不同硅铝比SAPO-44分子筛合成及甲醇制烯烃催化性能研究

以环己胺为模板剂,合成了不同硅铝比的SAPO-44分子筛,分别采用XRD、SEM、NH3-TPD等表征手段对所合成的样品进行了表征,并在固定床上考察了样品的甲醇制烯烃催化性能。结果表明,随着硅铝比的增加,样品的相对结晶度有所增加,表面酸性有增强的趋势,分子筛晶体出现一些非立方晶体物种;同时,初始烯烃选择性随着硅铝比的增加而降低,反应产物中的丙烯/乙烯质量比则呈现升高的趋势。     

基于模糊PI 控制的甲醇催化燃烧系统温度控制策略

为改善甲醇催化燃烧系统中由于温冲效应导致重整室温度达到稳态时间的滞后问题,运用模糊算法对传统的PI控制器进行优化,根据先验知识实时调整P、I参数,并通过Matlab软件仿真计算和设计实验对2种控制策略性能进行比较.仿真计算和实验结果均表明:在升温快速响应阶段,模糊PI控制器较传统PI控制器响应时间更短、速度更快;在稳定阶段,相较传统PI控制器,模糊PI控制器产生的超调量更小,且能更快使系统温度达到稳定状态.由此可见,模糊PI算法能有效提升系统快速性和稳定性,一定程度改善系统滞后的缺点.     

甲醇、戊二醛交联剂对丝素蛋白/明胶多孔支架的性能影响

为了对比甲醇、戊二醛两种交联剂对丝素蛋白/明胶复合多孔支架的性能影响,采用冷冻干燥法等比例制备该支架,分两组分别用甲醇和戊二醛进行交联。通过观察支架的微观形貌,测量支架的孔隙率、吸水率、溶胀率,测试热稳定性及力学性能,比较经两种交联剂处理后支架结构和性能的变化。结果表明,经戊二醛交联后的支架孔隙分布更加规则、均匀,孔隙率、吸水率、溶胀率更高,力学性能更强。采用戊二醛交联丝素蛋白/明胶复合多孔支架,能够使支架性能更加优良。     

γ-Al_2O_3催化尿素法合成二苯甲烷二氨基甲酸甲酯反应研究

首次尝试以二苯甲烷二胺(MDA)、尿素和甲醇为原料直接合成二苯甲烷二氨基甲酸甲酯(MDC),分别考察了催化剂种类和反应条件对MDC合成反应的影响。结果表明:经400℃焙烧2h的γ-Al2O3对该反应具有较高的催化活性。适宜反应条件为:反应温度180℃,反应时间6h,反应初压1.2 MPa,n(MDA)∶n(尿素)∶n(甲醇)∶n(γ-Al2O3)=1∶3∶50∶0.1。在此条件下,MDA的转化率为81.7%,MDC的收率和选择性分别为26.3%和32.2%。采用液相色谱-质谱联用技术对MDC合成反应的反应路径进行了分析,认为促进中间产物4-氨基-4′-氨基甲酸甲酯二苯甲烷(MMC)向MDC转化是提高MDC选择性的关键。     

Effect of particle shape on methanol partial oxidation in a fixed bed using CFD reactor modeling

Particle shape is one of the most important parameters in the design and optimization of fixed-bed processes. To address the impact of particle shape on methanol partial oxidation to formaldehyde over molybdate catalyst, packings of spheres, cylinders, rings, and trilobes are numerically generated. The generated packings are used to carry out resolved particle Computational Fluid Dynamics (CFD) simulations under industrial conditions. Pressure drop, voidage and velocity profiles, radial heat transfer, and local and overall conversion and selectivity results are presented. Despite their lower particle surface area, lower particle effectiveness and more uneven flow distribution than trilobes, and lower overall heat transfer coefficient than cylinders, rings had the best conversion and selectivity due to their balance between the factors. Three longer tubes of rings, rings and cylinders, and rings and trilobes are simulated and show a small gain in selectivity for the rings and trilobes.     

低温甲醇洗系统贫富甲醇换热器泄漏原因分析及处理

介绍了晋煤天溪煤制油分公司低温甲醇洗系统贫富甲醇换热器的泄漏情况。分析了贫富甲醇换热器泄漏初期生产运行指标的异常现象和造成泄漏的原因,认为泄漏是不同物质对设备的腐蚀、冲刷造成的,并针对泄漏的具体情况,提出了不同的检修处理措施:管束泄漏量低于10%时,可采用焊接锲形堵头将泄漏列管两端进行封堵;管束泄漏量高于10%时,如换热器设计余量足,可将封头内部隔板取出,短接进出口;将换热管材质由10#钢换为06Cr19Ni10不锈钢。     

“一锅三步法”合成苯基-2-吡啶基甲醇

以2-苄基吡啶氮氧化物和三氟乙酸酐为原料，通过“一锅三步法”（串联“酰化、[3,3]σ重排和水解”反应）合成了关键药理活性中间体苯基-2-吡啶基甲醇，并对反应条件进行了优化。结果表明：当n（2-苄基吡啶氮氧化物）：n（三氟乙酸酐）=1 : 1.2、N, N-二异丙基乙胺（DIPEA）为碱、甲苯为反应溶剂，室温反应6小时，经硅胶柱层析分离即可得到苯基-2-吡啶基甲醇，收率为81.0%。产物经1H NMR，13C NMR 和HRMS进行结构表征。本文以原子经济学的理念首次实现了由2-苄基吡啶氮氧化物到苯基-2-吡啶基甲醇的直接转化。     

Preparation and characterization of Pt nanoparticles supported on a Fe-doped hydroxyapatite-activated Vulcan XC72 composite material

In this research, the hydroxyapatite (HAp) could be directly deposited on carbon black (CB), which was the modified surface to generate more OH⁻ free radicals to strengthen the bond between HAp and CB, before adding ((NH₄)₂Fe(SO₄)₂·6H₂O) to engage the ion exchange with Fe²⁺ and Ca²⁺ to obtain FeHAp-CB composites. The Pt nanoparticles were then reduced on the FeHAp-CB composite surface to derive a Pt/FeHAp-CB catalyst of dual function. The catalyst revealed a steep desorption peak at −0.180 V (vs Ag/AgCl) in a hydrogen oxidation reaction ascribed to the characteristics of Pt (110) facet and the CO detoxication function in the methanol oxidation reaction. The superior performance of Pt/FeHAp-CB/CB catalyst was apparently related to the Pt (110) surface, the Fe concentration, and the homogeneous dispersion of Pt particles on the FeHAp-CB composites. And, the ratio of coexisting Pt⁰ and Pt²⁺ within Pt/FeHAp-CB/CB catalyst would definitely affect chemical stability and mass activity. By X-ray photoelectron spectroscopy (XPS), it was found that a high quantity of Pt⁰ could improve mass activity, while a high quantity of Pt²⁺ contributed to chemical stability.     

Methanol and proton transport through chitosan-phosphotungstic acid membranes for direct methanol fuel cell

Composite chitosan-phosphotungstic acid membranes were synthesized by ionotropic gelation. Their liquid uptake is higher for thin membranes (23 ± 2 μm), while it is lower (~70%) for thicker membranes (50-70 μm). Polarization curves recorded using single module fuel cell at 70°C allowed to estimate a peak power density of 60 mW cm⁻² by using 1 M as methanol and low Pt and Pt/Ru loadings (0.5 and 3 mg cm⁻²) at the cathode and at the anode, respectively. Electrochemical impedance spectroscopy was used to estimate the membrane conductivity and to model the electrochemical behavior of methanol electrooxidation inside the fuel cell revealing a two-step mechanism mainly responsible of overall kinetic losses. Transport of methanol inside the membrane was studied by potentiostatic measurements, allowing to estimate a methanol diffusivity of 3.6 × 10⁻⁶ cm² s⁻¹.