Solid-Liquid Equilibria of Several Binary and Ternary Systems Containing Maleic Anhydride

Solid-liquid equilibria (SLE) of three binary systems and seven ternary systems containing maleic an-hydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources, dortmund data bank(DDB), if there's any, and correlations based on our former presented experimental SLE data of twenty binary systems. New groups of MA, ACCOO group, COO group, >C=O group and cy-CH2 group are defined and the SLE data of rnaleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters, correlated with Wilson equation and the λh equation. The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing rnaleic anhydride.     

Adsorption of Basic Dyes on β-Cyclodextrin Functionalized Poly (Styrene-Alt-Maleic Anhydride)

A new [#x003B2]-cyclodextrin functionalized poly (styrene-alt-maleic anhydride) was synthesized for removal of basic fuchsin (BF) and methylene blue (MB) from water via grafting reaction of [#x003B2]-cyclodextrin onto poly (styrene-alt-maleic anhydride) and then acylation with chloroacetyl chloride. Its structure was characterized. At a dosage of 0.25 g[#x000B7]L^[#x02212]1, pH 6, and 25[#x000B0]C, adsorption equilibrium was reached in 600 min and maximum adsorption quantities to BF and MB were 295 mg[#x000B7]g^[#x02212]1 and 528 mg[#x000B7]g^[#x02212]1, respectively. The equilibrium data fitted the Langmuir isotherm and the adsorption kinetics data followed the pseudo-second-order model. Adsorption processes were endothermic, entropy gained, and spontaneous in nature within 288-308 K.     

ATR-FTIR Study of the Decomposition of Acetic Anhydride on Fosfotungstic Wells–Dawson Heteropoly Acid Using Concentration-Modulation Excitation Spectroscopy

The decomposition of acetic anhydride in liquid phase on a fosfotungstic Wells–Dawson heteropoly acid (HPA) was investigated by in situ ATR-FTIR spectroscopy. Transient and concentration-modulation excitation spectroscopy (MES) experiments in combination with phase-sensitive detection (PSD) were used to monitor the solid–liquid interface. The MES method is based on the periodic variation of a parameter of the reaction media such as, the reactant concentration. That periodic alteration causes varying infrared signals of the surface adsorbed species that are subsequently demodulated with the PSD methodology. Thus, the separation of the static signals from the changing ones is achieved, and species with different response can be observed in the spectra. Using MES-PSD coupled with ATR-FTIR, acetic anhydride was observed to decompose to acetic acid, acetate and acyl [CH₃C(O)⁺] species, involving Brønsted acid sites of the HPA catalyst. The CH₃C(O)⁺ is a very unstable intermediate species and it is the key intermediate in the Friedel–Crafts acylation reactions. Moreover, the acetate groups are spectator species since remain strongly adsorbed on the catalyst surface and do not further react.     

Demand for Acetic Anhydride Promoted by Downstream Products

Acetic anhydride, an important rawmaterial,is mainly used to producecellulose acetate,and then to pro-duce cigarette filter tips,films,span-     

What Limits the Selectivity Attainable in the Catalysed Oxidation of o-Xylene to Phthalic Anhydride?

The degree of selectivity obtained in the selective oxidation of o-xylene to phthalic anhydride by V₂O₅/TiO₂ catalysts under industrial conditions is no more than 75–80%: the mechanism of the non-selective oxidation has commanded little interest. Principal features of the reaction and the catalyst are reviewed: the formation of polymeric by-products at low conversion, when the surface is not highly oxidised, is noted, as these will lead to carbon oxides, but at high conversion it is probable that adsorbed intermediate species may undergo side-reactions with reduced V sites, or exposed Ti ions. The resulting strongly-held species can only lead to carbon oxides, so that limiting factors may be (i) degree of completeness of the V₂O₅ monolayer, and (ii) the rate of re-oxidation of reduced surface. © 1997 SCI.     

Reaction Profiles of High Silica MOR Zeolite Catalyzed Friedel–Crafts Acylation of Anisole Using Acetic Anhydride in Acetic Acid

Friedel–Crafts reaction of anisole over high silica mordenite zeolite was investigated. Detailed reaction profiles were obtained using various reaction conditions. In particular, the behavior of acetic anhydride during the reaction and the effect on the hydrophilicity of the mordenite zeolite catalyst were investigated.

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Gas Phase Hydrogenation of Maleic Anhydride to γ-Butyrolactone by Cu–Zn–Ce Catalyst in the Presence of n-Butanol

A series of Cu–Zn–Ce catalysts were prepared by coprecipitation method and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, temperature programmed reduction, and N₂ adsorption. The catalytic activities of the Cu–Zn–Ce catalysts in gas phase hydrogenation of maleic anhydride in the presence of n-butanol were studied at 220–280 °C and 1 MPa. The conversion of maleic anhydride was more than 97%. After reduction, CuO species present in the calcined Cu–Zn–Ce catalysts were converted to metallic copper (Cu°). The presence of ZnO in the Cu–Zn–Ce catalysts was beneficial to stabilizing the catalytic activity in maleic anhydride hydrogenation to γ-butyrolactone. At the same time, n-butanol was dehydrogenated to butyl aldehyde, then to butyl butyrate via reactions, such as disproportionation and esterification. Cu–Zn–Ce catalysts are beneficial to the H₂ compensation in the coupling process of hydrogenation and dehydrogenation.     

Hydrogenation of Succinic Acid to γ-Butyrolactone (GBL) Over Palladium-Alumina Composite Catalyst Prepared by a Single-Step Sol–Gel Method

Abstract  

Mesoporous palladium-alumina (Pd-A) composite catalysts prepared by a single-step sol–gel method were calcined at various temperatures to control palladium surface area and acidity. The Pd-A catalysts were characterized by XRD, BET, N₂ adsorption–desorption isotherm, H₂ chemisorption, ²⁷Al MAS NMR, NH₃-TPD, and HR-TEM analyses. Liquid-phase hydrogenation of succinic acid to γ-butyrolactone (GBL) was carried out over Pd-A catalyst in a batch reactor. The effect of calcination temperature of Pd-A catalyst on the palladium surface area and catalytic performance was investigated. In the hydrogenation of succinic acid, conversion of succinic acid increased with increasing palladium surface area of Pd-A catalyst. Selectivity for GBL depended on the formation of succinic anhydride (an intermediate product formed by acid catalysis) and by-products (formed by hydrogenolysis). Nevertheless, yield for GBL also increased with increasing palladium surface area of Pd-A catalyst. Thus, palladium surface area played an important role in enhancing the catalytic performance of Pd-A catalyst in the hydrogenation of succinic acid to GBL.     

Effect of Hyperbranched Poly (Trimellitic Anhydride Ethylene Glycol) Epoxy (HTME) on Thermal Degradation Activation Energies of HTME/Diglycidyl Ether of Bisphenol-A Epoxy Hybrid Resin by Kissinger and Flynn–Wall–Ozawa Method

The thermal degradation behavior and kinetics of hyperbranched poly (trimellitic anhydride ethylene glycol) epoxy (HTME)/diglycidyl ether of bisphenol-A epoxy (DGEBA) hybrid resin was investigated with thermogravimetric analysis (TGA) by using Kissinger method and Flynn–Wall–Ozawa method. The results show that the thermal degradation activation energies of DGEBA, 9 wt% HTME-1/91wt% DGEBA, 3 wt% HTME-2/97 wt% DGEBA, 9 wt% HTME-2/91 wt% DGEBA, 15 wt% HTME-2/85 wt% DGEBA, and 9 wt% HTME-3/91wt% DGEBA are 152.5, 144.4, 135.4, 133.2, 121.8 and 143.0 kJmol^?1, respectively, by Kissinger method. and the activation energies are 173.3, 165.0, 163.2, 151.7, 137.7 and 159.7 kJmol^?1, respectively by Flynn–Wall–Ozawa method. With the increase of HTME content, the activation energies of HTME/DGEBA hybrid resin decrease. Although molecular weight or generation of hyperbranched epoxy resins (HTME) has little effect on the thermal degradation activation energies and other kinetics data.     

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, ¹H Nuclear Magnetic Resonance (¹H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 10⁴ L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.     

Production and investigation of structure and properties of polyethylene–polylactide composites

Under conditions of shear deformations, low-density polyethylene (LDPE) and polylactide (PLA) composites are obtained in rotor disperser. The production of these composites allows one to use polymers derived from natural raw and to reduce the cost of the materials on their base. The addition of rigid PLA leads to increase in elastic modulus from 200 for LDPE to 1190 for LDPE–PLA (50:50 wt %) composites and in tensile strength from 13.3 for LDPE to 17.8 for LDPE–PLA. By differential scanning calorimetry method, it is shown that LDPE and PLA are incompatible. Using X-ray diffraction analysis, it is found that degree of crystallinity of composites decreases from 46.1 at 50:50 wt % to 36.9 at 80:20 wt % component ratios with the rise in LDPE content. Tests on fungus resistance show that the composites containing 50 wt % PLA are more resistant than the composites containing 30 wt % PLA. First by gel-permeation chromatography method, it is shown that composite degradation after exposure in soil is accompanied by the PLA chain scission and depolymerization with formation of monomers and dimers (M _w of PLA decreases from 118,860 to 80,100). The obtained composites can be applied as packaging materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47598.     

Investigation of Structure and Oxidation Behavior of Pitch and Resin Resultant Carbon

The structure and oxidation behaviors of pitch carbon,resin carbon and their mixture re-sultant carbon have been investigated.The results indicate that the pitch carbon has relative higher true specific gravity,well developed crystalline and better oxidation resistance than resin carbon,With 20%-35% resin added to pitch,the structure of the resultant carbon can be modified and oxidation resistance will be improved significantly.     

Characteristics and Application of Andalusite Material and Andalusite-Based Refractory

Andalusite material and Andalusite-based refractory are very popular in Europe and Japan, but its applications are restrained because of its low quality and misunderstanding in China. The paper introduced in detail the characteristics of andalusite material and andalusite-based refractory based on the authors‘ research work in recent years and on some references. Some information is illustrated clearly by figures and microstructure photographs. It is concluded the property of raw material and refractory is not determined by alumina content but by type and quantity of the impurities and microstructure.Mullitisation provide andalusite-based refractories more excellent macro and micro properties that guarantee itspopular application.     

Synthesis and Characterization of the Inclusion Complex of Dicationic Ionic Liquid and β-Cyclodextrin

The supramolecular structure of the inclusion complex of β-cyclodextrin (β-CD) with 1,1',2,2'-tetramethyl-3,3'-(p-phenylenedimethylene) diimidazolium dibromide (TetraPhimBr), a dicationic ionic liquid, has been investigated. The inclusion complex with 1:1 molar ratio was prepared by a kneading method. Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) analysis, (1)H NMR and thermogravimetric analysis (TGA) confirmed the formation of the inclusion complex. The results showed that the host-guest system is a fine crystalline powder. The decomposition temperature of the inclusion complex is lower than that of its parent molecules, TetraPhimBr and β-CD individually.     

Compaction and shear failure of refractory mortars – effects of porosity and binder hardening

With the aim to correlate the global properties of refractory mortars with the micro-mechanical processes, a series of uni-axial compression and shear tests was conducted. The test program was developed with the view that the shear grain slip and cracks are frequent failure mechanism under compressive loads. The micro-structural changes during compression were monitored by X-ray micro focus computed tomography. Discrete element modelling was used to highlight the effects of individual factors of influence. Mortars with a water glass binder of different maturity were tested. In compression the mortars demonstrated cracking and pore closure. Shear tests showed that the failure process consists of multiple local failure events. The combined effects of the porosity and immature binder promote increased tendency for crack branching and arrest. This results in low shear strength and high compressibility. Cohesion and interlocking between the grains prevents crack branching and increases the stiffness and the strength.     

Compositions and Properties of Hydration-Resistant Coating of Magnesia-Calcia Materials

The complex coating on the MgO-CaO clinker was prepared by dipping method and adding the second mineral to restrain the formation and expansion of the craks.Meansohile,the microstructure and the morphology of the coating and hydration resistance of the MgO-CaO clinker were also investigated.The result shows that the coating consists mainly of Ca2P2O7,MgO and CaCO3,its thickness ranges from 5μm to 20μm,and the coating is dense and even,no micro-cracks are observed.Also,the coating adheres closely to the matrix.The hydration resistance of the MgO-CaO clinker after treatment is improved greatly,and the castables prepared with the treated MgO-CaO clinker have better physical properties than MgO castable.     

Effect of Racemic and (+)- and (−)-Gossypol on the Survival and Development of Helicoverpa zea Larvae

Gossypol is a sesquiterpene that occurs naturally in seed and other parts of the cotton plant. Because of restricted rotation around the binaphthyl bond, it occurs naturally as enantiomeric mixtures with (+)-gossypol to (−)-gossypol ratios that vary between 97:3 and 31:69. Commercial cotton varieties (Gossypium hirsutum) normally exhibit an approximate 3:2 ratio. (+)-Gossypol is significantly less toxic than (−)-gossypol to nonruminant animals; thus, cottonseed containing high levels of (+)-gossypol might be safely fed to nonruminants. Gossypol, however, is an important component in the cotton plant's defense against insect herbivores, but it is not known how cotton plants that exhibit high levels of (+)-gossypol in the foliage might be affected by insect herbivory. To address this question, 1-d-old Helicoverpa zea larvae were fed diets with 0.16, 0.20, and 0.24% racemic, (+)-, and (−)-gossypol. Larval pupal weights, days-to-pupation, and survival were adversely affected by all gossypol diets compared with the control diet. Statistical differences were determined by comparing the compounds among themselves at the three levels and between the three compounds at the same level. When the compounds were compared among themselves, no large differences were observed in pupal weights or in days-to-pupation among any of the diets. Among the three compounds, at the 0.16% level, the diet containing racemic gossypol was the most effective at reducing survival. At the 0.20 and 0.24% levels of racemic (+)- and (−)-gossypol, survival was not statistically different. The overall results indicate that (+)-gossypol is as inhibitory to H. zea larvae as racemic or (−)-gossypol, and thus, cotton plants containing predominantly the (+)-enantiomer in foliage may maintain significant defense against insect herbivory.     

Design and optimization of purification process of sinomenine hydrochloride

Sinomenine hydrochloride is generally produced from Caulis Sinomenii. At present, the purification process in industrial production suffers from large amount of solid waste, high solvent toxicity, and low sinomenine hydrochloride yield. In this study, a new purification process for sinomenine hydrochloride was proposed by using the extract obtained from acid extraction of Caulis Sinomenii as the starting material.The process included the following steps: alkalization, extraction, water washing, ...