Hydrothermally stable mesoporous aluminosilicates with moderate acidity via degradation-assembly process and improved catalytic properties

Mesoporous aluminosilicates with hydrothermal stability and moderate acidity are synthesized via assembly of microporous zeolite precursors obtained by the degradation of zeolite NaY, denoted as “degradation-assembly” (DA) technique. By controlling the degradation degree of matrix NaY, precursors with larger spatial volume and stronger rigidity will be obtained. The characterization results showed that the walls of the mesophase in MDA (mesoporous aluminosilicate obtained by “DA” method) composed of the preformed zeolite Y building units and the moderate acidity was inherited from the introduced precursors. It was suggested that the more mature assembly units accounted for the increased acidity of MDA with more Al species retained in the framework of mesophases. The resulting aluminosilicates with simultaneously moderate acidity and hydrothermal stability showed superior catalytic properties when used in heavy oil catalytic cracking catalysts.     

Manganese(II)‐Mediated Domino Annulation Reaction of Vinyl Azides and 4‐Hydroxycoumarin: A Stereoselective Synthesis of Spirobenzofuranone‐lactams

A manganese(II) acetate‐catalyzed domino reaction of vinyl azides and 4‐hydroxycoumarin has been developed for the synthesis of polyfunctionalized spirofuranone‐lactams. A wide range of vinyl azides are capable of providing the desired spirofuranone‐lactams in good to excellent yields. The reaction was achieved via thermal decomposition of vinyl azides to 2H‐azirines, followed by an intramolecular nucleophilic attack and stereoselective cyclization. The mild reaction conditions and easy operation make this reaction advantageous for the synthesis of spirofuranone‐lactams.

     

Enantioselective One‐Pot Reaction: Organocatalyzed Synthesis of Fully Functionalized Oxabicyclo[2.2.2]octanes with Seven Contiguous Stereocenters

An enantioselective one‐pot Michael/Michael/Henry/hemiacetalization reaction between α,β‐unsaturated aldehydes, α‐ketoamides, and nitroalkenes under mild conditions catalyzed by a diarylprolinol silyl ether has been developed. The sequential methodology provides a direct approach to a wide range of fully substituted chiral oxabicyclo[2.2.2]octanes with seven contiguous stereocenters in moderate to excellent yields (up to 99%), high to excellent diastereoselectivities (up to >25:1 dr), and high to excellent enantioselectivities (up to 99% ee).

     

Enhanced mechanical,thermal and dielectric properties of polyimide nanocomposites containing SiCp (SiCw) nanofillers for high energy-storage applications

Journal of Polymer Research - In this paper, we aimed to develop the nanocarrier based on poly (N-isopropyl acrylamide)—allyl acetoacetate grafted MoS2 nanosheets. The obtained polymer...     

桁架结构中节点板失效模式分析及设计方法研究--以实验测试为例

本文通过实验测试的方法,研究了节点板在腹杆承受轴向压力作用下的破坏过程。     

新型建筑墙体材料及墙体保温技术

随着经济发展,新型建筑企业在国家的建设中不断崛起。在建筑中,墙体的施工是整个建筑的重要环节。因此,对于新型墙体的需求量逐渐增多。施工人员对墙体材料应进行熟悉,熟悉墙体的保温技术,这是现代建筑的重--求。     

Ⅴ级黄土隧道施工控制要点

中国黄土地域分布较广,黄土面积约占我国陆地面积的6.6%,黄土隧道施工的建设无法避免,其施工难度与设计也相对复杂。文章从黄土隧道施工方法、现场管理控制等方面提出了一些建议及施工工艺。     

水工建筑物施工软基处理对策探讨

在管理水工建筑工程项目的过程中,必须重视软土地基的加固处理等相关工作。一方面,要提升施工工序衔接效率,确保施工顺利进行;另一方面要防止返工,保证施工安全以及质量。