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Anisotropy of Resonant Inelastic X-Ray Scattering at the K Edge of SiTheoretical Analysis

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a r X i v :c o n d -m a t /0405009v 4 [c o n d -m a t .m t r l -s c i ] 18 A p r 2006Typeset with jpsj2.cls <ver.1.2>Full PaperAnisotropy of Resonant Inelastic X-Ray Scattering at the K Edge of Si:Theoretical Analysis Yunori Nisikawa 1∗,Manabu Usuda 1and Jun-ichi Igarashi 21Synchrotron Radiation Research Center,Japan Atomic Energy Research Institute,Mikazuki,Sayo,Hyogo 679-51482Faculty of Science,Ibaraki University,Mito,Ibaraki 310-8512(Received February 2,2008)We investigate theoretically the resonant inelastic x-ray scattering (RIXS)at the K edge of Si on the basis of an ab initio calculation.We calculate the RIXS spectra with systematically varying transfered-momenta,incident-photon energy and incident-photon polarization.We confirm the anisotropy of the experimental spectra by Y.Ma et al .(Phys.Rev.Lett.74,478(1995)),providing a quantitative explanation of the spectra.KEYWORDS:resonant inelastic X-ray scattering,K edge of Si 1.Introduction Inelastic x-ray scattering is a promising method to study electronic structures in matters.It is advantageous to use a resonant enhancement by tuning photon energy near absorption edge.Recently it has been revealed that the resonant inelastic x-ray scattering (RIXS)is a powerful tool for elucidating the electronic properties of solids.RIXS measurement has been applied to search for charge excitations in several cuprates 1,2and manganites,3with tuning incident photon energy to the absorption K edge.Since corresponding photon energies are in the hard-X-ray region,the momentum transfer can not be neglected.Analyzing the transfered-momentum dependence of the RIXS spectra,we can clarify the characteristics of charge excitations in strongly-correlated electron systems.In semiconductors such as Si and Ge,the interpretation of the RIXS spectra may be simpler because of weak electron correlations.The final state of RIXS consists of one electron in the conduction band and one hole in the valence band.With neglecting the interactionbetween the electron and the hole,one can draw useful information of single-particle spectra from the transferred-momentum dependence.Actually Ma has tried to determine valence band structures of Si by systematically varying scattering vectors in the RIXS experiment.4We have already carried out a RIXS experiment at the K edge of Ge with the same aim.Although we systematically varied transfered-momenta,we obtained merely a broad inelastic peak as a function of photon energy,whose shape was nearly independent of transfered-momenta.Performing the band structure calculation,we obtain the spectral shape in agree-ment with the experiment,and clarified the origin of the spectral shape.5This analysis led us to realize that the decisive factor whether the spectra are depending on the transferred momenta or not is the core-level width.If the core-hole level in the intermediate state is sharp enough,we can definitely select the momentum of the excited electron in the conduction band by sharply tuning the incident-photon energy,and thereby we can also specify the momentum of the hole in the valence band by setting the scattering geometry.In this situation,sharp peaks are expected to be observed as a function of scattered photon energy.If the core-level width is not small,many channels of exciting an electron with different momenta in the con-duction band are expected to be opened.Thereby,sharp peaks are blurred up by overlapping each contribution.In an extreme situation,the spectra become close to a superposition of the density of states(DOS)projected onto p-symmetric states.Unfortunately,for Ge,the1s core-level width is as large as∼2eV,an order of the width of conduction band,so that the RIXS spectra did not show clear momentum dependence.For Si,since the K edge energy is around1840eV,the transfered-momentum cannot be neglected in the RIXS experiment.The1s core-level width is estimated about0.6eV, which is smaller than the width of conduction band of Si.These facts imply a possibility of observing the transfered-momentum dependence at the K edge in the RIXS spectra.Actually, Ma et.al observed such transfered-momentum dependence.6In this paper,we analyze Ma’s experimental RIXS spectra with the help of ab initio band structure calculation,and elucidate the relation between the spectral shape and the underlying electronic structure.This paper is organized as follows.In§2,the formalism for calculating the spectra is described.In§3,the calculated results and discussion are presented.Section4is devoted to concluding remarks.2.FormulationRIXS is described by a second-order process that the incident photon with energy ω1, momentum q1and polarization e1is virtually absorbed by exciting the core electron to the conduction band and then a photon with energy ω2,momentum q2and polarization e2 is emitted byfilling the core-hole state with a valence electron.The scattering geometry is shown in Fig.1.The normal axis n and theta axis t in thisfigure are respectively defined as follows:n∝q2/|q2|−q1/|q1|,t∝q1×q2.The setup for scattering is uniquely determinedby choosing the normal and theta axis from crystal axes of Si.To obtain the double differential scattering cross-section,we use the generalized Fermi’s golden rule where the interaction between photon and electrons is treated by second order perturbation theory.An independent-particle approximation seems to be appropriate,since electron correlations are expected to be weak.4In such a situation,the double differentialscattering cross-section may be expressed asd2σt a(k′,h|e2)t a(k,e|e1) 2ψk′,h(r)e2·ˆpφ1s a(r−R a)describes the transition from the valence band to the1s core state,where R a,ψk′,h andφ1s a are the position vector of atom a in unit cell,Bloch-wave function of an electron in the valence band h with crystal momentum k′,and1s-atomic orbital,respectively.The crystal momentum conservation for the whole process is contained in the factor of Kroneckerδ,δGΩ,k−k′≡ 0:Ω−(k−k′)/∈G,(2)1:Ω−(k−k′)∈Gwhere G is the set of reciprocal lattice vectors.3.Calculated Results and Discussion3.1Band Structure Calculation of SiWe perform a band structure calculation using the full-potential linearized augmented-plane-wave(FLAPW)method within the local-density approximation(LDA).The local exchange-correlation functional of Vosko,Wilk and Nusair is employed.7The angular mo-mentum in the spherical-wave expansion is truncated at l max=6and7for the potential and wave function,respectively.The energy cutoffof the plane wave is12Ry for the wave function.Figure2shows the energy vs.momentum relation thus evaluated.The energy band is labeled by attached numbers for later use.3.2RIXS spectra3.2.1Anisotropy of RIXS at K edge of SiWefirst analyze the transfered-momentum dependence of RIXS spectra for the incident photon energy ω1=ǫmin−ǫc,whereǫmin is the minimum energy of conduction-bands.When Γis very small,the denominator in Eq.1forces the excited electron stay just at the bottom of the conduction band.There are six such points,which are denoted as k i(i=1,···,6)in Fig.3.They belong to band5(see Fig.2).We can specify the momentum of hole q i≡k i−Ωin the valence band by specifying the scattering vector.In such a situation,the double differentialscattering cross-section can be rewritten asd2σt a(q i,h|e2)t a(k i,5|e1) 2.(4) The sharp peaks are expected at ω= ω(i,h)≡ǫmin−ǫh(q i)in the spectra,where h (=1,···,4)indicates the valence band index.When the scattering vector is along a sym-metry line,the number of peaks is reduced because of degeneracy of peaks and no inten-sities to some peaks.For n=(100),for example,the momenta of the holes are shown in Fig.3,and the corresponding valence band energies are the same due to symmetry,that is,ǫh(q2)=ǫh(q3)=ǫh(q4)=ǫh(q5)with h=1,···4,except for q1and q6.Therefore, several excitation energies coincide with each other,and thereby different peak positions are ω= ω(1,h), ω(2,h), ω(6,h)with h=1,···,4.In addition,the spectral weights A(i,h|Ω,e1=σ)for momentum k1and k6are found to be almost zero.Thus only four peaks appear at ω= ω(2,h)(h=1,···,4),as shown in Fig.4(c).With slight increase of theΓvalue,the excited electron can stay at several states near the bottom of the conduction band, and thereby the valence hole can stay at several states near q i(i=2,···,5).Therefore the spectral peaks are obscured.We can make similar analysis for n=(111),(110).Such spectral changes are demonstrated in Fig.4for n=(111),(110)and(100),withΓchanged from0.02 eV to0.6eV.WhenΓis large,the momentum of the excited electron can take whole values in thefirst Brillouin zone,and so does the momentum of the hole in the valence band.The spectral peaks are smeared out,and thereby becoming close to the DOS projected onto p symmetric states.Thus we have the spectra almost independent of scattering vector.This behavior is demonstrated in Fig.5,whereΓ=1.6eV.For the actual Si case,Γis close to0.6eV,and the spectral shape is expected to show the transferred-momentum dependence.Figure6shows the RIXS spectra withΓ=0.6eV for ω1=1840.8eV,in comparison with experimental results by Ma et.al.6In the experi-mental setup of Ma et.al,6the normal axis n is(111),(110),and(100),but the theta axis t and incident-photon polarization are not clearly indicated in their paper.6Assuming theσpolarization for the incident photon and the theta axis t as given in thefigure,we are suc-cessful in reproducing the experimental shape such as three peak structure for n=(111)and the different spectral shape for n=(110)and(100).Corresponding to the above discussion, we can identify where the peak structures come from by decomposing the spectra into each contribution from the hole band and the electron band.Figure7shows such decomposition, where attached numbers indicates the band index given in Fig.2.3.2.2Incident-photon energy dependence of RIXS spectraThe spectra strongly depend on the incident-photon energy.Figure8shows the spectra with varying incident-photon energy from1840.0eV to1841.2eV.The scattering vector is fixed to be proportional to n=(111).The characteristic three peaks A,B and C are visible only in the narrow energy region between1840.2eV and1840.8eV.For ω1=1842.5eV,the anisotropy almost disappears,as shown in Fig.9.The result is consistent with experimental results of Ma et.al.63.2.3Incident-photon polarization dependenceFigure10shows the RIXS spectra calculated forσandπincident polarizations.It is found that the difference in RIXS spectra in higher ω2for n=(100)is large,while not for n=(111)and(110).This tendency is more clearly seen in the limit situationΓ=0.02 eV where ω1=ǫmin−ǫc,as shown in Fig.11.The positions of peaks expected to be madeby each electron-hole pairs are also presented in Fig.11.To make the discussion clear,we consider the limit situation mentioned above.Then,the1s electron is excited to the states with momentum k i(i=1,···,6).Corresponding wave functions projected onto p-symmetricstates centering on R a(a=1,2)are given by P l=1ψk1,5∝p x,P l=1ψk2,5∝p y,P l=1ψk3,5∝p y, P l=1ψk4,5∝p z,P l=1ψk5,5∝p z,P l=1ψk6,5∝p x,as shown in the left side of Fig.11.In the case of n=(100),t=(011),the incident-photon polarization vector e1is proportional√to(0,1,1)in theσpolarization and(From Fig.11(a),(b),we can see the following facts.In the case of n=(111),t=(1-10),the positions of the peaks made by the electron-hole pairs with momenta k4,q4and k5,q5in the πpolarization are same as these of the peaks made by other electron-hole pairs with momenta k i,q i(i=1,2,3,6).In the case of n=(110),t=(1-10),the position of the peak made by the electron-hole pairs with momenta k4,q4and k5,q5for h=2in theπpolarization is same as that of the main peak in theσpolarization.On the other hand,the positions of the peaks made by the electron-hole pairs with momenta k4,q4and k5,q5for h=3,4in the πpolarization are different from that of the peaks made by other electron-hole pairs with momenta k i,q i(i=1,2,3,6).But the new peaks made by electron-hole pairs with momenta k4,q4and k5,q5for h=3,4are not so significant.Summarizing,in the case of n=(111), t=(1-10)and n=(110),t=(1-10),significant peaks at new positions are not expected by varying incident-photon polarization.Therefore,the realistic RIXS spectra for n=(111), t=(1-10)and n=(110),t=(1-10)are not sensitive to the incident-photon polarization,as shown in Fig.10.4.Concluding RemarksWe have calculated the RIXS spectra at the K edge of Si on the basis of the band structure calculation.We have successfully reproduced the anisotropy of the RIXS spectra in the experiment by Ma et.al.6We have analyzed the spectra with systematically varying transfered-momenta,incident-photon energy and incident-photon polarization,thus having provided a quantitative explanation of the spectra.With the help of the band calculation,one can draw information on the valence band structure from the RIXS spectra,although it is indirect.This information seems helpful with considering that the RIXS is bulk-sensitive in contrast to photoemission with a lower energy photon which is surface-sensitive.Finally,we comment the following general tendencies.To have an anisotropy in RIXS at K edge of specific element in semiconductor or band-insulator,the sizable momentum transfer and core-level width smaller than conduction-bandwidth are required.The photon energy is required to obtain sizable momentum transfer but corresponding core-level widths are usually large.Therefore,it is difficult to satisfy the requirement of the sizable momentum transfer and small core-level width.AcknowledgmentAuthors greatly thank to N.Hamada for allowing us to use his FLAPW code,and to T. Iwazumi and A.Agui for valuable discussion.This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Educations,Science,Sports,and Culture.References1)M.Z.Hasan,E.D.Isaacs,Z.-X.Shen,ler,K.Tsutsui,T.Tohyama,and S.Maekawa,Science288(2000)1811.2)Y.J.Kim,J.P.Hill,C.A.Burns,S.Wakimoto,R.J.Birgeneau,D.Casa,T.Gog,and C.T.Venkataraman,Phys.Rev.Lett.89(2002),177003.3)T.Inami,T.Fukuda,J.Mizuki,S.Ishihara,H.Kondo,H.Nakao,T.Matsumura,K.Hirota,Y.Murakami,S.Maekawa,and Y.Endoh,Phys.Rev.B67(2003)045108.4)Y.Ma,Phys.Rev.B49(1994)5799.5)Y.Nisikawa,uda,J.Igarashi,H.Shoji,and T.Iwazumi,J.Phys.Soc.Jpn.73(2004)970.6)Y.Ma,K.E.Miyano,P.L.Cowan,Y.Aglitzkiy,and B.A.Karlin,Phys.Rev.Lett.74(1995)478.7)S.H.Vosko,L.Wilk and M.Nusair,Can.J.Phys.58(1980)1200.8)J.H.Scofield,Phys.Rev.179(1969)9.9)V.O.Kostroun,M.H.Chen,and B.Crasemann,Phys.Rev.A3(1971)533.Fig.1.Geometrical relations between q1,q2and crystal axis of Si.-14.-12.-10.-8.-6.-4.-2. 0.2. 4.6. 8.10.E n e r g y [e V ]XΓK XF Fig.2.Energy vs.momentum relation of Si calculated by the FLAPW method in the LDA scheme.Fig.3.Cross-section of thefirst Brillouin zone.The crystal momenta of electrons and holes generated infinal state are presented.1822 1824 1826 1828 1830 1832 1834 1836 1838 1840 1842incident-photon energy: εmin −εc incident-photon polarization: σEmitted Photon Energy (eV)normal axis n =(111)theta axis t =(1-10)normal axis n =(110)theta axis t =(1-10)normal axis n =(100)theta axis t =(011)Γ=0.6 eVΓ=0.02 eVΓ=0.6 eVΓ=0.02 eVΓ=0.6 eVΓ=0.02 eV4-53-52-51-54-53-52-51-54-53-52-51-54-53-52-51-54-53-52-51-54-53-52-51-5I n t e n s i t y (a r b . u n i t )(a)(b)(c)Fig.4.RIXS spectra for realistic value of core-level width (Γ=0.6eV)in comparison with the RIXSspectra for sufficiently small value of core-level width (Γ=0.02eV).Emitted Photon Energy (eV)Fig.5.RIXS spectra for large value of core-level width(Γ=1.6eV).The anisotropy almost disap-pears in the spectra.1826 1828 1830 1832 1834 1836 1838 1840 1842Emitted Photon Energy (eV)I n t e n s i t y (a r b . u n i t )normal axis n =(111)normal axis n =(110)normal axis n =(100)1826 1828 1830 1832 1834 1836 1838 1840 1842Emitted Photon Energy (eV)i n ci d ent-photon energy: 1840.8 eVincident-photon polarization: σnormal axis n =(111)theta axis t =(1-10)normal axis n =(110)theta axis t =(1-10)normal axis n =(100)theta axis t =(011)(a) experimental results(b) theoretical resultsΓ=0.6 eVFig.6.RIXS spectra obtained by (a)experiment 6and (b)theoryΓ=0.6 eVincident-photon energy: 1840.8 eVEmitted Photon Energy (eV)Fig.7.The spectra for ω1=1840.8eV,n=(111),(110),and(100)are decomposed into each contri-bution of band-to-band transitions specified by band indices.Emitted Photon Energy (eV)I n t e n s i t y (a r b . u n i t )Fig.8.Calculated RIXS spectra for n =(111)with varying incident-photon energy between 1840.0eV and 1841.2eV.Emitted Photon Energy (eV)I n t e n s i t y (a r b . u n i t )Fig.9.Calculated RIXS spectra for ω1=1842.5eV with varying n =(111),(110),and (100).1822 1824 1826 1828 1830 1832 1834 1836 1838 18401822 1824 1826 1828 1830 1832 1834 1836 1838 1840 1842Emitted Photon Energy (eV)Emitted Photon Energy (eV)I n t e n s i t y (a r b . u n i t )I n t e n s i t y (a r b . u n i t )incident-photon energy: 1840.0 eVincident-photon energy: 1840.8 eVnormal axis n =(111)theta axis t =(1-10)normal axis n =(111)theta axis t =(1-10)normal axis n =(110)theta axis t =(1-10)normal axis n =(100)theta axis t =(011)normal axis n =(110)theta axis t =(1-10)normal axis n =(100)theta axis t =(011)incident-photon polarization σ:incident-photon polarization π:Γ=0.6 eVFig.10.Calculated RIXS spectra with varying incident-photon polarization.(b) n =(110), t =(1-10)(c) n =(100), t =(011)Emitted Photon Energy (eV)( , )( , )( , )( , )( , )( , )( , )Emitted Photon Energy (eV)k 4k 134k 1k 3k 4k 1k 3Fig.11.Incident-photon polarization dependence of RIXS spectra for ω1=ǫmin −ǫc with sufficientlysmall value of Γ(=0.02eV).The positions of peaks expected to be made by each electron-holepairs are also presented.。

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人工智能英文参考文献(最新120个)

人工智能英文参考文献(最新120个)

人工智能是一门新兴的具有挑战力的学科。

自人工智能诞生以来,发展迅速,产生了许多分支。

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下面是搜索整理的人工智能英文参考文献的分享，供大家借鉴参考。

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纳米管制作皮肤感应器 翻译 中英

纳米管制作皮肤感应器 翻译 中英

最后译文：纳米管弹性制作出皮肤般的感应器美国斯坦福大学的研究者发现了一种富有弹性且透明的导电性能非常好的薄膜，这种薄膜由极易感触的碳纳米管组成，可被作为电极材料用在轻微触压和拉伸方面的传感器上。

“这种装置也许有一天可以被用在被截肢者、受伤的士兵、烧伤方面接触和压迫的敏感性的恢复上，也可以被应用于机器人和触屏电脑方面”，这个小组如是说。

鲍哲南和他的同事们在他们的弹透薄膜的顶部和底部喷上一种碳纳米管的溶液形成平坦的硅板，覆盖之后，研究人员拉伸这个胶片，当胶片被放松后，纳米管很自然地形成波浪般的结构，这种结构作为电极可以精准的检测出作用在这个材料上的力量总数。

事实上，这种装配行为上很像一个电容器，用硅树脂层来存储电荷，像一个电池一样，当压力被作用到这个感应器上的时候，硅树脂层就收紧，并且不会改变它所储存的电荷总量。

这个电荷是被位于顶部和底部的硅树脂上的纳米碳管测量到的。

当这个复合膜被再次拉伸的时候，纳米管会自动理顺被拉伸的方向。

薄膜的导电性不会改变只要材料没有超出最初的拉伸量。

事实上，这种薄膜可以被拉伸到它原始长度的2.5倍，并且无论哪种方向不会使它受到损害的拉伸它都会重新回到原始的尺寸，甚至在多次被拉伸之后。

当被充分的拉伸后，它的导电性喂2200S/cm，能检测50KPA的压力，类似于一个“坚定的手指捏”的力度，研究者说。

“我们所制作的这个纳米管很可能是首次可被拉伸的，透明的，肤质般感应的，有或者没有碳的纳米管”小组成员之一Darren Lipomi.说。

这种薄膜也可在很多领域得到应用，包括移动设备的屏幕可以感应到一定范围的压力而不仅限于触摸；可拉伸和折叠的几乎不会毁坏的触屏感应器；太阳能电池的透明电极；可包裹而不会起皱的车辆或建筑物的曲面；机器人感应装置和人工智能系统。

其他应用程序“其他系统也可以从中受益—例如那种需要生物反馈的—举个例子，智能方向盘可以感应到，如果司机睡着了，”Lipomi补充说。

x射线吸收谱xas的英文

x射线吸收谱xas的英文

x射线吸收谱xas的英文X-ray Absorption Spectroscopy (XAS): Principles, Applications, and Advancements.X-ray Absorption Spectroscopy (XAS) is a powerful technique that provides detailed information about the electronic structure and local atomic environment of materials. It has found widespread applications in various fields ranging from condensed matter physics, chemistry, materials science, and even environmental science. This article aims to introduce the principles behind XAS, its various applications, and recent advancements in this field.Principles of X-ray Absorption Spectroscopy.XAS is based on the absorption of X-rays by matter. When an X-ray photon interacts with matter, it can eitherbe absorbed or scattered. The absorption process occurs when the photon's energy matches the energy difference between two electronic states of the atom. This energydifference is typically in the range of a few thousand to tens of thousands of electron volts, making X-rays an excellent probe for studying the inner electronic structure of atoms.In XAS experiments, a monochromatic X-ray beam is passed through a sample, and the intensity of the transmitted X-rays is measured as a function of energy. The absorption spectrum is then obtained by plotting the absorbed X-ray intensity against the incident X-ray energy. The shape and features of this spectrum are directlyrelated to the electronic structure and local atomic environment of the sample.There are two main types of XAS: X-ray Absorption Near-Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). XANES probes the absorption near the absorption edge, providing information about the unoccupied states of the absorber atom. On the other hand, EXAFS focuses on the oscillatory structure that appears above the absorption edge and gives insights into the coordination geometry and bond lengths of the absorber atom.Applications of X-ray Absorption Spectroscopy.1. Materials Science: XAS is widely used in materials science to study the atomic-scale structure and electronic properties of various materials. It can provide information about the oxidation state, coordination geometry, and bond lengths of atoms in materials, which is crucial for understanding their physical and chemical properties.2. Chemistry: In the field of chemistry, XAS is often used to study the electronic structure and bonding in molecules and solids. It can reveal the oxidation states, ligand environments, and electronic configurations of atoms in complex molecules.3. Environmental Science: XAS has also found applications in environmental science, where it is used to study the speciation and transformation of elements in the environment. For example, it can be used to monitor the redox state of heavy metals in soils and waters, which is crucial for assessing their environmental risk.4. Energy Science: In the field of energy science, XAS is used to study materials for energy conversion and storage applications. For instance, it can provide insights into the electronic structure and atomic-scale structure of battery materials, which is essential for developing high-performance batteries.Advancements in X-ray Absorption Spectroscopy.With the continuous development of synchrotronradiation sources and advanced detector technologies, XAS has made significant advancements in recent years. Here are some of the key advancements in XAS:1. Higher Energy Resolution: Advancements in X-ray sources and detectors have led to improved energyresolution in XAS experiments. This higher resolution allows for more precise measurements of electronicstructure parameters and enhanced sensitivity to small changes in the local atomic environment.2. Faster Acquisition Times: With the advent of new detector technologies, XAS experiments can now be performed with much faster acquisition times. This reduction in measurement time not only improves experimental efficiency but also enables studies of dynamic processes and reactions in real time.3. Element-Specific Probing: Recent advancements in XAS have enabled element-specific probing, allowing researchers to study the electronic structure and local atomic environment of specific elements within a complex material. This capability is particularly useful in materials science and chemistry, where understanding the behavior of individual elements is crucial.4. In-Situ Studies: Another important advancement in XAS is the ability to perform in-situ studies, where the sample is exposed to various external stimuli (e.g., temperature, pressure, electric field) during the measurement. This approach allows researchers to study the evolution of materials' properties under realistic conditions, providing valuable insights into theirperformance and stability.In conclusion, X-ray Absorption Spectroscopy (XAS) is a powerful technique that provides detailed information about the electronic structure and local atomic environment of materials. Its applications span across various fields, and recent advancements in XAS have further expanded its capabilities and scope. With continued research and development, XAS is expected to play an even more critical role in understanding and developing advanced materials for various applications.。

蒸氨法制备NiSiO2 催化剂及其在2-MF 加氢制2-MTHF 反应中的应用

蒸氨法制备NiSiO2 催化剂及其在2-MF 加氢制2-MTHF 反应中的应用

DOI: 10.1016/S1872-5813(21)60007-5蒸氨法制备Ni/SiO 2催化剂及其在2-MF 加氢制2-MTHF反应中的应用王英文 ，张雅静* ，王康军* ，谈立美 ，陈姝颖（沈阳化工大学 化学工程学院，辽宁 沈阳 110142）摘　要：以硝酸镍为镍源，碱性硅溶胶为硅源，采用蒸氨法制备了Ni/SiO 2催化剂。

通过XRD 、N 2等温吸附脱附、H 2-TPR 、NH 3-TPD 、XPS 和TG 对催化剂进行表征。

采用固定床反应器，考察了催化剂焙烧温度及反应条件对催化剂应用于2-甲基呋喃（2-MF ）气相加氢合成2-甲基四氢呋喃（2-MTHF ）的反应性能。

结果表明，蒸氨法制备的Ni/SiO 2催化剂在焙烧后均呈现层状硅酸镍结构，还原后保持了该结构，活性组分Ni 晶粒尺寸较小、金属载体相互作用较强，从而具有较高的活性。

催化剂的焙烧温度影响催化剂Ni 晶粒尺寸及催化剂的表面酸性。

在500 ℃焙烧条件下制备的催化剂性能最佳，优化反应条件下，2-MF 转化率100%，2-MTHF 选择性为93.5%，反应15 h 内催化性能稳定；含碳的有机物在催化剂表面沉积是催化剂失活的主要原因。

关键词：2-甲基四氢呋喃；2-甲基呋喃；蒸氨法；加氢；Ni/SiO 2中图分类号： TQ 426, O643.36 文献标识码： APreparation of Ni/SiO 2 by ammonia evaporation method for synthesis of 2-MTHFfrom 2-MF hydrogenationWANG Ying-wen ，ZHANG Ya-jing *，WANG Kang-jun *，TAN Li-mei ，CHEN Shu-ying（College of Chemical Engineering , Shenyang University of Chemical Technology , Shenyang 110142, China ）Abstract: The Ni/SiO 2 catalysts were prepared by ammonia evaporation method, with nickel nitrate as Ni source and silica sol as the SiO 2 source, for synthesis of 2-MTHF from 2-MF hydrogenation. The catalytic performance of catalysts prepared at different calcination temperatures were tested on a fixed-bed reactor. XRD, N 2 adsorption-desorption, H 2-TPR, NH 3-TPD, XPS and TG were employed to characterize the structure and surface properties of these catalysts. The effect of calcination temperature on the structure, surface property and catalytic performance of catalysts were investigated. The result indicated that all the catalysts had a phyllosilicate structure after calcination,and maintained the structure after reduction. Ni particles dispersed well with smaller size and strong metal support interaction showed high activity. The surface acidity of catalysts was influenced by the calcination temperature. The maximum catalytic activity and selectivity were obtained on the catalyst calcined by at 500 ℃, which exhibited a 2-MF conversion of 100% and the 2-MTHF selectivity of 93.5% at the optimized condition, due to smaller particle size and suitable surface acidity.Key words: 2-methylfuran ；2-methyltetrahydrofuran ；ammonia evaporation ；hydrogenation ；Ni/SiO 2 catalysts2-甲基四氢呋喃（2-MTHF ）是一种重要的医药中间体和新型绿色溶剂。