Casein kinase-2 inhibition promotes retinal ganglion cell survival after acute intraocular pressure elevation

Intraocular pressure elevation can induce retinal ganglion cell death and is a clinically reversible risk factor for glaucoma,the leading cause of irreversible blindness.We previously demonstrated that casein kinase-2 inhibition can promote retinal ganglion cell survival and axonal regeneration in rats after optic nerve injury.To investigate the underlying mechanism,in the current study we increased the intraocular pressure of adult rats to 75 mmHg for 2 hours and then administered a casein kinase-2 inhibitor(4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole)by intravitreal injection.We found that intravitreal injection of 4,5,6,7-tetrabromo-2-azabenzimidazole or 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole promoted retinal ganglion cell survival and reduced the number of infiltrating macrophages.Transcriptomic analysis showed that the mitogen activated protein kinase signaling pathway was involved in the response to intraocular pressure elevation but was not modulated by the casein kinase-2 inhibitors.Furthermore,casein kinase-2 inhibition downregulated the expression of genes(Cck,Htrsa,Nef1,Htrlb,Prph,Chat,Slc18a3,Slc5a7,Scn1b,Crybb2,Tsga10ip,and Vstm21)involved in intraocular pressure elevation.Our data indicate that inhibition of casein kinase-2 can enhance retinal ganglion cell survival in rats after acute intraocular pressure elevation via macrophage inactivation.

Analysis of pressure response at an observation well against pressure build-up by early stage of CO_(2)geological storage project

To ensure a safe and stable CO_(2)storage,pressure responses at an observation well are expected to be an important and useful field monitoring item to estimate the CO_(2)storage behaviors and the aquifer parameters during and after injecting CO_(2),because it can detect whether the injected CO_(2)leaks to the ground surface or the bottom of the sea.In this study,pressure responses were simulated to present design factors such as well location and pressure transmitter of the observation well.Numerical simulations on the pressure response and the time-delay from pressure build-up after CO_(2)injection were conducted by considering aquifer parameters and distance from the CO_(2)injection well to an observation well.The measurement resolution of a pressure transmitter installed in the observation well was presented based on numerical simulation results of the pressure response against pressure build-up at the injection well and CO_(2)plume front propagations.Furthermore,the pressure response at an observation well was estimated by comparing the numerical simulation results with the curve of CO_(2)saturation and relative permeability.It was also suggested that the analytical solution can be used for the analysis of the pressure response tendency using pressure build-up and dimensionless parameters of hydraulic diffusivity.Thus,a criterion was established for selecting a pressure transducer installed at an observation well to monitor the pressure responses with sufficient accuracy and resolution,considering the distance from the injection well and the pressure build-up at the injection well,for future carbon capture and storage(CCS)projects.

Unveiling the pressure-driven metal–semiconductor–metal transition in the doped TiS_(2)

Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands,leading to increased electrical conductivity.Here,we report the electrical properties of the doped 1T-TiS_(2) under high pressure by electrical resistance investigations,synchrotron x-ray diffraction,Raman scattering and theoretical calculations.Up to 70 GPa,an unusual metal-semiconductor-metal transition occurs.Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17 GPa is due to the electron localization induced by the intercalated Ti atoms.This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms,and the Anderson localization arising from the disordered intercalation.At pressures exceeding 30.5 GPa,the doped TiS_(2) undergoes a re-metallization transition initiated by a crystal structure phase transition.We assign the most probable space group as P2_12_12_1.Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.

Evaluation of surface temperature and pressure derived from MERRA-2 and ERA5 reanalysis datasets and their applications in hourly GNSS precipitable water vapor retrieval over China

Temperature and pressure play key roles in Global Navigation Satellite System(GNSS) precipitable water vapor(PWV) retrieval. The National Aeronautics and Space Administration(NASA) and European Center for Medium-Range Weather Forecasts(ECMWF) have released their latest reanalysis product: the modern-era retrospective analysis for research and applications, version 2(MERRA-2) and the fifthgeneration ECMWF reanalysis(ERA5), respectively. Based on the reanalysis data, we evaluate and analyze the accuracy of the surface temperature and pressure products in China using the the measured temperature and pressure data from 609 ground meteorological stations in 2017 as reference values.Then the accuracy of the two datasets and their performances in estimating GNSS PWV are analyzed. The PWV derived from the pressure and temperature products of ERA5 and MERRA-2 has high accuracy. The annual average biases of pressure and temperature for ERA5 are-0.07 hPa and 0.45 K, with the root mean square error(RMSE) of 0.95 hPa and 2.04 K, respectively. The annual average biases of pressure and temperature for MERRA-2 are-0.01 hPa and 0.38 K, with the RMSE of 1.08 h Pa and 2.66 K, respectively.The accuracy of ERA5 is slightly higher than that of MERRA-2. The two reanalysis data show negative biases in most regions of China, with the highest to lowest accuracy in the following order: the south,north, northwest, and Tibet Plateau. Comparing the GNSS PWV calculated using MERRA-2(GNSS MERRA-2 PWV) and ERA5(GNSS ERA5 PWV) with the radiosonde-derived PWV from 48 co-located GNSS stations and the measured PWV of the co-location radiosonde stations, it is found that the accuracy of GNSS ERA5 PWV is better than that of GNSS MERRA-2 PWV. These results show the different applicability of surface temperature and pressure products from MERRA-2 and ERA5 data, indicating that both have important applications in meteorological research and GNSS water vapor monitoring in China.

Cloud Top Pressure Retrieval Using Polarized and Oxygen A-band Measurements from GF5 and PARASOL Satellites

Cloud top pressure(CTP)is one of the critical cloud properties that significantly affects the radiative effect of clouds.Multi-angle polarized sensors can employ polarized bands(490 nm)or O_(2)A-bands(763 and 765 nm)to retrieve the CTP.However,the CTP retrieved by the two methods shows inconsistent results in certain cases,and large uncertainties in low and thin cloud retrievals,which may lead to challenges in subsequent applications.This study proposes a synergistic algorithm that considers both O_(2)A-bands and polarized bands using a random forest(RF)model.LiDAR CTP data are used as the true values and the polarized and non-polarized measurements are concatenated to train the RF model to determine CTP.Additionally,through analysis,we proposed that the polarized signal becomes saturated as the cloud optical thickness(COT)increases,necessitating a particular treatment for cases where COT<10 to improve the algorithm's stability.The synergistic method was then applied to the directional polarized camera(DPC)and Polarized and Directionality of the Earth’s Reflectance(POLDER)measurements for evaluation,and the resulting retrieval accuracy of the POLDER-based measurements(RMSEPOLDER=205.176 hPa,RMSEDPC=171.141 hPa,R^(2)POLDER=0.636,R^(2)DPC=0.663,respectively)were higher than that of the MODIS and POLDER Rayleigh pressure measurements.The synergistic algorithm also showed good performance with the application of DPC data.This algorithm is expected to provide data support for atmosphere-related fields as an atmospheric remote sensing algorithm within the Cloud Application for Remote Sensing,Atmospheric Radiation,and Updating Energy(CARE)platform.

Integrated vacuum pressure swing adsorption and Rectisol process for CO_(2) capture from underground coal gasification syngas

An integrated vacuum pressure swing adsorption(VPSA) and Rectisol process is proposed for CO_(2) capture from underground coal gasification(UCG) syngas. A ten-bed VPSA process with silica gel adsorbent is firstly designed to pre-separate and capture 74.57% CO_(2) with a CO_(2) purity of 98.35% from UCG syngas(CH_(4)/CO/CO_(2)/H_(2)/N_(2)= 30.77%/6.15%/44.10%/18.46%/0.52%, mole fraction, from Shaar Lake Mine Field,Xinjiang Province, China) with a feed pressure of 3.5 MPa. Subsequently, the Rectisol process is constructed to furtherly remove and capture the residual CO_(2)remained in light product gas from the VPSA process using cryogenic methanol(233.15 K, 100%(mass)) as absorbent. A final purified gas with CO_(2) concentration lower than 3% and a regenerated CO_(2) product with CO_(2) purity higher than 95% were achieved by using the Rectisol process. Comparisons indicate that the energy consumption is deceased from 2.143 MJ·kg^(-1) of the single Rectisol process to 1.008 MJ·kg^(-1) of the integrated VPSA & Rectisol process, which demonstrated that the deployed VPSA was an energy conservation process for CO_(2) capture from UCG syngas. Additionally, the high-value gas(e.g., CH_(4)) loss can be decreased and the effects of key operating parameters on the process performances were detailed.

First-principles study of moderate phonon-mediated pairing in high-pressure monoclinic phase of BiS_(2)-based superconductors

Isotope effect on superconductive transition temperature(T_c)is an essential indicator to examine whether the mechanism of superconductors is conventional.Unconventional isotope effect of BiS_(2)-based superconductors has been previously reported in ambient-pressure tetragonal phase.However,to comprehensively ascertain the nature of superconductivity,the investigation of BiS_(2)-based system in high-pressure structure is highly desirable.In this work,we carried out the first-principles calculations of phonon spectra and superconductivity in high-pressure monoclinic phase of LaO_(0.5)F_(0.5)BiS_(2)with ^(32)S and ^(34)S,and observed that the corresponding isotope coefficient is 0.13≤α≤0.20.This value is much greater than that of BiS_(2)-based superconductors in ambient-pressure phase,but slightly smaller than that of conventional MgB_2.Taking into account the calculated T_(c) lower than experimental results,we finally conclude that the moderate phonon-mediated pairing plays a significant role in forming superconductivity of BiS_(2)-based system in high-pressure phase,moreover,the cooperative multiple paring interactions should also be considered.

Pressure induced insulator to metal transition in quantum spin liquid candidate NaYbS_(2)

Pressure induced insulator to metal transition followed by the appearance of superconductivity has been observed recently in inorganic quantum spin liquid candidate NaYbSe_(2).In this paper,we study the properties of isostructural compound NaYbS_(2)under pressure.It is found that the resistance of Na YbS_(2)single crystal exhibits an insulating state below 82.9 GPa,but with a drop of more than six orders of magnitude at room temperature.Then a minimum of resistance is observed at about 100.1 GPa and it moves to lower temperature with further compression.Finally,a metallic state in the whole temperature range is observed at about 130.3 GPa accompanied by a non-Fermi liquid behavior below 100 K.The insulator to metal transition,non-monotonic resistance feature and non-Fermi liquid behavior of NaYbS_(2)under pressure are similar to those of NaYbSe_(2),suggesting that these phenomena might be the universal properties in NaLnCh_(2)(Ln=rare earth,Ch=O,S,Se)system.

Structural stability and ion migration of Li_(2)MnO_(3) cathode material under high pressures

Some special fields,such as deep-sea exploration,require batteries and their electrode materials to withstand extremely high pressure.As the cathode material has the highest energy density,Li-excess Mn-based materials are also likely to be utilized in such an environment.However,the effect of pressure on the crystal structure and migration barrier of this kind of material is still not clear at present.Therefore,in this study,we investigate the properties of the matrix material of Li-excess Mn-based material,Li_(2)MnO_(3),under high pressure.The equation of state,bulk modulus,and steady-state volume of Li_(2)MnO_(3) are predicted by the method of first principles calculation.The calculations of unit cells at different pressures reveal that the cell parameters suffer anisotropic compression under high pressure.During compression,Li-O bond is more easily compressed than Mn-O bond.The results from the climbing image nudged elastic band(CINEB)method show that the energy barrier of Li^(+)migration in the lithium layer increases with pressure increasing.Our study can provide useful information for utilizing Li-excess Mn-based materials under high pressure.

A Numerical Simulation Study of Temperature and Pressure Effects on the Breakthrough Pressure of CO_(2)in Unsaturated Low-permeability Rock Core

Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock,and it also plays important roles in safety and capacity of CO_(2)geological storage.Based on the published experimental results,we present numerical simulations on CO_(2)breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions(which can keep CO_(2)in gaseous,liquid and supercritical states)and thus,a numerical method which can be used to accurately predict CO_(2)breakthrough pressure on rock-core scale is proposed.The simulation results show that CO_(2)breakthrough pressure and breakthrough time are exponential correlated with P-T conditions.Meanwhile,pressure has stronger effects on experimental results than that of temperature.Moreover,we performed sensitivity studies on the pore distribution indexλ(0.6,0.7,0.8,and 0.9)in van Genuchten-Muale model.Results show that with the increase ofλ,CO_(2)breakthrough pressure and breakthrough time both show decreasing trends.In other words,the larger the value ofλis,the better the permeability of the caprock is,and the worse the CO_(2)sealing capacity is.The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies.

Effect of N_(2) partial pressure on comprehensive properties of antibacterial TiN/Cu nanocomposite coating

Foreign body reactions to the wear debris and corrosion products from the implants,and bacterial infections are the main factors leading to the implant failures.In order to resolve these problems,the antibacterial TiN/Cu nanocomposite coatings with various N_(2) partial pressures were deposited on 304 stainless steels(SS)using an arc ion plating(AIP)system,named TiN/Cu-x(x=0.5,1.0,1.5 Pa).The results of X-ray diffraction analysis,energy-dispersive X-ray spectroscopy,and scanning electron microscopy showed that the N_(2) partial pressures determined the Cu contents,surface defects,and crystallite sizes of TiN/Cu nanocomposite coatings,which further influenced the comprehensive abilities.And the hardness and wear resistances of TiN/Cu coatings were enhanced with increase of the crystallite sizes.Under the co-actions of surface defects,crystallite sizes,and Cu content,TiN/Cu-1.0 and TiN/Cu-1.5 coatings possessed excellent corrosion resistance.Besides,the biological tests proved that all the TiN/Cu coatings showed no cytotoxicity with strong antibacterial ability.Among them,TiN/Cu-1.5 coating significantly promoted the cell proliferation,which is expected to be a novel antibacterial,corrosion-resistant,and wear-resistant coating on the surfaces of medical implants.

The effects of radio frequency atmospheric pressure plasma and thermal treatment on the hydrogenation of TiO_(2) thin film

The effects of radio frequency(RF)atmospheric pressure(AP)He/H_(2)plasma and thermal treatment on the hydrogenation of TiO_(2)thin films were investigated and compared in this work.The color of the original TiO_(2)film changes from white to black after being hydrogenated in He/H_(2)plasma at160 W(gas temperature~381℃)within 5 min,while the color of the thermally treated TiO_(2)film did not change significantly even in pure H_(2)or He/H_(2)atmosphere with higher temperature(470℃)and longer time(30 min).This indicated that a more effective hydrogenation reaction happened through RF AP He/H_(2)plasma treatment than through pure H_(2)or He/H_(2)thermal treatment.The color change of TiO_(2)film was measured based on the Commission Internationale d’Eclairage L*a*b*color space system.Hydrogenated TiO_(2)film displayed improved visible light absorption with increased plasma power.The morphology of the cauliflower-like nanoparticles of the TiO_(2)film surface remained unchanged after plasma processing.X-ray photoelectron spectroscopy results showed that the contents of Ti3+species and Ti-OH bonds in the plasma-hydrogenated black TiO_(2)increased compared with those in the thermally treated TiO_(2).X-ray diffraction(XRD)patterns and Raman spectra indicated that plasma would destroy the crystal structure of the TiO_(2)surface layer,while thermal annealing would increase the overall crystallinity.The different trends of XRD and Raman spectra results suggested that plasma modification on the TiO_(2)surface layer is more drastic than on its inner layer,which was also consistent with transmission electron microscopy results.Optical emission spectra results suggest that numerous active species were generated during RF AP He/H_(2)plasma processing,while there were no peaks detected from thermal processing.A possible mechanism for the TiO_(2)hydrogenation process by plasma has been proposed.Numerous active species were generated in the bulk plasma region,accelerated in the sheath region,and bumped toward the TiO_(2)film,which will react with the TiO_(2)surface to form OVs and disordered layers.This leads to the tailoring of the band gap of black TiO_(2)and causes its light absorption to extend into the visible region.

不同流向上小流道加热管内超临界CO_(2)的压降特性

针对不同流动方向上超临界CO_(2)流体在小流道加热管径为0.75mm内的压降特性进行了实验研究。结果表明,不同流动(水平流动、垂直向上流动以及垂直向下流动)方向上,实验总压降、摩擦压降以及加速度压降均随着系统压力的升高而逐渐减小,而随着质量流量的增大、加热功率以及进口温度的升高而增大。然而,在垂直流动方向上重力压降随着系统压力的升高以及质量流量的增大而逐渐增大,但随着加热功率以及进口温度的升高而逐渐减小。当系统压力、质量流量、加热功率以及进口温度保持恒定时,不同流动方向上超临界CO_(2)流体的摩擦压降均在实验总压降中所占有的比例最大,而重力压降在实验总压降中所占有的比例最小。通过两种测试管径的压降数据比较可知,超临界CO_(2)流体在不同流动方向上实验总压降的变化趋势始终保持一致,并且小管径的实验总压降远大于大管径的实验总压降,从而说明测试管径的尺寸大小对实验总压降的变化有着显著影响。

CO_(2)-EOR过程中油藏储层构造封存能力的模拟

为应对日益严峻的能源危机和温室效应,CO_(2)提高采收率技术脱颖而出,因此CO_(2)提高采收率后的地质封存安全性和相应的封存能力评估引起了广泛关注。借助数值模拟方法,基于吉林油田某区块油藏的实际储层条件,构建了注入CO_(2)含量为10%~90%的9个模型,分别探究了含水饱和度为30%,50%和90%以及储层压力为10 MPa,20 MPa和30 MPa时油藏各相组分的分布规律;基于前人对封存CO_(2)安全储存状态划分的研究,最终明确了CO_(2)的安全封存量。结果表明:1)当含水饱和度(30%)和压力(10 MPa)一定时,增加CO_(2)含量(10%~90%)可大幅提高CO_(2)的有效封存体积分数(26%~93%);2)压力的提升(10~30 MPa)促进了CO_(2)在油相中的溶解,从而略微降低了储层的封存能力(18%~7%);3)含水饱和度对储层封存CO_(2)的能力的影响微乎其微。该研究旨在阐明不同条件下CO_(2)的构造埋存量,为相关研究提供借鉴。

基于恒定梯度编码一维选层T_(2)谱的胶结砂岩层析成像方法

核磁共振成像是探究岩心尺度非均质性的先进技术,受岩石复杂性和编码技术影响,现有方法效果不佳。基于梯度场的二维/三维核磁共振技术成像容易但信噪比低,无梯度场的传统选层T_(2)谱(频率编码/相位编码)方法效率低。该研究提出恒定梯度编码一维选层T_(2)谱层析成像方法,做到了成像数据体量小、信噪比高且信号更完整。层析T_(2)谱图像及其热度分布,能够有效表征毛细管压力和成岩作用对流体非均匀分布的影响。饱和油状态时,T_(2)谱层间差异性反映成岩作用影响。高饱和油阶段,轴向热度图反映了低毛细管压力游离油的脱出规律。完全驱替后毛细管压力进入稳定状态,轴向热度图反映了微孔中吸附油赋存状态的差异。该技术在胶结砂岩气驱油实验中取得了良好效果,并对解析强非均质岩石渗流规律有重要作用。

高压水蒸气对β-Li_(2)TiO_(3:)Eu^(3+)荧光粉的全谱发光性能影响

采用水热法制备荧光粉前驱体后通过高温煅烧的方法,合成了由电偶极跃迁主导的高色纯度的β-Li_(2)TiO_(3):Eu^(3+)红色荧光粉.设计了适用于DHT11的拓扑电路,对荧光粉体湿度和温度进行测试.研究发现,高压腔体中加水量为5 mL,β-Li_(2)TiO_(3):0.5 mol%Eu^(3+)的相对湿度可达81%RH.在波长为396 nm的近紫外光激发下,β-Li_(2)TiO_(3):0.5 mol%Eu^(3+)发射由电偶极跃迁主导的613 nm的红光,荧光寿命为773.36μs,高压水蒸气处理对β-Li_(2)TiO_(3):0.5 mol%Eu^(3+)的电偶极跃迁发射峰和磁偶极跃迁发射峰位置没有变化,但发射峰强度增强并且荧光寿命降至386.81μs.高压水蒸气高压处理后的荧光粉色坐标x=0.47,y=0.51,色温为3300 K,红光色纯度为96.6%,比高压处理前显示出更优异的显色性能.高压水蒸气处理后的β-Li_(2)TiO_(3):0.5 mol%Eu^(3+)电偶极跃迁谱线强度参数Ω_(2)增加至4.21×10^(-19)cm^(2),^(5)D_(0)→^(7)F_(2)跃迁的荧光分支比β2也增加至96.9%,而量子效率η减小至57%,证实了湿度对荧光粉的发光效率具有极大的影响.

CO_(2)分注井气嘴节流特性及矿场应用

为了解决CO_(2)分注井节流压差建立困难,气嘴易冲蚀的技术难题,通过构建CO_(2)物性变化的流动-传热耦合模型,揭示2级和3级节流气嘴的流场演化机制,优化设计气嘴结构、建立了绕流气嘴节流图版并开展现场应用。结果表明:流量为10 m3/d时,2级嘴径1.4 mm和3级嘴径1.6 mm的绕流气嘴分别能产生将近6 MPa和8 MPa的节流压差,证明绕流气嘴结构合理、性能可靠、能够达到调整层间压差的技术要求;参照气嘴图版优选的节流气嘴,现场应用20口井,节流压差可达4 MPa左右,调整后注入压力上升2.4 MPa,加强层相对吸气比例由9.7%上升至50.7%,有效调整了层间差异,解决了分注井小层吸气不均的问题。研究结果指导现场测调,为CO_(2)分注规模化应用提供技术支撑。

第一性原理研究压力对Fe_(2)B的结构、机械性质的影响

基于密度泛函理论的第一性原理方法,系统研究了0~30 GPa压力下四方相Fe_(2)B的结构,稳定性和力学性质等.随着压力的增加,计算得到的晶格参数逐渐减小,所有结构均满足热力学稳定性,体积模量和剪切模量逐渐增大,韧性得到有效改善.硬度呈现先增大后减小的趋势,并在18 GPa压力时达到最大值,各向异性先增大后减小.德拜温度变化趋势与杨氏模量的变化趋势相同.同时还研究了相变结构——正交相的相关性质,结果表明其结构满足热力学稳定性但不满足力学稳定性,是否稳定存在还需要进行后续实验研究.

南川常压海相页岩气注CO_(2)吞吐提高采收率工程实践

当前研究实验和模拟论证了注CO_(2)吞吐提高页岩气采收率的理论可行性,然而其实际工程效果尚未得到现场试验的验证。为此,基于四川盆地南川常压海相页岩气藏地质赋存及生产特征,开展了页岩等温吸附和CO_(2)—CH_(4)竞争吸附机理研究,实施了国内首次常压海相页岩气衰减井CO_(2)吞吐现场试验,并提出了构建成套技术体系的攻关方向。研究结果表明:①气井生产到后期进入低压低产阶段,表现出地层能量不足的特征,是提高气井采出程度的重要阶段;②常压页岩的CH_(4)和CO_(2)吸附能力明显高于低压或高压页岩,采用CO_(2)提采更具可行性和必要性;③相同条件下的常压、高压和低压3组页岩样品均表现出对CO_(2)的吸附量大于对CH_(4)的吸附量,且对气体的吸附能力依次为南川(常压海相)页岩>长宁(高压海相)页岩>延长(低压陆相)页岩;④试验井注CO_(2)吞吐增产效果明显,页岩气单井预测最终可采储量(EUR)从0.75×10^(8) m^(3)上升到0.90×10^(8) m^(3),单井控制储量5.186×10^(8) m^(3),预计采收率提高了2.9%。结论认为:①实施的国内首次常压海相页岩气衰减井注CO_(2)吞吐试验取得突破性进展,为我国页岩气井提高采收率技术研发与应用提供了重要借鉴与参考;②亟需开展页岩气衰减井CO_(2)提采资源潜力与时机评估、提采效果定量评价与工艺优化等研究,并形成页岩气衰减井注CO_(2)吞吐提高采收率成套关键技术及标准体系。

Effect of Reaction Temperature and Pressure on the Metathesis Reaction between Ethene and 2-Butene to Propene on the WO_3/Al_2O_3-HY Catalyst

Effect of reaction temperature and pressure on the metathesis reaction between ethene and 2-butene to propene was studied on the WO3/γ-Al2O3-HY catalyst. The activity is found to increase with elevated temperature and reaches a plateau at 150-240 ℃. After that, the activity undergoes a remarkable decrement at too high temperature. The effect of temperature is elucidated by the oxidation state of tungsten species. The evaluation results also indicate that the stability is dependent on this reaction parameter. Medium pressure （0.5-0.8 MPa） is favorable for stability, while atmospheric pressure or too high pressure （〉1.0 MPa） deteriorates the stability. For explanation, UV Vis, FT-IR, O2-TPO, and TG techniques are used to characterize the spent catalysts.