温拌沥青混合料的技术与应用分析

温拌沥青混合料是正在研发推广的新型路用材料,分析了添加沸石、采用两阶段生产的温拌沥青混合料泡沫添加功能性改性剂三种生产温拌沥青混合料的生产技术与应用情况,结果表明这种材料和技术的应用对降低公路建设的能源消耗和环境污染、改善建设人员的工作环境有一定作用,并能提高生产效率。     

The disordered structure of silica zeolite EU-20b, obtained by topotactic condensation of the piperazinium containing layer silicate EU-19

Zeolite EU-20b was prepared by heating the piperazinium containing layer silicate EU-19 in air at 1000 °C. The microporous silica framework of EU-20b forms by topotactic condensation of the silicate layers of the crystalline precursor EU-19. According to the observed diffraction data, the EU-20b structure is closely related to the (orthorhombic) CAS zeolite framework type. However, the diffraction pattern revealed structural disorder of the material as indicated by the presence of sharp and broad reflections. In spite of the disorder, the XRD pattern of EU-20b can unambiguously be indexed based on a C-centered orthorhombic unit cell with lattice parameters a₀ = 13.817(4) Å, b₀ = 4.995(1) Å, c₀ = 16.637 (5) Å. The program DIFFaX was used to simulate diffraction diagrams of various stacking disordered silica-materials made up by layer-like building units. The best fit between simulated and observed patterns was obtained for a probability of about 88% CAS-type stacking and 12% NSI-type stacking. EU-20b is a small pore zeolite characterized by a one-dimensional pore system consisting of straight and non-intersecting 8-ring channels and has a very high framework density of ≈20.8 T/1000 Å³. Although the pore volume of EU-20b is free of organic pore fillers due to the heating process at 1000 °C, nitrogen sorption experiments showed that there is no “free” access to the pore volume. Two effects might block access to the pores: According to ²⁹Si MAS NMR spectroscopy a few defects are probably present caused by incomplete or random condensation of the silanol groups and the elliptical pores are very small in one direction (2.3–2.5 Å) compared to N₂ (kinetic diameter 3.64 Å). Thus, EU-20b is formally porous by topology, but apparently non-porous to N₂.     

Analysis of transient permeation fluxes into and out of membranes for adsorption measurements

A relationship between the integrated fluxes into and out of a membrane following a positive or negative step change in feed concentration was derived. This analysis allows adsorption isotherms in the transport pathways through membranes to be determined from transient permeation responses to step concentration changes in the feed without measuring the retentate response. For Fickian diffusion through a membrane with Langmuir adsorption and zero coverage at the permeate boundary, the difference between the time-integrated flux into and flux out of the membrane is shown to be three times the time-integrated difference between the steady-state flux and the flux out. For Maxwell-Stefan diffusion, this ratio of integrated flux differences is 3 at low coverages and decreases towards 2 at saturation coverage. Mass transfer resistance at the permeate boundary increases the Fickian ratio above 3, and the ratio increases with decreasing Sherwood number. The ratio of integrated flux differences is shown to be identical to the steady-state replenishment time divided by the time lag. Thus, the ratio can be calculated directly from the steady-state concentration profile and the concentration-dependent diffusion coefficient. Surface diffusion through zeolite membranes was analyzed to demonstrate the calculation of the flux relationship for specific adsorption and diffusion models, but the method developed can be applied to membrane permeation in general.     

Spectral Characteristic and Its Regularity of Rare Earth Ions in Inorganic Microporous Material Ⅰ.The Spectral Characteristics of Eu~(3 ) in NaY,NaX and NaA Zeolites

In this paper,we have investigated the spectral characteristics of Eu~(3 )ion sorbed on NaY,NaX and NaAzeolites.During calcination,the influence of Eu~(3 )ion's positions in zeolites on its spectral structures are dis-cussed emphatically.The experimental results show that the electric dipole-to-magnetic dipole transition inten-sity ratios of Eu~(3 )emission in NaY,NaX and NaA zeolites calcinated at the same temperature increase inproper order.The bonding actions between Eu~(3 )ion and framework oxygens are studied by the measurementsof excitation spectra and X-ray photoelectron spectroscopy.In the Eu~(3 )content ranging from 0.95% to10.5%,the concentration quenching of the fluorescence in Eu(Ⅲ)-NaY is not observed.     

乙酸与异戊醇酯化反应中沸石催化剂的改性与优选

以分子筛-HZSM-5(38),HZSM-5(55),USY和REY原粉为原料改性制备了四种催化剂.其中的HZSM-5(55)(在600℃焙烧)和REY(在300～400℃焙烧)对乙酸异戊醇酯化反应有较好的催化活性和稳定性,并讨论了催化剂失活的原因.     

湖北省沼山沸石矿的测定方法及评价指标

本文对湖北省沼山沸石矿进行了研究.在比较沸石阳离于交换容量(CEC)测定方法的基础上,拟定了以吸蓝量法代替四丁基溴化铵(TBAB)法测定沸石净交换量的方法.指出当试样蒙脱石的吸蓝量≤0.25mmol/g 时,本法结果与 TBAB 法的结果一致;对3个沸石样进行10次测定其相对标准偏差为1.3～2.3%.方法具有简便、快速、准确和重复性好等优点.根据湖北省沼山沸石矿的特点对沸石含量的计算方法和评价指标提出了建议。     

以高岭土为原料合成NaA沸石的实验研究

以天然黏土矿物高岭土为原料采用水热晶化法合成NaA沸石。通过XRD、静态饱和水吸附量等测试手段详细考察了初始反应混合物的Na2O／SiO2比和氢氧化钠溶液浓度对NaA沸石结晶度的影响。通过实验研究得到NaA沸石的二元结晶相图及结晶变化规律，并优化工艺参数得到NaA沸石最佳合成条件。     

Semi-indirect synthesis of LPG from syngas: Conversion of DME into LPG

Efficient conversion of dimethyl ether (DME) into liquefied petroleum gas (LPG) with a hybrid catalyst is a novel method for semi-indirect synthesis of LPG fuel from syngas. The hybrid catalysts consisting of zeolite and hydrogenation catalyst were investigated in a fixed bed reactor. Experimental results demonstrated that the hybrid catalyst consisting of (Pd/SiO₂) and USY efficiently converted DME into LPG and restrained decomposition of DME into CO and H₂. With that catalyst, the one through conversion of DME reached about 100%, almost no CO and CO₂ were produced and selectivity for LPG was more than 65%.     

氯苯在HZSM-5分子筛上选择性硝化的研究

研究了以HZSM-5分子筛为催化剂,氯苯-硝基化反应中各反应参数即反应物配比、反应时间、反应温度、催化剂用量以及HZSM-5分子筛硅铝比对p/o的影响。结果使用SiO_2/Al_2O_3为40的HZSM-5分子筛作催化剂可使p/o达到4.60,氯苯转化率21.0％。