experimental study provide evidence that the fine AP/binder mixture is affected most by the catalyst rather than the coarse AP at 1 atm.     

An experimental comparison of operating strategies for solar water systems

Three identical DHW (Domestic Hot Water) solar energy systems are experimentally compared in terms of the amount of energy collected during two extended periods. The goal of the experiment is to compare three different modes of operating the systems: (1) a single-pass mode, in which the circulating fluid passes once and only once through the collector; (2) a conventional forced circulation multipass mode, in which storage contents passes many times through the collector during each day, and (3) a thermosyphon mode.It is shown that the single-pass system performs better than the other two, with the multipass system being the worst. The thermal advantage of the single-pass mode is specially significant on days with poor radiation and can be as high as 16%, in comparison with the multipass system, being on the average 7% better. The thermosyphon system is shown to perform slightly better than the multipass, although the 1.4% difference found is within the experimental errors.     

Evaluation and optimization of two stage sequential in situ transesterification process for fatty acid methyl ester quantification from microalgae

This study demonstrates a direct transesterification (DT) method for reliable quantification of microalgal lipid. Primary screening of various transesterification methods and the types of biomass (wet, oven dried and lyophilized) were performed with heterotrophically grown Chlorella sp. FC2 IITG which revealed two stage DT with lyophilized biomass using NaOH in first stage and H₂SO₄ in second stage as the best combination with fatty acid methyl ester (FAME) yield of 39.17% (w/w, dry cell weight). Further optimization of transesterification parameters for selected method using response surface methodology, predicted the optimum values for catalyst to biomass ratio 0.67 (w/w) and 2.07 (v/w), methanol to biomass ratio 49.51 (v/w) and 61.07 (v/w) and reaction time 19.33 (min) and 10 (min) for first and second stages respectively. The optimum conditions showed 462.6% and 445.4% increment in FAME yield when compared with Bligh and Dyer method for Chlorella sp. FC2 IITG and Chlorella sorokiniana FC6 IITG respectively with highest transesterification efficiency of 98.96%. Improved transesterification efficiency of two stage DT was attributed to efficient destabilization of cell wall as confirmed by scanning electron microscopic imaging. FAME produced via DT of Chlorella sp. FC2 IITG satisfied most of the biodiesel properties as per ASTM D6751 and hence, could be an alternative to petro-diesel.     

An experimental study of convective heat transfer in silicon microchannels with different surface conditions

An experimental investigation has been performed on the laminar convective heat transfer and pressure drop of water in 13 different trapezoidal silicon microchannels. It is found that the values of Nusselt number and apparent friction constant depend greatly on different geometric parameters. The laminar Nusselt number and apparent friction constant increase with the increase of surface roughness and surface hydrophilic property. These increases become more obvious at larger Reynolds numbers. The experimental results also show that the Nusselt number increases almost linearly with the Reynolds number at low Reynolds numbers (Re<100), but increases slowly at a Reynolds number greater than 100. Based on 168 experimental data points, dimensionless correlations for the Nusselt number and the apparent friction constant are obtained for the flow of water in trapezoidal microchannels having different geometric parameters, surface roughnesses and surface hydrophilic properties. Finally, an evaluation of heat flux per pumping power and per temperature difference is given for the microchannels used in this experiment.     

Spray deposition process study of solar cells using orthogonal experimental design

With the “orthogonal experimental design” (OED), the dependence of conductivity and transparency of tin oxide films and open circuit voltage V_oc of SIS solar cells on the spray deposition process factors was studied. The OED technique was found to be a powerful method for realizing the best factor combination. Using OED, curves were obtained which clearly depict the effects of each factor on the SIS characteristics. The results of the experiments also illustrate exactly which variation in fabrication technique most affects the sheet resistance, V_oc, and film transparency. Under the optimal combination of conditions, a thin film doped with NH₄F was obtained, with about 90% transmission and a sheet resistance of about 80 Ω/□, along with an SIS structure with a V_oc of about 0.61 V.     

An experimental study of the gas entrapment process in closed-end microchannels

The physical mechanisms of the gas entrapment process in closed-end microchannels were investigated. Deionized water was the test fluid. The test pieces consisted of micromachined silicon squares with glass bonded on top. The microchannels had widths varying from 50 to 5 μm and had a mouth angle of 90°. Experiments show two main filling behaviors: (1) A single meniscus at the entrance, (2) Two or more menisci: one at the entrance and the other near the closed end. A single meniscus typically forms for higher contact angles ( > 50°), while two or more menisci form for lower contact angles ( 30°). For 30° 50°, one or two interfaces were observed. In all cases, after sufficient time (hours to days), the microchannel was completely flooded. In general, increasing the depth and/or width increases the time taken to fill. On the other hand, decreasing the contact angle decreases the time taken to fill. Comparison of experimental data with predictions based on a simple mass diffusion model shows reasonable agreement.     

An experimental investigation on performance and emissions study with port injection using diesel as an ignition source for different EGR flow rates

Exhaust gas recirculation, EGR, is one of the most effective means of reducing NO_x emissions from IC engines and is widely used in order to meet the emission standards. In the present work, experimental investigation has been carried out to study the NO_x reduction characteristics by exhaust gas recirculation in a dual fueled engine using hydrogen and diesel. A single cylinder diesel engine was converted to operate on hydrogen-diesel dual fuel mode. Hydrogen was injected in intake port and diesel was injected directly inside the cylinder. The injection timing and injection duration of hydrogen were optimized initially based on the performance and emissions. It was observed that start of injection at 5° before gas exchange top dead center (BGTDC) and injection duration of 30° crank angle gives the best results. The flow rate of hydrogen was optimized as 7.5 lpm for the best start of injection and injection duration of hydrogen. Cold exhaust gas recirculation technique was adopted for the optimized injection parameter of hydrogen and flow rate. Maximum quantity of exhaust gases recycled during the test was 25% beyond this the combustion was not stable resulting in increase in smoke.     

Concentration of liquid foods using desiccants: An experimental study

Liquid foods are often partially dehydrated to reduce their water content so as to enhance their storage stability. Evaporation, which consumes large amounts of energy, is the most widely used operation for concentrating liquid foods. The paper describes a novel system to concentrate liquid foods by using liquid desiccants. In the proposed system, water vapour, evaporated from the liquid food at reduced pressure, passes to the liquid desiccant, where it is absorbed while liberating its latent heat. The liquid desiccant temperature thereby increases. The warm liquid desiccant can then be used to provide a portion of the thermal energy for the evaporation of the water in the liquid food. A vertical, double-falling-film evaporator which uses calcium chloride solution was built and was used to concentrate liquid foods. The experimental set-up was tested to study the influence of the liquid-desiccant flow rate, the liquid-food flow rate, and the liquid-desiccant concentration and temperature. Some of the experimental results are discussed in this paper.     

国产灌注剂行经皮椎体成形术的实验研究

目的评估不同配比浓度国产灌注剂的材料性能,探讨国产灌注剂用于经皮椎体成形术的可行性.方法将国产灌注剂按粉液比(g/ml)为2∶1、3∶2、4∶3,及粉剂中BaSO4的百分比为0、10%、20%、30%,分成12个组,每组8个样本,测定其聚合时间、CT值、强度和刚度.对结果进行多因素方差分析.结果随着粉液比例及粉剂中BaSO4的百分比的改变,国产灌注剂的聚合时间、CT值、刚度和强度明显改变,差异有显著性(P＜0.05).结论通过改变国产灌注剂的配比浓度,可使其获得较满意的材料性能,其在椎体成形术中有良好的应