负载钛催化1-己烯聚合

研究了负载钛催化1-己烯(He)聚合的规律,考察了聚合条件对转化率和聚合物性能的影响。结果表明:以MgCl2为载体的负载钛高效催化剂体系催化合成的聚1-己烯(PHe)为高相对分子质量、无定型、透明的弹性体;较适宜的合成条件是Ti/He(摩尔比)为(3～5)×10-5,Al/Ti(摩尔比)为250～300,温度为30℃;氢气压力是调节相对分子质量的有效手段,随着氢气压力的不断增加,聚合物的相对分子质量急剧下降。     

Copolymerization of 1-butene and 1-hexene with supported titanium catalyst

With TiCl₄/MgCl₂ (Ti) and Al(i-Bu)₃ (Al) as catalysts, the thermoplastic copolymer of 1-butene(Bt) and 1-hexene(He) was synthesized successfully. The effects of Bt/He, Ti/(He+Bt), Al/Ti, temperature and reaction time on conversion, catalyst efficiency(CE), intrinsic viscosity([η]) and insoluble content were studied. The copolymer was analyzed with Fourier transform-infrared (FTIR) and nuclear magnetic resonance (¹H-NMR). Results showed that the optimal polymerization conditions were: He/Bt = 0.25, temperature 40°C−50°C, Al/Ti = 400−500, Ti/(Bt+He) = 3 × 10⁻⁵ − 4 × 10⁻⁵, time 4 h. Intrinsic viscosity was found to increase with increasing Ti/(Bt+He) and decreasing Al/Ti and polymerization temperature. When the molar content of He, Al/Ti and polymerization temperature increased, the insoluble content in CH₂Cl₂ of copolymers decreased. When Ti/(Bt+He) and reaction time increased, the insoluble content in CH₂Cl₂ of copolymers also increased. The crystallization and stereoregularity of poly(1-butene) decreased with the addition of He. Translated from China Synthetic Rubber Industry, 2006, 29(6): 429–434 [译自: 合成橡胶工业]     

水对载体型茂金属催化剂催化乙烯与1-己烯共聚合的影响

针对茂金属催化剂催化乙烯与1-己烯共聚合难以长周期运行的难题,研究了不同水含量时的聚合状态,探索了载体型茂金属催化剂催化乙烯与1-己烯共聚合体系中水含量对催化剂活性的影响以及水使其失活的机理。结果表明:载体型茂金属催化剂对水很敏感,水可使载体型茂金属催化剂失活。在保持反应压力、反应温度稳定的情况下,通过调整乙烯进料速率,在反应体系中水含量≤1μg/g时,反应状态稳定,且催化剂的活性较高。     

负载钛体系催化1-丁烯与1 - 己烯共聚合

以负载钛体系(简称Ti)为主催化剂,三异丁基铝(简称Al)为助催化剂,加氢汽油为溶剂,通过1-丁烯(Bt)与1-己烯(He)共聚合成了新型无规热塑性弹性体。研究了单体摩尔比、Ti/(He Bt)(摩尔比)、Al/Ti(摩尔比)、反应温度、反应时间对转化率、催化剂效率(CE)、聚合物的特性黏数([η])及其在CH2Cl2中不溶物含量的影响,并用傅里叶变换红外光谱、核磁共振对共聚物进行了表征。结果表明,Bt与He最佳共聚合条件为He/Bt0·25,Al/Ti400~500,Ti/(He Bt)3×10-5~4×10-5,反应温度40~50℃,反应时间4h。随着共聚单体中He初始含量、Ti/(He Bt)的增加,共聚物的[η]增大;随着Al/Ti的增加、反应温度的升高,共聚物的[η]减小;随着Al/Ti的增加及反应温度的升高,共聚物在CH2Cl2中的不溶物含量下降;随着Ti/(He Bt)的增加和反应时间的延长,共聚物在CH2Cl2中的不溶物含量增大;He的加入降低了聚1-丁烯(1-PBt)的立构规整性和1-PBt的结晶度。     

碳分子筛吸附氯气的性能研究

采用P-C-T氯气吸附装置对碳分子筛的氯气吸附性能进行了研究.结果表明,碳分子筛可反复多次吸附氯气,并且结构骨架依然存在,稳定性较好.在273℃、0.332 MPa下,氯气吸附质量分数可达35.92％.     

金属负载方式对Al-SBA-15/USY分子筛加氢裂化催化剂的影响

以Al-SBA-15/USY复合分子筛为主要成分,分别采用浸渍法、混捏法制备了催化剂。对催化剂进行了透射电镜（TEM）、氢程序升温还原（H₂-TPR）、氨程序升温脱附（NH₃-TPD）、氮气吸附-脱附表征。结果表明,催化剂具有微孔-介孔孔道,而且采用浸渍法制备的催化剂的孔容达到0.34 mL/g、孔径达到5.5 nm、酸量达到0.265 mmol/g,均高于混捏法制备的催化剂。以减压蜡油（VGO）为原料在200 mL评价装置上对催化剂进行评价。结果表明,与混捏法制备的催化剂相比,浸渍法制备的催化剂的中间馏分油收率提高1.6%、选择性提高1.9%。     

介孔分子筛B-SBA-15催化合成柠檬酸三丁酯

采用直接和间接合成法,将硼原子嵌入介孔分子筛SBA-15骨架中,用柠檬酸与正丁醇的酯化反应评价催化剂的催化性能。间接和直接合成法合成的催化剂活性对比结果表明,间接合成法制备催化剂的活性高于直接合成催化剂。重点考察了催化剂中硅硼比、催化剂用量、反应温度和酸醇比等因素对间接合成催化剂酯化反应性能的影响。筛选出B-SBA-15催化剂最佳硅硼摩尔比为30∶1,最佳反应条件：催化剂用量为原料质量的1.5%,反应温度为130 ℃,酸醇摩尔比1∶6。试验结果表明,介孔分子筛催化剂 B-SBA-15具有较高的稳定性,是合成柠檬酸三丁酯较为理想的分子筛催化剂。     

Y分子筛负载V基催化剂的丙烷氧化脱氢性能

以Y分子筛为载体,采用浸渍法制备不同V含量的V/Y系列催化剂,并考察其丙烷氧化脱氢制丙烯的催化性能。通过BET、XRD、H_2-TPR和NH_3-TPD等技术对催化剂的物化性能进行表征。结果表明,Y分子筛具有大比表面积和窄孔径分布的特点,使负载的V能够形成高分散和孤立态V—O物种,负载的V物种堵塞了Y分子筛的小孔孔道,同时Y分子筛的弱酸性位有助于丙烷的吸附,对晶格氧活化丙烷起到了协同作用,负载V质量分数6%时,催化效果最好。     

TS-1分子筛在过氧化氢氧化苯制苯酚反应中的催化性能研究

以TS-1分子筛为催化剂,在淤浆反应器中对过氧化氢氧化苯制苯酚反应的催化性能进行了研究,考察了不同溶剂、过氧化氢进料方式、原料配比和反应条件等对催化性能的影响,优化了反应工艺条件,苯的转化率约达12.5%,苯酚的选择性约达92%,为进一步开展研究奠定了基础。     

Transformation of thiophene, benzothiophene and dibenzothiophene over Pt/HMFI, Pt/HMOR and Pt/HFAU: Effect of reactant molecular dimensions and zeolite pore diameter over catalyst activity

Pt-based catalysts were prepared by ionic exchange over three zeolites with different pore sizes, HMFI, HMOR and HFAU. With them, the effect of zeolite pore size over the transformation of sulfur containing compounds with different molecular dimensions, such as: thiophene (T), benzothiophene (BT) and dibenzothiophene (DBT) was analyzed. For the Pt-containing catalysts, reaction data reveal changes in the overall conversion of T, BT and DBT with zeolite pore size (Pt/HMFI < Pt/HMOR < Pt/HFAU). Hydrogenated sulfur compounds such as tetrahydrothiophene (THT), dihydrobenzothiophene (DHBT) were detected in high yields, being Pt/HMOR the more active catalyst, indicating that hydrogenation took place on some metallic Pt clusters that remained un-poisoned by the sulfur molecule. Moreover, the yields of THT, DHBT and tetrahydrodibenzothiophene (THDBT) remain stable with time on stream, indicating that poisoning by H₂S and/or the sulfur compound was not enough to inhibit completely the hydrogenating function of the metal and that at least a fraction of Pt⁰ was protected by the zeolite from sulfur poisoning.     

Ring hydrogenation of naphthalene and 1-naphthol over supported metal catalysts in supercritical carbon dioxide solvent

Catalytic ring hydrogenations of naphthalene and 1-naphthol were studied over several supported metal catalysts in supercritical carbon dioxide solvent at low temperature. Higher concentration of hydrogen in supercritical carbon dioxide and lower reaction temperature were responsible for higher catalyst activity and selectivities to the desired partial ring hydrogenated products as compared with those observed in organic solvent for the same catalyst.     

New acid catalyst comprising heteropoly acid on a mesoporous molecular sieve MCM-41

New solid acid catalysts, consisting of heteropoly acid (HPA) H₃PW₁₂O₄₀ (PW) supported on a mesoporous pure-silica molecular sieve MCM-41, have been prepared and characterized by nitrogen physisorption, X-ray diffraction, FT-IR, and³¹P magic angle spinning NMR. The PW/MCM-41 compositions with PW loadings from 10 to 50 wt% have 30 Å uniformly-sized mesopores. HPA retains the Keggin structure on the MCM-41 surface and forms finely dispersed HPA species. No HPA crystal phase is developed even at HPA loadings as high as 50 wt%. PW/MCM-41 exhibits higher catalytic activity than H₂SO₄ or bulk PW in liquid-phase alkylation of 4-t-butylphenol (TBP) by isobutene and styrene. In the alkylation of TBP by styrene, PW/MCM-41 shows a size selectivity compared to bulk PW and PW/SiO₂, providing higher yields of a 2-(1-phenylethyl)-4-t-butylphenol, at the expense of the more bulky 2,6-bis-(1-phenylethyl)-4-t-butylphenol. The PW/MCM-41 compositions, having strong acid sites and a regular mesoporous system, are promising catalysts for the acid-type conversion and formation of organic compounds of large molecular size.     

Purification of coal mine methane on carbon molecular sieve by vacuum pressure swing adsorption

The vacuum pressure swing adsorption (VPSA) method, as an alternative way to separate the CH₄/N₂ mixture, was adopted to purify methane from coal mine methane. The performance of the VPSA process was investigated experimentally and theoretically with a reactivated carbon molecule sieve as the adsorbent. The computer calculations were compared to the experimental data. The concentrated methane with 79% purity could be collected directly during the high-pressure adsorption step with 93% recovery and 0.0720 mL·g^–1·min^–1 productivity, when the composition of raw gas was 10/90 vol% CH₄/N₂, which is of great significance for the utility of low quality energy gas.     

Effect of mixed support of carbon black and nanographite on the activity of Pt catalyst for ethanol oxidation

The effect of the mixed support of carbon black and nanographite (CG) on the electrocatalytic activity and stability of the CG supported Pt (Pt/CG) catalyst for ethanol oxidation was investigated. It was found that the electrocatalytic activity and stability of the Pt/CG catalyst for ethanol oxidation depend on the weight ratio of carbon black and nanographite because the carbon black has a large surface area and nanographite has high conductivity. The Pt/CG catalyst with a weight ratio of 10:1 produces the best electrocatalytic activity and stability of the Pt/CG catalyst for ethanol oxidation.     

二氧化碳加氢合成甲醇催化剂研究进展

介绍了CO2加氢合成甲醇催化剂的研究进展,重点对负载型铜基催化剂的最新进展进行了综述。     

制备工艺对蔗糖基碳分子筛结构的影响

以蔗糖为碳源,F127为表面活性剂,采用K₂CO₃活化合成蔗糖碳前体,在氮气保护下炭化制备碳分子筛。通过SEM、FTIR和N₂-吸/脱附手段对碳分子筛样品进行表征,优化样品制备工艺过程。结果表明,在炭化温度为800℃下,活化剂K₂CO₃浓度为0.5mol/L,F127/蔗糖质比1：3,反应温度45℃,反应时间12h制备的碳分子筛表面孔结构显著,孔隙发达,比表面积高达1366.4423m²/g,孔容为0.865796cm³/g,孔径集中在0.64nm。     

Effect of chemisorbed carbon monoxide on Pt/C electrode on the mechanism of the hydrogen oxidation reaction

The influence of poisoning of Pt catalyst by CO on the kinetics and mechanism of H₂ oxidation reaction (HOR) at Pt/C electrode in 0.5 mol dm⁻³ HClO₄, saturated with H₂ containing 100 ppm CO, was examined with rotating disc electrode (RDE) at 22 °C. Commercial carbon black, Vulcan XC-72 was used as support, while Pt/C catalyst was prepared by modified polyol synthesis method in an ethylene glycol (EG) solution. The kinetically controlled current (I_k) for the HOR at Pt/C decreases significantly at CO coverage (Θ_CO) > 0.6. For Θ_CO < 0.6 the HOR takes place through Tafel-Volmer mechanism with Tafel reaction as rate-determining step at the low CO coverage, while Volmer step controls the overall reaction rate at the medium CO coverage. When CO coverage is higher then 0.6, Heyrovsky-Volmer mechanism is operative for the HOR with Heyrovsky as the rate-determining step (rds).     

Cracking behavior of asphaltene in the presence of iron catalysts supported on mesoporous molecular sieve with different pore diameters

Cracking of a mixture of petroleum asphaltene and 10 wt% Fe catalyst supported on mesoporous molecular sieve (SBA-15) possessing a hexagonal array of uniform mesopores has been studied with a fixed bed reactor at 573 K under atmospheric He. When average pore diameter of Fe/SBA-15 is varied between 4.5 and 15 nm, asphaltene conversion increases almost linearly with increasing pore diameter up to 12 nm and reaches 65%, though the increment is small beyond this value. On the other hand, yield of maltene formed is almost independent of the diameter and less than 15% but greatly improved by using pressurized H₂ in place of He. Although pore volumes of all Fe/SBA-15 catalysts decrease by mixing with feed asphaltene, the extent of the decrease is larger for the catalyst with a larger pore diameter, which shows that higher asphaltene conversion may arise from the presence of larger amounts of asphaltene molecules held inside the larger mesopores. The N₂ adsorption measurements reveal that pore structures of Fe/SBA-15 catalysts are almost unchanged after cracking and subsequent re-calcination to remove deposited coke. The X-ray diffraction analysis and temperature programmed oxidation after cracking suggest that Fe species are highly dispersed inside the mesopores and present as the sulfided phases at the outermost layer.     

Molecular probe technique for the assessment of the carbon molecular sieve structure

Nitrogen adsorption at 77 K is the most common technique for defining the surface area and pore volume of a porous material. However it is not adequate to assess the microporosity of carbon molecular sieves (CMS), because of activated diffusion effects. In this paper, a molecular probe technique was used to defining the pore size of CMS materials. Adsorption of gases (vapors) with different molecular sizes, were measured by a gravimetric method using a spring balance. The amount adsorbed at room temperature was recorded over a 24-h period. The following molecular probes were chosen: CO₂ (0.33 nm), C₂H₆ (0.4 nm), n-C₄H₁₀ (0.43 nm), i-C₅H₁₁₂ (0.5 nm), and CCl₄ (0.6 nm). The micropore volumes were estimated by the Dubinin-Raduhkevich (DR) equation. Assuming that the diameters of the micropores are larger than those of the adsorbed molecules, the micropore volume distribution of each sample was estimated. The results demonstrated that the main pore size of the studied CMSs are less than 0.5 nm. One of the samples had a narrow pore size distribution in the range of 0.33–0.43 nm, which is the critical pore size for kinetic separation of oxygen from nitrogen. It is concluded that the molecular probe technique is an effective mean to assess the CMS adsorbents structure, which is not currently possible using conventional approaches with a single adsorbate, such as nitrogen or argon.