Effect of pretreatment methods on the performance of Cu-Zr-Ce-O catalyst for CO selective oxidation

The Cu-Zr-Ce-O catalysts prepared using the coprecipitation method exhibited better catalytic performance for CO selective oxidation. The Cu-Zr-Ce-O catalysts pretreated with different methods were studied by CO-TPR and XPS techniques. The results showed that the Cu-Zr-Ce-O catalyst pretreated with oxygen exhibited the best catalytic performance and had the widest operating temperature window, with CO conversion above 99% from 160 to 200 ℃. The O2 pretreatment caused an enrichment of the oxygen storaged on the Cu active species and promoted the conversion of adsorbed oxygen into surface lattice oxygen. It also improved the amount of Cu＋/Cu^2＋ ionic pair, and then facilitated the formation of CuO active species on the catalyst for selective CO oxidation.     

Development of two fully automated quick,easy, cheap,effective, rugged,and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples

Quick, easy, cheap, effective, rugged, and safe extraction strategies are becoming increasingly adopted in various analytical fields to determine drugs in biological specimens. In the present study, we developed two fully automated quick, easy, cheap, effective, rugged, and safe extraction methods based on acetonitrile salting-out assisted liquid-liquid extraction (method 1) and acetonitrile salting-out assisted liquid-liquid extraction followed by dispersive solid-phase extraction (method 2) using a commercially available automated liquid-liquid extraction system. We applied these methods to the extraction of 14 psychotropic drugs (11 benzodiazepines and carbamazepine, quetiapine, and zolpidem) from whole blood samples. Both methods prior to liquid chromatography–tandem mass spectrometry analysis exhibited high linearity of calibration curves (correlation coefficients, > 0.9997), ppt level detection sensitivities, and satisfactory precisions (< 8.6% relative standard deviation), accuracies (within ± 16% relative error), and matrix effects (81–111%). Method 1 provided higher recovery rates (80–91%) than method 2 (72–86%), whereas method 2 provided higher detection sensitivities (limits of detection, 0.003–0.094 ng/mL) than method 1 (0.025–0.47 ng/mL) owing to the effectiveness of its dispersive solid-phase extraction cleanup step. These fully automated extraction methods realize reliable, labor-saving, user-friendly, and hygienic extraction of target analytes from whole blood samples.     

液相色谱法测定饮料中咖啡因实验的改造与探讨

对液相色谱法测定饮料中的咖啡因实验进行了改造与拓展,增加去除色素和糖类等干扰物的步骤,以甲酸代替磷酸二氢钾缓冲溶液对流动相进行改进,增强了实验的可操作性和综合性,提高了检测结果的准确性,加深了学生对食品分析中液相色谱法应用的认识,提高了学生利用所学知识综合解决问题的能力。     

水体中纳米颗粒检测的研究进展

纳米颗粒在工业和化妆品等行业中的大规模应用,致使大量纳米颗粒进入水环境中,不可避免的产生了一系列的环境问题,同时对生物和人体造成不良影响,因此水环境中纳米颗粒的富集及其检测技术受到广泛关注。目前,多种技术可对水环境中痕量纳米颗粒浓度等特征进行检测,但其在灵敏度和精度方面均存在一定局限性。归纳了目前水环境中纳米颗粒的预处理技术,如超滤分离技术、色谱分离技术、固相萃取技术及浊点萃取技术;综述常用的纳米颗粒与离子检测技术,如光谱分析技术、电感耦合等离子质谱技术及电化学技术。通过对各种方法进行对比分析,使纳米颗粒预处理及检测技术能够被系统广泛的认识。并在此基础上对纳米颗粒的预处理及检测技术的发展前景进行了展望。     

铝矾土空心陶粒支撑剂的制备及性能研究

以尿素为成孔模板,MnO2为烧结助剂,铝矾土粉为球壳包覆材料,采用模板法制备了空心内半径可控的铝矾土空心陶粒支撑剂.运用X射线荧光分析,热分析、XRD和SEM等技术对铝矾土原料粉预处理前后矿物相组成和化学成分及支撑剂产品微观形貌的变化进行了比较分析,探究了原料预处理对支撑剂结构和性能的影响,并对其影响机理进行了分析.结果表明:原料粉体经预处理后可提高支撑剂的强度.在1440 ℃烧结后的主要物相为莫来石相和刚玉相.利用预处理后的铝矾土粉体制备出的空心支撑剂的体积密度为1.35 g·cm-3,视密度2.47 g·cm-3,25 MPa闭合压力破碎率为5.21;,单粒抗压平均值为58 N,试样质量稳定,制备过程较易控制.     

表面预处理对石墨烯上范德瓦耳斯外延生长GaN材料的影响

基于范德瓦耳斯外延生长的氮化镓/石墨烯材料异质生长界面仅靠较弱的范德瓦耳斯力束缚,具有低位错、易剥离等优势,近年来引起了人们的广泛关注.采用NH_3/H_2混合气体对石墨烯表面进行预处理,研究了不同NH_3/H_2比对石墨烯表面形貌、拉曼散射的影响,探讨了石墨烯在NH_3和H_2混合气氛下的表面预处理机制,最后在石墨烯上外延生长了1.6μm厚的GaN薄膜材料.实验结果表明:石墨烯中褶皱处的C原子更容易与气体发生刻蚀反应,刻蚀方向沿着褶皱进行;适当NH_3/H_2比的混合气体对石墨烯进行表面预处理可有效改善石墨烯上GaN材料的晶体质量.本研究提供了一种可有效提高GaN晶体质量的石墨烯表面预处理方法,可为进一步研究二维材料上高质量的GaN外延生长提供参考.     

Polish Varieties of Industrial Hemp and Their Utilisation in the Efficient Production of Lignocellulosic Ethanol

Nowadays, more and more attention is paid to the development and the intensification of the use of renewable energy sources. Hemp might be an alternative plant for bioenergy production. In this paper, four varieties of Polish industrial hemp (Białobrzeskie, Tygra, Henola, and Rajan) were investigated in order to determine which of them are the most advantageous raw materials for the effective production of bioethanol. At the beginning, physical and chemical pretreatment of hemp biomass was carried out. It was found that the most effective is the alkaline treatment with 2% NaOH, and the biomasses of the two varieties were selected for next stages of research: Tygra and Rajan. Hemp biomass before and after pretreatment was analyzed by FTIR and SEM, which confirmed the effectiveness of the pretreatment. Next, an enzymatic hydrolysis process was carried out on the previously selected parameters using the response surface methodology. Subsequently, the two approaches were analyzed: separated hydrolysis and fermentation (SHF) and a simultaneous saccharification and fermentation (SSF) process. For Tygra biomass in the SHF process, the ethanol concentration was 10.5 g∙L⁻¹ (3.04 m³·ha⁻¹), and for Rajan biomass at the SSF process, the ethanol concentration was 7.5 g∙L⁻¹ (2.23 m³·ha⁻¹). In conclusion, the biomass of Polish varieties of hemp, i.e., Tygra and Rajan, was found to be an interesting and promising raw material for bioethanol production.     

Ethanol production from lignocellulosic byproducts of olive oil extraction

The recent implementation of a new two-step centrifugation process for extracting olive oil in Spain has substantially reduced water consumption, thereby eliminating oil mill wastewater. However, a new high sugar content residue is still generated. In this work the two fractions present in the residue (olive pulp and fragm ented stones) were assayed as substrate for ethanol production by the simultaneous saccharification and fermentation (SSF) process. Pretreatment of fragmented olive stones by sulfuric acid-catalyzed steam explosion was the most effective treatment for increasing enzymatic digestibility; however, a pretreatment step was not necessary to bioconvert the olive pulp into ethanol. Theolive pulp and fragmented olive stones were tested by the SSF process using a fed-batch procedure. By adding the pulp three times at 24-h intervals, 76% of the theoretical SSF yield was obtained. Experiments with fed-batch pretreated olive stones provided SSF yields significantly lower than those obtained at standard SSF procedure. The preferred SSF conditions to obtain ethanol from olives stones (61% of theoretical yield) were 10% substrate and addition of cellulases at 15 filter paper units/g of substrate.     

Radiation and chemical pretreatment of cellulosic waste

RADIATION AND CHEMICAL PRETREATMENT OF CELLULOSIC WASTE. Combination pretreatment of cellulosic wastes such as corn stalk, cassava bark and peanut husk were studied using chemical and irradiation of electron beam. The effect of 2 % NaOH and irradiation at the doses of 100, 300 and 500 kGy on the cellulosic wastes were evaluated by measurement of the glucose yield in enzymatic hydrolysis. Irradiation was carried out with an electron beam machine EPS-300 (Energy 300 kev, current 50 mA). The result shows that the glucose yield were higher by increasing of dose irradiation and treated with 2 % of NaOH especially in corn stalk. The glucose yield of corn stalk were 20 % in untreated samples and increases to 43 % after treated with electron beam irradiation at the dose of 500 kGy and 2 % NaOH. Cassava bark and peanut husk show the glucose yield are only 3.5, and 2.5% respectively. The effect of E-beam current in enzymatic hydrolysis of corn stalk, and preliminary studied E-beam radiation pretreatment of cassava bark are also reported.     

乙醇蒸气预处理Cr基催化剂对丙烷脱氢性能的影响

丙烯是仅次于乙烯的重要有机化工基础原料,广泛应用于生产聚丙烯、丙烯醛、丙烯酸、甘油、异丙醇、聚丙烯氰、丁辛醇等化工产品.近年来,随着市场经济的发展,丙烯下游产品的需求量迅速上涨,极大地促进了全球对丙烯的需求.负载型氧化基催化剂因其良好的催化性能和低廉的生产成本而被广泛应用于低碳烷烃脱氢反应中,Catofin,Linde及FBD工艺使用的就是Cr2O3/γ-Al2O3催化剂.丙烷脱氢过程中,担载型氧化铬催化剂Cr物种的价态、配位结构及与载体之间的相1互作用会影响其催化性能.催化反应过程中,丙烷分子吸附在Cr-O上进行活化反应,因而研究清楚催化剂的活性物种是非常重要的.综合文献,一部分研究者认为Cr6+为反应的活性中心,在反应初期与丙烷接触立即被还原为活性比较弱的Cr3+.随着原位表征技术的发展,一些研究者认为,八面体配位结构的Cr3+物种为催化反应的活性中心,四面体配位结构的Cr6+仅仅是Cr3+活性物种的前驱体,而且Cr6+并没有被发现具有催化活性.但何种Cr物种是脱氢活性中心,至今仍没有一致结论,这是值得继续关注和解决的问题.同时,浸渍法制备催化剂的过程中,金属前驱体、浸渍溶剂、干燥时间、干燥温度及焙烧时间和温度等因素会影响所制备催化剂的催化活性.我们采用等体积浸渍法制备催化剂,并用饱和乙醇蒸气对其进行预处理,以丙烷脱氢为探针反应研究了预处理对催化剂脱氢反应性能的影响,采用X射线衍射(XRD)、透射电镜(TEM)、程序升温还原(H2-TPR)、X射线光电子能谱(XPS)和紫外-可见光谱(UV-Vis)等表征手段,揭示催化反应的活性中心及反应机理.在无氧脱氢反应中,经过乙醇蒸气预处理的催化剂CrH-Et催化活性稍高于原始催化剂CrH.在二氧化碳参与的反应中,催化剂CrH-Et催化活性远远高于CrH.当C3Hs∶CO2∶He=1∶5∶4时达到最佳效果,CrH-Et的丙烷转化率为41.4％,丙烯选择性为84.8％,同样条件下CrH的催化活性和丙烯选择性分别为28.0％和85.9％.但是乙醇作为浸渍溶剂,对催化剂并没有促进作用.XRD和TEM结果表明,Cr均匀分散在载体表面,Cr粒子簇的大小并不影响催化剂的催化活性.H2-TPR,XPS和UV-Vis结果说明,经过乙醇蒸气预处理后催化剂中的Cr6+被还原成低价Cr,因而可以证明Cr6+不是催化剂的活性中心.Cr3+作为活性中心而存在,Cr6+仅作为活性组分的前驱体而存在.而在反应过程中,Cr3+容易被反应中生成的H2还原成非活性组分.相对于催化剂CrH,经过乙醇蒸气预处理的催化剂(CrH-Et)上部分还原后的低价Cr更容易被CO2重新氧化成Cr6+.即在反应过程中,CrH-Et能保持相对CrH更多的活性组分,因而保持更高的催化活性.