Li＋交换的几种分子筛的氮氩分离性能

采用水溶液离子交换法制备了高Li＋交换度的4A、13X和LSX分子筛,并在25 ℃下测定了它们的静态吸附等温线和动态穿透曲线.研究发现,高Li＋离子交换度的4A、13X和LSX分子筛都具有较大的氮吸附容量和较高的氮氩分离选择性,说明高Li＋离子交换度的4A、13X和LSX分子筛是较好的氮氩分离吸附剂.从动态穿透曲线结果来看,所研究的三种分子筛都有一个最优的吸附分离压力,在本文研究的压力范围内,这个最优压力在0.6 MPa附近.对比高锂交换度的三种分子筛,以高锂交换度的LSX分子筛的氮氩吸附分离性能最好.     

不同分子筛的氮氩分离性能

采用水溶液离子交换法制备了不同离子交换的13X和4A分子筛,并在25℃下测 定了它们的静态吸附等温线和动态穿透曲线。研究发现,Ca~(2+)离子和Li~+离子 交换的13X和4A分子筛对氮的吸附性能都明显优于其相应的钠型分子筛,而它们对 氩的吸附量变化不大,说明这两种离子交换的分子筛是较好的氮氩分离吸附剂。从 动态吸附的结果来看,所研究的各种分子筛都有一个最优的吸附分离压力,在本论 文研究的压力范围内,这个最优压力在0.6MPa附近。通过穿透曲线推算出的混合气 体吸附量和纯气体吸附量的对比可以得出,对于氮氩吸附选择性较高的分子筛,氮 的存在对氩的吸附量有较大的影响。     

Ca2+交换的几种分子筛的氮氩分离性能

采用水溶液离子交换法制备了Ca2+交换的4A,13X和LSX分子筛,并在25 ℃下测定了它们的静态吸附等温线和动态穿透曲线.研究发现, Ca2+交换的4A,13X和LSX分子筛对氮的吸附性能都明显优于其相应的钠型分子筛,而它们对氩的吸附量变化不大,说明Ca2+交换的这三种分子筛是较好的氮氩分离吸附剂.从动态吸附的结果来看,所研究的各种分子筛都有一个最优的吸附分离压力,在本论文研究的压力范围内,这个最优压力在0.6 MPa附近.由穿透曲线可推算出混合气体的吸附量,通过氮和氩在混合气体中的吸附量和相应纯气体吸附量的对比可以得出,对于氮氩吸附选择性较高的分子筛,氮的存在对氩的吸附量有较大的影响.     

Ca2＋交换的几种分子筛的氮氩分离性能

采用水溶液离子交换法制备了Ca2＋交换的4A、13X和LSX分子筛，并在25 ℃下测定了它们的静态吸附等温线和动态穿透曲线.研究发现， Ca2＋交换的4A、13X和LSX分子筛对氮的吸附性能都明显优于其相应的钠型分子筛，而它们对氩的吸附量变化不大，说明Ca2＋交换的这三种分子筛是较好的氮氩分离吸附剂.从动态吸附的结果来看，所研究的各种分子筛都有一个最优的吸附分离压力，在本论文研究的压力范围内，这个最优压力在0.6 MPa附近.由穿透曲线可推算出混合气体的吸附量，通过氮和氩在混合气体中的吸附量和相应纯气体吸附量的对比可以得出，对于氮氩吸附选择性较高的分子筛，氮的存在对氩的吸附量有较大的影响.     

几种二价阳离子的交换对13X分子筛氮氩分离性能的影响

采用水溶液离子交换法分别制备了不同二价阳离子(Mg²⁺、Zn²⁺和Ca²⁺)交换的13X型分子筛，并在25 ℃下测定了各分子筛吸附剂的氮和氩的吸附等温线。研究发现，13X分子筛经Mg²⁺和Zn²⁺交换后，吸附剂的吸氮能力及氮氩分离能力降低；13X分子筛经Ca²⁺交换后，吸附剂的吸氮能力及氮氩分离能力随分子筛中钙离子交换度的增加而增大。对常压氮氩分离性能较好的CaNaX系列分子     

离子交换法分离乳酸

本文在对多种吸附剂和离子交换树脂进行筛选的基础上，获得了一种对乳酸具有优良吸附性能的弱碱型离子交换树脂，测定了乳酸在该树脂上的离子交换平衡数据，建立了数学模型，研究了其它无机盐的存在对离子交换平衡的影响，同时测量了乳酸在该树脂上的交换速率和穿透曲线．上述研究对于乳酸分离，特别是从稀溶液中分离乳酸提供了一种新的方法，对其它有机酸的分离也具有参考意义．     

氮、氩在5分子筛上的低温吸附分离

测定了不同温度下氮、氩在5分子筛上的吸附等温线,其中三参数的Langmuir-Freundlich方程和Toth方程在不同温度下都能获得较好的拟合结果;计算了不同温度下氮、氩在5分子筛上吸附的亨利常数,获得了氮、氩选择性和温度的关系。测定了125K温度下氮、氩混合气体在5分子筛吸附柱上的穿透曲线。结果表明:最先流出的5L气体中含有约70%的氩,通过收集5L气体即可实现混合气体中氩的初步分离。     

氮、氩在5A^。分子筛上的低温吸附分离

测定了不同温度下氮、氩在5分子筛上的吸附等温线,其中三参数的Langmuir-Freundlich方程和Toth方程在不同温度下都能获得较好的拟合结果;计算了不同温度下氮、氩在5分子筛上吸附的亨利常数,获得了氮、氩选择性和温度的关系.测定了125K温度下氮、氩混合气体在5分子筛吸附柱上的穿透曲线.结果表明:最先流出的5L气体中含有约70%的氩,通过收集5L气体即可实现混合气体中氩的初步分离.     

离子改性Y沸石吸附脱除二氧化碳中的乙醛

对比了纳米ZSM-5分子筛,5A分子筛,NaY分子筛,活性炭对二氧化碳中乙醛气体的吸附穿透性能,其中NaY穿透时间最长,与其较强的孔内极性和孔径大小有关。采用碱金属及碱土金属离子交换Y分子筛阳离子的方法改变其静电场强度,同时运用XRF、ICP手段对阳离子交换的Y分子筛进行了表征。结果表明,MgY的静电场最强,其乙醛穿透吸附量最大;程序升温脱附和再生实验表明,在150℃时,氮气吹扫4次再生后,MgY的乙醛穿透吸附量保持在550mg/g以上。     

Cu(Ⅰ)NH4Y吸附剂的制备及其乙烯/乙烷吸附分离性能

本研究采用液相离子交换法,用不同浓度的CuCl2对NH₄Y分子筛进行离子交换制得系列CuNH₄Y-x分子筛吸附剂,并通过固定床吸附穿透实验及一系列表征手段探究了Cu的价态和负载量对乙烯/乙烷吸附分离性能的影响。吸附穿透实验结果表明,Cu(Ⅰ)NH₄Y0.10的乙烯吸附量明显高于Cu(Ⅱ)NH₄Y0.10,且Cu(Ⅰ)NH₄Y系列吸附剂的乙烯吸附量随着Cu负载量的增加呈现先增加后减小的趋势。H₂-TPR和HRTEM表明,当Cu的负载量较低时,高度分散落位于Y分子筛超笼中的Cu(Ⅰ)物种是乙烯有效吸附位点。然而,当Cu的负载量较高时,部分Cu物种发生团聚,造成对乙烯吸附能力的减弱。DFT密度泛函理论计算表明相比于Cu(Ⅱ)NH₄Y吸附剂,乙烯更容易吸附在Cu(Ⅰ)NH₄Y吸附剂上。该研究结果可为乙烯分离用高效Cu离子改性分子筛吸附剂的开发提供重要理论依据与指导。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.