Plasma treated M1 MoVNbTeO_(x)-CeO_(2) composite catalyst for improved performance of oxidative dehydrogenation of ethane

High activity and productivity of MoVNbTeO_(x) catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE)for industrial application.In this work,phase-pure M1 with 30 wt%CeO_(2) composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between M1 and CeO_(2) capture active oxygen species in gas and transform V^(4+)to V^(5+)without damage to M1 structure.The space-time yield of ethylene of the plasma-treated catalyst was significantly increased,in which the catalyst shows an enhancement near~100% than that of phase-pure M1 at 400℃ for ODHE process.Plasma treatment for catalysts demonstrates an effective way to convert electrical energy into chemical energy in catalyst materials.Energy conversion is achieved by using the catalyst as a medium.

Adsorption dynamics of ethane from air in structured fixed beds with different microfibrous composites

Adsorption dynamics of ethane in two granular fixed beds and structured fixed beds with microfibrous composites was studied.5A zeolite membrane 5A/PSSF(paper-like sintered stainless steel fiber)and microfibrous entrapped activated carbon(MEAC)composites were prepared by wet layup papermaking/sintering technique and in-situ hydrothermal method.Microfibrous composites were characterized by X-ray diffraction,scanning electron microscopy and N2 adsorption/desorption.Structured fixed beds were designed by filling granular adsorbents(5A zeolite or activated carbon)and microfibrous composites at the inlet and outlet of the beds,respectively.Effects of flow rate,bed height and structure on the breakthrough curves were investigated.The length of unused bed(LUB)was determined,and Yoon–Nelson model was used to fit the breakthrough curves.The experimental results showed ethane was effectively adsorbed on the granular adsorbents and microfibrous composites.Both composites could decrease the LUB values and enhance bed utilization.All breakthrough curves fitted well to Yoon–Nelson model,with correlation coefficient exceeding 0.89.The adsorption rate of ethane could be improved in the structured fixed beds,which showed an enhanced mass transfer efficiency for ethane adsorption.LUB values of structured fixed beds with 5A/PSSF composites were larger,the bed utilization values were lower,and the adsorption rate constants were higher than those with MEAC composites under the same conditions.

乙烷-丙烷混合裂解不同维度的数值模拟

随着乙烯原料向着轻质化发展,乙烷、丙烷成为重要的裂解原料,乙烷-丙烷混合裂解自由基反应机理的研究对乙烯原料优化具有重要意义。利用FLUENT模拟软件对乙烷-丙烷混合裂解自由基反应机理进行一维和二维模拟,根据一维、二维模型轴向和径向的流速、温度、原料及产物浓度分布,分析其混合裂解规律。径向的传递过程会降低裂解温度,所需供热量减少,同时径向自由基的返混促进了管中心原料的裂解,因此二维模型中乙烯和甲烷的浓度高于一维模型。乙烷-丙烷混合裂解的链引发阶段只有丙烷参与,乙烷参与了链传递过程,反应体系内自由基需要一定量的积累后才生成乙烯和丙烯。

中高压贫气乙烷回收流程分析及优选

为解决中高压贫气乙烷回收流程中能耗高及设备利用率低带来的经济损失问题,对3种高效乙烷回收流程(部分气体循环流程RSV、带压缩的强精馏流程SRC、冷干气回流流程CRR)进行能耗、以及经济分析对比,选出最佳流程为SRC。在保证乙烷回收率在95%以上的条件下,利用HYSYS软件模拟计算。能耗分析表明,SRC流程能耗最低,比RSV和CRR分别低10.17%、2.25%。分析表明,主体工艺中SRC流程总损最小,比RSV和CRR分别低63.51%、11.73%。经济分析表明,SRC流程年消耗经济成本最低,年总经济效益最好,比RSV和CRR分别高4.98%、13.24%。

气相乙烷管道泄漏扩散特征模拟分析

为研究气相乙烷管道泄漏扩散后的影响,以某公司拟建的一条乙烷输送管道为工程背景,采用CFD(计算流体动力学)软件,对不同泄漏孔径、不同风速下的气相乙烷管道泄漏进行了模拟分析,探讨其泄漏扩散特征以及危险范围的演变情况。结果表明:随泄漏孔径增大,乙烷的扩散形状发生改变,小孔泄漏扩散在土壤中的形状演变特征分为前、中、后期3个阶段,而管道全尺寸泄漏在大气中的扩散分为无风时的垂直射流扩散以及有风时的横向扩散;随泄漏孔径的增大,乙烷泄漏扩散范围变大,危险区域变大;随风速增大,乙烷全尺寸泄漏扩散高度降低,且危险浓度最远扩散距离达到峰值的时间缩短。

不同温度下二氧化硫与乙烷水合物体系的模拟研究

采用分子动力学模拟计算方法,在10 MPa的压力条件下,对二氧化硫和乙烷水合物体系,分别在275、285、295、305 K等不同温度下的变化情况进行模拟研究。预测了二氧化硫、乙烷、水的扩散系数,探讨了密度、氢键数和配位数等结构性质。结果表明,水受到温度的影响较大,二氧化硫明显比乙烷更容易与水结合,乙烷被水和二氧化硫排挤而大量聚集,能够达到利用二氧化硫置换和收集乙烷的目的。

辨析基础有机化学教材中的争议问题:乙烷构象稳定性的来源

烷烃的构象及其稳定性是基础有机化学中重要的知识点,其中乙烷的交叉式与重叠式构象是其中最基础的部分。现行的国内外本科基础有机化学教材中关于乙烷的交叉式构象比重叠式构象稳定的原因给出了不同的解释,比较混乱,不易于本科教学。本文调研了文献,梳理出乙烷交叉式构象稳定性来源的不同论点和论据,并指出先前文献分析与计算方法的不足。通过文献调研,我们认为超共轭效应和空间位阻效应两种因素都需要写入教材中。

ODHE的世界展望与现代课题

ODHE的教育模式,近年来成为世界各国的教育新宠,它以先进的教学手段、灵活多样的教学方式,为没有机会或没有能力进入正规大学的学习者,提供了最佳的教育环境和教育条件,成为世界各国培养技能型人才最主要的教育手段,亚洲各国也同样享受着ODHE带来的利益,不过也面临着新的课题。

Electrifying Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) for focalized heating in oxygen transport membranes

Industry decarbonization requires the development of highly efficient and flexible technologies relying on renewable energy resources,especially biomass and solar/wind electricity.In the case of pure oxygen production,oxygen transport membranes(OTMs)appear as an alternative technology for the cryogenic distillation of air,the industrially-established process of producing oxygen.Moreover,OTMs could provide oxygen from different sources(air,water,CO_(2),etc.),and they are more flexible in adapting to current processes,producing oxygen at 700^(-1)000℃.Furthermore,OTMs can be integrated into catalytic membrane reactors,providing new pathways for different processes.The first part of this study was focused on electrification on a traditional OTM material(Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)),imposing different electric currents/voltages along a capillary membrane.Thanks to the emerging Joule effect,the membrane-surface temperature and the associated O_(2) permeation flux could be adjusted.Here,the OTM is electrically and locally heated and reaches 900℃on the surface,whereas the surrounding of the membrane was maintained at 650℃.The O_(2)permeation flux reached for the electrified membranes was~3.7 NmL min^(-1)cm^(-2),corresponding to the flux obtained with an OTM non-electrified at 900℃.The influence of depositing a porous Ce_(0.8)Tb_(0.2)O_(2-δ) catalytic/protective layer on the outer membrane surface revealed that lower surface temperatures(830℃)were detected at the same imposed electric power.Finally,the electrification concept was demonstrated in a catalytic membrane reactor(CMR)where the oxidative dehydrogenation of ethane(ODHE)was carried out.ODHE reaction is very sensitive to temperature,and here,we demonstrate an improvement of the ethylene yield by reaching moderate temperatures in the reaction chamber while the O_(2) injection into the reaction can be easily fine-tuned.

干气回收装置运行问题及对策

对浙江石油化工有限公司干气回收装置的运行情况进行了分析,并提出了相应的优化措施。结果表明:该干气回收装置运行中,存在干气实际产量高于设计值,多出部分只能在饱和干气压缩机入口缓冲罐顶部排放火炬的问题。通过采用将浆态床干气在上游装置改出,装置原料不足部分,由一期装置重整氢变压吸附氢气提纯解析气进行补充的方案,可实现原料气的优化。优化后,在装置总加工量不变的条件下,富乙烷气产量由优化前的62.02 t/h增至70.37 t/h,氢气产量也由优化前的57300 m^(3)/h降至53500 m^(3)/h。

富气乙烷回收工艺改进及能耗分析

目的针对国内处理原料气在气质较富时乙烷回收装置单一、产物回收率低的问题,在原有工艺冷干气回流流程(cold residue reflux process,CRR)的基础上提出两种高效乙烷回收流程,即带闪蒸的冷干气回流流程(cold residue reflux process with flash evaporator,CRR-FE)和部分原料气过冷分离的冷干气回流流程(cold residue reflux process with feed subcooled,CRR-PS)。方法在保证乙烷回收率高于95%的条件下,利用HYSYS软件模拟改进工艺流程,设置了3组逐渐变富的气质对CRR及改进流程进行了综合能耗和火用分析对比。结果改进后的流程有很好的节能效果,其中CRR-PS流程节能效果明显,在GPM值为4.3时,CRR-PS流程综合能耗节约了9.4%。3种流程火用损最大为主体设备压缩机中的外输压缩机,其次是塔设备中脱甲烷塔和丙烷制冷,最后是换热器、空冷器及水冷器;改进后的流程性能很好,整体火用效率在80%以上,总火用效率排序为CRR-PS>CRR-FE>CRR;当GPM值为4.3时,CRR-PS火用损为28471 kW,相比于CRR降低了3.9%,表明CRR-PS火用损失较少,有很好的节能潜力。结论CRR-PS流程对富气适应性更强,节能效果更好。

CO_(2)氧化乙烷脱氢制乙烯铬基催化剂研究进展

CO_(2)氧化乙烷脱氢制乙烯具有热力学更可行,乙烷转化率和乙烯选择性高,抑制积炭以及缓解温室效应等优点,备受研究者关注。综述近年来CO_(2)氧化乙烷脱氢制乙烯中铬基催化剂的研究进展,重点介绍铬催化的CO_(2)氧化乙烷脱氢反应机理,评述调变载体、助剂以及制备方法对催化性能的影响,并对后续催化剂的研究方向和应用前景作了展望。

液相乙烷输送管道放空工况研究

针对乙烷具有较低的临界温度和临界压力,放空过程中易发生相变的问题,建立乙烷管道瞬态放空模型,分析放空过程中管内乙烷参数响应规律。结果表明液相乙烷管道放空经历三个阶段,第一阶段压力迅速下降,液相乙烷进入气液两相区。第二阶段是气液共存阶段,温度压力沿着相态包络线逐渐下降,管内气相持续增加。第三阶段乙烷由气液两相全部变为气相,温度开始升高。分析了不同放空管径、初始压力、初始温度等因素的影响机制,提出“大管径+稳定时间+小管径”的液相乙烷管道放空方式,为液相乙烷管道放空系统设计提供参考与借鉴。

最大规模浅冷油吸收法C_(1)/C_(2)分离技术工业应用实践

某公司采用浅冷油吸收法干气回收专利技术新建了一套C_(1)/C_(2)分离装置,以正丁烷为吸收剂吸收干气中的碳二馏分,再以重石脑油为吸收剂回收燃料气中夹带的碳四馏分,得到富乙烷气、轻烃和粗氢气分别送入乙烯装置、液化气分离装置和PSA装置。该分离装置规模达到了1.6 Mt/a,可以实现将20 Mt/a炼化一体化项目中炼油装置的干气全部加工。装置投产运行1年后进行了标定,结果显示,乙烷回收率和纯度分别达到了92.7%和93.7%,产品分布良好,综合能耗达标,表明该技术的选择成熟可靠,值得推广应用。

Promoted catalytic performances of highly dispersed V-doped SBA-16 catalysts for oxidative dehydrogenation of ethane to ethylene

V-doped SBA-16 catalysts(V-SBA-16) with 3D nanocage mesopores have been successfully synthesized by a modified one-pot method under weak acid condition.The obtained materials were characterized by means of small angle XRD,N_2 adsorption–desorption,TEM,UV–Vis and UV-Raman spectroscopy.These characterization results indicated that well-order mesoporous structures were maintained even at higher vanadium loadings and high concentration of VOx species were incorporated into the framework of SBA-16 support.The catalytic performances of V-SBA-16,V/SBA-16 and V/Si O_2 catalysts were comparatively investigated for the oxidative dehydrogenation of ethane to ethylene.The highest selectivity to ethylene of 63.3% and ethylene yield of 25.6% were obtained over 1.0V-SBA-16 catalyst.The superior catalytic performance of V-SBA-16 catalysts could be attributed to the presence of isolated framework VO x species,the unique structure of SBA-16 support and weak acidity.Moreover,V/Si O_2 catalyst exhibited relatively poor catalytic activity duo to the formation of V_2O_5 nanoparticles on the surface of Si O_2 support and the low dispersion of VO x species.These results indicated that the catalytic performances of the studied catalysts were strongly dependent on the vanadium loading,the nature and neighboring environment of VO x species and the structure of support.

Room-temperature conversion of ethane and the mechanism understanding over single iron atoms confined in graphene

The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.

Synthesis and Spectral Properties of Mixed-Ligand Complexes of Lanthanide Perchlorate with Bis-(phenylsulfinyl)ethane and Organic Lewis Bases

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Reversed ethane/ethylene adsorption in a metal–organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry.Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year.Adsorptive separation using C2H6-selective porous materials to directly produce high-purity C2H4 is more energy-efficient.We herein report the"reversed C2H6/C2H4 adsorption"in a metal–organic framework Cr-BTC via the introduction of oxygen on its open metal sites.The oxidized Cr-BTC(O2)can bind C2H6 over C2H4 through the active Cr-superoxo sites,which was elucidated by the gas sorption isotherms and density functional theory calculations.This material thus exhibits a good performance for the separation of 50/50 C2H6/C2H4 mixtures to produce 99.99%pure C2H4 in a single separation operation.

Visible-light driven room-temperature coupling of methane to ethane by atomically dispersed Au on WO_(3)

Gold(Au)as co-catalyst is remarkable for activating methane(CH4),especially atomically dispersed Au with maximized exposing active sites and specific electronic structure.Furthermore,singlet oxygen(^(1)O_(2))typically manifests a mild redox capacity with a high selectivity to attack organic substrates.Peroxomonosulfate(PMS)favors to produce oxidative species 102 during the photocatalytic reactions.Thus,combining atomic Au as co-catalyst and ^(1)O_(2) as oxidant is an effective strategy to selectively convert CH4.Herein,we synthesized atomically dispersed Au on WO_(3)(Au/WO_(3)),where Au was in the forms of single atoms and clusters.At room temperature,such Au/WO_(3) exhibited enhanced photocata lytic conversion of CH4 to CH3 CH3 with a selectivity,up to 94%,under visible light.The radicals-pathway mechanism of CH4 coupling has also been investigated through detection and trapping experiment of active species.Theoretical calculations further interpret the electronic structure of Au/WO_(3) and tip-enhanced local electric field at the Au sites for promoting CH4 conversion.

Identifying factors controlling the selective ethane dehydrogenation on Pt-based catalysts from DFT based micro-kinetic modeling

Light olefins such as ethylene and propylene are important industrial feedstocks, having essential applications in the production of plastics, ethylbenzene, and ethylene dichloride [1]. Compared with the conventional route, in which alkane steam cracking (SC) at high temperature is applied to produce ethylene and propylene, the catalytic ethane/propane non-oxidative dehydrogenation (EDH/PDH) possess the advantages of high selectivity and low energy consumption. Industrially, Pt is the major component to catalyze this reaction, but it suffers from low selectivity and fast deactivation because of favorable coke formation [2].