Effect of Dispersity and Porous Structure of TiO2 Nanopowders on Photocatalytic Destruction of Azodyes in Aqueous Solutions

Photocatalytic activity of TiO2 nanopowders of anatase modification with various particle sizes and specific surface areas has been studied in the process of photocatalytic decolorization of aqueous solutions of methylene blue and direct blue 2C azodyes. By means of scanning electron microscopy and low-temperature N2 adsorption method, it was found that TiO2 nanopowders have the particles size of 5-120 nm with the specific surface area of 15-120 m2·g^-1. The used TiO2 samples are characterized by mesoporous structures with average pore size of 4.3-14.9 nm. The photocatalytic activity of TiO2 was evaluated via decolorization of azodyes solutions. It was shown that the efficiency of decolorization symbatically changes with the dye adsorption value on TiO2 surface and the degree of decolorization rises when the surface area of TiO2 nanopowders increases. It was found that TiO2 photocatalytic activity essentially depends on adsorption interactions between the dye molecules and catalytic active centers on TiO2 surface, and these interactions, in turn, are greatly affected by pH of the solution.     

Performance improvement of ionic surfactant flooding in carbonate rock samples by use of nanoparticles

Various surfactants have been used in upstream petroleum processes like chemical flooding. Ultimately, the performance of these surfactants depends on their ability to reduce the interfacial tension between oil and water. The surfactant concentration in the aqueous solution decreases owing to the loss of the surfactant on the rock surface in the injection process. The main objective of this paper is to inhibit the surfactant loss by means of adding nanoparticles. Sodium dodecyl sulfate and silica nanoparticles were used as ionic surfactant and nanoparticles in our experiments, respectively. AEROSIL~? 816 and AEROSIL~?200 are hydrophobic and hydrophilic nanoparticles. To determine the adsorption loss of the surfactant onto rock samples, a conductivity approach was used. Real carbonate rock samples were used as the solid phase in adsorption experiments. It should be noted that the rock samples were water wet. This paper describes how equilibrium adsorption was investigated by examining adsorption behavior in a system of carbonate sample(solid phase) and surfactant solution(aqueous phase). The initial surfactant and nanoparticle concentrations were 500–5000 and 500–2000 ppm, respectively. The rate of surfactant losses was extremely dependent on the concentration of the surfactant in the system, and the adsorption of the surfactant decreased with an increase in the nanoparticle concentration. Also, the hydrophilic nanoparticles are more effective than the hydrophobic nanoparticles.     

The Difference between ZSM-5 Zeolites Manufactured from Various Synthesis Systems and Their Catalytic Performances

ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine （BTA）, tetrapropylammonium bromide （TPABr） and no template （NT）] under hydrothermal conditions, The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template eiTects and the differences between the ZSM-5 santples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and withnut template. SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportiortation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9^＋ and C5^＋ was much less than that obtained from zeolite with small crystals.     

内插旋流片的缩放管内糖液自然对流的传热研究

The natural convection heat transfer of a 60% sucrose solution in a vertical converging-diverging tube （CD） withregularly-spaced twisted tapes （RSTT） has been investigated numerically and experimentally. The effects of wall temperatureand number of RSTT on the Nusselt number were studied in detail. The distributions of velocity and temperature inthe 60% sucrose solution were studied and the simulated results of CD with RSTT were compared with those of the smoothtube. The influence of Rayleigh number and RSTT on the Nusselt number was conducted experimentally. The results indicatethat the Nusselt number of the 60% sucrose solution obviously increased with the number of RSTT but increased inconspicuouslywith 2 and more twisted tapes. The simulation shows that the distance for achieving an optimal heat transferperformance is 46 times the diameter of the tube. The mechanism of the natural convection heat transfer enhancement of the60% sucrose solution in relationship with the CD and the RSTT was analyzed, and the change of average tangential velocitywith the axial distance was presented to demonstrate that the enhancement of heat transfer was realized mainly because of the increase in tangential velocity.     

Effect of Carrier Processing Temperature on Its Properties for Adsorption of Active Metals

The influence of the carrier pseudo-boehmite (PB), which was impregnated with a Ni-Mo-P solution under over-saturation conditions and treated at different temperatures, on its property for adsorption of active metals (Ni, Mo) was studied. The results showed that the amount for adsorption of active metal was decreased with an increasing treatment temperature of the carrier. After phase transition of the carrier PB to γ-Al2O3, its capacity for adsorption of active metals was significantly reduced. The difference in properties for adsorption of active metals (Ni, Mo) by PB dried at 120 ℃ and γ-Al2O3 calcined at 600 ℃ was studied in detail. The results suggested that the ability of the PB carrier to adsorb metals was higher than that of the γ-Al2O3 carrier. Especially, the ratio of chemically adsorbed metals on the PB support was much higher than γ-alumina. The chemical adsorption sites on the PB carrier were proved to be much more than those on the γ-Al2O3 carrier. Ni and Mo chemical adsorption sites differed a lot on the carrier possibly because of the difference in chemical adsorption sites.     

Effect of Operating Parameters on Composition of Dry Gas Obtained During Gasoline Cracking Process

The influence of operating parameters on ethylene content in dry gas obtained during catalytic cracking of gasoline was investigated in a pilot fixed fluidized bed reactor in the presence of the MMC-2 catalyst.The results have shown that the majority of dry gas was formed during the catalytic cracking reaction of gasoline,with a small proportion of dry gas being formed through the thermal cracking reaction of gasoline.The ethylene content in dry gas formed during the catalytic cracking reaction was highe...     

环烷氧基硅为内给电子体的负载型Ziegler-Natta催化剂合成宽分子量分布聚乙烯

Two kinds of cycloalkoxy silane compounds were synthesized and used as the internal electron donors （IEDs） of supported Ziegler-Natta catalyst for ethylene polymerization to produce polyethylene with broader molecular weight distribution （MWD）, The effect of the structure and the amount of these IEDs on the polymerization performance was in- vestigated. The results implied that the molecular weight distribution of the obtained polyethylene could be adjusted by the incorporation of IEDs. SEM result showed that the morphology of catalyst particle was spherical and uniform in size distribution. The titanium content of these catalysts was higher, the active TiCl4 species were easily anchored on the support than that without adding IED, which was determined by ICE The GPC result confirmed that the polyethylene with broader molecular weight distribution in the range of from 23.4 to 25.6 was obtained using triethoxy-（-cyclopentyloxy）-silane （ED1） and triethoxy-（-cyclohexyloxyl）- silane （ED2） as the internal electron donors.     

Commercial Application of the RAR Sulfur Recovery and Tail Gas Treating Process

The 40kt/a sulfur recovery unit for tail gas treating applying the reduction-absorption-recycling (RAR) technology is aimed at regeneration of the rich amine solution and recovery of sulfur to operate in tandem with the 1.2Mt/a diesel hydrofining unit. The process unit calibration data have revealed that the recovery of total sulfur reaches 99.86%, which is 6.65 percentage points higher than that before application of the RAR technology. The SO2 content in vented tail gas is 0.27 t/d, which is much less than the latest emission standard prescribed by the State. The factors that can affect the unit operation have been analyzed and corresponding measures have been suggested including the necessity to improve the control over the reaction temperature in the tail gas hydrogenation unit.     

Exploitation of methane in the hydrate by use of carbon dioxide in the presence of sodium chloride

The replacement process of CH4 from CH4 hydrate formed in NaCl solution by using pressurized CO2 was investigated with a self-designed device at temperatures of 271.05,273.15 and 275.05 K and a constant pressure of 3.30 MPa.The mass fraction of the NaCl solution was either 0.5 wt% or 1.0 wt%.The effects of temperature and concentration of NaCl solution on the replacement process were investigated.Experimental results showed that high temperature was favorable to the replacement reaction but high NaCl concentration had a negative effect on the replacement process.Based on the experimental data,kinetic models of CH4 hydrate decomposition and CO2 hydrate formation in NaCl solution were established.The calculated activation energies suggested that both CH4 hydrate decomposition and CO2 hydrate formation are dominated by diffusion in the hydrate phase.     

Study on Filtration Performance of Silica／Alumina Slurry in the Process of Recycling Mother Liquor of NaY Zeolite

In order to recover the SiO2 contained in the mother liquor in the course of NaY zeolite synthesis to minimize pollution, the influence of various preparation conditions on the filtering velocity of gel slurry was studied using the SiO2/Al2O3 gel recovered from the NaY mother liquor in the laboratory. The results of study had shown that at a SiO2/Al2O3 ratio in the feed equating to 9:1 the SiO2 recovery rate and Al2O3 utilization rate were high with a faster flow velocity of the filtrate. The pH value of the system had great impact on the flow velocity of filtrate. Between the two methods for regulating the pH value, the one for formation of silica/alumina gel slurry by addition of sulfuric acid prior to adding aluminium sulfate in the solution could secure a faster filtration velocity. The filtration velocity was decreased in tandem with increasing SiO2 concentration in mother liquor, meanwhile an increase in dry filter cake yield.     

拟薄水铝石胶溶指数影响因素的研究

采用铝酸钠-硫酸铝中和法制备了拟薄水铝石,研究了制备过程中铝酸钠溶液质量浓度、中和温度、中和pH及老化时间等制备条件对拟薄水铝石胶溶指数的影响,并考察了拟薄水铝石的胶溶指数对Al2O3载体物性的影响。实验结果表明,当铝酸钠溶液质量浓度(以Al2O3计)为100～180 g/L、中和温度为55～70℃、中和pH为6.5～8.5、老化时间60～120 min的条件下,可得到胶溶指数较高的拟薄水铝石。拟薄水铝石的胶溶指数对Al2O3载体的压碎强度影响很大,一般要得到压碎强度大于60 N的Al2O3载体,拟薄水铝石的胶溶指数要大于85%;拟薄水铝石的胶溶指数对Al2O3载体的吸水率、比表面积和孔体积影响较小。     

NaAlO_2-Al_2(SO_4)_3法制备拟薄水铝石成胶机理的研究

研究了拟薄水铝石和三水氧化铝的生成机理。考察了成胶pH、成胶温度对生成物类型的影响,在此基础上确定了NaAlO2溶液和Al2(SO4)3溶液成胶过程中完全中和时的临界体积比Ψ/Ψ0,在成胶过程中,当Ψ/Ψ0≤1时,NaAlO2溶液与Al2(SO4)3溶液发生中和反应生成拟薄水铝石和/或碱式硫酸铝;当Ψ/Ψ0>1时,过量的NaAlO2溶液发生自发水解反应,生成三水氧化铝。     

采用NaAlO2-CO2连续中和法制备拟薄水铝石

采用NaAlO2-CO2连续中和方式制备拟薄水铝石,研究了连续中和-母液老化和连续中和-净水老化2种工艺的规律,探讨了不同中和pH值、老化方式、老化温度以及老化时间对产物性质的影响。采用XRD、BET、XRF、TEM等手段表征了产物的晶相、相对结晶度、晶粒尺寸、孔结构、比表面积、杂离子含量以及晶粒的形貌和堆积方式。结果表明,连续中和与间歇中和工艺反应规律相似,但连续中和工艺更易生成丝钠铝石;采用连续中和-净水老化工艺可有效避免丝钠铝石的生成;随着中和pH值下降,拟薄水铝石晶粒堆积更加致密,其焙烧所得?-Al2O3的孔容和比表面积均有所降低,最可几孔直径增大。     

硫酸铝法制备拟薄水铝石过程研究

采用硫酸铝法制备拟薄水铝石,设计正交试验考察多种因素对拟薄水铝石物化性质的影响。用X 射线衍射、氮吸附脱附、扫描电镜等方法分析了制备样品的三水铝石含量、晶相结构、孔结构以及微观形貌。正交试验结果表明：样品的三水铝石含量与成胶pH值密切相关;在所考察的因素中,成胶pH值、成胶温度、酸浓度、碱浓度、成胶时间、老化时间是影响拟薄水铝石孔性质的主要因素;制备比表面积大于280 m2/g且孔体积大于0.70 mL/g的拟薄水铝石,需控制成胶pH值在8.5左右,成胶温度高于70 ℃,硫酸铝的浓度大于130 g/L,偏铝酸钠的浓度200 g/L左右,成胶时间60 min,老化时间5 min;本试验得到的高比表面积、大孔体积的拟薄水铝石微观晶粒为棍棒状,这些晶粒的疏松堆积形成了较大的空隙。     

拟薄水铝石工业生产中三水氧化铝含量的控制

针对中国石化催化剂长岭分公司NaAlO2-Al2(SO4)3法生产的拟薄水铝石产品中三水氧化铝含量高的问题,在拟薄水铝石反应机理研究的基础上,发现原工艺宏观上酸碱处于当量反应时,不能完全避免微观区域内pH值波动带来的NaAlO2局部过量,是产品中三水氧化铝含量高的本质原因.三水氧化铝含量的增加会严重影响拟薄水铝石产品的...     

低堆密度大孔体积γ-Al_2O_3的制备与表征

以Al2(SO4)3和NH3.H2O为原料合成了拟薄水铝石,经煅烧得到γ-Al2O3;采用X射线衍射、透射电子显微镜、热重-示差扫描量热和压汞法等方法对拟薄水铝石和γ-Al2O3进行了表征。表征结果显示,低堆密度大孔体积的γ-Al2O3的较佳制备条件为:反应液的pH为8、Al3+浓度为0.9mol/L、反应时间60min、反应温度70℃、NH3.H2O的质量分数为21%、800℃下煅烧5h。在此条件下制备的γ-Al2O3的比表面积为207.43m2/g、总孔体积为2.93mL/g、堆密度为0.23g/mL,且具有双孔分布,其中孔径大于100nm的孔的体积占总孔体积的58.91%,适用于大分子脱氢催化剂的载体。     

异丙醇对从铝酸钠溶液中析出拟薄水铝石种分过程的影响

以拟薄水铝石为晶种、异丙醇为添加剂,从铝酸钠溶液中析出了具有活性Al_2O_3前体特性的拟薄水铝石。研究了异丙醇添加量、Al_2O_3质量浓度、苛性比(铝酸钠溶液中Na_2O和Al_2O_3的摩尔比)和晶种循环使用次数对铝酸钠溶液分解率(简称分解率)的影响。实验结果表明,异丙醇能有效强化铝酸钠溶液的种分过程,在Al_2O_3质量浓度为110 g/L、苛性比为1.50、晶种比(晶种与铝酸钠溶液中Al_2O_3的质量比)为1.0、125℃的温和水热条件下种分3 h时,添加5 mg/L异丙醇可使分解率从不添加异丙醇时的27.2%提高到46.7%,并且晶种连续循环使用3次后,分解率仍达到36.5%。添加异丙醇不改变种分产物的晶型,对其形貌和织构性质也没有显著影响,但可在一定程度上调节其结晶度并使孔分布更集中。     

硫酸铵改性Al_2O_3负载Ni基催化剂的异丁烷脱氢性能

采用浸渍法制备了含NiO质量分数为20%的NiO/(SO2-4)w-Al2O3(w为SO2-4质量分数)催化剂,借助X射线衍射仪、热重分析仪等对催化剂的性能进行了表征,同时考察了催化剂在560℃时的异丁烷脱氢反应性能。结果表明,NiO/Al2O3催化异丁烷脱氢时,异丁烷几乎全部转化为CH4和积炭,目的产物异丁烯收率为零。以硫酸铵改性NiO/Al2O3作为催化剂,不仅能明显改善异丁烷脱氢产物分布,大幅度提高异丁烯的选择性,还能抑制积炭生成;NiO/(SO2-4)32-Al2O3催化异丁烷脱氢反应性能为最佳,在反应7 h时,异丁烷转化率和异丁烯收率可分别达到34.5%,23.8%。     

HY分子筛的SO2吸附性能研究

以3种不同硅铝比的HY分子筛HY-1,HY-2,HY-3为吸附剂,在小型固定床评价装置上进行SO2动态吸附试验,考察HY分子筛的SO2吸附性能,得到饱和吸附容量与分子筛硅铝比的关系。釆用BET比表面积测试、X射线衍射、X射线荧光光谱和CO2/O2程序升温脱附等分析手段对HY-1,HY-2,HY-3进行物理化学性质表征,并将表征结果与SO2动态吸附试验结果相关联。结果表明：随着硅铝比增大,HY分子筛HY-1,HY-2,HY-3的SO2穿透时间依次减短,饱和吸附容量依次减小,增大硅铝比不利于HY分子筛吸附SO2;HY分子筛的SO2饱和吸附容量与其表面碱性位含量成正比;分子筛对SO2的吸附性能与其表面氧物种和含量直接相关,随硅铝比增大,HY分子筛表面化学吸附氧含量依次降低,其化学吸附SO2的量也依次降低。     

改性纳米二氧化钛光催化降解水中微量溶解性亚甲基蓝

以TiCl4,(NH4)2SO4为主要原料,采用溶胶-凝胶法制备了SO42-/TiO2光催化剂,利用X射线衍射仪对所制备试样进行了表征,并将其用于光催化降解水中微量亚甲基蓝。结果表明,SO24-离子的掺杂修饰,使纳米TiO2结构明显改善。确定出亚甲基蓝溶液降解的最佳工艺条件为:紫外光照射下,在石英试管中,亚甲基蓝的初始浓度为6～9mg/L,催化剂投加量为1.0～1.5g/L。