Non-catalytic Method Research Articles

Non-catalytic production of modified hydroxyapatite for biomedical applications

In this work, we propose a convenient non-catalytic method for modifying hydroxyapatite (HA) with lactic acid to obtain a composite material suitable for traumatology fasteners. The affinity of the modified HA for the polylactide matrix increases, which has a positive effect on the composite mechanical properties. The modification process is carried out with lactic acids solutions in ethanol. It was shown that hydroxyapatite modified with 10–30% solutions retains its structure according to IR spectroscopy and X-ray diffraction analysis, and when modified with a 50% solution, calcium hydrophosphate is formed. Studies of the mechanical properties have shown that the modulus increases by almost 1 GPa for composites with modified HA compared to unmodified hydroxyapatite reaching a value close to that of native cortical bone tissue.

First highly effective non-catalytic nitrobenzene reduction in UV/dithionite system with aniline production – Advanced reduction process (ARP) approach

Advanced reduction processes (ARPs) are currently intensively investigated as an alternative to Advanced Oxidation Processes (AOPs). The study presents efficient reduction of nitrobenzene under non-catalytic conditions through reaction with free radicals having reductive potential. Effective conversion of nitrobenzene in a model wastewater solution, was obtained for sodium dithionite (SDT)/ dithionite (DTN). The developed process provide a nitrobenzene reduction efficiency of > 99.9 % within 10 min under neutral conditions, ambient temperature, with a molar ratio of reductant to pollutant (rred) of 3. Additional UV radiation lowered by 10 % the dose of DTN. Interestingly, addition of titanium dioxide (TiO2) as a photocatalyst did not show a positive effect. An extremely significant conclusion of this study is the observed excellent resistance of the reaction system to the negative influence of inorganic anions, with a reduction in efficiency in the following order: CO32-22%>NO3-6%>SO42-2%>Cl-2%>NO2-<1%>S2O32-<1%>N3-<1% and dissolved organic matter (DOM) (<13%). The study showed that the process works effectively across the pH range from 3 to 12. Studies on the reaction mechanism revealed that sulfur dioxide anion radical (SO2∙-)) was responsible for the main reduction effect. The main product of nitrobenzene reduction was aniline (>99.9 %). The total cost of purification process was USD 0.77/m3. The high efficiency, short process time, low cost, and lack of need for complicated equipment make this developed process potentially widely applicable in the industry. The developed method for the reduction of nitrobenzene to aniline is the first non-catalytic method with such high efficiency and without the formation of intermediate reaction products.

Programmable heating and quenching for efficient thermochemical synthesis

Conventional thermochemical syntheses by continuous heating under near-equilibrium conditions face critical challenges in improving the synthesis rate, selectivity, catalyst stability and energy efficiency, owing to the lack of temporal control over the reaction temperature and time, and thus the reaction pathways1-3. As an alternative, we present a non-equilibrium, continuous synthesis technique that uses pulsed heating and quenching (for example, 0.02 s on, 1.08 s off) using a programmable electric current to rapidly switch the reaction between high (for example, up to 2,400 K) and low temperatures. The rapid quenching ensures high selectivity and good catalyst stability, as well as lowers the average temperature to reduce the energy cost. Using CH4 pyrolysis as a model reaction, our programmable heating and quenching technique leads to high selectivity to value-added C2 products (>75% versus <35% by the conventional non-catalytic method and versus <60% by most conventional methods using optimized catalysts). Our technique can be extended to a range of thermochemical reactions, such as NH3 synthesis, for which we achieve a stable and high synthesis rate of about 6,000 μmol gFe-1 h-1 at ambient pressure for >100 h using a non-optimized catalyst. This study establishes a new model towards highly efficient non-equilibrium thermochemical synthesis.

Aqueous phase reforming of biocrude derived from lignocellulose hydrothermal liquefaction: Conditions optimization and mechanism study

Hydrothermal liquefaction (HTL) of biomass into biocrude is attractive but the biocrude themselves are poor fuels, which need to be upgraded for further utilization. Compared with the traditional catalytic upgradation process, a non-catalytic method for biocrude upgrading in the aqueous waste (HTL-AW) derived from HTL of cornstalk was proposed. Optimal reaction conditions of upgradation process were obtained at 356 °C (temperature), 37 min (reaction time) and 19 mL/g (HTL-AW/biocrude) based on the response surface methodology. The biocrude was effectively upgraded in the HTL-AW and a high hydrogen to carbon effective (H/Ceff) ratio of 1.07 with a higher heating value of 36.94 MJ/kg was observed. The energy recovery of ∼80% from biocrude to upgraded biocrude was feasible. GC–MS analysis showed that the contents of phenols and ketones were decreased from 65.61% to 48.38% and 22.39%–16.78%, respectively, while the contents of nitrogen-containing compounds n-hexadecanoic acid were increased from 2.25% to 10.15% and 9.56%–22.23%, respectively. The high H/Ceff was attributed to the promoted deoxygenation by alkali and alkaline earth metals as well as H+ enriched in the HTL-AW. This study demonstrates the feasibility of improving the H/Ceff of biocrude in the HTL-AW under a relatively mild reaction condition.

A non-catalytic process to produce levulinic acid from the flesh fruits of trembesi (Samanea saman) using a subcritical water

Levulinic acid (LA) has been identified as a promising green, biomass-derived platform chemical. A non-catalytic method to produce LA from the flesh fruits of trembesi (Samanea saman) using subcritical water has been performed. Effect of reaction time and operating pressure under CO2 atmosphere on the conversion of glucose and yield of LA has been investigated. The conversion of glucose was found to be affected by the reaction time rather than operating pressure. The longer reaction time from 30 to 480 min. increased the conversion of glucose from 87.72% ± 1.57% to 98.74 ± 1.76% or increased by 12.56% at 200 °C, 4 MPa and ratio of flesh fruit and water of 1/8 (g/ml). Increasing the operating pressure from 4 MPa to 8 MPa, only increased the conversion of glucose by 4.67%. The yield of LA was found to be affected by the reaction time and operating pressure. The yield of LA was increased by 61.88 % by increasing reaction time from 30 to 240 min, while extended further reaction time to 480 min. the reduced yield of LA by 24.05 %. The highest yield of LA (22.28 ± 0.04 %) can be achieved in 240 min at 200 °C and 8 MPa. The result showed that LA could be obtained by a green method.

Upgrading bio-heavy oil via esterification of fatty acids and glycerol

Bio-heavy oil (BHO), a crude mixture of fatty acids (FAs) and mono-, di-, and triglycerides unavoidably generated as waste during biodiesel production processes, is an alternative replacement of petro-heavy oil as a fuel for power generation. It is reported for the first time that upgrading the quality of raw BHO (lowering the acid value (AV) of BHO) can be achieved via a low-pressure non-catalytic esterification process. Esterification of the FAs contained in raw BHO on solid acid catalysts (tungsten trioxide and niobium pentoxide) were investigated by comparison with the non-catalytic method. The AV of raw BHO can be successfully reduced from 116 to ∼38 in 2 h under a low pressure (0.1 bar) via the non-catalytic esterification process. Catalytic esterification with Nb2O5 or WO3 showed similar performance to the non-catalytic esterification. It can be suggested a possibility to make a high-quality renewable fuel (e.g., BHO with a low acid value) for power generation from inexpensive feedstock.

Syngas production by non-catalytic reforming of biogas with steam addition under filtration combustion mode

Biogas conversion to syngas (mainly H2 and CO) is considered an upgrade method that yields a fuel with a higher energy density. Studies on syngas production were conducted on an inert porous media reactor under a filtration combustion mode of biogas with steam addition, as a non-catalytic method for biogas valorization. The reactor was operated under a constant filtration velocity of 34.4 cm/s, equivalence ratio of 2.0, and biogas concentration of 60 vol% Natural Gas/40 vol% CO2, while the steam to carbon ratio (S/C) was varied between 0.0 and 2.0. Total volumetric flow remained constant at 7 L/min. Combustion wave temperature and propagation rate, product gas composition, reactants conversion as well as H2 and CO selectivity were measured as a function of S/C ratio. Chromatographic parameters, method validation and measurement uncertainty were developed and optimized. It was observed that S/C ratio of 2.0 gave optimal results under studied conditions for biogas conversion, leading to maximum concentrations of 10.34 vol% H2, 9.98 vol% CO and highest thermal efficiency of 64.2% associated with a modified EROI of 46.3%, which considered energy consumption for steam supply. Conclusions indicated that the increment of the steam co-fed with the reactants favored the non-catalytic conversion of biogas and thus resulted in an effective fuel upgrading.

Fabrication of amorphous silica nanowires via oxygen plasma treatment of polymers on silicon

We demonstrate a facile non-catalytic method of fabricating silica nanowires at room temperature. Different polymers including photoresists, parylene C and polystyrene are patterned into pedestals on the silicon substrates. The silica nanowires are obtained via the oxygen plasma treatment on those pedestals. Compared to traditional strategies of silica nanowire fabrication, this method is much simpler and low-cost. Through designing the proper initial patterns and plasma process parameters, the method can be used to fabricate various regiment nano-scale silica structure arrays in any laboratory with a regular oxygen-plasma-based cleaner or reactive-ion-etching equipment.

A Review of Microwave-Assisted Reactions for Biodiesel Production.

The conversion of biomass into chemicals and biofuels is an active research area as trends move to replace fossil fuels with renewable resources due to society’s increased concern towards sustainability. In this context, microwave processing has emerged as a tool in organic synthesis and plays an important role in developing a more sustainable world. Integration of processing methods with microwave irradiation has resulted in a great reduction in the time required for many processes, while the reaction efficiencies have been increased markedly. Microwave processing produces a higher yield with a cleaner profile in comparison to other methods. The microwave processing is reported to be a better heating method than the conventional methods due to its unique thermal and non-thermal effects. This paper provides an insight into the theoretical aspects of microwave irradiation practices and highlights the importance of microwave processing. The potential of the microwave technology to accomplish superior outcomes over the conventional methods in biodiesel production is presented. A green process for biodiesel production using a non-catalytic method is still new and very costly because of the supercritical condition requirement. Hence, non-catalytic biodiesel conversion under ambient pressure using microwave technology must be developed, as the energy utilization for microwave-based biodiesel synthesis is reported to be lower and cost-effective.

A non-catalytic in situ process to produce biodiesel from a rice milling by-product using a subcritical water-methanol mixture

A non-catalytic method to produce biodiesel in situ from a rice milling by-product, i.e. rice bran, using subcritical water-methanol mixture has been investigated. The method was found to be unaffected by initial moisture and free fatty acids (FFA) contents in rice bran so that no pretreatment was required. The yield and purity of biodiesel were higher under CO2 atmosphere than those under N2 atmosphere due the ability of the gas to acidify water-methanol mixture. Oil extraction from the bran was identified as the limiting step and complete oil extraction could be achieved in 3 h at 200 °C, 4 MPa (under CO2 atmosphere) and 43.8 wt% methanol concentration. Consequently, the highest biodiesel yield was also achieved at those operating conditions. The experimental data suggested that hydrolysis of rice bran oil into FFA followed by methyl-esterification of FFA into biodiesel could be the preferred reaction path to direct transesterification of oil. Subcritical water-methanol mixture was also able to break down complex carbohydrates in rice bran into simple sugars soluble in aqueous phase so that it could be separated easily from biodiesel.

In Situ Generated Ag(II)-Catalyzed Selective Oxo-Esterification of Alkyne with Alcohol to α-Ketoester: Photophysical Study.

An expert and easy one-step catalytic method for the multi O-C coupling of alkyne is developed for the synthesis of valuable α-ketoesters and their chiral analogues, in contrast to the generation of esters by a noncatalytic method. The in situ generated powerful Ag(II) catalyst from AgOTf is the workhorse in the oxidative grafting of alkyne with PhIO and alcohol. The radical mechanism is confirmed in our controlled experiments and UV-vis study.

ChemInform Abstract: Synthesis of 2‐X‐, 3‐X‐4,4′‐Dicyanobiphenyls (X: CH3, OCH3, F) by Cross‐Coupling of the Terephthalonitrile Dianion with Substituted Benzonitriles.

Abstract2‐ and 3‐Substituted 4,4′‐dicyanobiphenyls are obtained by a concise and noncatalytic method using the in situ generated terephthalonitrile dianion as para‐cyanophenylation reagent.

Reaction kinetics of isopropyl palmitate synthesis

In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermediate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leaving group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very significant to both industrial application and determining the continuous production of isopropyl palmitate.

Catalytic combustion: Achievements and problems

A catalytic method of combustion of a solid fuel in a fluidized bed is compared with a noncatalytic method. It is shown that the use of catalysts reduces the fuel consumption and sizes of heat generators approximately by an order of magnitude, while the specific load on the reactor volume increases by more than a factor of 20. Emission of toxic substances with fuel combustion products drastically decreases. Comparative stability of oxide non-platinum catalysts is estimated in the course of catalytic burning of the fuel with addition of an inert material. In burning fuels with a large content of sulphur, the maximum deactivation is found to occur within the first several tens of hours; this process is accompanied by sulphur accumulation in catalysts. Later on, the catalyst activity remains almost unchanged. It is found that a critical factor of catalyst stability is attrition resistance. The prospects of fuel burning in a layer of cermet honeycomb catalysts are demonstrated.

Modification of Biodiesel Reactor by Using of Triple Obstacle within the Bubble Column Reactor

Abstract The aim of the study is to find the best model of triple obstacle for modifying of biodiesel reactor by non-catalytic method to increase the reaction rate of biodiesel production. Biodiesel is produced by trans-esterification reaction of oil and methanol. Superheated-methanol-vapour in the bubble column reactor as one of Non-catalytic method is used to produce biodiesel. Based on the analysis, the best configuration of obstacle having 52 holes 4 mm in diameter which spread on the top, middle and bottom of reactor obtained biodiesel production rate of 0.026 g · min –1 and the content of biodiesel of 89.9%.

Non-Catalytic and Catalytic Transesterification: A Reaction Kinetics Comparison Study

In the present study, a comparison of reaction kinetics for catalytic and non-catalytic transesterification processes using jatropha curcas oil has been evaluated. Optimization of reaction parameters was done using the response surface methodology (RSM) experimental design to establish the optimal parameters for the non-catalytic method. The optimal parameters for the catalytic methods were adopted from our previous published works. The study shows that the yield for non-catalytic method is lower compared to the catalytic methods. This might be attributed by the presence of poly-unsaturated fatty acids such as linoleic acid in jatropha oil which decompose easily at higher temperatures. The activation energies and methanol to oil ratios for catalytic and non-catalytic methods show that the latter is more energy and material consuming. However, the rate constants reveal that the non-catalytic method using supercritical methanol is faster than the catalytic methods.

Synergetic Sustainability Enhancement via Current Biofuel Infrastructure: Waste-to-Energy Concept for Biodiesel Production

The concept of waste-to-energy (WtE) with regards to the utilization of byproducts from the bioethanol industry (e.g., distiller's dried grain with solubles: DDGS) was employed to enhance the renewability of biodiesel, which would be an initiative stage of a biorefinery due to the conjunction between bioethanol and biodiesel. For example, DDGS is a strong candidate for use as a biodiesel feedstock due to the tremendous amount that is regularly generated. On the basis of an estimation of possible lipid recovery from DDGS, ∼30% of the biodiesel feedstock demand in 2010 could be supported by the total DDGS generation in the same year. Considering the future expansion of the bioethanol industry up to 2020, the possible lipid recovery from DDGS would provide more than 6 times the biodiesel feedstock demand in 2010. In order to enhance the renewability of biodiesel, the transformation of lipid extracted from DDGS into fatty acid ethyl ester (FAEE) via a noncatalytic transesterification reaction under ambient pressure was investigated in this work. The newly introduced method reported here enables the combination of the esterification of free fatty acids (FFAs) and the transesterification of triglycerides into a single step. This was achieved in the presence of a porous material (i.e., charcoal), and the optimal conditions for transformation into biodiesel via this noncatalytic method were assessed at the fundamental level.

Large-scale preparation of ZnO nanoflowers from nanowires with high length/diameter ratio

ZnO nanoflowers were successfully prepared by a new non-catalytic method based on directly heating of Zn strip using a direct current power supply. The Zn strip was obtained by electrodeposition on silicon wafer with laser etching. The nanoflowers, with a size more than 15μm, are assembled by nanowires with a length of 10μm and a diameter of 100nm, and the length/diameter ratio is about 100. The samples were characterized by means of scanning electron microscope, X-ray diffraction and Raman. X-ray diffraction results show that the formation of nanoflowers is controlled by the current density. Raman modes of nanoflower corresponds well with X-ray diffraction result. Photoluminescence property of ZnO nanoflowers shows strong green emission and violet emission.

Hydrogen generation from hydrolysis of MNH2BH3 and NH3BH3/MH (M = Li, Na) for fuel cells based unmanned submarine vehicles application

Hydrogen release from hydrolysis of LiNH2BH3, NaNH2BH3, LiH-NH3BH3 and NaH-NH3BH3 was investigated respectively in this paper. Their applications on man-free submarine vehicles were discussed in this paper. It is shown experimentally that LiNH2BH3 and NaNH2BH3 hydrolysis can release 3 equivalents of hydrogen at room temperature. Hydrolysis of LiNH2BH3 or NaNH2BH3 exhibits greatly improved kinetics in comparison with neat NH3BH3 hydrolysis. The mechanism of LiNH2BH3 and NaNH2BH3 hydrolysis is the combination of H+ and OH− ions of water with the polar ions of LiNH2BH3 and NaNH2BH3. The process of LiH-NH3BH3 and NaH-NH3BH3 hydrolysis involves the thermohydrolysis of NH3BH3. Our results present a novel noncatalytic method for hydrogen release from NH3BH3 by co-hydrolyzing it with other high exothermic hydrides, and also show a novel strategy to improve hydrogen release kinetics of LiNH2BH3 and NaNH2BH3. The hydrolyzing materials presented in this context are promising for use on fuel cells’ based vehicle.

Hydrogen generation from hydrolysis of NH3BH3/MH (M = Li, Na) binary hydrides

Hydrogen release from hydrolysis of LiNH2BH3, NaNH2BH3, LiH–NH3BH3 and NaH–NH3BH3 respectively was investigated in this paper. It is shown experimentally that LiNH2BH3 and NaNH2BH3 hydrolysis can release 3equiv. of hydrogen at 25°C. Hydrolysis of LiNH2BH3 or NaNH2BH3 exhibits greatly improved kinetics in comparison with neat NH3BH3 hydrolysis. The electronic and structural changes from NH3BH3 to [NH2BH3]− play a crucial role in the improvements. The mechanism of LiNH2BH3 and NaNH2BH3 hydrolysis is the combination of H+ and OH− ions of water with the polar ions of LiNH2BH3 and NaNH2BH3. The process of LiH–NH3BH3 and NaH–NH3BH3 hydrolysis comprises two steps: LiH or NaH first reacts with water and then the generated heat initiates thermohydrolysis of NH3BH3. LiH or NaH hydrolysis is prior to the reaction of LiH or NaH with NH3BH3. Our results show a novel strategy to promote hydrogen release kinetics of LiNH2BH3 and NaNH2BH3. Furthermore, our results also present a novel noncatalytic method for hydrogen release from NH3BH3 by co-hydrolyzing it with other highly exothermic hydrides.