Ca_(2)MnO_(4)-layered perovskite modified by NaNO_(3)for chemical-looping oxidative dehydrogenation of ethane to ethylene

Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.

Surface Acidity/Basicity and Catalytic Reactivity of CeO2/7-Al2O3 Catalysts for the Oxidative Dehydrogenation of Ethane with Carbon Dioxide to Ethylene

Dehydrogenation of ethane to ethylene in CO_2 was investigated overCeO_2/γ-Al_2O_3 catalysts at 700℃ in a conventional flow reactor operating at atmosphericpressure. XRD, BET and microcalori-metric adsorption techniques were used to characterize thestructure and surface acidity/basicity of the CeO_2/γ-Al_2O_3 catalysts. The results show that thesurface acidity decreased while the surface basicity increased after the addition of CeO_2 toγ-Al_2O_3. Accordingly, the activity of the hydrogenation reaction of CO_2 increased, which mightbe responsible for the enhanced conversion in the dehydrogenation of ethane to ethylene. The highestethane conversion obtained was about 15% for the 25%CeO_2/γ-Al_2O_3. The selectivity to ethylenewas high for all the CeO_2, γ-Al_2O_3 and CeO2/γ-Al_2O_3 catalysts.

CeO_(2)助剂对NiO/ZrO_(2)载氧体结构及性能的影响

采用共沉淀法制备了NiO-CeO_(2)/ZrO_(2)载氧体,利用XRD,H2-TPR,XPS,Raman光谱等方法对NiO-CeO_(2)/ZrO_(2)的物理化学性质进行表征。考察了NiO-CeO_(2)/ZrO_(2)作为乙烷化学链氧化脱氢制乙烯载氧体的反应性能。实验结果表明,添加CeO_(2)提高了NiO-CeO_(2)中晶格氧和吸附氧的含量,Ce^(4+)进入到ZrO_(2)晶格中形成了更多缺陷和晶格应力,有利于表面氧空位的产生,促进了乙烷的氧化。在反应温度为650℃、CeO_(2)添加量为3%(w)条件下乙烷转化率达100%,乙烯选择性约为40%。晶格氧数量的增加,有利于乙烷转化率的增大,但反应温度升高会导致乙烷转化副反应发生,降低乙烯收率。

MgX_(2)O_(4)(X=Cr、Fe、Mn)型尖晶石B位点阳离子对乙烷化学链氧化脱氢生成乙烯的影响

化学链循环氧化脱氢技术(CL-ODH)是一个多功能的平台,它可以利用载氧体中晶格氧的选择性氧化这一特性,实现乙烷向乙烯的高值化转化。本研究探讨了MgX_(2)O_(4)(X=Cr、Fe或Mn)型尖晶石载氧体中B位元素对乙烷CL-ODH性能的影响。采用固定床和H_(2)-TPR、O_(2)-TPD、TG、原位拉曼、SEM、TEM等方法对MgX_(2)O_(4)尖晶石进行了性能测试和表征。结果表明,MgCr_(2)O_(4)仅释放微量表面吸附氧,更倾向于催化乙烷转化为焦炭和氢气。MgFe_(2)O_(4)通过提供更多的表面晶格氧,促进乙烷深度氧化成CO_(2)。MgMn_(2)O_(4)载氧体在乙烷CL-ODH反应中能够释放出大量的体相晶格氧,它可以选择性燃烧氢气以推进反应正向进行,增加乙烯的选择性,实现了73.72%的乙烷转化率和81.46%的乙烯选择性。此外,MgMn_(2)O_(4)催化剂在乙烷CL-ODH反应中进行了30次的氧化还原循环实验,表现出稳定的反应性能,在整个循环测试中乙烯收率大约为62.00%。MgX_(2)O_(4)尖晶石氧化物中B位元素影响了其晶格氧的供应能力,从而影响了其在乙烷CL-ODH反应中的性能。

Enhanced stability of Pt/Al_(2)O_(3) modified by Zn promoter for catalytic dehydrogenation of ethane

Catalytic ethane dehydrogenation(EDH) to ethylene over Pt-based catalysts has received increasing interests in recent years as it is a potential alternative route to conventional steam cracking. However, the catalysts used in this reaction often suffer from rapid deactivation due to serious coke deposition and metal sintering. Herein, we reported the effects of Zn modification on the stability of Pt/Al2 O3 for EDH.The Zn-modified sample(PtZn2/Al2 O3) exhibits stable ethane conversion(20%) with over 95% ethylene selectivity. More importantly, it exhibits a significantly low deactivation rate of only 0.003 h-1 at 600 °C for70 h, which surpasses most of previously reported catalysts. Detailed characterizations including in situ FT-IR, ethylene adsorption microcalorimetry, and HAADF-STEM etc. reveal that Zn modifier reduces the number of Lewis acid sites on the catalyst surface. Moreover, it could modify Pt sites and preferentially cover the step sites, which decrease surface energy and retard the sintering of Pt particle, then prohibiting the further dehydrogenation of ethylene to ethylidyne. Consequently, the good stability is realized due to anti-sintering and the decrease of coke formation on the Pt Zn2/Al2 O3 catalyst.

Preparation of Composite Microporous Silica Membranes Using TEOS and 1,2-Bis(triethoxysilyl)ethane as Precursors for Gas Separation

This paper reports on a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate(TEOS)and a bridged silsesquioxane[1,2-bis(triethoxysilyl)ethane, BTESE]as precursors.A stable nano-sized composite silica sol with a mean volume size of^5 nm was synthesized. A 150 nm-thick defect-free composite silica membrane was deposited on disk support consisting of macroporous α-Al2O3 and mesoporousγ-Al2O3 intermediate layer by using dip-coating approach,followed by calcination under pure nitrogen atmosphere.The composite silica membranes exhibit molecular sieve properties for small gases like H2,CO2,O2,N2,CH4 and SF6 with hydrogen permeances in the range of(1-4)×10 -7mol·m -2·s -1·Pa -1(measured at 200°C,3.0×105 Pa).With respect to the membrane calcined at 500°C,it is found that the permselectivities of H 2 (0.289 nm)with respect to N2(0.365 nm),CH4(0.384 nm)and SF6(0.55 nm)are 22.9,42 and>1000,respectively, which are all much higher than the corresponding Knudsen values(H2/N2=3.7,H2/CH4=2.8,and H2/SF6=8.5).

Effect of methane co-feeding on the selectivity of ethylene produced from oxidative dehydrogenation of ethane with CO_2 over a Ni-La/SiO_2 catalyst

A Ni-La/SiO2 catalyst was prepared through the incipient wetness impregnation method and tested in the oxidative dehydrogenation of ethane （ODHE） with CO2. The fresh and used catalysts were characterized by XRD and SEM techniques. The Ni-La/SiO2 catalyst exhibited catalytic activity for the oxidative dehydrogenation of ethane, but with low ethylene selectivity in the absence of methane. The selectivity to ethylene increased with increasing molar ratio of methane in the feed. The carbon deposited on the catalyst surface in the sole ODHE with CO2 was mainly inert carbon, while much more filamentous carbon was formed in the presence of methane. The filamentous carbon was easy to be removed by CO2, which might play a role in improving the conversion of ethane to ethylene. The introduction of methane might affect the equilibrium of the CO2 reforming of ethane and the ODHE with CO2. As a consequence, the synthesis gas produced from CO2 reforming of methane partly inhibited the reaction of ethane and promoted the ODHE with CO2, thus increasing the selectivity of ethylene.

Cr-MCM-41 Molecular Sieves Crystallized at Room Temperature for Reaction of Ethane with CO_(2)

A series of Cr-containing MCM-41 molecular sieves crystallized at room temperature with a hexagonal and well-ordered structure were synthesized. XRD, FT-IR and DRS UV-Vis techniques were used to characterize the samples. The results indicate incorporation of Cr into the MCM-41 framework, and dispersion of some CrsO3 on the surface or/and in the bulk of the MCM-41. Test of catalytic properties of the series of samples for the topic reaction was carried out using a continuous-flow fixed-bed quartz reactor. Factors influencing the catalytic performance for this title reaction, such as Cr/Si ratio in MCM- 41 and reaction temperature were investigated. The experimental results indicate that over the 5%CrMCM-41 a 43.27% conversion of ethane and a 86.70% selectivity for ethylene were achieved in the ethane dehydrogenation with COs to ethylene at 973 K. It is suggested that both Cr^6＋ and Cr^3＋ are the catalytic activity center.

Two Cobalt(II) Complexes Derived from the Hydrolysis Product of Di-Schiff Base Ligand N,N'-Bis-(1-benzimidazo-2-yl-ethylidene)-ethane-1,2-diamine:Preparation,Characterization and Crystal Structure of the 6-Coordinate Species [CoL_2]X·H_2O (X = ClO_4^-, N

The reactions of Co（C1O4）2·6H2O and Co（NO3）2.6H2O with the di-Schiff base ligand N,N＇-bis-（1-benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine （LA） in ethanol have been investigated. The reactions of LA with excess amount of cobalt salts yield the six-coordinate complexes [CoL2]（ClO4）E·H2O 1 and [CoL2]（NO3）E·H2O 2 as isolatable products （L= N-（1- benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine）, where L is a tri-dentate mono-Schiff base ligand, resulting from the hydrolysis of the precursor di-Schiff base LA. Both complexes were characterized by X-ray crystallography. Crystal data for complex 1： monoclinic, space group P21/c, a = 11.9214（10）, b = 23.5828（17）, c = 14.0387（12）A, β = 135.219（4）°, C22H30Cl2CoN8O9, Mr = 680.37, V = 2780.1（4） A^3 ,Z = 4, Dc = 1.625 g/cm^3,μ（MoKa） = 0.876 mm^-1, F（000） = 1404, the final R = 0.0725 and wR = 0.1530 for 5726 observed reflections （I 〉 2σ（I））. Crystal data for complex 2： monoclinic, space group P21/c, a = 18.2162（16）, b = 10.0610（6）, c = 18.593（2）A, β = 130.099（3）°, C22H30CoN10O7, Mr = 605.49, V = 2606.5（4） A3 Z = 4, Dc = 1.543 g/cm^3,μ（MoKa） = 0.722 mm^-1, F（000） = 1260, the final R = 0.0619 and wR = 0.1429 for 5194 observed reflections （I 〉 2σ（I））. X-ray diffraction analysis reveals that each cobalt atom in the two complexes is chelated by six nitrogen atoms from two tridentate iigands L, exhibiting a slightly distorted octahedral coordination sphere. In both complexes, the strong hydrogen-bonding interactions between the lattice waters and N-H groups of the ligands result in 1D chains which are further connected by ClO4^- （or NO3^-） groups to form a 3D framework. In complex 2, the strong π-π interactions increase the stability of the structure.

Coupling CO_(2)reduction with ethane aromatization for enhancing catalytic stability of iron-modified ZSM-5

The shale gas revolution and the carbon-neutrality goal are motivating the landscape toward the synthesis of value-added chemicals or fuels from underutilized ethane with the assistance of greenhouse gas CO_(2).Combining ethane aromatization with CO_(2)reduction offers an opportunity to directly produce liquid products for facile separation,storage,and transportation.In the present work,Fe/ZSM-5 catalysts showed promise in the simultaneous CO_(2)reduction and ethane aromatization at atmospheric pressure and 873 K.The catalysts were further investigated using X-ray diffraction(XRD)and X-ray absorption fine structure(XAFS)measurements under in-situ conditions,indicating that most of Fe species existed in the form of Fe oxides and a portion of Fe was incorporated into the ZSM-5 framework generating Lewis acid sites.Both types of Fe species remained almost unchanged under reaction conditions,contributing to an enhanced aromatization activity of Fe/ZSM-5.The effects of CO_(2)and steam on the acid sites and in turn aromatization activity were also investigated by transient studies,which exhibited a reversible modification behavior.Moreover,CO_(2)was identified to be critical to enhance coke resistance and in turn catalyst stability.This work highlights the feasibility of using CO_(2)to assist the upgrading of abundant ethane from shale gas to aromatics over non-precious Fe-based zeolite catalysts.

Cofeeding of Methane and Ethane to Produce Syngas over a LiLaNiO/γ-Al_2O_3 Catalyst

Partial oxidation of methane and ethane to syngas over a LiLaNIO/γ-Al_2O_3 catalyst was investigated with a flow-reactor, XPS and XRD. Excellent reaction performance for CH_4-C_2H_6-O_2 to syngas over the LiLaNiO/γ-Al_2O_3 catalyst was achieved at 1073K, obtaining CO selectivity of 90%-95% and CH_4 conversion of ~ 97%, with a wide range of C_2H_6 content in the feed and of space velocity.

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。

Kinetics on Thermal Decomposition of Iron(III) Complexes of 1,2-Bis(Imino-4’-Antipyrinyl)Ethane with Varying Counter Anions

A comparative thermal decomposition kinetic investigation on Fe(III) complexes of a antipyrine Schiff base ligand, 1,2-Bis(imino-4’-antipyrinyl)ethane (GA)), with varying counter anions viz. CIO4-, NO3-, SCN-, Cl-, and Br-, has been done by thermogravimetric analysis by using Coats-Redfern equation. The kinetic parameters like activation energy (E), pre-exponential factor (A) and entropy of activation (ΔS) were quantified. On comparing the various kinetic parameters, lower activation energy was observed in second stage as compared to first thermal decomposition stage. The same trend has been observed for pre-exponential factor (A) and entropy of activation (ΔS). The present results show that the starting materials having higher activation energy (E), are more stable than the intermediate products, however;the intermediate products possess well-ordered chemical structure due to their highly negative entropy of activation (ΔS) values. The present investigation proves that the counter anions play an important role on the thermal decomposition kinetics of the complexes.

THE STUDY OF THE NON-STEADY KINETICS OF THE OXYDEHYDROGENATION OF ETHANE TO ETHYLENE OVER THE CATALYST OF Mo-V-Nb/Al_2O_3 BY THE TECHNIQUE OF TEMPERATURE PROGRAMMED TRANSIENT RESPONSE AND ELECTRIC CONDUCTIVITY

In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results.

An In Vitro and In Vivo Study of Thyroid Disruption of 1,2-Bis(2,4,6-tribromophenoxy)ethane(BTBPE)�A Novel Brominated Flame Retardant

The novel brominated flame retardant,1,2-bis-(2,4,6-tribromophenoxy)ethane(BTBPE),is an emerging environ-mental pollutant with undetermined toxicity.We investigated how BTBPE causes thyroid endocrine disruption with integrated in silico,in vitro,and in vivo assays.In yeast two-hybrid and T-Screen assays,BTBPE interacted with zebrafish thyroid hormone receptors with binding energies weaker than the TR agonist-3,3′,5-Triiodo-L-thyronine(T3),and disrupted thyroid function as a thyroid receptor(TR)agonist.We examined the bioconcentra-tion,developmental toxicity,and thyroid endocrine disruption in zebrafish after a 14-day exposure to BTBPE(1,3,10μg/L).Thyroxine(T4)was lower in BTBPE-treated larvae,whereas corticotropin-releasing hormone(CRH)and thyroid-stimulating hormone(TSH)were higher.The gene transcription alterations along the hypothalamic-pituitary-thyroid(HPT)axis were observed.Furthermore,reduced locomotion suggested that BTBPE imparts developmental neurotoxicity at zebrafish early developmental stage.Establishing that BTBPE has thyroid endocrine-disrupting effects is an important step for understanding and managing BTBPE toxicity.

ZnO-ZrO_(2)催化剂上CO_(2)辅助乙烷氧化脱氢制乙烯的研究

以焙烧商用氢氧化锆(Zr(OH)_(4))得到的ZrO_(2)为载体,通过沉积-沉淀法制备了ZnO-ZrO_(2)催化剂,并在873 K下对该催化剂上CO_(2)辅助的乙烷氧化脱氢反应(CO_(2)-ODHE)的催化性能进行了评价。利用X射线衍射(XRD)、扫描电镜(SEM)、拉曼光谱(Raman)、高分辨透射电镜(HRTEM)、X射线光电子能谱(XPS)、CO_(2)程序升温脱附(CO_(2)-TPD)等技术对ZnO-ZrO_(2)催化剂的表面物理化学性质和形貌进行了表征。结果表明,在5%ZnO-ZrO_(2)催化剂上,ZnO掺入到了ZrO_(2)的表面晶格之中,在催化剂表面产生了高度分散的ZnO物种和氧缺陷区域。5%ZnO-ZrO_(2)催化剂可以选择性地剪裁乙烷C-H键,抑制C-C键的断裂,具备良好的催化性能。210μmol/(g_(cat)·min)的C2H4形成率可以与贵金属和过渡金属碳化物催化剂的报道数据接近。此外,还对ZnO-ZrO_(2)催化剂上CO_(2)-ODHE反应可能的反应机制进行了讨论。

抑制IP3R-Ca^(2+)途径对对乙酰氨基酚所致肝损伤及其线粒体内质网结构偶联的影响

目的探讨抑制肌醇-1,4,5-三磷酸受体(IP3R)-Ca^(2+)途径对对乙酰氨基酚(APAP)所致肝损伤及其线粒体内质网结构偶联(MAMs)的影响。方法40只SPF级雄性C57BL/6小鼠随机分为正常对照组、模型组、IP3R抑制剂(2-APB)组、钙离子螯合剂(BAPTA-AM)组,每组10只。模型组、2-APB组、BAPTA-AM组单次腹腔注射APAP(300 mg/kg)。注射APAP前30 min,2-APB组腹腔注射2-APB(20 mg/kg),BAPTA-AM组腹腔注射BAPTA-AM(2.5 mg/kg)。腹腔注射APAP 24 h后处死各组小鼠。测定血清丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)水平;HE染色观察肝脏病理变化;透射电镜观察肝细胞中线粒体、内质网结构及MAMs变化;测定肝组织匀浆中的Ca^(2+)水平;Western blot测定肝组织中线粒体融合蛋白1(MFN1)、线粒体融合蛋白2(MFN2)、1,4,5-三磷酸肌醇受体1(IP3R1)、葡萄糖调节蛋白75(GRP75)蛋白表达水平。结果与正常对照组相比,模型组小鼠血清ALT及AST水平有所升高(P<0.01),肝脏组织病理学可见肝细胞排列紊乱,并出现肝细胞变性、小叶中心性坏死;透射电镜示线粒体嵴断裂、消失,内质网肿胀断裂,MAMs数量增加;肝组织匀浆中Ca^(2+)含量增加(P<0.01);MFN1、MFN2蛋白表达降低(P<0.01),IP3R1及GRP75蛋白表达增加(P<0.01)。与模型组相比,2-APB组和BAPTA-AM组小鼠血清ALT、AST水平下降(P<0.01),肝脏病理变化明显改善,MAMs减少,肝组织匀浆中Ca^(2+)含量减少(P<0.01),MFN1、MFN2的蛋白表达水平上调(P<0.01),IP3R1及GRP75蛋白表达降低(P<0.01)。结论抑制IP3R-Ca^(2+)途径可以保护APAP所致的肝损伤,其机制与降低肝脏Ca^(2+)水平、减少MAMs数量、调节MAMs相关蛋白的表达有关。

CO_(2)气氛下乙烷氧化脱氢制乙烯催化剂研究进展

CO_(2)是导致全球变暖的主要温室气体,又是宝贵的可再生C1资源,将其转化为有价值的化学品,在环境保护和碳资源合理利用方面具有双重意义。作为页岩气的重要组成部分,乙烷高效催化转化制乙烯不仅具有重要的理论研究意义,而且具有广阔的工业应用前景。在CO_(2)气氛下乙烷氧化脱氢制乙烯(CO_(2)-ODHE)已成为增产乙烯的有效手段之一。该文重点阐述了在CO_(2)-ODHE反应中不同类型的催化剂及影响该反应催化活性和稳定性的主要因素和关键问题,并对比介绍了乙烷直接氧化脱氢(O_(2)-ODHE)和乙烷化学链氧化脱氢(CL-ODHE)。最后,结合反应机制提出了构筑高效催化剂可能的方向和发展前景。

Synthesis,Spectra,X-ray Diffraction and Thermal Studies of New Zn(Ⅱ) Compounds Based on Dibenzoylmethane

Two new zinc（Ⅱ） compounds with dibenzoylmethane and N-donor ancillary ligands,[Zn（μ-pyz）（dbm）_2]_n（1） and [Zn（dbm）_2（μ-bpe）Zn（dbm）_2]（2）（Hdbm = dibenzoylmethane,pyz = pyrazine and bpe = 1,2-bis（4-pyridyl）ethane）,have been prepared and characterized using elemental analysis,IR,~1H NMR and 13 C NMR spectroscopy,and studied by thermal gravimetric analysis as well as single-crystal X-ray diffraction. The crystal and molecular structures of 1 and 2 have been solved by X-ray diffraction and they turned out to be a one-dimensional coordination polymer with linear dispositions of metal atoms and binuclear compound,respectively. These one-dimensional polymers are further connected to form a 3D supramolecular network by C–H···O（only in 2） and π-π interactions.