Pd和甲醛对Ag/C催化四氯化碳原位液相加氢脱氯性能的影响

采用100 mL反应釜,在N₂存在条件下,研究了Ag/C催化剂催化CCl₄液相原位加氢脱氯反应,考察了助催化剂Pd以及助剂甲醛溶液对CCl₄原位催化转化反应转化率和产物选择性的影响,并结合XRD、XPS表征技术分析了甲醛自身分解反应。结果表明,助催化剂Pd可以提高Ag/C催化剂的活性,以n(Pd)/n(Ag)为0.03的Pd-Ag/C催化剂的活性最高;但对产物CH₂Cl₂和CHCl₃的选择性没有影响,二者选择性之比仍维持在6/4。甲醛的加入明显提高Ag/C催化剂上CCl₄的转化率,同时也改变了产物分布;反应4 h,CCl₄转化率和CH₂Cl₂选择性均达到90%。甲醛主要起促进Ag/C催化剂表面Ag-Cl物种还原为Ag的作用。     

The Effect of Pd Precursors on the Catalytic Activity of a Pd/Al2O3 Catalyst for Cumene Hydroperoxide Hydrogenation

Abstract

Abstract Pd/Al₂O₃ catalysts were prepared by wet impregnation using K₂PdCl₄, (NH₄)₂PdCl₄, and Pd(NO₃)₂ as precursors. All catalysts were characterized by means of inductively coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction (TPR), X-ray diffraction (XRD), and CO chemisorption. The results obtained in the hydrogenation of cumene hydroperoxide (CHP) to α-cumyl alcohol (CA) showed that Pd/Al₂O₃ catalyst prepared from Pd(NO₃)₂ exhibited the highest turnover frequency (TOF) value and the greatest deactivation extent, whereas Pd/Al₂O₃ catalyst prepared from (NH₄)₂PdCl₄ displayed the lowest TOF value but the best stability.     

Removal of basic nitrogen compounds from fuel oil with [C4mim]Br/ZnCl2 ionic liquid

Metal-based ionic liquid [C₄mim]Br/ZnCl₂ was synthesized, and its structure was characterized using FTIR spectroscopy and a mass spectrometer. The denitrogenation performance of the ionic liquid was investigated using coker diesel oil as feedstock. Experiment results showed that [C₄mim]Br/ZnCl₂ presented a good denitrogenation performance, obtaining about 94.95% basic N-removal efficiency under the condition with a temperature of 50°C, 1:1 (w/w) IL:oil, extraction time of 30 min. In addition, the basic N-removal efficiency can still reach above 50% at 1:7 IL/oil (w/w) during four recycles of the ionic liquid.     

Effects of Impregnation Solvents on Catalytic Performance of Co-Ru-ZrO2/γ-Al2O3 Catalyst for Fischer-Tropsch Synthesis

Abstract

Used ZrO₂ modified γ-Al₂O₃ as support, Co-Ru catalysts were prepared by incipient impregnation method. The effects of impregnation solvents on the performances of catalysts were examined. The catalyst was prepared with ethanol solution and high Co dispersion was obtained, exhibiting highest activity of CO hydrogenation, very low methane selectivity, and high heavy hydrocarbon C₅ ⁺ selectivity. The catalysts were prepared with aqueous solution and methanol solution, and the reaction behaviors were similar. The solvent isopropanol caused the lowest catalytic activity and highest methane selectivity. Increasing the reaction temperature enhanced the CO hydrogenation rate, and the CO conversion slightly increased the CO₂ selectivity and favored the formation methane and light hydrocarbons, while the chain growth probability decreased. For the catalyst prepared with ethanol, the CO conversion, the CH₄ selectivity, and the C₅ ⁺ selectivity were 94.16%, 5.65%, and 88.2%, respectively, and the chain growth probability was 0.87 at 493 K, 1.5 MPa, 800 h^?1, and n(H₂):n(CO) = 2.0 in feed.     

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.     

Design of Catalyst Support for Deep Hydrodesulfurization of Gas Oil

Abstract

Alumina-silica (Al₂O₃-SiO₂) composite supports were examined to find the optimum state of support (i.e., composition and morphology). SiO₂ content in the Al₂O₃-SiO₂ support induced a shift of the main peak to higher frequency ascribed to an increased amount of Mo₈O₂₆ ^4?. A 75 wt% Al₂O₃-25 wt% SiO₂ support had homogeneously dispersed alumina particles of smaller size with high crystallinity. Hydrodesulfurization (HDS) of straight-run gas oil and its conventionally hydrotreated straight-run gas oil was performed over NiMo sulfides supported on Al₂O₃-SiO₂ composites. The high crystallinity of NMASA2-27 may be related to the high HDS and hydrogenation activity of NiMo sulfides due to its moderate interaction with the alumina surface.     

炼油厂燃料气中C_(3)+及H_(2)优化回收利用北大核心CSCD

目的回收利用炼厂燃料气中的C_(3)+及H_(2),提高经济效益。方法通过对不同来源的燃料气分析对比,找出其中富H_(2)、高C_(3)+燃料气。优化H_(2)利用及回收流程,增加脱氢膜面积,提高H_(2)回收量。利用催化装置和焦化装置的吸收稳定系统回收燃料气中的C_(3)+。结果技改总投资320万元,可回收C_(3)+1.23×10^(4) t/a,增效3000万元/年;H_(2)回收量可增加1050×10^(4) m^(3)/a,降低制氢成本1200万元/年。结论该方案充分利用炼厂现有吸收稳定系统及现有脱氢系统扩容,具有投资少、效益好、见效快的优点,对玉门炼化总厂高质量发展具有重要意义。     

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.     

Sulfuration Pretreatment of Ni/Al2O3 Catalyst to Remove Butadiene in FCC C4 Fraction

Abstract

The Ni-based catalysts have more advantages than the most widely used Pd-based catalysts in selective hydrogenating of the butadiene in fluid catalytic cracking (FCC) C₄ fraction. But the selectivity and stability of the Ni-based catalysts aren't good. The sulfuration pretreatment is an effective process to improve the performance of the Ni/Al₂O₃ catalysts. The sulfuration conditions of the Ni/Al₂O₃ catalyst have been studied in this article. The results showed the fittest conditions are that the catalyst was in-situ presulfurized for 60 min by the solution of S concentration 0.07 mol/L. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis indicated that the presulfurization declined the Ni crystal dimension.     

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.     

Characterization of Al2O3–ZrO2 Mixed Oxide Supported Mo Hydrotreating Catalyst

Abstract

A series of molybdenum catalysts supported on Al₂O₃–ZrO₂ mixed oxide containing 50% ZrO₂ and 50% Al₂O₃ were prepared by incipient wetness technique and characterized by BET surface area, X-ray diffraction, temperature programmed reduction and oxygen chemisorption. The catalytic activities for hydrodesulphurization (HDS), hydrogenation (HYD), and hydrocracking (HYC) were determined using thiophene, cyclohexene, and cumene as model compounds, respectively. Results indicate that up to 8 wt% Mo loading, the catalyst is well dispersed and crystallite growth occurred beyond this loading. Also both oxygen uptake and catalytic activities increase with Mo loading up to 8 wt% and then decreases at higher loading. A linear correlation was obtained between oxygen uptake and all catalytic activities and the correlation coefficients obtained suggest that the order of catalytic activities for HDS, HYD, and HYC is: HDS > HYD > HYC. Furthermore, the catalytic activities of the mixed oxide supported catalyst for HDS, HYD, and HYC were higher than those supported on pure alumina and pure zirconia. The incorporation of 3% Co on 8% Mo catalyst was determined to result in enhanced activity for HDS, HYD, and HYC.     

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.     

介孔CuO/SiO2用于汽油氧化-吸附脱硫

 利用[(C₁₆H₃₃) N(CH₃)₃]₃-[PW₁₂O₄₀]双亲催化剂与H₂O₂组成的催化氧化体系对汽油进行氧化后,以介孔SiO₂为载体等体积浸渍法制备的介孔CuO/SiO₂为吸附剂,采用固定床连续流动式吸附脱硫评价装置,考察了CuO/SiO₂的CuO负载量、焙烧温度、焙烧时间和吸附温度对汽油脱硫率的影响,并对介孔CuO/ SiO₂吸附剂性质进行了XRD表征。结果表明,采用在焙烧温度为400℃、焙烧时间为2.0 h、CuO负载量为2%制备的CuO/SiO₂, 在吸附温度为120℃时,汽油氧化-脱硫的脱硫效果较好,汽油脱硫率可达56.82%。     

氧化镁改性微米TS-1催化丙烯环氧化

合成了粒径在1~2 μm的廉价微米TS-1,并经MgO改性,杀灭其上少量的酸中心;采用SEM、XRD、BET对MgO改性前后的TS-1进行了表征,并考察了其在甲醇溶剂体系丙烯环氧化的催化性能。结果表明,TS-1催化剂经MgO改性后,可以显著提高其催化丙烯环氧化反应的环氧丙烷(PO)选择性,减少副反应的发生;在最优化反应条件CH₂O₂ =1.0 mol/L, θ = 60℃, t = 60 min, p_C3↓H6↓ = 0.6 MPa,以及按每1 gTS-1需80 mL CH₃OH的比例下,H₂O₂转化率达到99.5%,环氧丙烷选择性达到96.7%,环氧丙烷收率比未改性的微米TS-1也有明显提高。     

Desulfurization of FCC Gasoline Over Mordenite Modified with Al2O3

Abstract

Mordenite modified with Al₂O₃ (Al₂O₃/mordenite) was synthesized and used for the desulfurization of FCC gasoline. The influences of operating parameters on the results were studied for the model solution composed of dibenzothiophene (DBT) and isooctane. Al₂O₃/mordenite exhibits higher sulfur capacity than other kinds of chemisorbents. The suitable composition of the chemisorbent is 30 wt% Al₂O₃ to 70 wt% mordenite. The optimal operating parameters are: temperature 160°C; velocity 3 h^?1 (WHSV). Under the stated conditions, desulfurization was carried out for the FCC gasoline with sulfur content of 220.4 μg/g. The chemisorbent can maintain the sulfur content under 50 μg/g for 40 h and has good regeneration ability after desorption using benzene.     

Thermal Behaviors and Their Correlations of Mg(BH4)2-Contained Explosives

In order to explore the effect of metal hydride on energetic materials’ thermal behaviors and their correlations, we studied the heats of combustion and detonation of RDX, TNT, and Mg(BH₄)₂-containing explosives both theoretically and experimentally. The results showed that Mg(BH₄)₂ can significantly improve the energy of explosive. As the mass fraction of Mg(BH₄)₂ increases, the combustion heat of composite explosives increases gradually, while the combustion efficiency decreases. When its mass fraction is about 30%, the theoretical heats of detonation of RDX/Mg(BH₄)₂ and TNT/Mg(BH₄)₂ reach maximum, which are 7418.47 and 7032.46 kJ/kg, respectively. When we compared the errors between calculation and experimental values, we found that L-C method is more accurate in calculating oxygen-enriched and oxygen-balanced explosives, and that minimum free energy method is more suitable for seriously negative oxygen-balanced explosive. For single explosive, there are three kinds of relationships between heat of combustion and detonation according to the oxygen balance. For Mg(BH₄)₂-containing explosives, the relationship is in accordance with Boltzmann function.     

Contamination of UHT milk by aflatoxin M1 in Iran

In this study the levels of aflatoxin M₁ (AFM₁) in UHT milk samples were determined in May, August and November and February. Two hundred and ten UHT milk samples were obtained from supermarkets in Tehran, Iran. The occurrence and concentration range of AFM₁ in the samples were investigated by competitive enzyme-linked immunoabsorbent assay (ELISA) method. AFM₁ was found in 116 (55.2%) of 210 UHT milk samples examined. The levels of AFM₁ in 70 (33.3%) samples were higher than the maximum tolerance limit (0.05 μg/l) accepted by some European countries while none of the samples exceeded the prescribed limit of US regulations. The highest mean concentration of AFM₁ was recorded in February (0.087 μg/l). The lowest mean concentration of AFM₁ was recorded in August (0.021 μg/l). Statistical evaluation showed that there were significant difference (P < 0.01) between the mean concentrations of AFM₁ of UHT milk samples taken in February with May and August. AFM₁ contents of milk samples taken in February were not higher than UHT milk samples taken in November (P < 0.01). The AFM₁ incidence of exceeding legal limit in UHT milk samples (33.3%) was relatively much higher than some other countries. It was therefore concluded that, the levels of AFM₁ in UHT milk samples consumed in Iran were high and seemed to pose a threat to public health.     

Preparation and Characterization of the Solid Spherical HMX/F2602 by the Suspension Spray-Drying Method

Solid spherical octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine/fluororubber2602 (HMX/F₂₆₀₂) was prepared by the suspension spray-drying method as follows: firstly, thinning octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was obtained by a solvent–anti-solvent method. Secondly, thinning HMX suspended in ethyl acetate solvent in a solution of a binder—F₂₆₀₂—was made into a suspension. Finally, the samples were prepared by spray drying. The samples were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR), and its thermal stability as well as mechanical and spark sensitivities were measured. The results of SEM showed that the grain of HMX/F₂₆₀₂ was solid spherical and the particle distribution was homogeneous. The results of XPS indicated that F₂₆₀₂ can be successfully coated on the surface of HMX crystals. Compared to raw HMX, th characteristic drop height was increased from 19.60 to 40.37 cm, an increase of 79.10%. The friction sensitivities of HMX reduced from 100 to 28% and the spark sensitivity of HMX/F₂₆₀₂ increased. The critical explosion temperatures of raw HMX and HMX/F₂₆₀₂ were 275.43 and 274.30°C, respectively. The amount of gas evolution of raw HMX and HMX/F₂₆₀₂ was 0.15 and 0.12 ml·(5 g)^?1, respectively. The results of DSC and vacuum stability tests (VSTs) indicate that the thermal stability of HMX/F₂₆₀₂ was equal to that of raw HMX and HMX and F₂₆₀₂ had good compatibility.     

COMBINED EFFECT OF FLUORINE AND ZINC INCORPORATION ON THE HDS ACTIVITY OF Co-Mo CATALYSTS

Abstract

Conventional HDS-catalysts consist of Co and Mo supported on Y-Al₂O₃. The addition of Zn as a second promoter or the alumina acidification with F increase the catalitye activity in HDS of commercial feeds (Fierro et al., 1984; Boorman et al., 1984). In this paper the combined effect of both Zn and F incorporation is discussed. A series of Zn-Co-Mo catalysts supported on fluorinated alumina (0.0 –2.0 wt% F) was prepared and tested for HDS activity using a commercial gas-oil. The data gathered showed a decrease in HDS activity for intermediate F contents (0.4 – 1.0 wt%). This result could be tentatively explained through alumina surface deterioration during impregnation with NH₄HF₂ solutions al low pH.     

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%。