Research and Implementation of Decreasing the Acetic Acid Consumption in Purified Terephthalic Acid Solvent System

Decreasing the acetic acid consumption in purified terephthalic acid （PTA） solvent system has become a hot issue with common concern. In accordance with the technical features, the electrical conductivity is in direct proportion to the acetic acid content. General regression neural network （GRNN） is used to establish the model of electrical conductivity on the basis of mechanism analysis, and then particle swarm optimization （PSO） algorithm with the improvement of inertia weight and population diversity is proposed to regulate the operating conditions. Thus, the method of decreasing the acid loss is derived and applied to PTA solvent system in a chemical plant. Cases studies show that the precision of modeling and optimization are higher. The results also provide the optimal operating conditions, which decrease the cost and improve the profit.

The Structure Development of Cellulose Dissolved in the Phosphoric Acid/Polyphosphoric Acid Solvent

Cellulose,being as the most abundant nature polymer material and the most promising oil substitute,attracts more and more interests.A new cellulose dissolution system,phosphoric acid(PA)/polyphosphoric acid(PPA) solvent,was investigated in this study.It had been found that a larger cellulose solid content could be dissolved quickly in a hypothermic situation.By evaluating the stability of regenerated cellulose film and the formation of anisotropic solution,the dissolution behavior of cellulose was investigated.Wide-angle X-ray diffraction(WAXD) and Fourier transform infrared spectroscopy(FT-IR) were employed to characterize the crystalline structure and morphology of regenerated cellulose.The measurement results revealed a transition from cellulose-Ⅰ of raw cellulose to cellulose-Ⅱ of regenerated cellulose and a decrease of crystallinity of cellulose after dissolved.This was attributed to the interaction between cellulose and acid solvent,which leaded to the breakage of cellulose intra-and inter-molecule hydrogen bonds and the conformation change of cellulose C6-OH.Moreover,the formation process of cellulose liquid crystal solution was illustrated by polarized light microscope(PLM).That may be induced by the rearranging movement of the cellulose macromolecular chains.

Oxidative desulfurization of diesel fuel with caprolactam-based acidic deep eutectic solvents: Tailoring the reactivity of DESs by adjusting the composition

Despite the significance of hydrogen bonding in deep eutectic solvents（DESs） for desulfurization processes, little is understood about the relationship between the DES composition, hydrogen-bonding strength, and oxidative desulfurization activity. In this study, a new family of caprolactam-based acidic DESs was prepared with different molar ratios of caprolactam and oxalic acid. The prepared DESs were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, 1 H nuclear magnetic resonance, and thermogravimetric analyses. These DESs were employed for oxidative desulfurization reactions and the desulfurization efficiency was found to vary regularly with the DES composition. The factors influencing the removal of dibenzothiophene were systematically investigated and the desulfurization efficiency of the caprolactam-based acidic DESs reached as high as 98% under optimal conditions. The removal of different sulfur compounds followed the order： dibenzothiophene 4,6-dimethyldibenzothiophene benzothiophene. The combined experimental data and characterization results revealed that the oxidative desulfurization efficiency of the system was influenced by the hydrogen bonding interactions with the DES, which can be optimized by adjusting the DES composition. These findings regarding hydrogen bonding in DESs provide new insight for better understanding of the mechanism of diesel deep desulfurization processes.

Overview of acidic deep eutectic solvents on synthesis,properties and applications

This review divides the acidic deep eutectic solvents(ADES) into Br?nsted and Lewis DES according to their diversity of acidic character.The hydrogen bond donors and halide salts for formulating an ADES are classified, the synthesis methods are described, and the physicochemical properties including freezing point, acidity, density, viscosity and conductivity are presented. Furthermore, the applications of Br?nsted acidic deep eutectic solvents(BADES) and Lewis acidic deep eutectic solvents(LADES) are overviewed, respectively, covering the fields in dissolution, extraction, organic reaction and metal electrodeposition. It is expected that the ADES has great potential to replace the pollutional mineral acid, expensive and unstable solid acid, and costly ionic liquid in many acid-employed chemical processes, thus meeting the demands of green chemistry.

Oxalic acid catalyzed solvent-free one pot synthesis of coumarins

Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.

Extracting vanadium from stone-coal by oxygen pressure acid leaching and solvent extraction

Vanadium extraction from stone-coal was investigated by oxygen pressure acid leaching and solvent extraction.The mineralogy of the stone-coal from Tongren City of Guizhou Province,China,was investigated by various determination methods. The effects of leaching time,leaching temperature,leaching agent concentration,leaching L/S ratio,granularity of material,additive consumption were investigated based on the mineralogy.The results show that under the conditions of leaching time of 3-4 h, temperature of 150℃,sulfuric acid consumption of 25%?30%,ratio of liquid to solid of 1.2:1,the granularity less than 0.074 mm, additive consumption of 3%-5%,and oxygen pressure of 1.2 MPa,and the vanadium leaching rate can be more than 92%by the method of two-step pressurized acid leaching.The powdery V2O5 product with 99.52%in V2O5 content is obtained by the flowsheet of acid recovery,removing iron by reduction process,solvent extraction,precipitating vanadium with ammonium water,and pyrolysis from the stone-coal oxygen pressure acid-leaching solution.The total recovery efficiency of vanadium is above 85%,which is more than 20%higher than that obtained in the conventional process.Furthermore,the new process does not cause air pollution since no HCl or Cl2 is released by calcination of the raw material.

A Bifunctional Brønsted Acidic Deep Eutectic Solvent to Dissolve and Catalyze the Depolymerization of Alkali Lignin

Lignin is an abundant renewable macromolecular material in nature,and degradation of lignin to improve its hydroxyl content is the key to its efficient use.Alkali lignin(AL)was treated with Brønsted acidic deep eutectic solvent(DES)based on choline chloride and p-toluenesulfonic acid at mild reaction temperature,the structure of the lignin before and after degradation,as well as the composition of small molecules of lignin were analyzed in order to investigate the chemical structure changes of lignin with DES treatment,and the degradation mechanism of lignin in this acidic DES was elucidated in this work.FTIR and NMR analyses demonstrated the selective cleavage of the lignin ether linkages in the degradation process,which was in line with the increased content of phenolic hydroxyl species.XPS revealed that the O/C atomic ratio of the regenerated lignin was lower than that of the AL sample,revealing that the lignin underwent decarbonylation during the DES treatment.Regenerated lignin with low molecular weight and narrow polydispersity index was obtained,and the average molecular weight(Mw)decreased from 17680 g/mol to 2792 g/mol(130°C,3 h)according to GPC analysis.The lignin-degraded products were mainly G-type phenolics and ketones,and small number of aldehydes were also generated,the possible degradation pathway of lignin in this acidic DES was proposed.

Carbon dioxide capture by solvent absorption using amino acids: A review

The emission of large amounts of carbon dioxide is of major concern with regard to increasing the risk of climate change. Carbon capture, utilisation and storage (CCUS) has been proposed as an important pathway for slowing the rate of these emissions. Solvent absorption of CO_2 using amino acid solvents has drawn much attention over the last few years due to advantages including their ionic nature, low evaporation rate, low toxicity, high absorption rate and high biodegradation potential, compared to traditional amine solvents. In this review, recent progress on the absorption kinetics of amino acids is summarised, and the engineering potential of using amino acids as carbon capture solvents is discussed. The reaction orders between amino acids and carbon dioxide are typ- ically between 1 and 2. Glycine exhibits a reaction order of 1, whilst, by comparison, lysine, proline and sarcosine have the largest reaction constants with carbon dioxide which is much larger than that of the benchmark solvent monoethanolamine (MEA). Ionic strength, p H and cations such as sodium and potassium have been shown to be important factors influencing the reactivity of amino acids. Corrosivity and reactivity with impurities such as SOx and NOxare not considered to be significant problems for amino acids solvents. The precipitation of CO_2 loaded amino acid salts is thought to be a good pathway for increasing CO_2loading capacity and cutting desorption energy costs if well-controlled. It is recommended that more detailed research on amino acid degradation and overall process energy costs is conducted. Overall, amino acid solvents are recognised as promising potential solvents for car- bon dioxide capture.

A convenient synthesis of pyrroles catalyzed by acidic resin under solvent-free condition

A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition.Macroporous strongly acidic styrol resin(D001) as a novel,efficient,cost-effective,and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions.The pyrroles were obtained in high yields in short reaction times.

Wet carbon-based solid acid/NaNO_3 as a mild and efficient reagent for nitration of aromatic compound under solvent free conditions

Nitro aromatic compound can be obtained in high yields via nitration of aromatic compound with wet carbon-based solid acid and NaNO_3 under solvent free oxidation at room temperature.

Boric acid as an efficient catalyst for the synthesis of 1,1-diacetate under solvent-free condition

Boric acid （BO3H3） is an inexpensive, efficient and mild catalyst for the synthesis of 1,1-diacetate （acylal） from the various aromatic and heteroaryl aldehydes with acetic anhydride at room temperature under solvent-free condition. The present method does not involve any hazardous organic solvents or catalysts. This method gives notable advantages such as excellent chemoselectivity, mild reaction condition, short reaction times and excellent yield.

Recovery of oxalic acid from mother-liquor containing hydrochloric acid and cobalt by solvent extraction with P350

The solvent of P350 was applied to extract and separate the oxalic acid from the mother-liquor originated from the precipitation of cobalt by oxalic acid,and its extraction mechanism was deduced.Some factors,including the concentration of P350, the concentration of hydrochloric acid and the concentration of oxalic acid were investigated to determine the best distribution coefficient of the oxalic acid.In the case of phase ratio(O/A)at 2.0,the extraction of the oxalic acid was more than 95%and its concentration in the extraction raffinate was lower than 0.004 0 mol/L after six-stage counter-current extraction.While the phase ratio(O/A)of the stripping was at 1.0,the recovery of oxalic acid attained more than 95%after ten-stage counter-current stripping.

Efficient one-pot synthesis of 14-substituted-14H-dibenzo[a,j]xanthenes using boric acid under solvent-free conditions

Boric acid efficiently catalysed the one-pot reaction of alkyl or aryl aldehydes with 2-naphthol to afford the corresponding 14- alkyl-or aryl-14H-dibenzo[a,j]xanthenes in good yields under solvent-free conditions.

Temperature and Acidified Solvent Effect on Total Anthocyanins and RP-HPLC Phenolic Acids Determination in Selected Spices

Total anthocyanins of spices (Syzygium aromaticum L., Coriadrum sativum L., Cuminum cyminum L., Zingiber officinale Rosc., Elettaria cardamomum, Curcuma longa, Rhus coriaria L., Cinnamomum zeylanicum Blume, Foeniculum vulgare Mill and Laurus nobilis L.) were determined using acidified (1% HCl) solvents (methanol, ethanol and acetone) at three temperatures (20℃, 40℃ and 60℃). Also phenolic acids were separated and identified by RP-HPLC. Results showed that sumac and cinnamon had the highest levels of anthocyanins, while for the acetone the cinnamon indicated the highest amount of anthocyanins when methanol and ethanol were used as extracting solvents at 20℃. At 40℃ using ethanol, sumac showed the highest level of anthocyanins whereas acetone solvent yielded the highest anthocyanin contents for cinnamon. At 60℃, cinnamon showed the highest level of anthocyanins when methanol and acetone were the solvents, while sumac had the highest anthocyanins level using ethanol as solvent. HPLC results showed ten phenolic acids found in those spices and varied in their concentrations. Gallic acid had the highest level (1642.3 mg/100g) (cloves). Gentisic acid had the lowest level (1.2 mg/100g) in ginger. Also sumac showed the highest level of chlorogenic acid (1528.7 mg/100g). Some acids were not found in some spices, for instance, benzoic acid was not found in coriander, cumin, ginger, green cardamom, cinnamon and sweet laurel.

Regioselective ring opening of epoxides using NH_4SCN/silica sulfuric acid:An efficient approach for the synthesis of β-hydroxy thiocyanate under solvent-free conditions

Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.

Sulfanilic acid catalyzed solvent-free synthesis of 1,5-benzodiazepine derivatives

Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better yields.

Responsive mechanism of three novel hypochlorous acid fluorescent probes and solvent effect on their sensing performance

Optical properties and responsive mechanisms of three newly synthesized fluorescent probes for hypochlorous acid （HOC1） are investigated by employing time-dependent density functional theory. The computational results show that the absorption and emission properties of these probes change obviously when they react with hypochlorous acid. It is found that the probe FHZ has the best performance according to the probing behavior. Moreover, the responsive mechanisms of the probes are studied by analyzing the distributions of molecular orbitals and charge transfer, which are shown as the photon- induced electron transfer （PET） for FHZ and the intramolecular charge transfer OCT） for the other two probes. Specially, solvent effect on optical properties of the probe FHZ before and after reaction is studied within the polarizable continuum model （PCM）. It is shown that performance of the probe depends crucially on the solvent polarity. Our computational results agree well with the experimental measurement, and provide information for design of efficient two-photon fluorescent probes.

Solvent extraction of vanadium from sulfuric acid solution

The behaviour of vanadium（V） extracted from sulfuric acid solution was investigated using Cyanex 923 as an extractant. The effects of the concentration of Cyanex 923 and the pH of the solution were studied. The extraction of vanadium（V） increases with the increase of Cyanex 923 concentration and shaking time. Cyanex 923 can extract vanadium（V） from sulfuric acid solution at low pH conditions, and the best pH conditions for extraction of vanadium（V） are at pH 1.0-2.0. The species extracted into the organic phase is VO2HSO4 with one molecule of Cyanex 923. Equilibrium studies were used to assess the extraction efficiency of vanadium（V） recovery from the sulfuric acid solution.

Facile One-Pot Synthesis of Novel Hexahydro-2-quinolinecarboxylic Acids under Solvent-Free Reaction Conditions

A simple and fastthree-component synthesis of new and biologically active hexahydro-2-quinolinecarboxylic acid scaf-fold 4 was carried out using cyclocondensation reaction of arylmethylidenepyruvic acids 1, 1,3-cyclohexandiones 2 and ammonium acetate 3 under solvent-free conditions and at room temperature. This protocol has the advantages of facility, easy work-up, high yields, short reaction time and environmentally friendly character.