新型HPWs/MIL-101催化剂的制备及其对环戊烯选择氧化反应的催化性能

采用浸渍法在介孔金属-有机骨架材料MIL-101上负载磷钨酸(HPWs),制得一种新型HPWs/MIL-101非均相催化剂。利用XRD、N2吸附、TG和FTIR等手段对该催化剂进行了表征,研究了该催化剂在环戊烯(CPE)选择氧化制备戊二醛(GA)反应中的催化性能。实验结果表明,MIL-101对HPWs具有很高的负载阈值,且将HPWs固载到MIL-101上后MIL-101仍能很好地保持其晶体骨架结构。HPWs高度分散在MIL-101的介孔笼中,与MIL-101有较强的相互作用,提高了该催化剂的热稳定性且可有效防止HPWs的流失。在HPWs负载量为30%(w)、n(CPE)∶n(H2O2)∶n(HPWs)=1 000∶2 100∶3、V(叔丁醇)∶V(CPE)=10、35℃、24 h时,CPE转化率达到100.0%,GA收率达到70.1%。该催化剂具有较好的重复使用性能。     

Pt/PTA-MIL-101(Cr)的合成及其正庚烷异构催化性能

使用磷钨酸(PTA)对金属有机骨架材料MIL-101(Cr)进行改性,制备了0.4%Pt/PTA-MIL-101(Cr)催化剂,并首次应用于正庚烷异构化反应。通过对样品进行一系列表征,得出以下结论:所合成的样品为介孔-微孔复合材料,具有正八面体结构,孔道结构规整有序,比表面积高;掺杂PTA后,未破坏MIL-101(Cr)的骨架结构和热稳定性;PTA在催化剂中仍可保持其Keggin结构,可为催化反应提供良好的酸性环境;Pt在MIL-101(Cr)中的分散度较高。通过正庚烷异构化反应对催化剂性能进行评价,得出在PTA掺杂量(w)为30%、反应温度为260℃时,催化剂的酸性位点与金属位点的匹配度最适宜催化庚烷异构化反应,此时催化剂上正庚烷转化率与异庚烷选择性分别可达69.1%和93.7%。     

氨基改性MIL-101(Cr)用于CH4/CO2吸附分离的研究

采用浸渍法合成氨基改性金属有机骨架材料MIL-101(Cr),并用XRD、N2吸附和脱附、FT-IR和TG等表征手段考察材料的结构和性能,测试氨基改性MIL-101(Cr)吸附剂在101.3kPa、25℃下的CO2、CH4吸附量。结果表明,氨基改性后的MIL-101(Cr)与CO2作用力显著增强,提高了CO2吸附量和CO2/CH4分离性能。 PEI/MIL-101(Cr)质量比为70的MIL-101-PEI-70吸附剂的CO2吸附量由50.55cm3/g增加到89.43cm3/g,提升76%,而CH4吸附量由10.62cm3/g下降为5.91cm3/g,降低44%,用理想吸附溶液理论预测其CH4/CO2吸附选择性由11增加到255。吸附CO2后的吸附剂可在80℃、真空下再生,脱附条件温和。     

氨基改性MIL-101(Cr)用于CH_4/CO_2吸附分离的研究

采用浸渍法合成氨基改性金属有机骨架材料MIL-101(Cr),并用XRD、N2吸附和脱附、FT-IR和TG等表征手段考察材料的结构和性能,测试氨基改性MIL-101(Cr)吸附剂在101.3k Pa、25℃下的CO2、CH4吸附量。结果表明,氨基改性后的MIL-101(Cr)与CO2作用力显著增强,提高了CO2吸附量和CO2/CH4分离性能。PEI/MIL-101(Cr)质量比为70的MIL-101-PEI-70吸附剂的CO2吸附量由50.55cm3/g增加到89.43cm3/g,提升76%,而CH4吸附量由10.62cm3/g下降为5.91cm3/g,降低44%,用理想吸附溶液理论预测其CH4/CO2吸附选择性由11增加到255。吸附CO2后的吸附剂可在80℃、真空下再生,脱附条件温和。     

TS-1/H2O2催化氧化脱除CO2气体中甲硫醇的研究

以钛硅分子筛(TS-1)为催化剂,过氧化氢(H2O2)为氧化剂,考察了TS-1/H2O2对二氧化碳(CO2)气体中甲硫醇的氧化脱除性能。在c(H2O2)=1.243×10-3mol/L,催化剂加入量为0.5g每100mL双氧水,反应温度为30℃时,TS-1/H2O2体系能够将原料气中φ(CH3SH)由1×10-3脱除至φ(CH3SH)<5×10-9。催化剂再生5次后,反应体系的穿透时间基本保持不变。通过X-射线衍射(XRD)、傅里叶红外、N2物理吸附等对反应前后的催化剂进行了表征,结果显示再生后催化剂的比表面积和晶体骨架结构基本不变。质谱分析显示甲硫醇的氧化产物有CH3SOH、CH3SO2H和CH3SO3H。     

H6P2W18O62/MCM-48催化剂的制备、表征及催化绿色合成己二酸

以MCM-48为载体,通过浸渍法制备了H6P2W18O62/MCM-48催化剂,并采用FT-IR、XRD、SEM、EDS对催化剂进行表征。以微波促进30%(质量分数)H2O2氧化环己酮合成己二酸反应为探针,考察了H6P2W18O62/MCM-48的催化性能,并通过正交实验确定了优化的工艺条件。结果表明,采用H6P2W18O62负载量40%的H6P2W18O62/MCM-48催化剂,在优化的合成己二酸的工艺条件下,即催化剂质量分数(以环己酮质量计)5.1%、n(C6H10O)∶n(H2O2)∶n(H2C2O4.2H2O)=100∶450∶1.88、反应温度95℃、微波功率300 W、反应时间3.5h,己二酸收率可达81.3%;催化剂重复使用5次,己二酸收率仍可达到64.6%。     

氨基离子液体功能化MIL-101在温和条件下催化转化CO_2

利用研磨法将氨基离子液体(3-(3-氨基丙基)-1-甲基-1H-咪唑-3-氯化物)浸渍到MIL-101中,制备了氨基离子液体功能化的NH2-MIL-101,并考察了其在CO_2与环氧氯丙烷环加成反应中的催化性能。结果表明,NH2-IL/MIL-101在无溶剂条件下可温和高效地催化转化CO_2。最佳条件:0.5MPa,50℃,24h。此反应条件下,环氧氯丙烷的转化率为96%,4-氯甲基-1,3-二氧环戊-2-酮的选择性为98%。     

H6P2W18O62·nH2O/MWCNTs催化剂的制备、表征及其对乙酸正丁酯合成的催化性能

以多壁碳纳米管(MWCNTs)为载体,采用浸渍法制备了H6P2W18O62·nH2O/MWCNTs催化剂,对其进行了FT-IR、EDX、XRD、SEM表征,并以乙酸和正丁醇合成乙酸正丁酯为探针反应,考察了催化剂的酸催化性能,以及反应条件和催化剂重复使用次数对酯化率的影响。结果表明,H6P2W18O62·nH2O/MWCNTs催化活性高于单一组分的H6P2W18O62·13H2O和MWCNTs。该酯化反应的最佳条件为磷钨酸负载量50%,催化剂用量(按反应体系总质量计)0.6%,醇/酸摩尔比2,反应温度120℃,反应时间2.0h。此时,酯化率可达97.1%。催化重复使用5次后,酯化率仍可达60.9%。     

钛硅沸石催化C3H6和H2O2合成丙二醇单甲醚反应条件的研究

在加压固定床反应器上,将钛硅沸石和SiO2混合制备的TS-1/SiO2催化剂,用于H2O2、C3H6及甲醇反应制备丙二醇单甲醚(MME).考察了反应温度、操作压力、原料中H2O2浓度、H2O2与C3H6的摩尔比、进料总空速、空塔线速等反应参数对该催化剂催化性能的影响,找到了较佳的操作条件.实验结果表明,当反应温度60℃,操作压力3.0MPa,H2O2浓度0.85mol/l,H2O2与C3H6的摩尔比14.17,液相进料总质量空速3.36h-1,空塔线速43.74×10-2m/h时,MME的选择性达到91.35%,H2O2有效利用率达94.37%,H2O2转化率达98.26%,C3H6实际转化率达22.24%(此时C3H6理论转化率为23.98%).     

UV/H2O2/草酸铁络合物体系处理压裂废液实验研究

针对油田压裂废液COD高、难降解的特点,分别采用UV/Fenton和UV/H2O2/草酸铁络合物法对其进行氧化处理,并研究了废液初始pH值、H2O2投加量、n(H2O2)/n(Fe2+)、n(Fe2+)/n(草酸)对压裂废液CODCr去除效果的影响。结果表明,在紫外光照射下、介质pH值为6.0、双氧水(H2O2)投加量为0.25%、n(H2O2)/n(Fe2+)为2.0,n(Fe2+)/n(C2O42-)为3.0条件下,UV/H2O2/草酸铁络合物体系对压裂废液的CODCr去除率达50%,与UV/H2O2氧化体系相比,去除效果较明显。     

天然气净化厂Cansolv尾气处理装置废水处理

目的 解决Cansolv尾气处理装置胺液净化单元(APU)废水高盐、高有机物与还原性硫的高浓水质特征影响水处理系统的稳定运行问题。方法 详细分析了两个天然气净化厂的文丘里和APU废水的水质特征,其中,APU废水成分复杂,是影响水处理系统稳定运行的关键。采用臭氧(O₃)、O₃耦合催化剂、臭氧/双氧水(O₃/H₂O₂) 3种氧化技术处理APU废水,通过废水中COD值和TOC值变化来评价有机物降解效果,研究了反渗透膜污堵原因和O₃/H₂O₂降解有机物机理。结果 O₃/H₂O₂氧化技术为去除废水中有机物的最优方法,当200 mL废水中O₃质量浓度为22 500 mg/L、H₂O₂投加量为2 mL、反应时间为60 min时,达到最佳处理效果,COD去除率为60.8%。结论 采用O_3<...     

Pt/SO42-/ZrO2-Al2O3在正己烷异构化反应中的催化行为

采用连续流动的固定床微反装置考察了Pt/SO24-/ZrO2-Al2O3(PSZA)在正己烷异构化反应中的催化行为。采用NH3-TPD、H2-TPR及TG表征了催化剂的酸性、还原性能及硫物种含量。结果表明,PSZA的初始异构化催化活性几乎不受反应温度的影响,而稳定性则与反应温度密切相关。低温下反应,催化剂在短时间内迅速失活,而提高反应温度可大大提高PSZA的反应稳定性。PSZA具有良好的再生性能,与新鲜催化剂相比,多次再生后的催化剂异构化催化活性基本没有变化。PSZA在低温下的快速失活与其催化活性中心产生的机理有关,而与其硫损失或硫物种的还原无关。在异构化反应过程中,催化剂通过氢溢流可产生强酸活性中心,并在反应过程中不断被消耗;在高温下通过氢溢流不断产生新的强酸中心,使催化活性保持稳定;而低温下氢溢流难以发生,消耗的强酸活性中心不能及时补充,使催化活性下降。     

Oxidative Desulfurization of Dibenzothiophene Catalyzed by VO(acac)2 in Ionic Liquids at Room Temperature

A simple extraction and catalytic oxidative desulfurization (ECODS) system composed of VO(acac)₂, 30% H₂O₂, and 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄) has been found to be suitable for the deep removal of dibenzothiophene (DBT) in model oil at room temperature. The optimal conditions were as follows: [n(H₂O₂)/n(DBT)/n(catalyst) = 100:20:1], model oil = 5 mL, ionic liquid [IL] = 1 mL, T = 30°C, t = 2 hr. With the ECODS system, the sulfur removal of DBT could reach 99.6%, which was superior to that of the simple extraction with IL (15.6%) or oxidation without catalyst (17.1%). The IL could be recycled five times without a significant decrease in activity.     

Synthesis of amphiphilic peroxophosphomolybdates for oxidative desulfurization of fuels in ionic liquids

Three amphiphilic peroxophosphomolybdates [C₄mim]₃PMo₄O₂₄, [C₈mim]₃PMo₄O₂₄ and [C₁₆mim]₃PMo₄O₂₄ were synthesized and characterized. These catalysts were used for extraction and catalytic oxidative desulfurization of fuel with H₂O₂ as an oxidant and ionic liquid [C₄mim]BF₄ as an extractant. It was found that [C₁₆mim]₃PMo₄O₂₄ showed the highest catalytic activity and the sulfur content could decrease to 7.5 ppm. In contrast, the desulfurization system shows very low performance without H₂O₂ or ionic liquid. The detailed reaction conditions were optimized including reaction time, temperature, the dosage of H₂O₂ and catalyst, and different sulfur compounds. After the reaction, the catalysts and the ionic liquid can be cycled 8 times with a little decrease in desulfurization efficiency.     

Hydrogen production by catalytic methane decomposition over Ni,Co, and Ni-Co/Al2O3 catalyst

Hydrogen is a chief source of energy. Catalytic decomposition produces hydrogen and carbon. In this work, x%M/Al₂O₃ (where M is Ni, Co and combined Ni-Co, and x is 10%, 15%, and 30%) has been successfully employed as a catalyst. The effect of activation temperature and active metal type and loading on catalyst perfomance was investigated. The catalysts were characterized with BET, XRD, TPO, TPR, TEM, XPS, and Raman. The results displayed that the 30%Co/Al₂O₃ catalyst activated at 500°C provided the greatest catalytic performance toward methane conversion. 30%Co/Al₂O₃ catalyst activated at 500°C formed amorphous carbon.     

Nanocatalysts: Effect of Active-phase and Promoter on Catalytic Properties and Performance in the Hydrodesulfurization Reaction

The influence of various amounts of phosphorus addition on performance of NiMoP/Al₂O₃ and CoMoP/Al₂O₃ nanocatalysts was examined in hydrodesulfurization of thiophene. The nanocatalysts were synthesized via sonochemical technique. The prepared samples were characterized by XRD, FESEM, BET, and FTIR analysis. The catalytic activity in hydrodesulfurization reaction was investigated in a batch stirred slurry reactor at 160°C and atmospheric pressure. The characterizations confirmed highly dispersion of active phase and formation of amorphous AlPO₄ species on the support surface. The results obtained from thiophene hydrodesulfurization showed the nanocatalysts contained 1 wt% of phosphorus had the highest activity. The CoMoP/Al₂O₃ and NiMoP/Al₂O₃ nanocatalysts with optimum phosphorus loading nearly gave 100% conversion of thiophene, so that the sulfur compound concentration in final solution was less than 50 ppm.     

超声波辐照浸渍法制备MnO2/γ-A12O3催化剂及其柴油催化氧化脱硫性能

 分别采用超声波辐照浸渍法和普通浸渍法制备了MnO₂/γ-Al₂O₃催化剂,运用电感耦合等离子体原子发射光谱（ICP-AES）和X射线衍射（XRD）对催化剂进行表征,在空气-异丁醛-MnO₂/γ-Al₂O₃体系中评价其对加氢柴油的氧化脱硫催化性能,并考察了反应温度、异丁醛用量、空气流量、溶剂类型和剂/油体积比对柴油氧化脱硫反应的影响。结果表明,超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂对柴油氧化脱硫的催化性能明显优于普通浸渍法制备的催化剂。最适宜的催化柴油氧化脱硫反应的条件为：乙腈为溶剂、加氢柴油30 mL、温度35℃、异丁醛20 mmol、空气流量0.06 L/min、超声波辐照浸渍法制备的MnO₂/γ-Al₂O₃催化剂0.08 g、剂/油体积比1/6和催化氧化时间10 min。在此条件下可将柴油硫质量分数从542μg/g 降至31μg/g,柴油脱硫率和回收率分别为94.3%和93.3%。     

Mathematical modeling of catalytic behavior of catalyst pellets in crude oils after blocking by liquid sulfur

The sulfur recovery unit converts H₂S to elemental sulfur by the Claus process. The process occurs during two combustion and catalytic reactions. Alumina (γ-Al₂O₃) and bauxite (Al₂O₃H₂O) are the main Claus catalysts in crude oils. The volume distribution of micro- and macropores and the parameter of Bethe lattice representing the complex structure of catalyst pellets pores are the most important parameters affecting catalyst performance. This research is aimed at evaluating these parameters impact on effective efficiency of catalyst bed after blocking by liquid sulfur for the second and third reactors. It can be done by considering micro- and macropores as a function of pellet diameter. The results show that pellets with a minimum coordination number or Bethe lattice parameter of 6 are more suitable to use in catalytic reactors. There is a great consistency between the modeling results and the industrial ones. In addition, a catalytic pellet with a diameter of 4.55 mm has the most optimal performance for sulfur recycling processes in industrial crude oil.     

Facile preparation of Cr2O3 nanoparticles and their use as an active catalyst on the thermal decomposition of ammonium perchlorate

ABSTRACT

Cr₂O₃ nanoparticles were prepared by repeated wet mechanical milling technique. Three drying methods, oven drying, vacuum drying, and vacuum freeze-drying were comparatively used to dry Cr₂O₃ nanoparticles. These processes can be easily scaled up to 10-kg quantities. It took only 2–3 h to cut bulk size to nanometer by milling. The obtained Cr₂O₃ nanoparticles are semi-spherical and homogeneous with an average size of 30 nm measured by SEM and TEM and show similar diffraction peak positions to bulk one investigated by XRD. The TG/DSC study indicated that, compared with bulk Cr₂O₃, Cr₂O₃ nanoparticles obtained by oven drying and vacuum drying, the catalytic performance of Cr₂O₃ nanoparticles obtained by vacuum freeze-drying is the best in lowering the peak temperature of high temperature decomposition and the activation energy, while increasing the apparent decomposition heat and the reaction rate constant of ammonium perchlorate (AP) due to their good dispersion and large specific surface area. The possible catalytic mechanism of Cr₂O₃ on the thermal decomposition of AP was proposed by TG-MS analysis. These findings showed that wet mechanical milling technique combined with vacuum freeze-drying technology is suitable for efficient preparation of Cr₂O₃ nanoparticles, which could be a promising additive for accelerating the thermal decomposition of AP.