Alleviation of the plastic deformation of gel ink under strong stress through an esterification of xanthan gum reinforcing its double helix structure

As a natural organic polymer,xanthan gum(XG)can alleviate the plastic deformation of gel ink under strong stress and realize the reasonable regulation of the rheological properties of gel ink.However,as the double-helix structure connected by hydrogen bonds cannot resist the mechanical environment of strong stress,XG shows poor shear resistance.In this study,a polymer gel with interpenetrating polymer network structure was prepared by esterifying XG,taking polystyrene maleic anhydride(SMA)as the modifier.In addition to retaining the excellent rheological properties of XG,the generated polymer gel also exhibited high shear resistance.The optimal addition amount of the esterification reaction modifier was determined as mXG:mSMA=5:3 according to the gel ink standard.With this amount,the viscosity of the modified xanthan gum(SXG)gel increased to 1578.8 mPa·s and 100.7 mPa·s at shear rates of 4 s1 and 383 s1,respectively,and the shear resistance increased more than 2 times compared to the unmodified one.It is because of the ester bond formed by esterification that the reaction strengthens the interaction between molecular segments,enabling the new gel to resist to strong mechanical stress.The new polymer gel studied in this paper and the proposed mechanism of action provide new insights for the development of high-end gel ink and also provide theoretical support for the study of rheological properties of non-Newtonian fluids.

Complete kinetic model for esterification reaction of lauric acid with glycerol to synthesize glycerol monolaurate

Glycerol monolaurate(GML)is a widely used industrial chemical with excellent emulsification and antibacterial effect.The direct esterification of glycerol with lauric acid is the main method to synthesize GML.In this work,the kinetic process of direct esterification was systematically studied using p-toluenesulfonic acid as catalyst.A complete kinetic model of consecutive esterification reaction has been established,and the kinetic equation of acid catalysis was deduced.The isomerization reactions of GML and glycerol dilaurate were investigated.It was found that the reaction was an equilibrium reaction and the reaction rate was faster than the esterification reaction.The kinetic equations of the consecutive esterification reaction were obtained by experiments as k_(1)=(276+92261Xcat)exp(-37720/RT)and k_(2)=(80+4413Xcat)exp(-32240/RT).The kinetic results are beneficial to the optimization of operating conditions and reactor design in GML production process.

Catalytically active membranes for esterification:A review

Esterification is an important process in the food industry and can be carried out via homogeneous or heterogeneous catalysis.The homogeneous catalyst,despite providing high conversion,can cause corrosion in reactors,which is not observed with the use of heterogeneous catalysts.However,some of these catalysts require a high process temperature and may lose their catalytic activity with reuse.Thus,catalytic membranes have been proposed as a promising alternative.The combination of catalysis and separation in a single module provides greater conversion,reduction of excess reagents,compact industrial plant,making the process more efficient.Within this context,this work aims to present a literature review on the catalytic membrane for the synthesis of esters,improving the understanding of the production and development.This review examines the materials,catalysts used,and synthetic pathways.A comparison between the methods,as well as limitations and gaps in the literature,are highlighted.

Esterification of acetic acid with isobutanol catalyzed by ionic liquid n-sulfopropyl-3-methylpyridinium trifluoromethanesulfonate:Experimental and kinetic study

As an important organic,isobutyl acetate(IbAc)has been widely used in industries because of its good biodegradability,low surface tension,and other properties.The industrial production of IbAc is usually catalyzed by sulfuric acid.However,the use of sulfuric acid has the drawbacks of causing considerable corrosion to equipment and being difficult to be separated.In this work,n-sulfopropyl-3-methylpyridinium trifluoromethanesulfonate([HSO_(3)-PMPY][CF_(3)SO_(3)])Bronsted acidic ionic liquid(BAIL)was used as the catalyst and the catalytic activity,solubility,and corrosiveness were evaluated for the esterification of acetic acid with isobutanol.The reaction kinetics and chemical equilibrium were systemically studied.Compared to conventional acid catalysts,[HSO_(3)-PMPY][CF_(3)SO_(3)]showed higher catalytic activity,more excellent reusability,more favorable phase separation,and non-corrosiveness.Three kinetic equations based on ideal homogeneous(IH),non-ideal homogeneous(NIH),and modified nonideal homogeneous(NIH-M)models were established and correlated with the experimental data to determine the parameters and errors.The NIH-M model exhibited the best agreement with the experimental data,owing to its prediction considering the non-ideality and the self-catalysis effect of acetic acid in this system.Besides,the error of NIH-M model fitting was mainly caused by the difference in solubility between[HSO_(3)-PMPY][CF_(3)SO_(3)]with reactants and products in the reaction system.Furthermore,the applicability of the NIH-M model was investigated by simulating the esterification of acetic acid with three short-chain alcohols(ethanol,n-butanol,and isobutanol)catalyzed by BAILs.The NIH-M model displayed an acceptable simulation for this type of acetic acid esterification reaction catalyzed by BAILs at different ranges of the BAILs concentration and temperature.This study confirmed the industrial prospects of[HSO_(3)-PMPY][CF_(3)SO_(3)]in isobutyl acetate production and the applicability of the NIH-M kinetic model in the esterification of acetic acid.

Investigation into Protective Groups for Anilino Functionality upon Oxone-Mediated Oxidative Esterification

In the course of organic synthesis, particularly for multi-step synthesis or natural product total synthesis, the selection of appropriate protective groups for the intended functionality is crucial in order to achieve chemoselective synthetic goals. The development of many useful protective groups has been reported based on the functionality of the anilino group. Herein, we discuss our study of various protective groups and the processes we used to establish compatibility with anilino functionality via the implementation of Oxone-mediated oxidative esterification in methanol. The results and the details of our experiments are reported herein.

Conjugation of Candida rugosa lipase with hydrophobic polymer improves esterification activity of vitamin E in nonaqueous solvent

We described a novel polymer-lipase conjugate for high-efficient esterification of vitamin E using vitamin E and succinic anhydride as the substrates in nonaqueous media.In this work,the monomer,N-isopropylacrylamide(NIPAM),was grafted onto Candida rugosa lipase(CRL)to synthesize poly(NIPAM)(pNIPAM)-CRL conjugate by atom transfer radical polymerization via the initiator coupled on the surface of CRL.The result showed that the catalytic efficiencies of pNIPAM-CRL conjugates(19.5-30.3 L·s^(-1)·mmol^(-1))were at least 7 times higher than that of free CRL(2.36 L·s^(-1)·mmol^(-1))in DMSO.It was attributed to a significant increase in Kcat of the conjugates in nonaqueous media.The synthesis catalyzed by pNIPAM-CRL co njugates was influenced by the length and density of the grafted polymer,water content,solvent polarity and molar ratio of the substrates.In the optimal synthesis,the reaction time was shortened at least 7 times,and yields of vitamin E succinate by pNIPAM-g-CRL and free CRL were obtained to be 75.4%and 6.6%at 55℃after the reaction for 1.5 h.The result argued that conjugation with pNIPAM induced conformational change of the lid on CRL based on hydrophobic interaction,thus providing a higher possibility of catalysis-favorable conformation on CRL in nonaqueous media.Moreover,pNIPAM conjugation improved the thermal stability of CRL greatly,and the stability improved further with an increase of chain length of pNIPAM.At the optimal reaction conditions(55℃and 1.5 h),pNIPAM-g-CRL also exhibited good reusability in the enzymatic synthesis of vitamin E succinate and kept~70%of its catalytic activity after ten consecutive cycles.The research demonstrated that pNIPAM-g-CRL was a more competitive biocatalyst in the enzymatic synthesis of vitamin E succinate and exhibited good application potential under harsh industrial conditions.

Liquid-phase esterification of methacrylic acid with methanol catalyzed by cation-exchange resin in a fixed bed reactor:Experimental and kinetic studies

The kinetic behavior of esterification between methacrylic acid and methanol catalyzed by NKC-9 resin was studied in a fixed bed reactor.The reaction was conducted in the temperature range of 323.15 to 368.15 K with the molar ratio of reactants from 0.8 to 1.4 under certain pressure.The measurement data were regression with the pseudo-homogeneous(P-H),Eley-Rideal(E-R),and Langmuir-Hinshelwood(L-H)heterogeneous kinetic models.Independent adsorption experiments were implemented to gain the adsorption equilibrium constants of four components.Among the above three models,the L-H model exhibited the best fitting results.The stability of NKC-9 was evaluated by long-term running with the yield of methyl methacrylate no decrease during 3000 h operation.The structure and physicochemical properties of the new and used catalyst were performed by several characterizations including thermogravimetric analysis(TG),scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FT-IR)and so on.

Insight into the green route to dimethyl succinate by direct esterification of bio-based disodium succinate using CO_(2)and CH_(3)OH

The fermentation for succinic acid production outperforms other methods by low energy consumption and environmental benignity,with the resulting products mainly as disodium succinate(DSA).By directly esterifying DSA using CO_(2) and CH3OH,it is expected to avoid the use of inorganic acids.By high-resolution mass spectrometry analysis and theoretical calculation,this study establishes that the reaction consists of three steps,i.e.,first forming 3-carboxypropanoate,then monomethyl succinate(MMS),and finally dimethyl succinate(DMS).A detailed kinetic analysis is further performed,the results demonstrate that the transformation of DSA to MMS is regarded to be a second-order reaction for reactant DSA,while the transformation of MMS to DMS is a first-order reaction for reactant MMS.The activation energy for the generation of MMS from DSA is 37.15 kJ·mol^(-1),and that for the generation of DMS from MMS is 85.80 kJ·mol^(-1),indicating the latter one is the rate-determining step.

Encapsulation of lipases on coordination polymers and their catalytic performance in glycerolysis and esterification

In this study,lipases of CALB(Candida antarctica lipase B),TLL(Thermomyces lanuginosa lipase),RML(Rhizomucor miehei lipase),CALA(Candida antarctica lipase A)and LU(Lecitase?Ultra)were encapsulated into the nucleotidehybrid metal coordination polymers(CPs)for diacylglyerols(DAG)preparation.Guanosine 5'-monophosphate(GMP)and adenosine 5'-monophosphate(AMP)were used as coordinating molecules,and metal ions of Fe^(3+),Ba^(2+),Mn^(2+),Ni^(2+)and Cr^(3+)were applied to prepare matrix.Results indicated that,besides Ba^(2+)with AMP,all other metal ions can coordinate with AMP and GMP to generate CPs.In addition,the AMP/Ni was amorphous when standing temperature was 4℃,while it was crystalline when standing temperature was from 30 to 180℃.DAG content from 47.55%to 64.99%was obtained from glycerolysis by CALB@GMP/Ba,RML@GMP/Ba,TLL@GMP/Ba,RML@GMP/Mn and TLL@GMP/Mn.Additionally,CALB@GMP/Fe showed selectivity towards DAG formation in the esterification and DAG content up to 61.88%was obtained.

Gold/Mg-Al mixed oxides catalysts for oxidative esterification of methacrolein:Effects of support size and composition on gold loading

Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.

Multi-output Gaussian Process Regression Model with Combined Kernel Function for Polyester Esterification Processes

In polyester fiber industrial processes,the prediction of key performance indicators is vital for product quality.The esterification process is an indispensable step in the polyester polymerization process.It has the characteristics of strong coupling,nonlinearity and complex mechanism.To solve these problems,we put forward a multi-output Gaussian process regression(MGPR)model based on the combined kernel function for the polyester esterification process.Since the seasonal and trend decomposition using loess(STL)can extract the periodic and trend characteristics of time series,a combined kernel function based on the STL and the kernel function analysis is constructed for the MGPR.The effectiveness of the proposed model is verified by the actual polyester esterification process data collected from fiber production.

Efficient and Stable Inverted Perovskite Solar Modules Enabled by Solid-Liquid Two-Step Film Formation

A considerable efficiency gap exists between large-area perovskite solar modules and small-area perovskite solar cells.The control of forming uniform and large-area film and perovskite crystallization is still the main obstacle restricting the efficiency of PSMs.In this work,we adopted a solid-liquid two-step film formation technique,which involved the evaporation of a lead iodide film and blade coating of an organic ammonium halide solution to prepare perovskite films.This method possesses the advantages of integrating vapor deposition and solution methods,which could apply to substrates with different roughness and avoid using toxic solvents to achieve a more uniform,large-area perovskite film.Furthermore,modification of the NiO_(x)/perovskite buried interface and introduction of Urea additives were utilized to reduce interface recombination and regulate perovskite crystallization.As a result,a large-area perovskite film possessing larger grains,fewer pinholes,and reduced defects could be achieved.The inverted PSM with an active area of 61.56 cm^(2)(10×10 cm^(2)substrate)achieved a champion power conversion efficiency of 20.56%and significantly improved stability.This method suggests an innovative approach to resolving the uniformity issue associated with large-area film fabrication.

Two-step growth of β-Ga_(2)O_(3) on c-plane sapphire using MOCVD for solar-blind photodetector

In this work,a two-step metal organic chemical vapor deposition(MOCVD)method was applied for growingβ-Ga_(2)O_(3) film on c-plane sapphire.Optimized buffer layer growth temperature(T_(B))was found at 700℃ and theβ-Ga_(2)O_(3) film with full width at half maximum(FWHM)of 0.66°was achieved.A metal−semiconductor−metal(MSM)solar-blind photodetector(PD)was fabricated based on theβ-Ga_(2)O_(3) film.Ultrahigh responsivity of 1422 A/W@254 nm and photo-to-dark current ratio(PDCR)of 10^(6) at 10 V bias were obtained.The detectivity of 2.5×10^(15) Jones proved that the photodetector has outstanding performance in detecting weak signals.Moreover,the photodetector exhibited superior wavelength selectivity with rejection ratio(R_(250 nm)/R_(400 nm))of 105.These results indicate that the two-step method is a promising approach for preparation of high-qualityβ-Ga_(2)O_(3)films for high-performance solar-blind photodetectors.

Preparation, Characterization and Catalytic Performance of La-SO_4^(2-)/SBA-15 in Esterification of Acetic Acid with n-Butanol

La-SO42-/SBA-15 was synthesized with various amounts of lanthanum via incipient-wetness impregnation. Characterization was done by X-ray diffraction（XRD）, transmission electron micrographs（TEM）, nitrogen adsorption, FTIR spectroscopic analysis, thermogravimetric analysis, and the total amount of acidity of catalyst was estimated by TPD of NH3. The results indicate that lanthanum has been incorporated into SBA-15 molecular sieve. The prepared materials（La-SO42-/SBA-15） keep the highly ordered mesoporous two-dimensional hexagonal structure and do not change the mesoporous channel structure of the support SBA-15. The catalyst showed best catalytic activity in the synthesis of n-butyl acetate. The optimum conditions of the esterification by orthogonal experiments were studied： the molar ratio of n-butanol to acetic acid 1：1.2, the amount of catalyst 7.5%, reaction time 80 min. The yield of n-butyl acetate could reach 93.2% under the optimum conditions. The catalyst was recyclable, cost effective and environmental friendly.

Preparation of solid acid catalyst SO4^2-/TiO2/γ-Al2O3 for esterification: A study on catalytic reaction mechanism and kinetics

In this work, a series of SO4^2-/TiO2/γ-Al2O3 solid acid catalysts were synthesized by impregnation method, in which nano-TiO2 was prepared by sol–gel method, and then the nano-TiO2 sol was loaded on porous γ-Al2O3 supporter through impregnation. The structure and property of catalyst were characterized by XRD, N2-BET,SEM, TEM, XPS, NH3-TPD, Pyridine-IR and FT-IR. In addition, the catalyst of chelate bidentate coordination acid center model was established. The catalytic performance test was carried out in the esterification of n-butyl alcohol with lauric acid and the catalyst showed excellent activity. The experimental results showed that the medium strength acid sites were more dominant active sites than the strong and weak acid sites for the rapid esterification reaction. Its kinetic behaviors and activation energy were studied for the esterification under the catalytic reaction condition.

Oxidative Esterification of Methacrolein to Methyl Methacrylate over Supported Palladium Catalyst

Supported palladium catalysts, which were used in the oxidative esterification of methacrolein to methyl methacrylate, have been prepared with different carriers and Pd precursors. Experimental results revealed that Pd catalysts with r-Al2O3 support and Na2PdC14 precursor showed good performance. Pd catalyst modified with Pb and Mg indicated that Pd-Mg bimetallic catalyst exhibited considerably higher activity and Pd-Pb exhibited both higher activity and selectivity. 92.27% methacrolein conversion and 90.57% methyl methacrylate selectivity were obtained on Pd-Pb-Mg catalyst.

4-(Benzylamino)formoyldiphenylammonium Triflate (BDPAT):An Efficient, Recoverable Biphasic Catalyst For Esterification of Carboxylic Acids with Equimolar Amounts of Alcohols

Esterification of carboxylic acid with equimolar amounts alcohol can be efficiently catalyzed by biphasic 4-(benzylamino)formoyldiphenylammonium triflate (BDPAT, 3) in good yield. The catalyst can be easily recovered without loss of activity.

ZrOCl_2·8H_2O: An Efficient and Cheap Catalyst for Esterification of Free Fatty Acids to Methyl Esters

The esterification of lauric acid with methanol could be efficiently catalyzed by ZrOCl2·8H2O, and this reaction was studied to develop a green method for biodiesel production. The influencing factors, such as amount of catalyst, reaction time and molar ratio of acid to methanol, were investigated. The results indicated that the ZrOCl2·8H2O catalyst showed high catalytic activity, and gave a 97.0% methyl laurate conversion rate under the following optimized conditions, viz.: a lauric acid/methanol molar ratio of 1:10, a catalyst dosage of 4%, and a reaction duration of 2 h at methanol refluxing temperature. The catalyst could be easily recovered while its activity could be well retained after three cycles. The ZrOCl2·8H2O catalyst also exhibited excellent catalytic activity for the esterification of different free long-chain fatty acids(including nonedible oils with high acid value) with different short carbon chain alcohols. Therefore, the ZrOCl2·8H2O catalyst has good potential for the synthesis of biodiesel from low-cost feedstocks such as waste vegetable oils and non-edible oils.

The Intermetallic Catalysts for Oxidative Esterification of Methacrolein to Methyl Methacrylate

A series of supported intermetallic Pb-Pb catalysts were prepared with the impregnation method by changing the support(silica,molecular sieve or γ-alumina)and the pore size.The chemical states of the two metals were characterized by XPS analysis,the process for producing methyl methacrylate based on the direct oxidative esterification of methacrolein with methanol in the presence of oxygen was performed in a slurry reactor with the above-mentioned catalysts.The influence of the calcination temperature and the kinds of support as well as the pore size on catalytic activity had been extensively investigated.Under the conditions of temperature at 80℃,catalyst 3.8%(ω)and the reaction time 2 h,the conversion rate of methacrolein reached 85%,the selectivity and the yield of methyl methacrylate were 90% and 76.5%,respectively.