Fe-Mn催化剂的FTO性能研究

采用低温(-10℃)共沉淀技术制备Fe-Mn催化剂,研究Mn助剂对合成气直接制低碳烯烃(FTO)反应的影响。考察了不同Mn摩尔分数对催化剂的结构和性能的影响,结果表明,添加的Mn具有显著的几何分散效应和电子效应。构效关系研究发现,催化活性与催化剂的H_2吸附量有关,而与催化剂比表面积和Fe-Mn间相互作用关系不大,其中添加摩尔分数20%的Mn可以使Fe基催化剂表面形成最多的吸附活性位,转换频率(TOF)为5. 7×10~(-3)s~(-1)。     

Mn2CuCe0.2-SiC整体式催化剂的制备、表征及其催化降解VOCs的中试应用

利用蜂窝碳化硅为催化剂载体,采用浸渍法制备了Mn2 CuCe0.2-SiC整体式催化剂.通过扫描电镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)和X射线光电子能谱(XPS)对催化剂的表面结构和组成进行了表征分析,并初步研究了在中试条件下整体式催化剂对VOCs的催化降解效果.研究表明,通过浸渍法制备的Mn2 CuCe0.2-SiC整体式催化剂主要活性成份为Cu1.5 Mn1.5 O4、CeO2、CuO和Mn3 O4;用于催化降解浓度在15～80 ppm范围内的甲苯,VOCs转化率为90％时的反应温度T90为300℃.     

超细粒子Fe-Mn工业催化剂F-T合成集总机理动力学(Ⅰ)反应机理与动力学模型描述式

为获得超细粒子Fe-Mn工业催化剂在F-T合成中CO转化的动力学模型描述式,为其工业放大过程中反应器设计提供依据,将F-T合成这样一个包括数百个反应的体系集总为F-T烃生成反应和水煤气转换（WGS）反应.这样,反应物CO的转化速率可近似地用烃生成速率与CO₂生成速率之和来表示.在碳化物机理基础上建立烃生成基元反应步骤,以决定烃“结构单元”CH^*₂生成的步骤为速控步骤建立动力学模型.同时,在甲酸盐机理基础上建立CO₂生成的基元反应步骤,以甲酸盐物种的生成步骤为速控步骤建立动力学模型.将二者组合,获得同时包括F-T烃生成反应和WGS反应的F-T合成集总动力学模型.     

天然硼矿石负载铁锰氧化物的合成及应用研究

采用溶胶凝胶法制备天然硼矿石负载Fe-Mn氧化物的Fe-Mn-B复合纳米微孔催化剂，通过X射线衍射(XRD)、扫描电镜(SEM)及能谱对催化剂的物相结构进行表征；并考察该复合纳米催化剂作为非均相芬顿催化剂深度处理丁腈橡胶废水的性能。结果表明，在初始pH值5,双氧水加药量0.8 mL/L,催化剂加药量5 g/L,反应时间30 min后，处理液COD值小于70 mg/L,COD去除率69.7%,出水指标满足GB 27632—2011《橡胶制品工业污染物排放标准》的直接排放标准。     

一步法制备FeMn@GC催化剂用于费-托合成制低碳烯烃

为了研究锰元素添加对Fe@GC催化剂在费-托合成制低碳烯烃中作用机制的影响,利用均相熔融法一步制备了Fe@GC催化剂和FeMn@GC催化剂.采用了X射线衍射(XRD)、透射电镜(TEM)、扫描电镜(SEM)、X射线光电子能谱(XPS)、N2物理吸附等方法对催化剂结构进行了表征,并在固定床反应器上考察了Mn的加入对费-托...     

Pd-Co/Hopcalite混合氧化物催化苯酚氧化羰基化合成碳酸二苯酯的研究

以Hopcalite氧化物作为载体,浸渍后得到Pd-Co/Hopcalite混合氧化物负载型催化剂,用于氧化羰基化合成碳酸二苯酯(DPC)。通过扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对催化剂进行表征,结果表明:催化剂颗粒大小均匀,具有良好的孔结构;稳定晶相Cu Mn2O4、Co Mn2O4和Pd0.5Pd3O4的形成使反应前后催化剂表面活性组分Mn、Co的价态保持不变,有利于催化剂的重复使用;Pd0.5Pd3O4产生晶格缺陷,增加了晶格中的氧空位,可促进气相氧的吸附,加速整个催化循环,有利于活性组分再生,催化活性进一步提高。通过合成实验,DPC收率和选择性分别达到43.5%和99.6%。     

Ce-Mn/ZSM-5催化剂的制备及其低温脱硝性能分析

采用浸渍法制备了不同Ce与Mn质量比的Ce-Mn/ZSM-5催化剂,并研究其理化特性和NH_3-SCR反应的低温脱硝性能。借助X射线衍射、扫描电镜、N_2吸附/脱附、X射线光电子能谱和电感耦合等离子体光谱等手段对催化剂表征分析表明,活性组分分散良好,且主要分布在催化剂表面,其中Mn以其多种氧化物形态存在,Ce多以Ce~(3+)的形式存在。脱硝性能测试表明,Ce的质量分数影响催化剂脱硝性能,当Ce与Mn质量比为0.4时,Ce-Mn/ZSM-5催化活性最佳,在100~300℃之内,脱硝效率一直保持在90%以上。适量Ce的引入增加了催化剂表面吸附氧含量,促使低温下反应加速进行。     

MnO2/γ-Al2O3催化尿素与1,2-丙二醇合成碳酸丙烯酯

以γ-Al2O3为载体,采用超声浸渍法制备了MnO2/γ-Al2O3催化剂,结合X射线衍射、X射线光电子能谱和CO2程序升温脱附的表征,考察了催化剂对尿素与1,2-丙二醇合成碳酸丙烯酯反应的影响。结果表明,以Mn(NO3)2为锰源经焙烧后形成的MnO2表面碱性最强,对尿素醇解反应的活性最高;采用超声浸渍法,当Mn在γ-Al2O3上的负载量(质量分数,下同)为30%时,Mn在γ-Al2O3表面主要以Mn4+的形式存在,且分散度高,催化剂表面的碱中心的碱性最强。当其催化尿素醇解时,碳酸丙烯酯收率达65.0%。     

2-甲基吡啶的合成工艺研究

以Fe-Mn/ZSM-5分子筛为催化剂,固定床为反应器,采用吡啶与甲醇合成2-甲基吡啶.系统地考查了Fe含量、Mn含量、催化剂用量、原材料摩尔比、反应温度对2-甲基吡啶吸收率的影响,筛选出合适的反应条件.反应的最优条件为Fe含量1.2％,Mn含量0.8％,反应温度350℃,催化剂用量5％,吡啶∶甲醇=1∶1.3,此时2-甲基吡啶的收率达93％以上.该工艺操作简单,安全性高,收率高,适合工业化生产.     

MnO超微粒子的制备及其对PEMFC电催化性能的研究

用微乳液法合成了 Mn O超微粒子 ,探讨了影响萃取率及粒度的因素 ,得到了最佳反应条件 ,并用透射电子显微镜 (TEM)、X射线衍射仪 (XRD)及红外光谱 (FTIR)进行了表征。得到了粒径为 5 nm左右的 Mn O超微粒子 ,并在质子交换膜燃料电池 (PEMFC)的铂电极中加入 5 nm的Mn O超微粒子作为催化剂 ,改变了电池的放电机理 ,提高了输出电压。为 PEMFC的商品化进行了有价值的探索。     

Fischer–Tropsch synthesis with promoted iron catalyst: Reaction pathways for acetic acid, glycol, 2-ethoxyethanol and 1,2-diethoxyethane

Reaction pathways for oxygenates, acetic acid, ethylene glycol (EG), 2-ethoxyethanol (2-EE) and 1,2-diethoxyethane (1,2-DEE) added during Fischer–Tropsch synthesis (FTS) over a doubly promoted fused iron catalysts were studied. The addition of acetic acid, EG and 2-EE affected only slightly the CO conversion but resulted in a significant reduction in H₂ conversion while addition of 1,2-DEE results in slight increase in both H₂ and CO conversion. Addition of these oxygenates caused a large decrease in the alkene ratio for C₂ hydrocarbons as compared to an increase for the C₃ and C₄ hydrocarbons suggesting a direct formation pathway of ethane from added oxygenate molecules. The 1-alkene/2-alkene fraction was found to increase significantly when these oxygenates were added and then return to the original value once the addition is terminated, indicating inhibition of secondary reactions of 1-alkene by added oxygenates. Added acetic acid reversibly increased the CO₂ production rate while EG, 2-EE and 1,2-DEE reversibly decreased the CO₂ selectivity. Addition of these oxygenates reduced the production rate of methane. Addition of acetic acid and 1,2-DEE decreased methanol selectivity significantly while added EG results in a significant increase in methanol production. In the case of 2-EE addition, methanol selectivity was nearly constant. Reaction of acetic acid during FTS was found to produce products such as ethyl butanoate, ethylene glycol and its ether, 1,2-diethoxyethane, which are not generally observed in the normal FTS product spectrum. Addition of EG results in a significant increase in the production rate of 1,2-DEE only and no measurable amount of 2-EE was found. While addition of 2-EE caused a significant increase in the production rate of glycol, the addition of 1,2-DEE indicated a significant increase in 2-EE production rate without any measurable change in EG selectivity. The results suggest that acetic acid undergoes some CC bond rupture while 2-EE and 1,2-DEE undergoes cleavage of the ether linkage (COC bond). On the contrary, EG undergoes fast and equally probable COC chain growth in both terminal positions. The results indicate that neither of these oxygenates is a significant intermediate in FTS with an iron catalyst. Product distribution in most of the oxygenate compounds are consistent with hydrogenation of the added oxygenate to acetaldehyde and/or ethanol as primary products followed by secondary reaction of these two primary oxygenate products.     

Effect of manganese on an iron-based Fischer–Tropsch synthesis catalyst prepared from ferrous sulfate

The effects of manganese on the textural properties, bulk and surface phase compositions, reduction/carburization behaviors and surface basicity of an Fe–Mn–K/SiO₂ catalyst prepared from ferrous sulfate were investigated by N₂ physisorption, Mössbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), H₂ (or CO) temperature-programmed reduction (TPR) and CO₂ temperature-programmed desorption (TPD). The Fischer–Tropsch synthesis (FTS) performance of the catalysts with different contents of manganese was studied in a slurry-phase continuously stirred tank reactor. The characterization results suggested that the added manganese suppressed the crystal growth of hematite and the catalyst reduction from FeO to Fe in H₂. An appropriate amount of manganese improved the FTS activity, increased the surface basicity and enhanced the carburization of the catalyst. However, the excessive addition of manganese retarded the catalyst carburization in CO and syngas due to the high enrichment of manganese on the catalyst surface. At the same time, the addition of manganese suppressed the formation of CH₄ and shifted the selectivity to heavy hydrocarbons (C₁₂₊).     

Recyclable Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@Tween20@Ag Nanocatalyst for Catalytic Degradation of Azo Dyes

Silver nanoparticles supported on superparamagnetic iron oxide (SPION)-Tween20 nanocomposite were prepared by a combined polyol and chemical reduction routes. The morphology, composition and structure of Fe₃O₄@Tween20@Ag nanocatalyst were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analyzer, and X-ray powder diffraction. In addition the magnetic properties were evaluated with vibrating sample magnetometry. It was found that Fe₃O₄@Tween20@Ag nanocatalyst could catalyze the degradation of various organic azo dyes and could easily be recovered from the reaction medium with external magnet. Also, the magnetic catalyst can be succesfully recycled and reused for at least five successive degradation cycles of methyl orange, methylene blue and Rhodamine B, confirming a high recycling efficiency. The cost effective and recyclable Fe₃O₄@Tween20@Ag nanocatalyst provide an novel nanomaterials architecture for environmental remediation applications.     

An efficient recycling process of glycolysis of PET in the presence of a sustainable nanocatalyst

We demonstrate that the catalyst Perkalite F100 efficiently works as a nanocatalyst in the depolymerization of poly(ethylene terephthalate) (PET). After depolymerization of PET in the presence of ethylene glycol and the Perkalite nanocatalyst, the main product obtained was bis(2‐hydroxylethyl) terephthalate (BHET) with high purity, as confirmed by Fourier transform infrared spectroscopy and NMR. The BHET monomers could serve directly as starting materials in a further polymerization into PET with a virgin quality and contribute to a solution for the disposal of PET polymers. Compared with the direct glycolysis of PET, the addition of a predegradation step was shown to reduce the reaction time needed to reach the depolymerization equilibrium. The addition of the predegradation step also allowed lower reaction temperatures. Therefore, the strategy to include a predegradation step before depolymerization is suitable for increasing the efficiency of the glycolysis reaction of PET into BHET monomers. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46285.     

Effect of manganese on a potassium-promoted iron-based Fischer-Tropsch synthesis catalyst

The effects of manganese promoter on the reduction–carburization behavior, surface basicity, bulk phase structure and their correlation with Fischer-Tropsch synthesis (FTS) performances have been emphatically studied over a series of spray-dried Fe–Mn–K catalysts with a wide range of Mn incorporation amount. The catalysts were characterized by means of H₂ and CO temperature-programmed reduction (TPR), CO₂ temperature-programmed desorption (TPD), Mössbauer spectroscopy etc.. The results indicated that small amount of Mn promoter can promote the reduction of the catalyst in H₂. However, FeO phase formed during reduction is stabilized by MnO phase with the further increase of Mn content, making FeO phase difficult to be reduced in H₂. The addition of Mn promoter can stabilize the Fe²⁺ and Fe³⁺ ions, and suppresses the reduction and carburization of the catalyst in syngas and CO. Mn promoter can also enhance the amount of the basic sites and weaken the strength of the basic sites, which possibly come from the reason that the Mn–K interaction is strengthened with the addition of Mn promoter. The change of surface basicity can modify the selectivity of hydrocarbons and olefins, and the change of bulk structure phase derived from the addition of Mn promoter will affect the catalyst activity and run stability. The synergetic effects of the two main factors result in an optimized amount of Mn promoter for the highest catalyst activity and heavy hydrocarbon selectivity in slurry FTS reaction of Fe–Mn–K catalysts.     

Effect of calcium promoter on a precipitated iron–manganese catalyst for Fischer–Tropsch synthesis

A series of precipitated Fe/Mn Fischer–Tropsch synthesis (FTS) catalysts incorporated with calcium promoter were prepared by the combination of co-precipitation and spray-drying technology. The catalysts were characterized by using N₂ physisorption, CO₂ temperature-programmed desorption and Mössbauer spectroscopy methods. FTS performances of the catalysts were tested in a 1 dm³ continuous stirred tank reactor. It is found that calcium promoter has negligible effect on the textural properties, and the addition of calcium promoter can enhance the surface basicity of the catalyst. An appropriate amount of calcium promoter can promote the reduction and carburization of the catalysts during the reduction and Fischer–Tropsch synthesis (FTS) reaction in syngas, but the excessive addition of calcium promoter will decrease the extent of reduction and carburization. The reaction results indicated that the activities of both FTS and water-gas shift (WGS) decrease with the incorporation of calcium promoter. Calcium promoter can inhibit the hydrogenation ability, suppress the formation of methane, and enhance the selectivities to olefin and higher molecular weight products.     

A novel method of surface modification on thin-film composite reverse osmosis membrane by grafting poly(ethylene glycol)

A novel method of surface modification by grafting hydrophilic poly(ethylene glycol) (PEG) chains onto the surface of a thin-film composite (TFC) polyamide reverse osmosis (RO) membrane was performed. Aminopolyethylene glycol monomethylether (MPEG-NH₂) was used as grafting monomer. The membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The changes in chemical composition and morphology of the membranes' surface indicated the successful grafting process. Furthermore, a preliminary experiment confirmed that the grafting of PEG chains improved membrane antifouling property.     

乙二醇为原料制备乙二醇乙醚用催化剂及其失活

以硫酸铵浸渍改性的HZSM-5为催化剂催化乙二醇和乙醇合成乙二醇乙醚和乙二醇二乙醚时催化剂效率很高,乙二醇转化率能达到69.1%,乙二醇乙醚选择性达到72.9%,乙二醇二乙醚的选择性为25.3%。但催化剂在重复使用时催化活性降低较快,因此分别采用X射线衍射仪（XRD）,NH3-TPD,扫描电子显微镜（SEM）,电子能谱（EDS）,比表面积及孔径测定仪和热重/差热分析仪（TG）对催化剂改性及使用前后晶型结构,表面酸强和酸量,表面吸附物,催化剂形貌,表面元素变化,比表面积,孔径大小等对催化剂失活原因及再生条件进行研究。结果表明,在使用后未对催化剂处理情况下,催化剂失活主要是由于表面积碳导致催化剂孔道堵塞造成的。经多次使用后催化剂缓慢失活主要是由于催化剂表面负载的S流失造成的,在整个过程中催化剂晶型结构未发生变化。     

Cross-Linking of Multi-Walled Carbon Nanotubes with Polyethylene Glycol

In this paper a new approach to cross-link two individual multi-walled carbon nanotubes (MWCNTs) by a nucleophilic substitution of brominated MWCNTs using polyethylene glycol anion was introduced. The functionalized MWCNTs were characterized using thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. It is found that polyethylene glycol act as cross-linking agents to interconnect or cross-link the MWCNTs within and among the bundles, as demonstrated by TEM analysis, and few defects will be induced to the nanotube sidewalls. After cross-linking of PEG, the functionalized MWCNTs are still insoluble in any solvent; however, the morphologies of the cross-linked MWCNTs were largely intact, undoubtedly which will provide a useful way to construct nanoscale devices with MWCNTs in the future.