茶多酚-TiO_(2)光催化材料的制备及光催化时间的确定

目前生物基二氧化钛聚合物得到了广大学者们的研究,本实验用溶胶-凝胶法制备了二氧化钛胶,并在此基础上制得高效率茶多酚-TiO_(2)光催化材料。通过测量对相同浓度甲基橙溶液的吸光度,计算其对甲基橙染料的去除率,最后对比确定出了最佳制备配比,在100 mL的二氧化钛胶中加入0.08 g的茶多酚,经恒温2 h 400℃锻烧后,制得的茶多酚-TiO_(2)光催化材料对甲基橙染料的最佳光催化时间为20 min,甲基接去除率达到93.7%。

满足欧5排放标准的涡轮增压直喷汽油机催化剂起燃时间及减排研究

未来动力总成的开发目标是具有更好的燃油经济性。为了实现这一目标,在研发新车型时,发动机将更多地采用涡轮增压技术。涡轮增压发动机的动力性和燃油经济性较好,但排放性能欠佳,这是因为涡轮增压发动机冷起动时,由于涡轮响应滞后而会损失大量热能。因此,对于涡轮增压发动机,需要采用相应技术缩短催化剂起燃时间,以降低排放。尤其是配装涡轮增压发动机的车型按新欧洲行驶循环测试时,在城市低速循环起动阶段,其排放不能满足欧5标准要求。研究得出缩短催化剂起燃时间和降低排放的方法,使涡轮增压直喷汽油机满足欧5排放标准要求。进行全面的排放测试,如增加贵金属用量及载体的孔密度,缩短到催化剂的距离,以及采用二次空气系统等附加装置。通过这些独到的试验研究,使发动机逐步达到欧5排放标准。

酶催化浸出米糠油

对水酶催化浸出米糠油进行了研究。影响浸出最显著因素是酶催化时间、水中米糠浓度、己烷体积、酶用量。米糠和水混合物在 pH =4 .5 ,温度 5 0℃左右、催化反应 6h ,2 %纤维素酶 ,2 %果胶酶 ,水糠比率 5∶1(v/w)、己烷 /米糠 (v/w) 2 5∶1,油回收率达 10 0 %

麦草阳离子型吸附剂的合成及对硝酸根的去除

以环氧氯丙烷为醚化剂,二甲胺为反应剂,对麦草秸秆改性合成阳离子型吸附剂。该文以改性后产物对NO3-的去除率为指标,分别考察了制备过程中单一影响因素,并结合正交实验得出影响因素结论与最佳改性条件。实验结果表明,催化时间是影响麦草秸秆改性效果的主要因素,麦草投加量、催化剂用量、二甲胺用量、活化反应和反应时间是次要因素;最佳改性条件为,当固定环氧氯丙烷和N,N-二甲基甲酰胺分别为20 mL和25 mL时,麦草投加量是2 g,催化剂用量是15 mL,二甲胺用量是30 mL,活化时间1 h,催化时间1 h,反应时间3 h。在此条件下硝酸根的去除率可达78.13%。

Time-resolved infrared spectroscopic investigation of Ga_(2)O_(3) photocatalysts loaded with Cr_(2)O_(3)-Rh cocatalysts for photocatalytic water splitting

Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated electrons in Ga_(2)O_(3) loaded with Cr_(2)O_(3)-Rh cocatalysts was studied using time-resolved mid-infrared spectroscopy.The structure of these Cr_(2)O_(3)-Rh cocatalysts was identified with high-resolution transmission electron microscopy and CO adsorption Fourier-transform infrared spectroscopy,as Rh particles partly covered with Cr_(2)O_(3).The decay dynamics of photogenerated electrons reveals that only the electrons trapped by the Rh particles efficiently participate in the H2 evolution reaction.The loaded Cr_(2)O_(3) promotes electron transfer from Ga_(2)O_(3) to Rh,which accelerates the electron-consuming reaction for H2 evolution.Based on these observations,a photocatalytic water-splitting mechanism for Cr_(2)O_(3)-Rh/Ga_(2)O_(3) photocatalysts has been proposed.The elucidation of the roles of the Cr_(2)O_(3)-Rh cocatalysts aids in further understanding the reaction mechanisms of photocatalytic water splitting and guiding the development of improved photocatalysts.

Optimization of conditions for preparation of ZSM-5@silicalite-1 core–shell catalysts via hydrothermal synthesis

Although the preparation of ZSM-5@silicalite-1(ZS) core–shell catalysts has been reported in the literature,their selectivity to para-xylene(PX)in the toluene alkylation with methanol is difficult to control.Here we present the effects of water and ZSM-5 adding amounts in the synthesis solution,the hydrothermal synthesis time,and the Si/Al ratio of core ZSM-5 on the catalytic performance of ZS core–shell catalysts.The ZS core–shell catalysts were characterized by X-ray diffraction (XRD),N_2 adsorption,and NH_3 temperature-programmed desorption (NH_3-TPD) techniques.The highest PX selectivity of 95.5%was obtained for the ZS(Si/Al=140) catalyst prepared in the synthesis solution with a molar ratio of 0.2 TPAOH:1TEOS:250H_2O at 175°C and 10 r·min^(-1) for only 2 h and the corresponding toluene conversion is as high as 22.8% for the alkylation of toluene with methanol.

Catalytic synthesis of acetals and ketals with H3PW6Mo6O40/TiO2

A new environmental friendly catalyst, H3PW6Mo6O40/TiO2 was prepared. The optimum conditions have been found, that is, mass ratio of m （TiO2）： m （H3PW6Mo6O40） is 1：2.0, volume of water is 30 mL, the reflux reaction time is 2 h, and activated temperature is 150 ℃. H3PW6Mo6O40/TiO2 was used as catalyst in catalytic synthesis ofacetals and ketals. Effects ofn （aldehyde（ketone））： n （glycol）, catalyst dosage and reaction time on yield were investigated. Optimal conditions were： n（aldehyde （ketone））： n （glycol）=1.0 ： 1.4; mass fraction of catalyst to reactants, 0.8%; reaction time, 1.0 h and cyclohexane as water-stripped reagent, 10 mL. Under these conditions, yields of acetals and ketals can reach 53.0% -86.9 0%

High efficiency production of ginsenoside compound K by catalyzing ginsenoside Rb1 using snailase

The rare ginsenoside Compound K （C-K） is attracting more attention because of its good physiological activity and urgent need. There are many pathways to obtain ginsenoside C-K, including chemical and biological methods. Among these, the conversion of PPD-type ginsenosides by enzymatic hydrolysis is a trend due to its high efficiency and mild conditions. For effectively extracting from the other panaxadiol saponins, the conversion process for ginsenoside C-K was investigated using snailases in this study. The univariate experimental design and response surface methodology were used to determine the optimal hydrolysis conditions for the conversion of ginsenoside Rbl into ginsenoside C-K by snailases. The optimum conditions were as follows： pH 5,12, temperature 51 ℃, ratio of snailase/substrate 0.21, and reaction time 48 h. On the basis of these parameters, the addition of 1.0 mmol· L- 1 ferric ion was found to significantly improve the enzymolysis ofsnailases for the first time. With the above conditions, the maximum conversion rate reached 89.7%, suggesting that the process can obviously increase the yield of ginsenoside C-K. The bioassay tests indicated that the ginsenoside C-K showed anti-tumor activity in a series of tumor cell lines. Based on these results, we can conclude that the process of rare ginsenoside C- K production by enzymolysis with snailase is feasible, efficient, and suitable for the industrial production and application.

Process optimization study on the carbonylation of methyl acetate

Acetic anhydride is the important organic chemical raw material, and is used widely in chemical industry,pharmaceutical industry, dyes, spices and other fields. In this paper, the process of carbonylation of methyl acetate in rhodium iodine catalyst system was studied, and the suitable reaction conditions were determined.At the same time, the kinetic model was established. The optimum reaction conditions were as follows： the reaction pressure was 5 MPa, the hydrogen content was 8%, the amount of iodomethane was 15%, the amount of lithium iodide was 3%, the reaction temperature was 150 ℃ and the reaction time is 3 h. Under the above reaction conditions, the selectivity of the reaction is close to 100% and the conversion is as high as 92%. The macroscopic kinetic model of the reaction was established in the temperature range of 120 ℃–150 ℃. The reaction is an irreversible reaction without the formation of by-products and the dynamic equation is also given in the Conclusions section.

Design of p-n homojunctions in metal-free carbon nitride photocatalyst for overall water splitting

Two-dimensional(2D)carbon nitride(CN)photocatalysts are attracting extensive attention owing to their excellent photocatalytic properties.In this study,we successfully prepared CN materials with heterogeneous structures via hydrothermal treatment,high-temperature roasting,ball milling,sintering,and other processes.Benefitting from interface interactions in hybrid architectures,the CN photocatalysts exhibited high photocatalytic activity.The rate of hydrogen production using these CN photocatalysts reached 17028.82μmol h^(−1)g^(−1),and the apparent quantum efficiency was 11.2%at 420 nm.The ns-level time-resolved photoluminescence(PL)spectra provided information about the time-averaged lifetime of fluorescence charge carriers;the lifetime of the charge carriers causing the fluorescence of CN reached 9.99 ns.Significantly,the CN photocatalysts displayed satisfactory results in overall water splitting without the addition of sacrificial agents.The average hydrogen and oxygen production rates were 270.95μmol h^(−1)g^(−1)and 115.21μmol h^(−1)g^(−1)in 7 h,respectively,which were promising results for the applications of the catalysts in overall water splitting processes.We investigated the high efficiency of the prepared CN photocatalysts via a series of tests(UV-vis diffuse reflectance spectroscopy,photocurrent response measurements,PL emission spectroscopy,time-resolved PL spectroscopy,and Brunauer-Emmett-Teller analysis).Furthermore,the Mott-Schottky plot and current-voltage curve were acquired via electrochemical tests.The fabricated CN photocatalyst had a small p-n junction in its heterogeneous structure,which further enhanced its photocatalytic efficiency.Therefore,this work can promote the development of CN photocatalysts.

One-pot synthesis of 5-hydroxymethylfurfural from glucose over zirconium doped mesoporous KIT-6

Zirconium doped mesoporous KIT-6 samples with different Si/Zr ratios were synthesized by the direct hydrothermal method.Various characterization techniques confirm that highly distributed ZrO_2 nanoparticles and multicoordinated Zr^(4+) species are incorporated in the mesoporous composites.One-pot synthesis of 5-hydroxymethylfurfura(HMF) from glucose was examined in the presence of Zr-KIT-6(20) the molar ratio of Si to Zr is 20 under aqueous system.The effects of temperature,reaction time,catalyst dosage and biphasic solvent system on the conversion of glucose and the HMF yield were investigated.It was found that the glucose conversion and the HMF yield have been improved from 54.8% to 79.0% and from 19.5% to 34.5% in the biphasic MIBK-water system,respectively.Both the acidity of Zr-KIT-6(20) and the biphasic MIBK-water system are responsible for the improved performance of glucose dehydration to HMF.

Synthesis of Novel Ionic Liquid ([C_4 CNmim]^+ PF_6^-) and Application to Preparation of Polyketone

N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.

H4SiW6Mo6O40-Doped Polyaniline-Synthesis, characterization and catalytic properties of acetals and ketals

A new environmental friendly catalyst, HaSiWrMo6O40/PAn was prepared and identified by means of FT-IR, XRD and TG/DTA. The optimum conditions have been found, that was, mass ratio of m（PAn）： m（HaSiW6Mo6On.） was 1：1.25, volume of methanol was 20 mL, and the reflux reaction time was 2h. The structural identity of Keggin units was preserved after the incorporation into polyaniline matrix. H4SiW6Mo6040/PAn was used as catalyst in catalytic synthesis of acetals and ketals. Effects of n（aldehyde（ketone ））： n（glycol）, catalyst dosage and reaction time on yield were investingated. Optimal conditions were： n（aldehyde（ketone））： n（glycol）=1.0： 1.5; mass fraction of catalyst to reactants, 0.5%; reaction time, 1.0 h and cyclohexane as water-stripped reagent, 15 mL. Under these conditions, yields of actels and ketals were 31.9%-91.6%.

Study on the Effect of the Fe^2＋/NaClO Oxidation of CN

The effects of various parameters on the removal rate of CN were discussed in the paper. The results showed that under the conditions of 30℃ pH = 3.0, Fe2＋ dosage was 80 mg/L, the NaCIO concentration of 0.10 mol/L, reaction time in 60 min, Fe2＋ has a satisfactory catalytic activation, and the removal rate of CN was about 37.89%.

Preparation of Sodium Cobalt Tetracarbonyl and Optimization of Process Conditions for Hydroesterification of Ethylene Oxide

In this paper, sodium cobalt tetracarbonyl （NaCo（CO）4） was synthesized by using sodium dithionite and zinc powder as the reduction system and cobalt hexahydrate acetate as the precursor in the presence of methanol solvent. Methyl 3-hydroxypropionate was synthesized via hydroesterification of ethylene oxide （EO） catalyzed by NaCo（CO）4. The influencing factors on the reaction results were discussed, including the different ligands, the molar ratio of solvent and ethylene oxide, the reaction temperature, the reaction time, and the reaction pressure. An optimal catalytic system was obtained by using 3-hydroxypyridine as the ligoad under reaction conditions covering a reaction temperature 65 ℃, a reaction time of 7 h, a reaction pressure of 6 MPa, and a methoaol/EO molar ratio of 3：2. Under the optimal conditions, the conversion of ethylene oxide was equal to 97.86%, while the selectivity and yield of methyl 3-hydroxypropionate reached 88.19% and 86.30%, respectively. Finally, the reaction mechanism of hydroesterification of ethylene oxide catalyzed by NaCo（CO）4 was proposed.

Catalytic synthesis of benzaldehyde glycol acetal over H3PW6Mo6O40/PAn

Catalytic activities of H3PWrMo6O40/PAn in synthesizing benzaldehyde glycol acetal were reported. It has been demonstrated that H3PW6MorO40/PAn is an excellent catalyst. Various factors concerned in the reaction have been investigated. The optimum conditions have been found, that is, the molar ratio of benzaldehyde to glycol is 1/1.4, the mass ratio of the catalyst used to the reactants is 0.8%, and the reaction time is 45min. Under these conditions, the yield of benzaldehyde glycol acetal is 79.0%.

Enhanced single-nanoparticle collisions for the hydrogen evolution reaction in a confined microchannel

Single nanoparticle(NP)collisions technique has been widely employed in electrocatalysis.However,the short collision duration of single NPs hinders the further improvement in their electrocatalytic performance.Here,to increase the dynamic collision duration of single NPs in the electron tunneling region,enhanced near-wall hindered diffusion is introduced in the stochastic collision process by coupling a Au ultramicroelectrode(UME)with a confined microchannel.In the case of single palladium nanoparticle(Pd NP)collisions for the hydrogen evolution reaction(HER),the hydrodynamic trapping confined in the microchannel effectively permits the activation of the HER on the single Pd NPs.The microchannel-based Au UME is promising in the application of single-NP collisions to energy conversion.

Synthesis, Characterization and Catalytic Application of H3PW12O40/MCM-48 in the Acetalization of Butyraldehyde with Glycol

A novel environmental friendly catalyst, H3PW12O40/MCM-48, was prepared by impregnation method. The catalysts were characterized by means of XRD and FT-IR. The synthesis of butyraldehyde glycol acetal catalyzed by H3PW12O40/MCM-48 was studied with butyraldehyde and glycol as reactants. H3PW12O40/MCM-48 was an excellent catalyst for the synthesizing butyraldehyde glycol acetal and Keggin structure of H3PW12O40 kept unchanged after being impregnated on surface of the molecular sieve support. Effects of n（butyraldehyde）： n（glycol）, catalyst dosage, cyclohexane（water-stripped reagent） and reaction time on yields of the product were investigated. The optimum conditions had been found, that was, molar ratio of butyraldehyde to glycol was 1： 1.6, mass ratio of catalyst used to the reactants was 0.25% and reaction time was 75 min. Under these conditions, the yield of butyraldehyde glycol acetal can reach 79.74%.

Residue Upgrading in Slurry Phase over Ultra-fine NiMo/γ-Al_2O_3 Catalyst

In this article, residual oil hydroconversion was studied in slurry phase in the presence of fine solid Ni Mo/γ-Al2O3 catalyst and the effects of operating conditions were carefully studied. The results showed that residue conversion was only affected by the reaction temperature and reaction time. The coke yield increased with a higher reaction temperature, a bigger catalyst particle size, a longer reaction time, a lower initial hydrogen pressure and a lower catalyst concentration. Heteroatoms removal rate increased with a higher reaction temperature, a longer reaction time, a higher initial hydrogen pressure, a higher catalyst concentration, and a smaller catalyst particle size. The role of catalyst in the slurry bed technology was discussed and its function could be stated as follows: the metal was applied to activate the hydrogen atoms for removing heteroatoms and saturating aromatics, while the support of the catalyst was used to prevent the mesophase coalescence for reducing coke formation.

Study on the catalyst in the decomposition reaction for BI organic waste water to adipic acid

The influences of kinds and level of catalyst, time of decomposition reaction on the distribution of dibasic acid and apparent yield of adipic acid were researched; the acidic washing waste water （BI waste water） producing from the equipment of cyclohexane oxidation by air was as stuff, the component of products by decomposed and oxidated in different conditions were analysed. It indicated that in the presence of cobalt salt the apparent yield of adipic acid was upto 10%-12% for the total BI waste water after the concentrated BI waste water refluxed for two hours, and then oxidated by nitric acid.