Tuning the crystallite size of monoclinic ZrO_2 to reveal critical roles of surface defects on m–ZrO_2 catalyst for direct synthesis of isobutene from syngas

The effects of crystallite size on the physicochemical properties and surface defects of pure monoclinic ZrO_2 catalysts for isobutene synthesis were studied. We prepared a series of monoclinic ZrO_2 catalysts with different crystallite size by changing calcination temperature and evaluated their catalytic performance for isobutene synthesis from syngas. ZrO_2 with small crystalline size showed higher CO conversion and isobutene selectivity, while samples with large crystalline size preferred to form dimethyl ether(DME) instead of hydrocarbons, much less to isobutene. Oxygen defects(ODefects) analyzed by X-ray photoelectron spectroscopy(XPS) provided evidence that more ODefectsoccupied on the surface of ZrO_2 catalysts with smaller crystalline size. Electron paramagnetic resonance(EPR) and ultraviolet–visible diffuse reflectance(UV–vis DRS) confirmed the presence of high concentration of surface defects and Zr~(3+) on mZrO_2-5.9 sample, respectively. In situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS) analysis indicated that the adsorption strength of formed formate species on catalyst reduced as the crystalline size decreased. These results suggested that surface defects were responsible for CO activation and further influenced the adsorption strength of surface species, and thus the products distribution changed. This study provides an in-depth insight for active sites regulation of ZrO_2 catalyst in CO hydrogenation reaction.     

Real-time observation of frequency Bloch oscillations with fibre loop modulation

Bloch oscillations(BOs)were initially predicted for electrons in a solid lattice to which a static electric field is applied.The observation of BOs in solids remains challenging due to the collision scattering and barrier tunnelling of electrons.Nevertheless,analogies of electron BOs for photons,acoustic phonons and cold atoms have been experimentally demonstrated in various lattice systems.Recently,BOs in the frequency dimension have been proposed and studied by using an optical micro-resonator,which provides a unique approach to controlling the light frequency.However,the finite resonator lifetime and intrinsic loss hinder the effect from being observed practically.Here,we experimentally demonstrate BOs in a synthetic frequency lattice by employing a fibre-loop circuit with detuned phase modulation.We show that a detuning between the modulation period and the fibre-loop roundtrip time acts as an effective vector potential and hence a constant effective force that can yield BOs in the modulation-induced frequency lattices.With a dispersive Fourier transformation,the pulse spectrum can be mapped into the time dimension,and its transient evolution can be precisely measured.This study offers a promising approach to realising BOs in synthetic dimensions and may find applications in frequency manipulations in optical fibre communication systems.     

Measurement of ^17F（d,n）^18Ne Reaction

Explosive hydrogen burning occurs in very massive （M≥ 10^5-10^8 M） star with high temperature and density. Hot pp chain, hot CNO, hot NeNa-MgAl chain and the flowing γp and ap process will play a prominent role in hydrogen burning as. the temperature goes higher. When the temperature of the star is hither than 10^8 K. high temnerature CNO chain is dominant in hydrogen burning,     

Thermodynamic calculation on the smelting slag of direct recycling of electric arc furnace stainless steelmaking dust

1　ＩＮＴＲＯＤＵＣＴＩＯＮＥｌｅｃｔｒｉｃａｒｃｆｕｒｎａｃｅ (ＥＡＦ)ｄｕｓｔｈａｓｂｅｅｎｃｌａｓｓｉｆｉｅｄａｓａｈａｚａｒｄｏｕｓｗａｓｔｅｄｕｅｔｏｉｔｓｈｉｇｈｃｏｎｔｅｎｔｏｆｓｏｍｅｈｅａｖｙｍｅｔａｌｓｌｅａｃｈａｂｉｌｉｔｉｅｓｓｕｃｈａｓｚｉｎｃ ,ｌｅａｄ ,ｃａｄｍｉｕｍａｎｄｃｈｒｏｍｉｕｍ ,ｓｏｉｔｈａｓｂｅｅｎｂａｎｎｅｄｆｒｏｍｌａｎｄｆｉｌｌｓｉｎｍａｎｙｃｏｕｎ ｔｒｉｅｓ .Ａｎｅｓｔｉｍａｔｅｄ 1 % 2 %ｍａｓｓｆｒａｃｔｉｏｎｏｆｔｈｅｓｃｒａｐｃｈａｒｇｅｄ…     

Thermo-analytical study on stainless steelmaking dust

1　INTRODUCTIONStainlesssteelmakingdustisaby productwastegeneratedfromsteelmakingindustry .Itcontainssig nificantamountsofiron ,lead ,nickel,chromium ,etc .Heavymetalmaybeleachedintotheenviron mentbyrainorundergroundwater ,soitisclassifiedashazardouswastesandbannedbeingdisposedinreg ularlandfill[1] .Thevaluablemetalsinthedustcanberecoveredinthewayofdirectrecycling[2 6 ] andtheworthlessdustshouldbetreatedinthewayofvitrifi cation[7] .But,itisnecessarytocommandthether malbehaviorofthedustbe…     

一种微小型无人机地面监控系统软件设计与实现

针对微小型无人机飞行监测和控制的任务需求,设计了一种地面监控系统软件。系统实现了导航参数实时获取、飞行控制参数在线调整、航迹规划与回显、数据存储及分析等功能,并为超视距飞行提供了有利保障。经过大量完全自主飞行实验,结果表明,所设计的地面监控系统软件不仅能够满足小型无人机下行信道传输数据量大的监测要求,而且可以确保上行信道控制参数高精度、高可靠性的要求。     

New cobweb-structure hollow Bragg optical fibers

So far, there are two kinds of hollow-core fibers, i.e. Bragg fibers[1] and photonic bandgap fibers[2]. The lowest loss re- ported in hollow-core photonic bandgap fibers with fused silica is 1.2 dB/km at 1620 nm[3]. The ultimate limit to the attenuation o…     

Half-life measurement of neutron-rich isotope 237Th

1 INTRODUCTIONIt has been rePorted[1l that the new neutron-rich isotoPe 237Th was produced via'"U(n,2P):"Th reaction by 14MeV/u neutron irradiations of natural uxedum and thehdelife of:3vTh has been given. Some experimental results reveal that in multi-nucleontransfer reaction (MNTR), neutron-rich projectile, neutron-rich taxget and reasonablyhigher incident energy favor the production of a heavy neutron-rich nuclei. In addition,dissiPative fragmntation of heavy taxget in the interme…     

Thermodynamics calculation on the oxidation and sulfur removal abilities of slag in EAF dust pellet reduction process

ＥＡＦｄｕｓｔｈａｓｂｅｅｎｃｌａｓｓｉｆｉｅｄａｓｈａｚａｒｄｏｕｓｗａｓｔｅ ,ａｎｄｉｔｉｓｈａｒｍｆｕｌｉｎｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｌａｎｄ ｆａｌｌｄｕｅｔｏｃｏｎｔａｉｎｉｎｇｈｅａｖｙｍｅｔａｌｓ[1] .Ｍｏｓｔｒｅｃｙ ｃｌｉｎｇｍｅｔｈｏｄｓ[2 8] ｄｅｖｅｌｏｐｅｄｆｏｒｔｈｅｄｕｓｔｓａｒｅｏｎｌｙｆｏｒｔｈｅｒｅｃｏｖｅｒｙｏｆｌｅａｄ ,ｚｉｎｃａｎｄｃａｄｍｉｕｍ .ＴｈｅＥＡＦｄｕｓｔｆｒｏｍｓｔａｉｎｌｅｓｓｓｔｅｅｌｍａｋｉｎｇｍａｉｎｌｙｃｏｎ ｔａｉｎｓｎｉｃｋｅ…