具有多级孔结构的丝光沸石的合成与性能研究

以表面活性剂十六烷基三甲基溴化铵(CTAB)作为模板剂, 在不添加晶种和有机共溶剂的情况下采用简单的一步水热合成法制备了含有2~4 nm介孔的多级孔纳米丝光沸石。 通过改变 CTAB引入量可以调节所得多级孔丝光沸石样品的外比表面积以及介孔孔容, 最大外比表面积和介孔孔容可分别达到191 m²/g和0.17 cm³/g。均三甲苯在丝光沸石样品上的吸附行为表明, 微孔丝光沸石仅能吸附少量的吸附质, 而多级孔丝光沸石吸附量较大, 并呈现出IV型等温线的特征, 展示出多级孔丝光沸石中介孔的特征。以均三甲苯与苄基氯的苄基化反应来考察多级孔丝光的催化性能。相比于传统微孔丝光沸石, 苄基化反应在多级孔丝光沸石的转化率提高了近7倍, 反应的表观速率常数提高了近19倍。这是由于多级孔丝光沸石较高的外表面积和介孔孔容可以有效地改善大分子反应物的可接近性和产物的传质速率, 从而提高了大分子催化反应的效率。     

以聚乙二醇为模板凝胶转化制备介孔ZSM-5沸石及其催化性能

以聚乙二醇为介孔导向剂, 通过凝胶转化制备了介孔ZSM-5沸石。研究表明, 在TPA⁺/SiO₂=0.1时经过9~15 h溶剂挥发制得的凝胶, 在160℃处理24 h可得到介孔ZSM-5沸石; 挥发时间太短或太长会得到纯的ZSM-5沸石或介孔材料, 说明在凝胶的制备过程中, 通过控制溶剂的挥发程度, 既可为沸石生长过程提供所需的水分, 又能避免沸石晶体形成过程中无定型相的产生, 从而在较低的TPA⁺浓度下获得介孔ZSM-5沸石。与传统的ZSM-5沸石相比, 利用该方法制备的介孔ZSM-5沸石不仅具有微孔/介孔多级孔结构, 同时具有沸石材料较强的酸性、较高的水热稳定性和择形催化性能, 使其在苯甲醛与正丁醇的大分子醇醛缩聚反应中能有效地克服传统沸石孔径限制的缺点, 收率高达42.4%。     

多级孔Co/Al-SiO2催化剂制备及其费-托合成催化性能

多级孔硅铝材料因优异的性能而成为金属催化剂的重要载体。研究采用水热法以硝酸铝为铝源、正硅酸乙酯(TEOS)为硅源合成了Al掺杂SiO₂(Al-SiO₂)的多级孔材料, 然后采用等体积浸渍法负载钴, 制备了具有多级孔结构的 Co/Al-SiO₂催化剂。对Al-SiO₂材料的表征结果表明: 以四丙基氢氧化铵(TPAOH)为结构导向剂, 经80 ℃水热处理可以合成多级孔Al-SiO₂, 呈尺寸在30~40 nm范围的 “蠕虫状”大孔分布形态。将催化剂用于费-托合成反应, 与商业SiO₂负载的钴催化剂相比, Co/Al-SiO₂的CO转化率提高近一倍, CH₄选择性降低19.3wt%, C₂-C₄选择性降低13.3wt%, 汽油段产物(C₅-C₁₂)选择性达到53.3wt%。     

溶胶-凝胶法工艺参数对铜锌锡硫薄膜质量及性能影响研究

以乙酸铜(Cu（CH₃COO）₂·H₂O)、乙酸锌(Zn（CH₃COO）₂·H₂O)、氯化亚锡（SnCl₂·2H₂O）、硫脲（CH₄N₂S）为原料,按一定配比制得前驱体溶液,以三乙醇胺(C₆H₁₅NO₃)、乙醇胺（C₂H₇NO）为稳定剂采用溶胶-凝胶法旋涂制备铜锌锡硫（Cu₂ZnSnS₄）薄膜。通过扫描电镜（SEM）、X射线衍射仪（XRD）、X射线能谱分析（EDS）、紫外-可见-近红外分光光度计表征手段对薄膜的表面形貌、物相结构、成分组成和光学性能等进行分析。研究烧结温度、旋涂转速、稳定剂加入等工艺参数对铜锌锡硫（CZTS）薄膜的形貌、物相结构及光学性能的影响规律。结果表明,前驱体溶液浓度为0.2 mol/L,旋涂速度...     

几种改性剂对稻草纤维/ABS复合材料挥发性有机化合物释放的影响

以稻草纤维及丙烯腈-丁二烯-苯乙烯（ABS）为原料,分别以活性炭、Al₂O₃、SiO₂为改性剂,通过混炼-模压工艺制备了稻草纤维/ABS复合材料,采用热重-质谱联用仪对复合材料的挥发性有机化合物（VOC）释放情况进行对比分析,探讨了几种改性剂对稻草纤维/ABS复合材料VOC释放的影响。研究发现:ABS及稻草纤维均能在热解过程中释放CH₂O、C₂H₄O及C₃H₄O,而C₆H₆、C₇H₈、C₈H₈等苯类及烷烃类物质的释放源则主要为ABS;活性炭的添加能够显著降低稻草纤维/ABS复合材料的VOC释放,其VOC释放总量降低了55.5%;Al₂O₃和SiO₂虽然能比较明显地降低复合材料中苯类物质的释放含量,分别降低了32.4%和30.9%,但是其中的Fe、Cu等金属杂质却能够催化醛类物质的产生,导致VOC释放总量分别增加了11.8%和235.7%。      

Pd纳米颗粒协同氧空位增强TiO2光催化CO2还原性能

针对TiO₂表面活性位点不足、反应动力学缓慢、CO₂还原产物中碳氢化合物的产率低以及选择性差等问题,研究通过Pd催化氧还原法在缺氧环境中构筑了具有表面氧空位的一维单晶TiO₂纳米带阵列(Pd-Ov-TNB)。通过形貌结构、载流子行为及光催化性能分析,探究了表面氧空位和Pd的氢溢流效应对光生载流子分离传输及还原产物选择性的影响。结果表明,Pd-Ov-TNB的CO₂还原活性强,产物中CH₄、C₂H₆和C₂H₄的产率分别为40.8、32.09和3.09μmol·g^-1·h^-1,碳氢化合物的选择性高达84.52%,在C-C偶联方面展现出巨大的潜力。其一维单晶纳米带结构提高了材料的活性比表面积和结晶度,为CO₂还原反应提供了更多的活性位点,并加速载流子的分离传输。同时,氧空位增强了光生电荷的表面积累,为CO₂还原提...     

多级孔沸石的孔结构调控合成及其催化应用研究进展

沸石由于特殊的离子交换性, 丰富的酸性位以及较高的水热稳定性, 被广泛地应用于工业催化和分离吸附等领域。但是由于其较小的微孔尺寸(< 1.5 nm), 在一些大分子参与的催化反应中受到极大的限制。多级孔沸石在保留传统沸石晶化骨架、酸性位以及高水热稳定性的同时引入了多级孔结构, 可极大改善分子的扩散和传质, 减少积碳, 延长催化剂的使用寿命, 使其在催化领域获得更为广泛的应用。本文系统综述了多级孔沸石在孔结构调控方面的研究进展, 着重介绍了无序介孔/大孔结构的多级孔沸石、有序介孔结构的多级孔沸石、取向排列的双介孔结构多级孔沸石、空心结构的多级孔沸石、集大孔-介孔-微孔为一体的多级孔沸石等的合成策略与机理以及结构表征。概述了多级孔沸石在催化领域中的应用进展; 通过与传统沸石和无定型介孔材料的对比, 这种新型的多级孔沸石展现出独特的优势。最后, 对未来多级孔沸石的发展与应用潜力进行了展望。     

掺磷非晶氧化钛负载铂用于高效催化氧化挥发性有机化合物（英文）

高活性催化剂是挥发性有机化合物(VOCs)催化氧化消除的关键因素。本研究通过简单的共沉淀法成功制备了具有高比表面积的非晶介孔磷掺杂氧化钛负载铂催化剂(Pt/ATO-P)。通过P掺杂,既可获得非晶介孔结构,又可获得高ATO-P比表面积(可达278.9m²·g^-1)。非晶介孔Pt/ATO-P催化剂显示出优异的VOCs催化氧化性能和良好的热稳定性。Pt/ATO-P样品在空速为36000m L·h^-1·g^-1、甲苯浓度为10000m L·m^-3的反应条件下,对甲苯催化氧化的T₅₀和T₉₀(实现50%和90%转化率所需的温度)分别为130℃和140℃,明显优于无磷催化剂Pt/TiO₂。这些发现可以为拓展非晶介孔磷化材料在环境净化和能源转化等领域的应用提供重要参考。     

掺磷非晶氧化钛负载铂用于高效催化氧化挥发性有机化合物

高活性催化剂是挥发性有机化合物(VOCs)催化氧化消除的关键因素。本研究通过简单的共沉淀法成功制备了具有高比表面积的非晶介孔磷掺杂氧化钛负载铂催化剂(Pt/ATO-P)。通过P掺杂, 既可获得非晶介孔结构, 又可获得高ATO-P比表面积(可达278.9 m²·g^-1)。非晶介孔Pt/ATO-P催化剂显示出优异的VOCs催化氧化性能和良好的热稳定性。Pt/ATO-P样品在空速为36000 mL·h^-1·g^-1、甲苯浓度为10000 mL·m^-3的反应条件下, 对甲苯催化氧化的T₅₀和T₉₀(实现50%和90%转化率所需的温度)分别为130 ℃和140 ℃, 明显优于无磷催化剂Pt/TiO₂。这些发现可以为拓展非晶介孔磷化材料在环境净化和能源转化等领域的应用提供重要参考。     

A chemically stable nanoporous coordination polymer with fixed and free Cu2+ ions for boosted C2H2/CO2 separation

Safely and highly selective acetylene(C₂H₂)capture is a great challenge,because of its highly explosive nature,as well as its nearly similar molecule size and boiling point toward the main impurity of carbon dioxide(CO₂).Adsorption separation has shown a promising future.Herein,a new nanoporous coordination polymer(PCP)adsorbent with fixed and free Cu ions(termed NTU-66-Cu)was prepared through post-synthetic approach via cation exchanging from the pristine NTU-66,an anionic framework with new 3,4,6-c topology and two kinds of cages.The NTU-66-Cu shows significantly improved C₂H₂/CO₂selectivity from 6 to 32(v/v:1/1)or 4 to 4₂(v/v:1/4)at low pressure under 298 K,along with enhanced C₂H₂capacity(from 89.22to 111.53 cm³·g^-1).More importantly,this observation was further validated by density functional theory(DFT)calculations and breakthrough experiments under continuous and dynamic conditions.Further,the excellent chemical stability enables this adsorbent to achieve recycle C₂H₂/CO₂separation without loss of C₂H₂capacity.     

具有固-液转变的磁性Fe3O4纳米流体的制备、结构及性能

Fe3O4纳米粒子与离子型改性剂N,N-二癸基-N-甲基-N-三甲氧基硅正丙基氯化铵进行接枝反应,再采用反离子脂肪醇聚氧乙烯醚磺酸盐的长链阴离子交换Cl-,在Fe3O4纳米粒子表面得到具有阴、阳离子双电层结构的表面处理层,制备出了无溶剂Fe3O4纳米流体。分析结果表明,表面处理鏖已成功地接枝在Fe3O4纳米粒子表面,改...     

Raman Spectroscopy of the Charge Transfer Complex (TTF)x C60 Br8

We report Raman studies on powder samples of the charge transfer complex (TTF)_x C₆₀Br₈ at room temperature. The phonons show considerable softening with respect to the frequencies observed in the Raman spectrum of solid C₆₀ Brg. The strongest mode at 1464 cm^-1 in C₆₀Br₈ is red shifted to a doublet with peaks at 1414 and 1421 cm^-1, implying an average phonon softening Δω of -47 cm^-1. A comparison with the phonon softening of the corresponding A_g(2) mode in alkali-doped C₆₀ (Δω ~ - 36 cm^-1 for A₆C₆₀, A = K, Rb or Cs) suggests that 8 electrons are transferred per C₆₀Br₈ molecule in the charge transfer complex. The mode at 503 cm_--1 in C₆₀Br₈ is shifted upwards, similar to that in A₆ C₆₀ compounds.     

Bromination of [60]Fullerene. II. Crystal and Molecular Structure of [60]Fullerene Bromides, C60Br6, C60Br8, and C60Br24

The crystal and molecular structures of the bromofullerene solvates C₆₀Br₆·0.5C₆H₅Cl·0.5Br₂, C₆₀Br₈·1.5(o-C₆H₄Cl₂), C₆₀Br₈·Br₂, C₆₀Br₈·0.5C₆H₅Br·0.5Br₂, and C₆₀Br₂₄·2Br₂ have been determined by single crystal X-ray diffraction. The molecular species C₆₀Br₆, C₆₀Br₈, and C₆₀Br₂₄ which have idealized C_s, C_2v , and T_h symmetries, respectively, have several different types of C-Br and C-C bonds. A comparison between different solvates of the same bromofullerenes revealed a larger stability of the packing modes for the C₆₀Br₆ and C₆₀Br₂₄ solvates, whereas the C₆₀Br₈ solvates showed different packing motifs dependent on the nature and amount of the solvent molecules.     

INCORPORATED C70 IN SOL AND GEL

C₇₀ is incorporated in gel by a sol-gel process with using 3-amino-propyltriethoxysilane (NH₂(CH₂)₃Si(OC₂H₅)₃, APTS) and 3-glycidoxypropltrimethoxysilane (CH₂OCHCH₂O(CH₂)₃Si(OCH₃)₃, GPTMS) as precursors. C₇₀ is firstly mixed with APTS to form C₇₀-NH₂(CH₂)₃Si(OC₂H₅)₃ compound by the reaction between C₇₀ and amino-group of APTS, and then the compound is hybridized with GPTMS to form solid gel. The linkage of C₇₀ and APTS is estimated and confirmed with FT-IR spectra, and the UV/Visible spectra of the sol and gel are measured.     

Arylation of [60]Fullerene with Br2/FeCl3/PhH: Formation of C58 Derivatives via CO Loss

Heating a mixture of [60]fullerene, bromine, ferric chloride and benzene under reflux for 24 h products a range of phenylated [60]fullerene derivatives. The main product is C₆₀Ph₅H but other components identified by mass spectrometry (and in some cases separated by HPLC) are: C_6oPh_n(n = 4, 6, 8, 10, 12), C₆₀Ph_nO₂(n = 4, 6, 8, 10, 12), C₆₀Ph_nOH (n = 7, 9, 11), C₆₀Ph_nH₂ (n = 4, 10), C₆₀Ph₄H₄, C₆₀Ph₅H₃, C₆₀Ph_n0₂H (n = 5, 9), C₆₀Ph₄C₆H₄O₂, C₆₀Ph₉OH₃, and C₆₀Ph₁₁ O₃H₂. In the corresponding reaction with toluene, the crude reaction mixture contained C₆₀(MeC₆H₄)₄ as a main product; C₆₀(ClC₆H₄)₅H was obtained from the reaction with chlorobenzene. Formation of these derivatives is believed to involve radical bromination of the fullerene, followed by electrophilic substitution of the hatogenofullerene into the aromatic, accompanied in some case by hydrolysis, elimination and epoxide formation; oxidation may also introduce ketone/dioxetane functionality. The EI mass spectra of C₆₀Ph₄O₂ and C₆₀Ph₈O₂show degradation to C₅₈Ph_n (n = 0-8), having structures believed to be related to the pseudofollerenes C₆₈Ph_n (n = 0-8) reported recently. These results suggest that some derivatisations of fullerenes confer stability, due to the relief of strain.     

Evidence for η6 Coordination to a Fullerene

Evidence for the first η⁶ derivative of a fullerene, [MoC₆₀F₁₈(CO)₃] has been obtained from reaction between [Mo(CH₃CN)₃(CO)₃] and C₆₀F₁₈.     

Optical Spectra of C60 Complexes At High Pressures

A new absorption band assigned to C₆₀^- was observed around 1000 nm in the electronic spectra of (BEDT-TTF)₂C₆₀ and (ferrocene)₂C₆₀ at high pressures. The result suggests an increase in the ionicity of the complexes with increasing pressure.     

ISOLATION AND CHARACTERISATION OF C60(CF3)2

From the products of reactions of [60]fullerene with either K₂PtF₆ at 470 °C or AgF at 520 °C, we have isolated C₆₀(CF₃)₂, the simplest trifluoromethylfullerene, which gives a single ¹⁹F NMR line at -69.5 ppm. The HPLC retention time is less than that of C₆₀F₂ confirming the trend observed for other fluoro- vs. trifluoromethylfullerenes namely that the latter elute more rapidly. Other trifluoromethyl- containing species, C₆₀(CF₃)₄O, C₆₀F₅CF₃, C₆₀(CF₃)₄H₂, C₆₀(CF₃)₆H₂, and C₆₀(CF₃H)₃ were detected in the product mixture.     

Burning velocity measurements of nitrogen-containing compounds

Burning velocity measurements of nitrogen-containing compounds, i.e., ammonia (NH₃), methylamine (CH₃NH₂), ethylamine (C₂H₅NH₂), and propylamine (C₃H₇NH₂), were carried out to assess the flammability of potential natural refrigerants. The spherical-vessel (SV) method was used to measure the burning velocity over a wide range of sample and air concentrations. In addition, flame propagation was directly observed by the schlieren photography method, which showed that the spherical flame model was applicable to flames with a burning velocity higher than approximately 5 cm s⁻¹. For CH₃NH₂, the nozzle burner method was also used to confirm the validity of the results obtained by closed vessel methods. We obtained maximum burning velocities (S_u0,max) of 7.2, 24.7, 26.9, and 28.3 cm s⁻¹ for NH₃, CH₃NH₂, C₂H₅NH₂, and C₃H₇NH₂, respectively. It was noted that the burning velocities of NH₃ and CH₃NH₂ were as high as those of the typical hydrofluorocarbon refrigerants difluoromethane (HFC-32, S_u0,max = 6.7 cm s⁻¹) and 1,1-difluoroethane (HFC-152a, S_u0,max = 23.6 cm s⁻¹), respectively. The burning velocities were compared with those of the parent alkanes, and it was found that introducing an NH₂ group into hydrocarbon molecules decreases their burning velocity.     

Excitons in self-organized layered perovskite films prepared by the two-step growth process

Thin films of microcrystalline (C₈H₁₇NH₃)₂PbBr₄ were prepared by a two-step growth process as follows: (1) deposition of PbBr₂ films on substrates and (2) self-organized growth of layered perovskite compounds by exposing the PbBr₂ film to C₈H₁₇NH₃Br vapor in a vacuum chamber. As-synthesized (C₈H₁₇NH₃)₂PbBr₄ films were characterized by using X-ray diffraction, temperature dependence in optical absorption and photoluminescence spectra. (C₈H₁₇NH₃)₂PbBr₄ films created by this synthesis approach were found to microcrystalline form, single phase and highly oriented with a c-axis perpendicular to the substrate surface. (C₈H₁₇NH₃)₂PbBr₄ films showed clear exciton absorption and photoluminescence even at room temperature in the near-ultraviolet region. Exciton binding energy of (C₈H₁₇NH₃)₂PbBr₄ was estimated about 200 meV.