CuIr-ZSM-5催化剂催化还原NO_X的研究

采用浸渍法制备分子筛催化剂Cu Ir-ZSM-5,考察了焙烧温度、铜铱含量等对催化剂选择性催化还原NOX性能的影响。结果表明,分子筛的预处理温度580℃,铜质量分数为3%,铱质量分数为0.4%催化剂有着良好的酸性分布、氧化还原特性和较强的NO吸附能力,铜铱双组分发生了良好的协同促进作用。     

CuIr-ZSM-5催化剂催化还原NO_X的研究

采用浸渍法制备分子筛催化剂Cu Ir-ZSM-5,考察了焙烧温度、铜铱含量等对催化剂选择性催化还原NOX性能的影响。结果表明,分子筛的预处理温度580℃,铜质量分数为3%,铱质量分数为0.4%催化剂有着良好的酸性分布、氧化还原特性和较强的NO吸附能力,铜铱双组分发生了良好的协同促进作用。     

乙醇中硝酸还原工艺条件及Pd-Cu催化剂研究

在间歇反应釜中进行了硝酸催化还原实验,考察了NO体积浓度、气体流量、反应温度和反应时间对硝酸转化率的影响。发现硝酸的转化率随原料气NO的浓度、反应时间及反应温度的增加而增大,气体流量增大,硝酸转化率先增大后趋于稳定。同时采用浸渍法制备了单金属Pd和双金属Pd-Cu催化剂,考察了催化剂焙烧温度及载体类型对催化剂催化性能的影响。结果表明,Cu离子的引入能够增强催化活性,较高的焙烧温度不利于硝酸的还原,以活性炭为载体制备的催化剂催化效果最佳。     

Pd-Cu/γ-Al_2O_3双金属催化剂脱除水中硝酸盐

采用分步浸渍法和共浸渍法制备系列Pd负载质量分数为1%的Pd-Cu/γ-Al2O3双金属催化剂,以氢气为还原剂研究其对水中硝酸盐催化脱除的性能。结果表明,催化剂中Cu与Pd物质的量比以及Cu、Pd的浸渍顺序对催化剂性能有重要影响,硝酸根转化率随着Cu与Pd物质的量比的增大而增大;硝酸根转化活性以Cu与Pd物质的量比为5∶1、先浸渍Pd再浸渍Cu所得催化剂较优;从氨氮选择性方面看,以先浸渍Cu后浸渍Pd制备的催化剂选择性较低,在Cu与Pd物质的量比为1∶1、先浸渍Cu再浸渍Pd所得催化剂较优。     

新型稀土固体超强酸SO42-/MnO2/La3+的合成研究

以硫酸锰和硝酸镧为原料,采用共沉淀-浸渍法制备不同比例的SO^2-₄/MnO₂/La³⁺。以催化合成乙酸苄酯为探针反应,考察H₂SO₄浓度、La（NO₃）₃的质量分数、焙烧温度、焙烧时间等因素对其催化活性的影响。结果表明,催化剂制备的最佳条件为:硝酸镧的加人为硫酸锰的3%（质量分数）,浸渍浓度为1 mol·L^-1的H₂SO₄,焙烧温度为450℃,焙烧时间3 h,酯化率到达最大,为89.7%。     

活性炭负载铑基催化剂的制备条件研究

为研制高碳醛合成用易分离催化剂,文中以RhCl3为前体,以活性炭为载体,采用等体积浸渍法制备了负载铑基催化剂。使用N2吸附-脱附和Boehm滴定对不同载体进行了表征,考察了载体预处理和制备条件对催化剂活性的影响。结果表明,经过高温热处理的活性炭载体比表面积和孔容略有降低,中孔分布变窄,表面含氧基团大大增加,从而使催化剂氢甲酰化性能得到提高。合适的铑负载质量分数为0.6%—1.0%,磷酸负载质量数为5.0%。焙烧温度低于400℃时,对催化剂性能影响不大。     

催化剂工业制备过程中减少NO_x排放的研究

以醋酸代替硝酸作为胶溶剂制备催化剂载体,考察了不同酸对催化剂载体性质的影响;催化剂表征结果表明,醋酸可以代替硝酸作为胶溶剂制备催化剂载体。另外,在配制催化剂的浸渍液时添加尿素,考察了尿素浓度、浸渍时间、浸渍温度对催化剂物化性质及焙烧尾气浓度的影响,发现最佳制备条件为尿素浓度12 wt%,浸渍温度25℃,浸渍时间1 h。研究发现的环保型催化剂制备方法,既减少了NOx的排放,又无其他废气排放。具有生产工艺简单、成本低、安全可靠、无三废污染等优点。     

制备工艺条件对新型MoO_3/Al_2O_3-Al催化精馏元件酯化性能的影响

为了制备新型催化精馏元件,采用铝阳极氧化法制备了填料型Al2O3-Al载体,采用浸渍法制备了MoO3/Al2O3-Al催化剂。以乙酸乙酯的合成为模型反应考察了制备条件对酯化活性的影响。结果表明,催化剂适宜的制备条件为焙烧温度450℃,焙烧时间4 h,浸渍液质量分数2.2%,浸渍时间12 h,水封时间2.5 h,醋酸的转化率为62.09%,乙酸乙酯选择性100%。     

MoO3改性SO2-4/Al2O3-ZrO2固体酸的制备和表征

以硝酸锆为锆源、硝酸铝为铝源,采用共沉淀法制备了Al2O3-ZrO2复合载体,通过MoO3改性和H2SO4浸渍法制备了MoO3改性的SO2-4/Al2O3-ZrO2催化剂.用XRD和FT-IR对催化剂进行表征,用元素分析仪测定硫含量,用乙酸和正丁醇的酯化反应对其催化活性进行考察.结果发现,当MoO3添加质量分数达12.0%时,出现MoO3衍射峰,表明适当的MoO3可以单层分布在催化剂表面,从而稳定SO2-4的存在.FT-IR分析结果表明,催化剂具有固体酸的特征峰.在MoO3添加质量分数为8.0%和焙烧温度650 ℃时,催化剂的催化活性达最大值,催化活性与硫含量的增加不一致.     

SiO2纤维负载金属组分催化臭氧降解化工废水

以静电纺丝制多孔二氧化硅纤维(Epsf)为催化剂载体,以Co、Zn作为双金属活性组分,采用等体积浸渍法制备Co-Zn/Epsf双金属负载型催化剂,并对其进行SEM、XRF等技术表征,探究该催化剂催化臭氧降解化工废水的效果.结果表明,当催化剂中Zn、Co双金属组分质量比为1:1时,其协同臭氧对废水具有较好的处理效果,10...     

水相中Ir-N@C催化的胺和伯醇的N-烷基化反应

以商品化的活性炭为载体,采用浸渍法制备了稳定、易回收且Ir质量分数为5%的多相催化剂Ir-N@C,考察了不同组分的铱基催化剂、反应温度、反应时间、碱对N-烷基化反应的影响。结果表明,n(Ir)∶n(1,10-Phenanthroline)=1∶2的铱基催化剂,可以在水相中高效催化包括氨水在内的多种胺类与伯醇的N-烷基化反应。运用XRD、TEM、XPS、BET测定手段对催化剂进行了表征。在循环实验中,催化剂体现了较好的稳定性和催化活性,其中,苄醇的转化率为79.1%~92.3%,三苄胺的选择性为74.3%~85.6%。     

Separation of Platinum Metals Using the Ring-Oven Technique

Abstract

A scheme has been developed for the qualitative separation of the six platinum metals from a drop of mixture by using the ring-oven technique. Osmium (VIII), palladium(II), ruthenium(III), rhodium(III), iridium(III), and platinum(IV) were transferred one by one to the ring zone by washing, respectively, with acetic anhydride, acetone, dimethylformamide–benzene mixture (1:3 v/v), methanol, dimethylformamide, and nitric acid (0.5 N) The rings obtained were developed by Alizarin Red S (Os); 1-(2-pyridylazo)-2-napthol (Pd); acidic solution of rubeanic acid (Ru); stannous chloride-potassium iodide (Rh and Pt); and benzidine in acetic acid after fuming the paper with bromine (Ir). The time required for the separation is not more than 45 min.     

羰基合成醋酐联产醋酸工艺研究

在确定选用均相铑系催化剂后,为了进一步研究中试放大,需对羰基合成小试工艺进行研究。实验采用贵金属铑为主催化剂,碘甲烷为助催化剂,以醋酸甲酯、甲醇和一氧化碳为原料,选用锆材高压釜,均相羰基化合成醋酐并联产醋酸。在温度180—200℃下,压力3.0—6.0MPa,催化剂质量分数700×10-6—1000×10-6,碘甲烷质量分数10%—15%和停留时间70—90min的工艺条件下,按一氧化碳计醋酐选择性为95.4%,CO转化率为97.4%,羰基产物醋酐收率为92.9%;催化剂的时空收率(按醋酐计)为38671.28g/(mol.h)。此工艺参数的提出可以初步指导中试放大并为工业化生产提供基础数据。     

Preparation,Characterization of Dawson-type Heteropoly Acid Cerium (III) Salt and Its Catalytic Performance on the Synthesis of n-Butyl Acetate

A novel cerium (III) salt of Dawson type tungstophosphoric acid (Ce₂P₂W₁₈O₆₂·16H₂O) was prepared by doping cerous nitrate in H₆P₂W₁₈O₆₂·13H₂O powder and characterized by thermogravimetry and differential thermal analyses (TG/DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), pyridine infrared spectroscopy (Py-IR) and scanning electron microscopy (SEM). Its catalytic activity was evaluated by the probe reaction of synthesis of n-butyl acetate with acetic acid and n-butanol. The effects of various parameters such as molar ratio of n-butanol to acetic acid, reaction temperature, reaction time, and catalyst amount have been studied by single factor experiment. The results show that Ce₂P₂W₁₈O₆₂·16H₂O behaved as an excellent heterogeneous catalyst in the synthesis of n-butyl acetate. The optimum synthetic conditions were determined as follows:molar ratio of n-butanol to acetic acid at 2.0:1.0, mass of the catalyst being 1.44% of the total reaction mixture, reaction temperature of 120 ℃ and reaction time of 150 min. Under above conditions, the conversion of acetic acid was above 97.8％. The selectivity of n-butyl acetate based on acetic acid was, in all cases, nearly 100%. The catalysts could be recycled and still exhibited high catalytic activity with 90.4% conversion after five cycles of reaction. It was found by means of TG-DTA and Py-IR that the catalyst deactivation was due to the adsorption of a complex of by-product on the active sites on catalysts surface or the catalyst loss in its separation from the products. Compared with using sulfuric acid as catalyst, the present procedure with Ce₂P₂W₁₈O₆₂·16H₂O is a green productive technology due to simple process, higher yield, catalyst recycling and no corrosion for the production facilities.     

Efficient Heterogeneous Dual Catalyst Systems for Alkane Metathesis

A fully heterogeneous and highly efficient dual catalyst system for alkane metathesis (AM) has been developed. The system is comprised of an alumina‐supported iridium pincer catalyst for alkane dehydrogenation/olefin hydrogenation and a second heterogeneous olefin metathesis catalyst. The iridium catalysts bear basic functional groups on the aromatic backbone of the pincer ligand and are strongly adsorbed on Lewis acid sites on alumina. The heterogeneous systems exhibit higher lifetimes and productivities relative to the corresponding homogeneous systems as catalyst/catalyst interactions and bimolecular decomposition reactions are inhibited. Additionally, using a “two‐pot” device, the supported Ir catalysts and metathesis catalysts can be physically separated and run at different temperatures. This system with isolated catalysts shows very high turnover numbers and is selective for the formation of high molecular weight alkanes.     

纳米Au-Pd@Ce修饰介孔磷酸铝的制备及其催化氧化环己烷性能

采用水热合成法制备Ce修饰介孔磷酸铝,再通过原位还原法负载纳米Au-Pd制备催化剂;通过以空气为氧化剂的环己烷选择性氧化反应测试催化剂的催化性能,并考察水热温度、Ce掺杂量、负载贵金属对催化剂催化氧化环己烷的的影响。结果表明,以140℃水热制备的Ce掺杂质量分数为0. 15%的Ce0. 15-APO(140)负载Au-Pd双金属(Au与Pd质量比3∶1)催化剂活性最高。在反应温度120℃,空气压力1 MPa和反应1 h的条件下,环己醇+酮的产率可达11. 81%,选择性达99%,催化剂在同样条件下循环使用5次,活性无明显下降。     

Selective Hydrogenation of 5‐Ethoxymethylfurfural over Alumina‐Supported Heterogeneous Catalysts

We report here the synthesis and testing of a set of 48 alumina‐supported catalysts for hydrogenation of 5‐ethoxymethylfurfural. This catalytic reaction is very important in the context of converting biomass to biofuels. The catalysts are composed of one main metal (gold, copper, iridium, nickel, palladium, platinum, rhodium, ruthenium) and one promoter metal (bismuth, chromium, iron, sodium, tin, tungsten). Using a 16‐parallel trickle‐flow reactor, we tested all 48 catalyst combinations under a variety of conditions. The results show that both substrate conversion and product selectivity are sensitive towards temperature changes and solvent effects. The best results of >99% yield to the desired product, 5‐ethoxymethylfurfuryl alcohol, are obtained using an iridium/chromium (Ir/Cr) catalyst. The mechanistic implications of different possible reaction pathways in this complex hydrogenation system are discussed.     

Characterization of bimetallic rhodium-germanium catalysts prepared by surface redox reaction

The preparation of bimetallic rhodium-germanium/silica and rhodium-germanium/alumina catalysts was investigated by controlled surface reaction. Their catalytic performances were measured for two gas phase reactions (toluene hydrogenation at 323 K and cyclohexane dehydrogenation at 543 K) and for a liquid phase reaction (citral hydrogenation at 343 K).

Elemental analysis of bimetallic catalysts showed that germanium can be deposited by redox reaction between hydrogen activated on a parent monometallic rhodium catalyst and germanium tetrachloride dissolved in water (catalytic reduction method). EDX microanalysis of rhodium-germanium/silica catalysts indicated that rhodium and germanium were deposited in close contact on the silica support. However, on alumina-supported catalysts, germanium deposition occurred also separately on the support. For the different test reactions, the catalytic properties of rhodium were strongly altered by the addition of germanium. On alumina-supported catalysts, interesting catalytic effects were observed in citral hydrogenation when not only close contact exists between both metals but when, in addition, the second metal was deposited on the support in the close vicinity of rhodium.     

水热改性SO_4~(2-)/ZrO_2催化剂的制备及其对酯化反应的催化性能

通过水热改性氢氧化锆制备了SO42-/ZrO2固体酸催化剂。以冰乙酸和正丁醇的酯化反应为探针反应,确定了固体超强酸的最佳制备条件。分别考察了浸渍硫酸浓度、硫酸浸渍时间和焙烧温度等对催化活性的影响。并以水热改性和未经水热改性氢氧化锆制备SO42-/ZrO2固体超强酸做了对比实验,采用XRD、BET对催化剂进行了表征。实验结果表明:水热改性氢氧化锆制备SO42-/ZrO2固体酸催化剂的最佳条件是:浸渍硫酸浓度为0.5mol/L,浸渍时间是120 m in,焙烧温度500℃。乙酸正丁酯较佳的合成工艺条件是:反应温度105~110℃,反应时间2 h,n(正丁醇)∶n(冰乙酸)=2∶1,催化剂用量占反应投料总质量的0.27%,冰乙酸的酯化率达99.1%。催化剂重复使用4次后催化活性降低5%。     

均相铑膦催化体系下1-癸烯氢甲酰化反应研究

氢甲酰化反应是目前生产醛醇化合物最重要的反应之一,高碳烯烃氢甲酰化工艺改进是研究的难点和热点之一。探索了一种C10烯烃氢甲酰化反应的工艺,以三苯基膦（Ph₃P）和亚磷酸三（2-叔丁基-4-甲氧基苯基）酯（L_A）混合物为配体,与乙酰丙酮二羰基铑原位合成的催化体系催化1-癸烯氢甲酰化反应。系统考察了反应温度、反应压力、铑浓度、膦铑比、无机盐添加剂对反应的影响。结果表明,在n（Ph₃P）/n（L_A）=10、铑质量分数为280 mg/kg,1-癸烯用量（相对于甲苯）为0.3 g/mL,n（膦）/n（铑）=45、反应温度为90 ℃、反应压力为2.0 MPa、n（一氧化碳）/n（氢气）=1条件下反应4 h,1-癸烯转化率为98.1%、醛收率为93.2%、正异比为7.5。研究还发现,在减压蒸馏产物与催化剂分离时,加入无机盐添加剂能够提高催化剂的稳定性,减少铑损失。