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1.
氯代芳烃催化氢转移脱氯的研究 总被引:12,自引:0,他引:12
本文以甲酸钠为氢源,对聚乙烯吡咯烷酮锚定的PdCl2催化氯代芳烃脱氯进行了研究,考察了反应条件对反应的影响,研究了脱氯的选择性。结果表明;该方法具有卓越的脱氯选择性,催化剂用量少,反应条件温和,操作简便。本文并对其脱氯反应机理进行了初步探讨。 相似文献
2.
Xiaomin Zhang Wenjie Xiong Zengyu Yin Yongle Chen Youting Wu Xingbang Hu 《绿色能源与环境(英文)》2022,7(1):137-144
In this work, a series of novel proton-gradient-transfer acid complexes (PGTACs) were developed. Their physicochemical properties, including thermal stability, melting point, and Hammett acidity, were measured. The effects of catalyst loading, reaction temperature, and substrate expansion on the catalytic performance were systematically studied. It is found that the combination of bidentate N-heterocycle and H2SO4 (1:2 M ratio) could form simultaneously N–H covalent bond and N…H hydrogen bond, which makes the PGTACs excellent catalysts integrate the advantages of strong acids (high catalytic activity) and ionic liquids (phase separation) in the esterification reaction. Moreover, these PGTACs can be reused by convenient phase separation without obvious diminution of catalytic activity. It is concluded that these PGTACs are potential alternative candidates for esterification reaction in the process of industrial catalysis. 相似文献
3.
研究了负载于氧化锆载体上的多种金属氧化物在富氧条件下,以丙烯为还原剂,选择性还原NO的活性,考察了CuO和Ag的负载量与活性关系,CuO和Ag单独负载与共同负载时的催化性能,以及氧气浓度对催化剂活性影响.结果表明:在CuO,MgO,La2O3 ,CoO,Fe2O3 ,MoO3和WO3等七种金属氧化物中,CuO活性最好,NO转化率为47.5%,加入活性组分银可明显提高催化剂的NO还原能力,转化率提高到61%.单独负载银时,催化剂活性较差,NO转化率仅为22.1%.在对氧气浓度的考察中,确定在0.4%NO,0.4?H6的反应气中,氧气的最佳含量为2%. 相似文献
4.
Shuyu Chen Run Li Yaqi Shen Lu Zhan Zhenming Xu 《Frontiers of Environmental Science & Engineering》2022,16(11):146
5.
In this study, stabilized Pd, Pt and Au nanoparticles were successfully prepared in aqueous phase using sodium carboxymethyl cellulose (CMC) as a capping agent. These metal nanoparticles were then tested for catalytic hydrodechlorination toward two classes of organochlorinated compounds (vinyl polychlorides including trichloroethylene (TCE), tetrachloroethylene (PCE), and alkyl polychlorides including 1,1,1-trichloroethane (1,1,1-TCA), and 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA)) to determine the rate-limiting steps and to explore the reaction mechanisms. The surface area normalized reaction rate constant, kSA, showed a systematic dependence on the electronic structure (the density of states at the Fermi level) of the metals, suggesting that adsorption of organochlorinated reactants on the metal catalyst surfaces is the rate-limiting step for catalytic hydrodechlorination. Hydrodechlorination rates of 1,1,1-TCA and 1,1,1,2-TeCA agreed with the bond strength of the first (weakest) dissociated C-Cl bond, suggesting that C-Cl bond cleavage, which is the first step for dissociative adsorption of the alkyl polychlorides, controlled the catalytic hydrodechlorination rate. However, hydrodechlorination rates of TCE and PCE correlated with the adsorption energies of their molecular (non-dissociative) adsorption on the noble metals rather than with the first C-Cl bond strength, suggesting that molecular adsorption governs the reaction rate for hydrodechlorination of the vinyl polychlorides. 相似文献
6.
陈科 《湖南环境生物职业技术学院学报》2008,14(2):18-21
介绍苯和苯甲醇在环境友好型催化剂硫酸亚铈的催化下合成二苯甲烷,研究了催化剂用量、反应时间对该傅克反应的影响.实验结果表明,该催化剂具有良好的催化活性,实验过程简单,无腐蚀,无废水污染.表1,参4. 相似文献
7.
Advances in research on haloalkane dehalogenases and its sulfur mustard degradation function北大核心CSCD
Xi H.Liu C.Wen X.Chen L. 《应用与环境生物学报》2015,(5):842-847
Sulfur Mustard (bis-(2-chloroethyl) sulphide, HD), also known as yperite, is one of the most important blister agents. It could react with a large number of biological molecules with a strong cytotoxicity effect, resulting in blistering, erosion and necrosis of the skin and various tissues. Recently, several classes of microbial enzymes have been found to be able to degrade HD with high catalytic activity but no disadvantages of the common chemical decontamination of HD. Haloalkane dehalogenases (HLDs, EC3.8.1.5) draws great research attention for environmentally friendly decontaminating HD with only nontoxic thiodiglycol produced. In order to provide theoretical reference basis for enzymatic decontamination of HD, this paper reviews the observation and evolutionary relationship, structures, substrate specificities, catalytic properties and potential applications of these HLDs with high catalytic hydrolysis of HD. The analysis shows that these HLDs belonging to the same subfamily have different substrate specificities but similar spatial structures of the catalytic triad contributing to the common SN2 nucleophilic substitution reaction mechanism for catalytic hydrolysis of HD. The paper also suggests that the problems on improving poor stability of HLDs and efficiency of catalytic hydrolysis of HD should be addressed by methods of molecular biology, genetic engineering and immobilized techniques. 相似文献
8.
半焦负载Na-Fe催化还原NO的研究 总被引:6,自引:0,他引:6
在石英固定床反应器上于常压下研究了煤焦负载Na或Fe催化还原NO的反应,同时研究了Na-Fe复合催化剂的催化特性。研究结果表明:Na或Fe催化剂的催化行为差异较大,低温下Na的催化活性高于相同负载量的Fe,而温度较高时,二者的催化活性顺序与低温时相反。Na的催化活性随负载量的增加而迅速增大,而Fe的催化活性随温度的升高增加迅速。在保持相同的负载量下,一定配比的Na-Fe复合催化剂的催化活性高于其中任何单一催化剂的催化活性。在不加其他还原剂的条件下,负载于煤焦上的Na-Fe复合催化剂可有效地催化还原NO,得到了高的还原转化率。复合催化剂高的催化活性预示Na-Fe在制备过程中的相互作用以及催化半焦还原NO的反应中具有协同作用。 相似文献
9.
10.
高选择性手性酯酶产生菌的筛选及应用 总被引:3,自引:0,他引:3
从土壤中分离得到230株产酯酶菌株,经反复筛选,从中挑选出一株酶活及选择性均较高的菌株YQ231,该菌株所产酯酶能将外消旋的酯水解为手性醇(环戊烯酮),且该酶优先水解(R)-型酯。经生理生化试验鉴定,该细菌为不动杆菌属(Acinetobacter sp.)。研究了该菌株的产酶过程,结果表明:酶活在24h达最高值。同时研究了该菌株的催化特性,在反应12h时其转化率达48.8%,eep为92.3%,ees为70.3%。图3表2参9 相似文献
11.
研究了过渡金属硝酸盐及Al2O3为载体担载催化剂在罗丹明B臭氧氧化过程中的催化作用,考察了温度、pH值以及催化剂浓度等因素对反应的影响.结果表明,过渡金属离子可显著地提高罗丹明B的脱色速率,而担载型过渡金属氧化物催化剂活性较低.较低的pH值和反应温度有利于罗丹明B的催化臭氧化.罗丹明B溶液经过催化臭氧氧化后COD去除率可提高24%. 相似文献
12.
Zeinab Jamalzadeh Mohammad Haghighi Nazli Asgari 《Frontiers of Environmental Science & Engineering》2013,7(3):365-381
In this work, xylene removal from waste gas streams was investigated via catalytic oxidation over Pd/carbon-zeolite and Pd/carbon-CeO2 nanocatalysts. Activated carbon was obtained from pine cone chemically activated using ZnCl2 and modified by H3PO4. Natural zeolite of clinoptilolite was modified by acid treatment with HCl, while nano-ceria was synthesized via redox method. Mixed supports of carbon-zeolite and carbonceria were prepared and palladium was dispersed over them via impregnation method. The prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller surface area (BET), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) techniques. Characterization of nanocatalysts revealed a good morphology with an average particle size in a nano range, and confirmed the formation of nano-ceria with an average crystallite size below 60 nm. BET analysis indicated a considerable surface area for catalysts (~1000 m2·g?1). FTIR patterns demonstrated that the surface groups of synthesized catalysts are in good agreement with the patterns of materials applied in catalyst synthesis. The performance of catalysts was assessed in a low-pressure catalytic oxidation pilot in the temperature range of 100° C-250°C. According to the reaction data, the synthesized catalysts have been shown to be so advantageous in the removal of volatile organic compounds (VOCs), representing high catalytic performance of 98% for the abatement of xylene at 250°C. Furthermore, a reaction network is proposed for catalytic oxidation of xylene over nanocatalysts. 相似文献
13.
NO如直接排放会引起酸雨、光化学烟雾等一系列大气环境问题,采用高压脉冲放电等离子体活化NH3还原去除NO,这种新方法结合了脉冲放电等离子体技术和催化还原技术的优点来提高NO的去除率。采用浸渍法制备催化剂V2O5/TiO2,用NH3作为还原气体,升温的同时利用针头作为阳极,大地作为阴极进行放电处理。结果表明,在有氧条件下(含氧量为10%),当V2O5含量为4.5%,温度为310℃,脉冲电源电压在14000~22000V变化时,NO的去除率可达95.3%。还探讨了放电等离子体活化NH3去除NO的机理。 相似文献
14.
The present work, in which cellulose isolated from formic acid fractionation (FAC) is decorated with polyetherimide (PEI) to attain highly efficient cellulose-derived PdAgbimetallic catalyst (PdAg-PEI-FAC), has been investigated, and the catalyst properties are characterized by XRD, XPS, BET, ICP-AES and HAADF-STEM. The as-obtained Pd3.75Ag3.75-PEI-FAC exhibits excellent catalytic performance for H2 evo-lution from a sodium formate-free formic acid (FA) aqueous medium at ambient temperature and the turnover frequency (TOF) reaches a high value of 2875 h-1, which is superior to most of the previously reported Pd-based heterogeneous catalysts supported on a carbon matrix in the literature. The remarkable catalytic activities of PdAg-PEI-FAC result from high dispersion Pd and synergistic effects between the PdAg bimetallic system. Furthermore, the amide (-NH) group in PEI coated on cellulose acting as a proton scavenger efficiently improves the catalytic property of catalyst. In addition, the critical factors affecting H2 release, such as FA concentration, reaction temperature, PdAg compositions and support matrix type, are also evaluated. Based on the experimental results, the probable three-step mechanism of H2 evolution from FA over Pd3.75Ag3.75-PEI-FAC is proposed. In the end, the activation energy (Ea) of Pd3.75Ag3.75-PEI-FAC catalyst is calculated to 53.97 kJ mol-1, and this catalyst shows unique robustness and satisfactory re-usability with no loss of catalytic activity after five recycles. The findings in this work provide a novel routine from lignocellulose fractionation towards cellulose-derived catalyst for H2 evolution. 相似文献
15.
Lina Gan Kezhi Li Hejingying Niu Yue Peng Jianjun Chen Yuandong Huang Junhua Li 《Frontiers of Environmental Science & Engineering》2021,15(4):70
16.
Liyun Song Shilin Deng Chunyi Bian Cui Liu Zongcheng Zhan Shuangye Li Jian Li Xing Fan Hong He 《Frontiers of Environmental Science & Engineering》2023,17(8):96
17.
Maocong Hu Yin Liu Zhenhua Yao Liping Ma Xianqin Wang 《Frontiers of Environmental Science & Engineering》2018,12(1):3
Treating water contaminants via heterogeneously catalyzed reduction reaction is a subject of growing interest due to its good activity and superior selectivity compared to conventional technology, yielding products that are non-toxic or substantially less toxic. This article reviews the application of catalytic reduction as a progressive approach to treat different types of contaminants in water, which covers hydrodehalogenation for wastewater treatment and hydrogenation of nitrate/nitrite for groundwater remediation. For hydrodehalogenation, an overview of the existing treatment technologies is provided with an assessment of the advantages of catalytic reduction over the conventional methodologies. Catalyst design for feasible catalytic reactions is considered with a critical analysis of the pertinent literature. For hydrogenation, hydrogenation of nitrate/nitrite contaminants in water is mainly focused. Several important nitrate reduction catalysts are discussed relating to their preparation method and catalytic performance. In addition, novel approach of catalytic reduction using in situ synthesized H2 evolved from water splitting reaction is illustrated. Finally, the challenges and perspective for the extensive application of catalytic reduction technology in water treatment are discussed. This review provides key information to our community to apply catalytic reduction approach for water treatment.
相似文献
18.
以活性氧化铝为载体,采用浸渍法制备催化剂,对甲基橙及草酸模拟废水进行处理.在中性条件下,臭氧催化氧化比单独臭氧氧化能提前30 min使得甲基橙溶液褪色,反应105 min时,臭氧催化氧化对TOC的去除率高达96.53%,比单独使用臭氧氧化对甲基橙TOC去除率提高了47.19%,在处理草酸废水时臭氧催化氧化对TOC去除率高达80.59%,比单独使用臭氧氧化对草酸TOC去除率提高了59.14%.在处理甲基橙及草酸的小试实验中催化剂对有机污染物的吸附作用起到了加快反应进行的作用.在对垃圾渗滤液超滤出水时,O3与COD质量比为1:1时,臭氧催化氧化对COD去除率为49.09%,比单独使用臭氧氧化提高36.37%,臭氧催化氧化对TOC的去除率是单独使用臭氧氧化的2.54倍,在处理垃圾渗滤液纳滤浓水时,臭氧催化氧化对COD去除率高达88.72%,比单独使用臭氧氧化提高37.60%,并且臭氧催化氧化对TOC的去除率是单独臭氧氧化的1.6倍.臭氧催化氧化反应过程中产生的羟基自由基对有机物更快的反应速率. 相似文献
19.
In this paper, sulfonic groups functionalized annealed bio-based carbon microspheres loaded polytetrafluoroethylene (A-BCMSs-SO3H@PTFE) fibers with high activity, high stability, and easy regeneration were successfully fabricated by a simple method using low-cost raw materials. The characterization results showed that the annealed biomass carbon microspheres derived from waste Camellia oleifera shells were evenly distributed on the polytetrafluoroethylene fibers and the sulfonic groups can be successfully loaded on the surface of annealed biomass carbon microspheres by room temperature sulfonation. Subsequently, the as-prepared A-BCMSs-SO3H@PTFE fibers were applied to the acid-catalyzed synthesis of liquid biofuel 5-ethoxymethylfurfural. The catalytic experiment results indicated that the annealing temperature and time during catalyst preparation have a significant effect on the activity and selectivity of A-BCMSs-SO3H@PTFE fibers. The results of catalytic reaction kinetics showed that the yield of 5-ethoxymethylfurfural can reach more than 60%after 72 h of acid-catalyzed reaction. The stability test showed that the as-prepared A-BCMSs-SO3H@PTFE fibers still maintained a stable acid catalytic activity after four recycles. 相似文献