Combustion of a suspension of biofuel droplets in air

This paper presents the results of theoretical and experimental studies of the combustion of rapeseed methyl ester droplets in comparison with mineral diesel fuel. Droplets of 0.7–1.2 mm diameter were investigated. The effect of the oxidizer equivalence ratio in the range of 1.7–4.0 on the duration of droplet combustion was analyzed using the model of combustion of droplets in an adiabatic shell taking into account Stefan flow. It is shown that the burning time of rapeseed methyl ester droplets is smaller than that of diesel fuel droplets, all other things being equal.     

An investigation of the operating parameters of a low energy wet scrubber for fine particulates

Tests performed on an inexpensive, low energy wet scrubber are described. The device employs a centrifugal fan, operated at 550–750 rpm, and co-current spray nozzles producing a relatively fine spray, from 20μ to 180μ. The fan acts as the prime mover of air, as contacting device, agglomerator, and precipitator. Variations in the scrubber's collection efficiency with changes in fan speed, water flow rate, nozzle position and with particle size in the range 0.1–3μ. have been studied.     

Microemulsions in the preparation of highly active combustion catalysts

Catalytic activity in combustion of toluene in toluene–air mixtures and physical–chemical properties of platinum catalysts prepared from reverse microemulsions (water-in-oil) and by classical impregnation from water solutions of H₂PtCl₆ were studied. Microemulsion catalysts were more active than those prepared classically from water solutions. Size of Pt in classically impregnated catalysts was three times higher than that of catalysts prepared from microemulsions. In case of microemulsion preparation method, platinum is located near the pellet surface or its position in the pellet can be optimised. The effect of oil used in microemulsion system seems to be negligible for the activity of the catalysts with 0.1 wt.% Pt.     

FeVO4 as a highly active heterogeneous Fenton-like catalyst towards the degradation of Orange II

The iron vanadate, FeVO₄, was prepared and characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). It was found that FeVO₄ could effectively catalyze H₂O₂ to generate active hydroxyl radical OH, which was confirmed with electron spin resonance (ESR) spin-trapping technique. Therefore, it was employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the degradation efficiency of Orange II. Compared with the conventional heterogeneous Fenton-like catalysts, α-Fe₂O₃, Fe₃O₄ and γ-FeOOH, FeVO₄ possessed a much higher catalytic activity. The high catalytic activity possibly involved in a special two-way Fenton-like mechanism, that is, the activation of H₂O₂ by both Fe(III) and V(V) in FeVO₄. Moreover, FeVO₄ possessed a wide applicable pH range and its catalytic activity was slightly affected by the solution pH values in the range of 3–8.     

双峰聚乙烯生产过程中细粉产生的原因分析

基于目前反应器串联工艺生产双峰聚乙烯过程中细粉较多的现状,分别考察了预聚小环管反应器、超临界环管反应器以及气相流化床反应器的生产状况.通过扫描电子显微镜以及激光粒径分析仪等手段,比较了两种不同催化剂生产的聚乙烯颗粒的形态.结果表明,催化剂的不规整形态是引起细粉的主要原因.同时,超临界环管反应器内的颗粒破碎现象也不容忽略...     

Use of dried air in the active oxygen method of determining relative stabilities of fats

Summary The active oxygen method, when used for the study of lards to which no antioxidant has been added, yields essentially the same stability figures whether or not the air stream is passed through a drying tower after being scrubbed. This is not always true when antioxidants have been added to the lard. Among the antioxidants whose effects have been found to be essentially unaffected by moisture under the conditions used are gum guaiac, tocopherols, Age-Rite resin, and nordihydroguaiaretic acid. Lard to which d-isoascorbyl palmitate, ascorbic acid, triethanolamine, or certain other materials have been added shows a much higher stability in the presence of moist air than in the presence of dry air. Preliminary storage tests indicate that the data obtained through the use of dried air are more reliable as an indication of storage behavior than are the data obtained by the use of the moist air commonly used in the active oxygen method. A recognition of this effect of moisture is of great importance in the study of the effects of various antioxidant materials on the stability of lard.     

Heterostructures of MXenes and CoNx-Graphene as highly active electrocatalysts for hydrogen evolution reaction in alkaline media

Journal of Applied Electrochemistry - Hydrogen evolution reaction (HER) plays a vital role in renewable energy conversion for the development of hydrogen-based energy sources. Lately,...     

Nb/HUSY as a highly active catalyst for the direct transformation of fructose to methyl lactate

One-pot conversion of biomass-based carbohydrates to methyl lactate (MLA), a versatile platform chemical for the production of food additives as well as the starting material of pharmaceutical industry, is an attractive green process. In this study, the Nb/HUSY catalysts with highly catalytic performance are successfully synthesized and used for the production of MLA from fructose. Remarkably, when using 2%Nb/HUSY as catalyst, the highest MLA yield of 56.1% is obtained with complete conversion of fructose under optimal conditions (140 °C for 6 h). The introduction of niobium into HUSY enhances the Lewis acid properties, which facilitates the stepwise process, involving the retro-aldol condensation and dehydration reactions. The as-prepared catalysts have shown promising potential for conversion of fructose to MLA and effectively inhibited the formation of by-products. More importantly, the catalyst exhibits superior stability and could be reused for at least four cycles.     

Defect-induced strategies for the creation of highly active hydrotalcites in base-catalyzed reactions

Mg–Al hydrotalcites have demonstrated their superior performance in numerous base-catalyzed applications, especially their meixnerite-type analogues. The effect of using mechanical stirring or ultrasound during reconstruction of the mixed oxides leads to an enhancement in the catalytic activity. This can be correlated to modifications in the structure and basicity of the resulting materials, together with an increased surface area and improved accessibility to the active sites. However, increasing the rehydration time during stirring or sonication strongly affects the final catalyst, as observed by high-resolution transmission electron microscopy. An important amount of defects in the lamellar structure of the small hydrotalcite nanoplatelets are likely responsible of the presence of stronger and more accessible active basic sites, as determined by CO₂-TPD and benzoic acid titration. The greater performance of these materials has been disclosed for the epoxidation of styrene.     

FeVO4 as a highly active heterogeneous Fenton-like catalyst towards the degradation of Orange II

The iron vanadate, FeVO₄, was prepared and characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). It was found that FeVO₄ could effectively catalyze H₂O₂ to generate active hydroxyl radical OH, which was confirmed with electron spin resonance (ESR) spin-trapping technique. Therefore, it was employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the degradation efficiency of Orange II. Compared with the conventional heterogeneous Fenton-like catalysts, α-Fe₂O₃, Fe₃O₄ and γ-FeOOH, FeVO₄ possessed a much higher catalytic activity. The high catalytic activity possibly involved in a special two-way Fenton-like mechanism, that is, the activation of H₂O₂ by both Fe(III) and V(V) in FeVO₄. Moreover, FeVO₄ possessed a wide applicable pH range and its catalytic activity was slightly affected by the solution pH values in the range of 3–8.     

An energy‐limited model of algal biofuel production: Toward the next generation of advanced biofuels

Algal biofuels are increasingly important as a source of renewable energy. The absence of reliable thermodynamic and other property data, and the large amount of kinetic data that would normally be required have created a major barrier to simulation. Additionally, the absence of a generally accepted flow sheet for biofuel production means that detailed simulation of the wrong approach is a real possibility. This model of algal biofuel production estimates the necessary data and places it into a heuristic model using a commercial simulator that back‐calculates the process structure required. Furthermore, complex kinetics can be obviated for now by putting the simulator into energy limitation and forcing it to solve for the missing design variables, such as bioreactor surface area, productivity, and oil content. The model does not attempt to prescribe a particular approach but provides a guide toward a sound engineering approach to this challenging and important problem. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4641–4654, 2013     

Biologically active synthetic fibres and materials of the new generation

A new generation of biologically active suture materials capable of a combined action on wound pathology is being developed. The effect of the developed organoelemental biologically active complex on the wound process in all three of its phases is demonstrated. Biologically active fibre material with a honeycomb structure for scleroplastic operations that accelerates regeneration processes in ocular membranes and prevent possible primary and secondary infection of wound tissues was developed. __________ Translated from Khimicheskie Volokna, No. 6, pp. 43–46, November–December, 2005.     

Magnetically recyclable Fe@Pd/C as a highly active catalyst for Suzuki coupling reaction in aqueous solution

In this work, a novel catalyst Fe@Pd/C was synthesized by sequential reduction method. The core–shell catalyst exhibited efficient catalytic activity in Suzuki coupling reaction at mild condition in water. Moreover, the catalyst could be recycled by external magnetic field and the yields achieved above 86% after reused at least 5 times.     

Small-sized HZSM-5 zeolite as highly active catalyst for gas phase dehydration of glycerol to acrolein

The catalytic properties of nanocrystalline HZSM-5 catalysts with high Si/Al molar ratio (ca. 65) were investigated in the gas phase dehydration of aqueous glycerol. Compared with bulk HZSM-5, the small-sized catalyst exhibits greatly enhanced catalytic performance in glycerol dehydration even with very high GHSV (=1438 h^?1). Catalysts with different Si/Al ratios were studied, but it is difficult to separate the influence of Si/Al ratio from that of particle size. However, by varying the proton exchange degree for one mother batch of zeolite, a series of H_xNa_1–xZSM-5 catalysts with same particle size and different Brønsted acid site densities was prepared. The catalytic results for this series of samples show that high density of Brønsted acid sites favors the production of acrolein. Based on these results, small-sized HZSM-5 with high aluminum content appears to be most promising for gas phase dehydration of glycerol.     

Composites as cracking catalysts in the production of biofuel from palm oil: Deactivation studies

Composite catalysts HZSM-5/alumina (CZA) and Al-MCM-41/alumina (CMA) were synthesized and tested for their catalytic cracking activity in the production of biofuel from palm oil. Both composite catalysts were characterized for their structure, acidity and surface morphology. The addition of alumina in the composite catalysts improved their hydrothermal stability due to the changes in the surface morphology. The deactivation of the catalysts was studied by obtaining time on stream data by varying the palm oil to catalyst ratio of 8–16. The deactivation data were analyzed using different activity models and the deactivation parameters were determined.     

In situ active chlorine generation for the treatment of dye-containing effluents

This study examined the possibility to remove colour causing-compounds from synthetic effluent by indirect electrochemical oxidation using iridium oxide anode electrodes. Using a high concentration of chloride ions (17.1 mM) and various current densities, it was possible to produce high concentration of active chlorine with a specific production rate of 2.8 mg min⁻¹ A⁻¹. The best performance for acid methyl violet 2B dye (MV2B) decomposition was obtained using Ti/IrO₂ anodes operated at a current density of 15 mA cm⁻² during 40 min of treatment in the presence of 3.42 mM of chloride ions. Under these conditions, more than 99% of MV2B was removed (with a reaction rate apparent constant of 0.20 min⁻¹), whereas COD and TOC removal were 51% and 75%, respectively. The electrolytic cell was then used for the degradation of three other synthetic dye solutions: Eosin yellowish (EOY), Trypan Blue (TRB), Acridine Orange (ACO). TRB was the most difficult dye to remove from solution with a value reaction rate constant of 0.12 min⁻¹, compared to 0.19 min⁻¹ and 0.24 min⁻¹ recorded for ACO and EOY dyes, respectively. More than 99% of these dyes were removed by electrochemical oxidation.