磷酸钛固载磷钨酸非均相催化合成异戊酸己酯

通过在300℃下焙烧2h制备了磷酸钛固载15%磷钨酸H3PW12O40(简记为HPW)非均相酯化催化剂HPW/Ti3(PO4)4;采用红外光谱仪分析了催化剂的结构;基于异戊酸与正己醇的酯化反应考察了催化剂用量、n(正己醇)∶n(异戊酸)、反应时间、带水剂种类和催化剂重复使用性能等因素对酯化率的影响.结果表明,该催化剂催化合成异戊酸己酯的适宜反应条件为:0.2mol异戊酸,催化剂用量0.6g,n(正己醇)∶n(异戊酸)=1.6∶1,反应时间4.5h,环己烷10mL;相应的酯化率达95.1%.与此同时,该催化剂循环利用6次后酯化率不低于84%.     

生物质炭基固体酸催化剂的制备

 以生物质木粉为原料, 采用炭化-磺化法制备了炭基固体酸催化剂, 并用于油酸与甲醇的酯化反应, 考察了制备条件对炭基固体酸催化剂活性的影响. 采用 X 射线衍射、红外光谱、热重分析、高分辨透射电子显微镜及元素分析等手段对催化剂进行了表征. 结果表明, 由生物质木粉制备的炭基固体酸催化剂具有较高催化酯化反应活性, 在 400 oC 下炭化 0.5 h, 135 oC 下磺化 1 h 制备的炭基固体酸催化剂在精馏分水连续酯化装置中催化油酸与甲醇的酯化反应 2 h 时, 酯化转化率达到 96%. 采用炭化-磺化法制备的生物质炭基固体酸催化剂具有蠕虫状的无序乱层炭结构, 磺酸基 (－SO3H) 含量高达 13.25%, 并且在 220 oC 以下时具有良好的热稳定性.     

高单酯含量的甲基丙烯酸-β-羟乙酯磷酸酯的催化合成

采用浸渍法将磷钨酸及其盐[TEAH]₃PW₁₂O₄₀负载到活性炭上制备出HPW/AC和TEAPW/AC 2个系列的催化剂,并用IR、XRD、N₂-吸附脱附和NH₃-TPD等技术手段对它们的结构和酸性进行了表征。进一步,以P₂O₅为磷酸化剂考察了上述催化剂在功能性磷酸酯-甲基丙烯酸-β-羟乙酯磷酸酯合成中的催化性能。结果显示,上述催化剂在该酯化反应中不仅具有很高的活性,而且由于催化剂的微孔结构抑制了双、三酯的生成,明显提高了单酯的选择性。在优化的反应条件和催化剂上,酯化率可达94%,单酯选择性可达95%。且催化剂高度稳定,可以重复使用。该催化剂和催化工艺不仅克服了磷酸酯合成中使用含氯原料的缺点,而且大大提高了产物中单酯的含量。     

稻壳炭基固体酸催化剂的制备及其催化酯化反应性能

以热解稻壳炭为原料, 浓硫酸为磺化剂制备了固体酸催化剂. 采用X射线衍射、X射线光电子能谱、元素分析、孔结构分析和热重-质谱联用等手段对其进行了表征. 以油酸和甲醇的酯化为探针反应, 考察了磺化温度和时间对催化剂活性的影响, 探讨了反应条件对油酸转化率的影响, 并对所制催化剂的稳定性进行了研究. 结果表明, 制备该催化剂的适宜磺化温度和时间分别为90℃和0.25 h, 在该条件下制得的催化剂为无定形碳结构, 磺酸基密度为0.7 mmol/g. 该催化剂表现出较高的催化酯化反应活性, 在催化剂用量为5%、甲醇/油酸摩尔比为4、酯化温度和时间分别为110℃和2 h的条件下, 油酸的酯化率可达98.7%. 该催化剂具有较好的稳定性, 经7次连续反应后, 油酸的酯化率仍可达96.0%.     

S_2O_8~(2-)/TiO_2催化合成乙酸正丁酯

通过浸渍—焙烧法制备了固体超强酸S_2O_8~(2-)/TiO_2催化剂,并以醋酸和正丁醇为原料合成了乙酸正丁酯.考察了催化剂的焙烧温度、酸/醇比、反应时间等因素对反应的影响.结果表明S_2O_8~(2-)/TiO_2的最佳制备条件为:过硫酸铵浸渍浓度0.5mol/L,焙烧温度500℃,焙烧时间3h,在最佳反应条件下,乙酸正丁酯的酯化率可达97.8%,催化剂重复使用3次后,对醋酸的转化率仍可达90.8%.     

有机-无机复合型固体酸催化剂的制备及其催化甘油乙酸甲酯酯交换反应

酸性催化剂在传统的炼化工艺和最近的生物炼制技术中均起着十分重要的作用.相较于传统的液体酸,固体酸催化剂由于具有易分离、可重复使用、无腐蚀性和环保等优点而引起了广泛的研究兴趣.在过去的几十年中,研究者们成功研制出多种不同类型的固体酸,如沸石、杂多酸、金属氧化物和磺化的碳基材料等.但是,传统的固体酸仍存在一些不足,如酸中心类型和酸强度不确定、表面酸位点分布不均以及活性位点易流失、稳定性较差等.甘油是生物柴油生产过程中的主要副产物.据统计,2022年全球生物柴油的年产量将达到1410亿升,这意味着甘油的产量也将增加.因此,将过剩的甘油催化转化制备高附加值产品具有重要的意义.甘油在酸催化的作用下可以制备得到丙酮缩甘油、甘油酯、丙烯醛和甘油醚等高附加值产品.其中,乙酸甘油酯(包括单乙酸甘油酯(MAG)、二乙酸甘油酯(DAG)和三乙酸甘油酯)在工业中具有广泛的应用,它们既可用于医药、食品和化妆品行业,又可作为燃料添加剂改善生物柴油的性能.目前乙酸甘油酯的主要合成路径为甘油与乙酸或乙酸酐酯化法,但乙酸和乙酸酐对反应设备有腐蚀性,限制了其在工业上的大规模应用.乙酸甲酯是聚乙烯醇生产过程中的主要副产物,具有来源广泛、安全、无味、易分离(沸点低)等优点,因此,以乙酸甲酯为乙酰化试剂与甘油进行酯交换反应制备乙酸甘油酯这一新的合成路径引起了关注.然而固体酸催化剂在该反应中的应用鲜有文献报道.对羟基苯磺酸(PSA)是一种有机液体强酸,可用于缩醛化、酯化、酯交换等酸催化反应中,但它不可分离、无法重复使用而且对环境污染严重.因此,本文采用一锅法,将均相PSA固载在经硅烷偶联剂KH560改性的磷酸锆载体(K-ZrP)上,制备得到一系列不同PSA含量的无机-有机复合型固体酸催化剂(PSA/K-ZrP-x).通过X射线衍射、红外光谱、固体核磁共振碳谱(13C SSNMR)表征方法研究了催化剂的精细结构,吡啶吸附红外(Py-IR)光谱结果表明催化剂的酸性中心主要是布朗斯特酸,通过热重、X射线光电子能谱表征结果计算催化剂中活性组分([H+],S)的整体与表面含量,结果表明PSA/K-ZrP-2中PSA的含量已饱和,且PSA在K-ZrP载体表面分散均匀,从而增加了表面酸位点的可接触性,通过氮气吸脱附和扫描电镜研究了PSA/K-ZrP-x的形成过程,线扫描元素分析表明PSA/K-ZrP-2具有蒲公英状结构.以甘油乙酸甲酯酯交换反应为模型反应,考察了所制备催化剂的活性,结果表明PSA/K-ZrP-2催化剂的稳定性明显高于H3PW12O40,Amberlyst-45,HBEA和HZSM-5等常见的商业化固体酸和AlCl3,FeCl3等路易斯酸.在2.2％[H+]含量的PSA/K-ZrP-2催化剂作用下,10 mmol甘油与100 mmol乙酸甲酯于100℃反应4h,甘油转化率可达81.3％,MAG和DAG的选择性之和达97.7％.在反应初期(0.17 h),该催化剂的比活性可达24028.2 mg-glycerol/g-cat/h,且五次循环使用后活性无明显降低.结合本文表征结果,偶联剂KH560可增强对羟基苯磺酸和磷酸锆之间的相互作用,从而提高催化剂的稳定性.同时,该催化剂在甘油与其它酯类的酯交换反应中也表现出优异的反应活性,表明PSA/K-ZrP-2固体酸催化剂具有较好的普适性.     

固体超强酸ZrO_2/S_2O_8~(2-)催化合成乙酸正己酯

以固体超强酸ZrO2/S2O2-8为催化剂,乙酸和正己醇为原料合成了乙酸正己酯,考察了反应条件对酯化率的影响.结果表明,最佳反应条件为:醇酸摩尔比1.4,催化剂用量0.5g(当乙酸用量为0.1mol时),带水剂苯15mL,在110～118℃反应1.5h,其酯化率达92%以上.该方法的优点是酯化率高,催化剂可重复使用且基本不腐蚀设备.     

Nafion树脂负载的钯催化Suzuki偶联反应和Heck酰基化反应

相对于均相催化剂,高分子负载的催化剂有诸多优点,如催化剂易分离并可重复使用,后处理简便有利于连续反应[1,2].我们首先制备了3-二苯膦基-1-丙胺,然后在微波促进下与磺酰氟型Nafion-F树脂薄膜反应得到负载的含膦配体,再与烯丙基氯化钯二聚体进行配位反应得到负载在Nafion薄膜上的Pd催化剂1.该催化剂在Suzuki偶联和Heck酰基化反应中表现出非常高的催化活性,催化剂重复使用五次活性均未见明显降低(Scheme 1).     

制备方法对H2SO4固体酸结构和催化性能的影响

 以溶胶-凝胶法和浸渍法制备了H2SO4固体酸催化剂. FT-IR, XRD和 29Si MAS NMR结果表明,两种方法得到的催化剂结构不同. FT-IR和 29Si MAS NMR结果表明,溶胶-凝胶法制备的固体酸H2SO4-SiO2中H2SO4和载体SiO2间存在相互作用; 1H MAS NMR结果表明,H2SO4-SiO2固体酸的酸强度和液体浓硫酸相当. 通过对柠檬酸与正丁醇的液/固相催化酯化反应比较了溶胶-凝胶法与浸渍法制备的固体酸的催化性能,结果表明,浸渍法得到的固体酸重复使用4次后活性消失; 溶胶-凝胶法制备的H2SO4-SiO2固体酸重复使用6次后仍显示出较高的活性和选择性.     

硫酸化剂和制备方法对锆基固体酸催化剂的结构和性能的影响

采用沉淀法制备ZrO2氧化物,用氯磺酸和硫酸对其进行改性制备了Zr基固体酸催化剂,以XRD、BET和NH3-FTIR等手段考察了制备条件对催化剂晶相结构和表面性质的影响,研究了催化剂结构与其对棕榈油酯化反应的催化活性之间的关系.NH3-FTIR表明催化剂表面有B酸和L酸中心的生成.硫酸化剂的种类及其引入顺序都将影响催化剂的晶相结构和孔结构.酸的引入将阻止ZrO2·nH2O在焙烧时直接向单斜相ZrO2转变,氯磺酸将使ZrO2·nH2O转变为四方相ZrO2,而硫酸将导致四方相ZrO2和Zr(SO4)2·5H2O的生成.以氯磺酸改性的四方相和单斜相ZrO2基催化剂均具有很高的催化酯化活性,比硫酸改性的S-Z固体酸催化活性高.CS-ZrO2固体酸催化活性最高,在醇油比6:1、催化剂用量7 wt%、温度338 K和常压下反应2 h,棕榈油的酯化率可达98.9%.     

Nutrient removal and energy production in a urine treatment process using magnesium ammonium phosphate precipitation and a microbial fuel cell technique

Urine pretreatment has attracted increasing interest as it is able to relieve the nitrogen and phosphorus overloading problems in municipal wastewater treatment plants. In this study, an integrated process, which combines magnesium ammonium phosphate (MAP) precipitation with a microbial fuel cell (MFC), is proposed for the recovery of a slow-release fertilizer and electricity from urine. In such a two-step process, both nitrogen and phosphorus are recovered through the MAP process, and organic matters in the urine are converted into electricity in the MFCs. With this integrated process, when the phosphorus recovery is maximized without a dose of PO(4)(3-)-P in the MAP precipitation process, removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 94.6% and 28.6%, respectively, were achieved with a chemical oxygen demand (COD) of 64.9% accompanied by a power output of 2.6 W m(-3). Whereas removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 42.6% and 40%, respectively, and a COD of 62.4% and power density of 0.9 W m(-3) were obtained if simultaneous recovery of phosphorus and nitrogen was required through dosing with 620 mg L(-1) of PO(4)(3-)-P in the MAP process. This work provides a new sustainable approach for the efficient and cost-effective treatment of urine with the recovery of energy and resources.     

Reliable sequence determination of ribosome- inactivating proteins by combining electrospray mass spectrometry and Edman degradation

The primary structure of saporin-S9 and MAP-S, two type-1 ribosome-inactivating proteins isolated from the seeds of Saponaria officinalis L. and Mirabilis jalapa, respectively, was determined using a combined approach based on Edman degradation and electrospray ionization mass spectrometry (ESMS). Saporin-S9 has 253 amino acids with a calculated molecular mass of 28,492.99, which is in good agreement with that determined by ESMS (28 495 +/- 2 Da). Unlike other saporins with known primary structure, saporin-S9 contains four histidinyl residues (positions 111, 121, 216 and 248). By comparing the amino acid sequence of saporin-S9 with that of saporin-S6, we found 22 amino acid substitutions (8.7%), 13 of which are conservative and nine non-conservative. The residues known to be involved in the definition of the active site and with RNA base recognition are conserved. The four histidinyl residues and especially Lys for Gln203 contribute to the higher calculated pI value (10.17) of saporin-S9 compared with saporin-S6 (9.98). MAP-S contains 250 amino acid residues with a calculated molecular mass of 27,789.49, in good agreement with that determined by ESMS (27,789 +/- 2). Cys36 and Cys220 form a disulphide bridge and only four amino acid residues are different from the amino acid sequence of MAP, isolated from the roots of the same plant, i.e. Leu34 (Glu), Ile161 (Leu), Asp185 (Glu) and Asp191 (Glu) (in parentheses, the residues present in MAP). The reported approach can provide rapid and reliable sequence screening in the analysis of homologous proteins, including the presence of disulphide bridges.     

Physical Characteristics and Microbial Quality of Ostrich Meat in Relation to the Type of Packaging and Refrigerator Storage Time

The aim of this study was to evaluate the effect of the packaging system type on the physical characteristics and microbial changes in ostrich meat during refrigerated storage. The applied packaging systems were vacuum packaging (VP) and modified atmosphere packaging (MAP) using two combinations of gases: MAP1 (40% O₂/40% CO₂/20% N₂) and MAP2 (60% O₂/30% CO₂/10% N₂). Eight meat samples were obtained in three replicates for all parameters, except for pH, for which six replicates were obtained from the M. ilifibularis (IF) muscle, and were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days for the effect of packaging methods on physical meat quality. The initial pH (5.99) decreased at the end of the storage time for MAP1 to 5.81, whereas VP was stable from day 0 to 12 and increased up to 6.08 on day 16. Regarding meat color, the L* value increased during storage for MAP1 and MAP2 from 36.99 to 40.75 and 41.60, respectively, whereas it declined for VP to 34.22. The same tendencies were reported for redness (a*) and yellowness (b*). Drip loss was the lowest in MAP1 and highest in VP. The lowest total viable bacteria counts were identified in VP, as compared to MAP1 and MAP2.     

Continuous on-line derivatization and selective separation of D-aspartic acid by a capillary electrophoresis system with a continuous sample introduction interface

A rapid and selective method is described for the separation of D-aspartic acid (D-Asp) using a continuous on-line derivatization system coupled to capillary electrophoresis (CE). D-Asp was derivatized using o-phthaldialdehyde/N-acetyl-L-cysteine (OPA/NAC). By on-line derivatization, amino acid enantiomers were automatically and reproducibly converted to the UV-absorbing diastereomer derivatives which were separated by capillary zone electrophoresis (CZE) in the presence of 10 mmol/L beta-cyclodextrin (beta-CD). Under the investigated separation conditions, D-Asp is resolved from L-aspartic acid (L-Asp) and other amino acids in a standard mixture of amino acids. The separation could be achieved within 4 min and the sample throughput rate can reach up to 16 h(-1). The repeatability (defined as relative standard deviation, RSD) was 3.21%, 3.58% with peak area evaluation and 3.72%, 4.03% with peak height evaluation for L-Asp and D-Asp.     

Use of sodium tungstate as a permanent chemical modifier for slurry sampling electrothermal atomic absorption spectrometric determination of indium in soils

A number of chemical modifiers have been assessed for the direct determination of indium in soils using electrothermal atomic absorption spectrometry and slurry sampling. The best results were obtained when the graphite atomizer was impregnated with sodium tungstate, which acts as a permanent chemical modifier. Slurries were prepared by suspending 100 mg sample in a solution containing 1% (v/v) concentrated nitric acid and 10% (v/v) concentrated hydrofluoric acid and then 15-microL aliquots were directly introduced into the atomizer. Standard indium solutions prepared in the suspension medium in the range 4-80 microg L(-1) indium were used for calibration. The relative standard deviation for ten consecutive measurements of a 40 microg L(-1) indium solution was 2.8%. The limit of detection in soils was 0.1 microg g(-1). The reliability of the procedures was confirmed by analysing two standard reference materials and by using an alternative procedure.     

不完全抑制电导检测离子色谱法测定饮料中的苹果酸

采用一种抑制型离子色谱检测技术－－不完全抑制电导检测,以０．７５ｍｍｏｌ／ＬＮａ２ＳＯ４＋ＮａＯＨ（ｐＨ＝１１．５）为淋洗液对弱酸根离子如苹果酸、酒石酸等进行了测定,得到苹果酸、酒石酸的检测限分别为１．３１ｍｇ／Ｌ、３．０４ｍｇ／Ｌ;在２００ｍｇ／Ｌ以下相关系数分别为０．９９９８、０．９９９９;;各离子峰高的相对标准偏差（ＲＳＤ）分别为０．５７％、１．６０％。上率为９７．７￣１０４％。常见的强酸离     

Determination of Se using a solid-phase micro-extraction device coupled to a graphite furnace and detection by gas chromatography-mass spectrometry

A solid-phase micro-extraction (SPME) method using an SPME fiber device and graphite furnace (GF) for extracting Se compounds was proposed. Various factors affecting the derivatization and extraction of Se(IV) by SPME-GF were evaluated, including the effect of acid (type and concentration), the concentration of the derivatizing agent, the derivatization temperature, the extraction and derivatization times and the extraction temperature. After optimizing these conditions, the quantification of Se(IV) was performed by Gas Chromatography-Mass Spectrometry (GC-MS). The limit of detection was 0.37 μg L(-1) for Se(IV). The method was successfully applied to the total Se determination in certified reference materials (BCR-414 and SRM 1643e). A recovery of 97% was obtained for water (SRM 1643e). After microwave oven decomposition and the reduction of selenium using a mixture of 2 mol L(-1) HCl and 1% (w/v) KBr, a recovery of 101% and a relative standard deviation of 3.5% were attained for plankton (BCR-414). The SPME-GF method combined with GC-MS was also applied to the determination of the total selenium in a drug sample (selenium chelate).     

Diastereoisomeric cationic pi-allylpalladium-(P,C)-MAP and MOP complexes and their relationship to streochemical memory effects in allylic alkylation

The axially chiral ligands 2-(diphenylphosphanyl)-2'-methoxy-1,1'-binaphthalene (MOP; 6) and 2'-dimethylamino-2-(diphenylphosphanyl)-1,1'-binaphthalene (MAP; 7) coordinate to a cationic allylpalladium fragment in an unusual bidentate (P,C)-mode through the triarylphosphane and ipso-carbon atom (C1'). The readily prepared MAP and MOP complexes [Pd[(P,C)-(L)](n3-allyl)][OTf] (9 (L = 7) and 10 (L = 6)) have been characterised in solution (NMR), in which two diastereoisomeric rotamers are observed. The stereochemical identity of the rotamers is established by one- and two-dimensional NMR spectroscopy experiments. In both the solid state and in solution, the allyl unit is shown to coordinate in a slightly distorted n3-mode that results in a more alkene-like character at the allyl terminus trans to phosphane ligand. The opposite allyl terminus, which is trans to the ipsocarbon atom (C1'), is more strongly bound and the dominant allyl stereodynamic process involves C-C bond rotation in an n'-allyl intermediate bound through this carbon. Palladium complexes of MAP and MOP are very efficient catalysts for allylic alkylation of racemic cyclopentenyl pivalate with [NaCH(CO2Me)2] in THF. Isotopic desymmetrisation revealed that the reaction occurs with powerful stereochemical memory effects and consequently with low global ee values. The memory effect is suggested to arise through selective generation of diastereoisomeric [Pd[(P,C)-L](n3-cyclopentenyl)]+ ions (L = MAP or MOP) and subsequent capture by nucleophile before ion-pair collapse or equilibration occurs.     

Development of a fast capillary electrophoresis method for determination of creatinine in urine samples

The aim of this work was to develop a fast method using capillary electrophoresis for the determination of creatinine in human urine samples. The pH and constituents of the background electrolyte were selected by inspection of effective mobility of creatinine and candidate urine interferents versus pH curves. The tendency of the analyte to undergo electromigration dispersion and the buffer capacity were evaluated by the Peakmaster software and considered in the optimization of the background electrolyte, composed by 10 mmol L(-1) tris(hydroxymethyl)aminomethane and 20 mmol L(-1) 2-hydroxyisobutyric acid (HIBA) at pH 3.93. Separation was conducted in a fused-silica capillary (32 cm total length and 8.5 cm effective length, 50 microm I.D.), with short-end injection configuration and direct UV detection at 215 nm. The migration time of creatinine was only 22s. A few figures of merit of the method are as follows: good linearity in the concentration interval of 5-70 mg L(-1) (R(2)>0.99), limit of detection of 0.5 mg L(-1), inter-day precision better than 2.7% (n=9) and recovery in the range 99.0-103.7% at three concentration levels (50, 100 and 150 mg L(-1)). Urine samples were prepared by deproteination with acetonitrile (1:3 sample:acetonitrile, v/v), centrifugation and dilution of a deproteinated aliquot with 12.5 mmol L(-1) HIBA (1:4, v/v). Creatinine concentrations between 489 and 1063 mg L(-1) were obtained in the urine of four healthy volunteers.     

Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10~(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1％ (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1％ HNO_3(3.0 mL/min). A good precision(1.6％ for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h~(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.