One-step conversion of syngas to light olefins over bifunctional metal-zeolite catalyst

Light olefins(C_(2)–C_(4))are fundamental building blocks for the manufacture of polymers,chemical intermediates,and solvents.In this work,we realized a composite catalyst,comprising MnxZry oxides and SAPO-34 zeolite,which can convert syngas(CO+H_(2))into light olefins.MnxZry oxide catalysts with different Mn/Zr molar ratios were facilely prepared using the coprecipitation method prior to physical mixing with SAPO-34 zeolite.The redox properties,surface morphology,electronic state,crystal structure,and chemical elemental composition of the catalysts were examined using H_(2)-TPR,SEM,XPS,XRD,and EDS techniques,respectively.Tandem reactions involved activation of CO and subsequent hydrogenation over the metal oxide catalyst,producing methanol and dimethyl ether as the main reaction intermediates,which then migrated onto SAPO-34 zeolite for light olefins synthesis.Effects of temperature,pressure and reactant gas flow rate on CO conversion and light olefins selectivity were investigated in detail.The Mn_(1)Zr_(2)/SAPO-34 catalyst(Mn/Zr ratio of 1:2)attained a CO conversion of 10.8%and light olefins selectivity of 60.7%,at an optimized temperature,pressure and GHSV of 380℃,3 MPa and 3000h^(−1) respectively.These findings open avenues to exploit other metal oxides with CO activation capabilities for a more efficient syngas conversion and product selectivity.

New Solution Method of Pi-Orbital Axis Vector and Its Applications in Fullerenes and Carbon Nanotubes

A new solution method to perform the pi-orbital axis vector analysis was developed in this paper. The model of circular cone was built and the solution equations of the pyramidalization angle were obtained based on the model and the space analytic geometry. Our method merely requires the atomic coordinates of the conjugated central atom and the three attached atoms. Moreover, systematic calculations on the pyramidalization angles of fullerenes and carbon nanotubes were performed using the method we developed. The relationship of pyramidalization angle and the stability for the carbon cages and tubes was also discussed.

Controlling synthesis and gas-sensing properties of ordered mesoporous In2O3-reduced graphene oxide(r GO) nanocomposite

Herein, we describe a strategy for fabricating ordered mesoporous In2O3-reduced graphene oxide(r GO)nanocomposite through ultrasonic mixing, where ordered mesoporous In2O3 nanoparticles are synthesized via the nanocasting route by using mesoporous silica as a hard template, which possess ordered mesostructure with a large surface area of 81 m2g-1, and r GO nanosheets are synthesized from graphite via graphene oxide(GO) as intermediate. After coupled with r GO, mesoporous In2O3 could maintain its ordered mesostructure. We subsequently investigate the gas-sensing properties of all the In2O3 specimens with or without r GO for different gases. The results exhibit the ordered mesoporous In2O3-r GO nanocomposite possesses significantly enhanced response to ethanol even at low concentration levels, superior over pure mesoporous In2O3 nanoparticles. Similar strategy could be extended to other ordered mesoporous metal oxide–r GO nanocomposite for improving the gas-sensing property.

First total synthesis of four natural prenylated flavonoids

A facile approach for the first total synthesis of prenylated flavonoids, （±）-abyssinone-VI-4-O-methyl ether 1, （±）-abyssinone- IV-4＇-O-methyl ether 2, （±）-abyssinone-V-4＇-O-methyl ether 3 and （±）-sigmoidin E 4 has been described. The key intermediate 4-hydroxy-3,5-di-（3-methylbut-2-enyl）benzaldehyde 6 was also first synthesized that features regioselective prenylation of 4-hydroxybenzaldehyde and crystallizing with petroleum ether from the reaction mixture by freeze-out effect.

First total synthesis of (±)-malaysianone A and (±)-tanariflavanones B

A concise approach for the frst total synthesis of two naturally occurring flavanoids,（）-malaysianone A（1）and（）-tanariflavanones B（2）,has been accomplished with total yields of 12.9%and 10.4%,respectively.The key steps were regioselective deprotection and regioselective synthesis of 5-formaldehyde-8-hydroxy-2-[40-methyl-30-penteneyl]-dihydro-1-benzopyran（8）.

First total synthesis of(±)-sepicanin A

A facile approach for the first total synthesis of naturally occurring geranylated flavanoids sepicanin A has been obtained with total yield 16%starting from 2,4,6-trihydroxyacetophenone after four steps.The key step was the protic acids（HCl or p-TsOH）-catalyzed benzopyrone formation in a protic polar solvent by deprotection and cycUzation of chalcone in one step.

Facile Synthesis of Mesoporous Si-containing γ-Al2O3 Nanofiber with Enhanced Thermal Stability

Mesoporous γ-Al2O3 nanofiber was prepared via a simple reverse precipitation route using Si-containing Al（OH）3 and HNO3 as raw materials. The resultant Si-containing mesoporous γ-Al2O3 nanofiber exhibited high surface area of 320 m^2/g, large pore volume of 1.17 cm^3/g and large pore size of 10.5 nm. The introduction of Si element remarkably enhanced the thermal stability of mesoporous γ-Al2O3. The as-prepared nanofiber could maintain relative high surface area（110 m^2/g） and pore volume（0.73 cm^3/g） up to 1100 ℃. The effects of various experimental conditions, such as pH value, reaction temperature and aging temperature on the structural properties of the mesoporous γ-Al2O3 were also investigated.

Preparation of imidazolines from aziridines and nitriles via TfOH promoted Ritter process

An efficient preparation of imidazolines from nitriles and aziridines in the presence of TfOH via Ritter reaction is described. It indicates that different kinds of nitriles can undergo the process. Among the nitriles, pivalonitrile is proven to be better than acetonitrile. The reaction is performed at room temperature and the yields are excellent.

Effcient transesterifcation resolution of 2-(4-chlorophenyl)-4-hydroxytetrahydropyran with magnetically separable immobilized lipase

We report an efficient kinetic resolution of racemic 2-（4-chlorophenyl）-4-hydroxytetrahydro-pyran （CLP-4-HTHP） via Pseudomonas cepacia lipase （PSL）-catalyzed transesterification, where PSL is immobilized on a core-shell MnFe204@SiO2-（CH2）3-NH2 carrier and used as a magnetically separable catalyst. The as-synthesized PSL/MnFe204@SiO2-（CH2）3-NH2 catalyst exhibits enhanced catalytic activity for resolving racemic CLP-4-HTHP to the corresponding optically pure （2R,4S）-CLP-4-HTHP compared to the free PSL. The ees for the former is 2.3 times larger than that for the latter under optimized conditions （99.4% and 44.1%, respectively）, although the eep for them are same （99.2%）. Meanwhile, the PSL/MnFe204@SiO2-（CH2）3-NH2 catalyst possesses a high saturate magnetization of 59.7 emu/g and could be easily recovered by magnetic separation and reused. The catalytic activity in six recycling tests did not significantly decrease, suggesting its great potential for industrial applications.