Presence Of Formic Acid Research Articles

Bimetallic IrAu mesoporous nanovesicles

Two-dimensional metallic nanosheets and mesoporous nanostructures attract increasing attentions in fields of energy conversion and storage due to their own different structural advantages. However, integration of their structural advantages into bimetallic or multimetallic systems for constructing highly efficient catalysts by facile methods is still a challenge yet greatly desired. Herein, we propose a feasible one-pot strategy for the synthesis of mesoporous IrAu nanovesicles (mIrAu NVs). The synthesis could be achieved by co-reduction of metal precursors in the presence of formic acid as reducing agent and poly(styrene-b-ethylene oxide) as structure-directing agent, resulting in bimetallic IrAu nanovesicles composed of curly mesoporous nanosheets. With the synergism of compositional and structural advantages, the as-obtained mIrAu NVs exhibit Pt-like catalytic activity for the oxygen reduction reaction in alkaline conditions, accompanied with enhanced durability and improved methanol tolerance.

An optimization study on heavy oil upgrading in supercritical water through the response surface methodology (RSM)

For clean upgrading of heavy oil, catalytic treatment in supercritical water (SC-H2O) is known as an attractive green methodology. To gain quantitative and qualitative insights of heavy oil upgrading in SC-H2O, optimization of operating conditions was performed where higher heating value (HHV), low sulfur contents as well as low rate of coke formation are desirable. A series of experiments for upgrading the vacuum residue (VR) feed in SC-H2O were designed with response surface methodology (RSM) and performed in presence of formic acid and hematite iron oxide nanoparticles as hydrogen donor and catalyst, respectively. The key process parameters including temperature, water, formic acid, catalyst contents and reaction time were optimized by the mentioned statistical methodology. The proposed optimization model displayed an acceptable correlation between the predicted and experimental results. From the experimental results it was apparent the incorporation of hematite nanoparticles with SC-H2O and formic acid exhibited higher degree of light fraction product and low coke formation derived from oxygen vacancy and better catalyst reducibility in SC-H2O.

Reductive fractionation of larch in a supercritical ethanol medium in the presence of bifunctional Ru/C catalyst and hydrogen donors

Lignin is a bulky waste of the hydrolysis and paper-pulp industry. To solve the problem of its utilization, approaches to deep processing of wood biomass are being developed; they are based on a preliminary catalytic fractionation of wood biomass into main components, which are processed into target products. For the first time, the reductive catalytic fractionation of larch was studied in a supercritical ethanol medium in the presence of 3%Ru/С bifunctional catalyst containing acid groups. The goal of the study was to reveal the effect of the catalyst and features of a hydrogen donor (ethanol, H2, formic acid) on the yields and composition of the products. It was shown that wood hemicelluloses efficiently (ca. 95 wt.%) depolymerize to ethanol at 250 °С. The use of hydrogen in the presence of the catalyst makes it possible to increase the conversion of lignin to 61 wt.% with retaining 47 wt.% cellulose in a solid residue. The maximum conversion of lignin equal to 67 wt.% was obtained in the presence of formic acid; however, the indicated conditions lead to undesirable depolymerization of cellulose (the conversion of 66 wt.%). The main monomeric products of lignin conversion on the catalyst are propenylguaiacol and propylguaiacol. In the liquid products obtained with ethanol and formic acid as the reductants, the content of propenylguaiacol reaches 36 and 33 rel.%, respectively. In the products obtained with hydrogen, the content of propylguaiacol increases to 33 rel.% in the presence of the catalyst.

Synthesis of Iron Oxide@Pt Core-Shell Nanoparticles for Reductive Conversion of Cr(VI) to Cr(III) and Antibacterial Studies.

Herein, we report the facile synthesis of Iron oxide@Pt core-shell nanoparticles (NPs) by facile two step synthesis process. The first step follows the growth of iron oxide nanoparticle by thermal decomposition process while the second step deals with the formation of iron oxide@Pt core-shell nanoparticles by the chemical reduction method. The synthesized core-shell nanoparticles were characterized by several techniques and used for the catalytic reductive translation of Cr(VI) to Cr(III) in the presence of formic acid by a UV-vis spectrophotometer. The UV photo-spectrometer analysis confirmed the conversion efficiency from 12% to as high as 98.8% at the end of 30 minutes. Thus, the presence of Iron oxide @Pt core-shell nanoparticles (NPs) can be effectively used as a catalyst for the reducion of Cr(VI) to Cr(III) ions. Additionally, antibacterial studies were performed for the prepared core-shell nanoparticles against two bacterial strains, i.e., gram (+ve) Staphylococcus Aureus (S. Aureus) and gram (-ve) Escherichia Coli (E. Coli).

Formic acid motivated photocatalytic reduction of Cr(VI) to Cr(III) with ZnFe2O4 nanoparticles under UV irradiation

ABSTRACT UV-light irradiated photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solution using ZnFe2O4 nanoparticles in the presence of formic acid was reported. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy (DRS) were employed to characterize ZnFe2O4 nanoparticles. The photocatalytic activity of pure ZnFe2O4 under UV irradiation was significantly low. However, the Cr(VI) reduction efficiency on nano-sized ZnFe2O4 in the presence of 0.40% formic acid reached 95.4% within 4 h. Herein, the effect of pH, photocatalyst amount, initial concentration of Cr(VI) and formic acid concentration on the photocatalytic reduction of Cr(VI) was investigated. The results indicated that the photocatalytic reduction of Cr(VI) decreased with increase in the initial concentration of Cr(VI), photocatalyst dosage and pH. The reduction rate constant declined from 0.017 min−1 to 0.0023 min−1 with the increase in initial concentration of Cr(VI) from 5 to 25 mg L−1. However, the reduction rate constant sharply increased from 0.000075 min−1 to 0.0127 min−1 with the increase in formic acid concentration from 0.05% to 0.40%. The formic acid could capture the photogenerated holes, and eventually formate (HCOO–) ions could be converted into carbon dioxide radicals (•CO2 −). Because of more negative redox potential for •CO2 − radicals, Cr(VI) species could easily be reduced to Cr(III) under UV irradiation. The pseudo-first-order kinetic reaction was confirmed for this reduction process. A tenable mechanism for the photocatalytic Cr(VI) reduction has also been demonstrated.

Liquid–liquid equilibria of the ternary system (cyclopentanol + water + cyclopentyl formate) at (298.2–338.2) K: Measurements and correlation

Cyclopentanol is an important intermediate in a production of many chemical specialties. This paper relates to a development of a new technology of indirect cyclopentene hydration in the presence of formic acid and presents the data of liquid-liquid equilibrium (LLE) for the ternary system of (cyclopentanol + water + cyclopentyl formate) under atmospheric pressure and within a temperature range from 298.2 K to 338.2 K. The experiments were conducted in a temperature-controlled glass cell and the received data were correlated with nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) equations in order to obtain binary coefficients describing LLE of the given system. A consistency of the experimental tie-lines data was validated by the Bachman and Othmer-Tobias equations and the data fitting accuracy was evaluated by the use of the calculated average absolute deviation and the root-mean-square-error values. According to our best knowledge, the LLE of this system have not yet been published elsewhere and the values of binary interaction parameters should be used for the design of the reactor and separation units in the process of indirect cyclopentene hydration.

Interface Nanoengineering of PdNi-S/C Nanowires by Sulfite-Induced for Enhancing Electrocatalytic Hydrogen Evolution.

The interfacial structural design of materials in nanoscale is a promising approach to regulate the physicochemical properties of materials and further optimize material properties for a variety of potential applications. Herein, PdNi-S/C nanowires with inductive sulfite has been successfully crafted through hydrothermal synthesis and applied as a superior hydrogen evolution reaction (HER) catalyst. Based on the autocatalytic mechanism, PdNi alloy nanoparticles were synthesized by controlling reduction kinetics with the presence of formic acid. Meanwhile, the sulfite is selected as an effective inductive agent to form PdNi-S/C nanowires with amorphous interfaces. The morphology, composition, and electronic structure of the synthesized PdNi-S/C were studied in detail. The PdNi-S/C manifests excellent HER performance in alkaline solution with an overpotentials of 67 mV at current density of 10 mA cm-2, a Tafel slope of 69.4 mV dec-1, and significantly long-term durability. The improvement of HER performance of the PdNi-S/C is attributed to the one-dimensional nanowire structure, abundant sulfur vacancies and defects, and the synergistic effect between PdNi-S nanowires with the graphite carbon. Furthermore, this present work offers a novel method for structure adjustment of materials to effectively control their property and catalytic performance.

Enhanced carbon tetrachloride degradation by hydroxylamine in ferrous ion activated calcium peroxide in the presence of formic acid

Hydroxyl radicals (HO•) show low reactivity with perchlorinated hydrocarbons, such as carbon tetrachloride (CT), in conventional Fenton reactions, therefore, the generation of reductive radicals has attracted increasing attention. This study investigated the enhancement of CT degradation by the synergistic effects of hydroxylamine (HA) and formic acid (FA) (initial [CT] = 0.13 mmol/L) in a Fe (II) activated calcium peroxide (CP) Fenton process. CT degradation increased from 56.6% to 99.9% with the addition of 0.78 mmol/L HA to the CP/Fe(II)/FA/CT process in a molar ratio of 12/6/12/1. The results also showed that the presence of HA enhanced the regeneration of Fe(II) from Fe(III), and the production of HO• increased one-fold when employing benzoic acid as the HO• probe. Additionally, FA slightly improves the production of HO•. A study of the mechanism confirmed that the carbon dioxide radical (CO2•−), a strong reductant generated by the reaction between FA and HO•, was the dominant radical responsible for CT degradation. Almost complete CT dechlorination was achieved in the process. The presence of humic acid and chloride ion slightly decreased CT removal, while high doses of bicarbonate and high pH inhibited CT degradation. This study helps us to better understand the synergistic roles of FA and HA for HO• and CO2•− generation and the removal of perchlorinated hydrocarbons in modified Fenton systems.

Palladium nanoparticles uniformly and firmly supported on hierarchical flower-like TiO2 nanospheres as a highly active and reusable catalyst for detoxification of Cr(VI)-contaminated water

The rational design of highly active and stable nanocatalysts towards the detoxification of Cr(VI)-contaminated water is of great importance for environmental remediation. In the present work, a novel Pd-based hybrid nanomaterial, composed of Pd nanoparticles (Pd NPs) supported on three-dimensional hierarchical titania nanoflowers (fTiO2), was fabricated and systematically investigated as the catalyst of chromium detoxification. Pd NPs with diameter of ~ 2.8 nm were found to be uniformly and firmly supported onto the crystalline nanosheets of fTiO2. More importantly, the highly open porous flower-like architecture of Pd NPs/fTiO2 could not only endow the catalyst with high surface area (237.5 m2 g−1) and large pore volume (0.86 cm3 g−1), but also facilitate reactant diffusion and exposure of active sites. Benefitting from these remarkable features, the Pd NPs/fTiO2 exhibited superior catalytic performance for reduction of Cr(VI) in the presence of formic acid. The TOF reached up to 633.0 h−1, which was several and even more than one hundred times as high as those obtained by previously reported supported Pd-based catalysts. Moreover, the catalytic activity of Pd NPs/fTiO2 could remain almost unchanged after being recycled several times, demonstrating its long-term stability. Therefore, the Pd NPs/fTiO2 would be promising for practical wastewater treatment.

One-pot synthesis of ZnS-rGO nanocomposites using single-source molecular precursor for photodegradation of methylene blue and reduction towards toxic Cr(VI) under solar light

A simple approach is described for the preparation of zinc sulfide-reduced graphene oxide (ZnS-rGO) nanocomposites using a single-source molecular precursor. The Zinc(II) benzaldehyde thiosemicarbazone complex has been used as a single-source molecular precursor to attain desired zinc and sulfur stoichiometry in the coexistence of graphene oxide, using a solvothermal method. Zinc metal chalcogenalato complex and nanocomposites were characterized using various techniques. The ZnS-rGO nanocomposites were used for the chemical reduction of highly toxic Cr(VI) to non toxic Cr(III) state in the presence of formic acid as a reducing agent. The reduction of hexavalent to trivalent chromium is carried out at room temperature using natural sunlight within 80 min. Furthermore, these zinc sulfide-reduced graphene oxide nanocomposites exhibit enhanced photocatalytic degradation efficiency toward methylene blue (MB) dye using solar light irradiation.

Cyclodextrin-Assisted Synthesis of Pd/Co/C Nanopolyhedra by ZIF-67 as a Highly Acid Tolerant Catalyst for Hexavalent Chromium Reduction.

The palladium/cobalt/carbon (Pd/Co/C) nanopolyhedra were synthesized by calcinating the precursor prepared by a cyclodextrin (CD) modified palladium acetylacetonate loaded on ZIF-67, hydroxypropyl-β-cyclodextrin (HP-β-CD)-[Pd(acac)2]/ZIF-67. On one hand, the HP-β-CD was used to increase the solubility of Pd(acac)2 by supramolecular interactions, and on the other hand, ZIF-67 was employed to provide the Co/C as the magnetic support. The Pd/Co/C nanopolyhedra obtained with the assistance of HP-β-CD have high activity and reusability for the reduction of the dichromate ion in the presence of formic acid without using any buffer solution, and no significant leaching of metallic Co of the catalyst was observed. This could be ascribed to the fact that the presence of HP-β-CD could lead to a more homogeneous distribution of metallic Pd in the Pd/Co/C nanopolyhedra, which could prevent the dissolution of metallic Co by formic acid.

Thermal Conversion of Heavy Crude Oil in the Presence of Formic Acid as a Hydrogen-donor Solvent

In this study, thermal conversion experiments of heavy oil using steam and formic acid as a hydrogen donor were carried out in a batch reactor at T = 380 °C and P = 165 bar. Material balance and products distribution were calculated after the experiments. Properties of crude oil before and after thermal conversion were analyzed including: viscosity, API gravity, SARA and elemental analysis measurements. It was shown, that application of formic acid as a hydrogen-donor solvent leads to the reduction of coke and gaseous products formation and to the increase of liquid products yield. In addition, the viscosity of upgraded oil was decreased by 23.2% due to addition of formic acid in comparison with thermal conversion without the hydrogen-donor solvent.

Recovery of precious metals from spent Mo–Co–Ni/Al2O3 catalyst in organic acid medium: Process optimization and kinetic studies

In present study, the leaching kinetics of the spent Mo–Co–Ni/Al2O3 catalyst was investigated in the presence of formic acid as an organic leaching agent. Firstly, the spent catalyst was roasted in different roasting temperature (200–700 °C) and time (15–240 min), the maximum metal extraction was achieved that at 500 °C with 90 min. Then, the leaching experiments were carried out to determine the influences of process parameters following; particle size, liquid/solid ratio, formic acid concentration, leaching temperature, leaching time and stirring speed. According to the experimental results, the highest dissolution rates of molybdenum (Mo, 75.82%), cobalt (Co, 96.81%), nickel (Ni, 93.44%) and aluminum (Al, 19.46%) were reached under optimum experimental conditions; particle size +75 − 30 µm; liquid/solid ratio 10 ml/g; formic acid concentration 0.6 M; leaching temperature 80 °C; leaching time 90 min and stirring speed 300 r/min. Moreover, the leaching kinetics clearly reveal that the leaching reaction is controlled by liquid film diffusion and that the activation energy values (Ea) of Co, Ni, Mo and Al were to be 24.49, 25.98, 32.36 and 33.47 kJ/mol, respectively. In conclusion, the leaching process can be conducted in the presence of formic acid for the various industrial wastes in similar structure and composition to Mo–Co–Ni/Al2O3 spent catalyst.

Nitrate reduction via micro-electrolysis on Zn-Ag bimetal combined with photo-assistance

A selective and efficient chemical reduction of nitrate to nitrogen gas using micro-electrolysis on ZnAg combined with a photo-assisted reduction in the presence of formic acid was investigated. The 99.58% removal of nitrate, 0.073 min−1 of rate constant and 94.3% nitrogen selectivity were achieved in Zn-Ag/hv/HCOOH system under the initial pH 2.5, 13.8 mmol/L of formic acid and 60 g/L of Zn-0.06%Ag dose at 60 min. The Zn-Ag/hv/HCOOH system had the highest removal rate and nitrogen selectivity for nitrate reduction compared with the alone or two combinations of ZnAg bimetals, formic acid, and UV-A. Furthermore, the co-existence anions of HCO3− and CO32− showed a negative effect on nitrate reduction while SO42− had slightly promoted the reduction process. During the nitrate reduction by Zn-Ag/hv/HCOOH process, rapid reduction of NO3− to NO2− was primarily caused by ZnAg bimetal. Subsequently, the conversion of NO2− to N2 was mainly owing to the produced CO2− by the reaction of formic acid and UV-A. The results suggested a novel strategy of chemical reduction combined with photoreduction for denitrification with high reaction kinetic as well as high nitrogen gas selectivity.

Efficient visible-light photocatalytic degradation of imidacloprid and acetamiprid using a modified carbon nitride/tungstophosphoric acid composite induced by a nucleophilic addition reaction

This study proposed a novel method to combine modified carbon nitride (MCN) and tungstophosphoric acid (HPW). First, carbon nitride (CN), containing more uncondensed amino and carbonyl groups, was prepared by thermal condensation from urea at a low temperature. Then, in the presence of formic acid, a reversible nucleophilic addition reaction was performed between the carbonyl groups of formaldehyde (or CN) and amino groups of CN. Subsequently, during the HPW impregnation, the reverse reaction occurred, which increased the HPW loading. The results of the XPS and FTIR analyses verified the occurrence of a nucleophilic addition reaction during the formaldehyde treatment, as well as the formation of hydroxyl functional groups in the intermediate products. After impregnation with HPW, the disappearance of the hydroxyl groups and the recovery of the carbonyl groups were observed in the XPS C1s spectra. The as-prepared MCN450/HPW, obtained by modifying CN450 (CN calcined at 450 °C) with formaldehyde and loading with HPW, exhibited excellent visible-light (λ > 400 nm) photocatalytic degradation of imidacloprid and acetamiprid. The degradation rate constant (0.70 h−1) of imidacloprid was 6.4 times that of CN450, while the degradation rate of acetamiprid by MCN450/HPW was 11 times that of CN450. The results of the active species capture experiments showed that OH and h+ were the main active species in the visible-light photocatalytic degradation process.

Photocatalytic Reduction of Hexavalent Chromium with Nanosized TiO2 in Presence of Formic Acid

Nanosized titanium dioxide (TiO2) nanoparticles were used for the photocatalytic reduction of hexavalent chromium in the presence of formic acid. The photoreduction of Cr(VI) in the absence of formic acid was quite slow. When formic acid was added in the chromium solution as the hole scavenger, a rapid photocatalytic reduction of Cr(VI) was observed, owing to the consumption of hole and the acceleration of the oxidation reaction. Furthermore, three commercial TiO2 nanoparticles (AEROXIDE® P25; Ishihara Sangyo ST-01; FUJIFILM Wako Pure Chemical Corp.) were evaluated for the photoactivity of reduction of Cr(VI).

Measurements and Correlation of Liquid–Liquid Equilibria for the Ternary System Cyclohexanol + Water + Cyclohexyl Formate at 298.2–338.2 K

Cyclohexanol is an important intermediate in production of adipic acid and e-caprolactam. On the industrial scale, cyclohexanol is produced by several methods that suffer from considerable drawbacks, such as a low conversion of the initial substance, low selectivity of the process, or explosion risks in the oxidation unit. To design a new process of indirect hydration of cyclohexene in the presence of formic acid, it is necessary to know the given system properties. In this paper, the data of liquid–liquid equilibrium (LLE) are presented for the system of cyclohexanol + water + cyclohexyl formate under atmospheric pressure and within a temperature range from 298.2 to 338.2 K. The experiments were conducted in a temperature-controlled glass cell and the received data were correlated with the nonrandom two-liquid (NRTL) and universal quasichemical equations in order to obtain binary interaction parameters describing LLE of the given system. The measured data accuracy was specified by the Bachman and Othmer–...

Palladium catalyzed carbonylations of alkenyl halides with formic acid to get corresponding α,β-unsaturated carboxylic acids and esters

Palladium-catalysed carbonylation reactions have been developed in the presence of formic acid as carbon monoxide source. α,β-Unsaturated carboxylic acids and esters were synthesized by the transformation of alkenyl halides in moderate to good yields. The selection of the base proved to be crucial regarding the reaction outcome. A set of various substrates were proven under optimised reaction conditions. Compared to aliphatic alcohols, phenols showed excellent reactivity as O-nucleophiles.

The production of ethanol from lignocellulosic biomass by Kluyveromyces marxianus CICC 1727-5 and Spathaspora passalidarum ATCC MYA-4345

Efficient bioconversion of lignocellulosic biomass is one of the key challenges for the production of bioethanol and chemicals. Therefore, the present work focuses on finding a robust microorganism able to convert all sugars in lignocellulosic hydrolysates efficiently. The fermentation performance showed that Kluyveromyces marxianus CICC 1727-5 could produce ethanol from glucose with productivity 4.2g/L/h and higher ethanol yields (0.44g/g) under 40°C, outdistance the productivity 0.258g/L/h of S. passalidarum ATCC MYA-4345. The xylose utilization of S. passalidarum ATCC MYA-4345 was faster than K. marxianus CICC 1727-5 with the ethanol yield 0.31g/g at 30°C. However, K. marxianus CICC 1727-5 could produce xylitol from xylose with the yield 0.58g/g at 40°C. Meanwhile, the two yeasts both had the ability to use arabinose naturally, but K. marxianus CICC 1727-5 could consume arabinose completely and quickly. Furthermore, the two yeasts both could ferment glucose and xylose simultaneously, but K. marxianus CICC 1727-5 showed much better performance in the cofermentation. The peak ethanol concentration of K. marxianus CICC 1727-5 and S. passalidarum ATCC MYA-4345 was 42.6 and 31.9g/L, respectively. In the saccharification and cofermentation (SSCF) process using non-detoxificated corncob, K. marxianus CICC 1727-5 showed better performance. K. marxianus CICC 1727-5 was more tolerant in the presence of formic acid, acetic acid, and mix inhibitors and even was capable to grow in the medium with the acetic acid concentration up to 15g/L. K. marxianus CICC 1727-5 is a promising candidate strain for further metabolic engineering to develop robust industrial strains for the lignocellulosic ethanol.

Extraction and Functional Group Characterization of Fulvic Acid from Hami Lignite

AbstractThis research investigates the extraction of fulvic acid (FA) from Hami lignite from Xinjiang, China, by microwave‐hydrogen peroxide and microwave‐hydrogen peroxide‐formic acid methods. The effects of reaction time, oxidant concentration, oxygen‐coal ratio and microwave power on FA yield are determined. Sulfuric acid‐acetone was applied to purify the primary FA products. The results indicate that the oxidant concentration is a sensitive factor affecting the yield of FA, while reaction time has little effect. Formic acid can promote the extraction of FA from lignite by hydrogen peroxide, and under optimal experimental conditions, the yields of FA were 5.34% and 9.13%, respectively. UV‐Vis analysis shows that FA has a lower aromaticity and degree of carbonyl conjugation in the presence of formic acid. Additionally, Fourier transform infrared spectroscopy was used to characterize the purified FA. The results show that the benzene rings of FA have one, two, three and four substitutions, oxygen‐containing functional groups containing –COOH, C=O, ‐OCH3, C−O−C, Ar‐OH, and R‐OH and, furthermore, primary oxygen‐containing functional groups consisting of C=O and C–OH. The aliphatic functional groups contain symmetrical and anti‐symmetrical stretching vibrations of ‐CH2 and ‐CH3. Finally, the hydrogen bonds are mainly composed of phenolic hydroxyls and alcoholic hydroxyls, while some hydrogen carboxylate is present.