Fast pyrolysis of biomass to produce bio-oil is an important technology to utilize lignocellulosic biomass, because the liquid bio-oil is regarded as a promising candidate of petroleum fuels. However, bio-oil is a low-grade liquid fuel, and required to be upgraded before it can be directly utilized in existing thermal devices. Catalytic cracking is an effective way to upgrade bio-oil, which can be performed either on the liquid bio-oil or the pyrolysis vapors. Various catalysts have been prepared and used for catalytic cracking, and they exhibited different catalytic capabilities. This paper will review the recent progress of the catalytic cracking of liquid bio-oil or pyrolysis vapors.
The assembly of multiple catalytic functionalities within a single mesoporous silica as a catalyst for multistep enantioselective organic transformations in an environmentally friendly medium is a significant challenge in heterogeneous asymmetric catalysis. Herein, we took advantage of a BF4− anion hydrogen bonding strategy to anchor a chiral cationic rhodium/diamine complex within base‐functionalized mesostructured silica nanoparticles conveniently to construct a bifunctional heterogeneous catalyst. The solid‐state 13C NMR spectrum discloses the well‐defined chiral Rh/diamine active species, and we used XRD, N2 adsorption–desorption, and electron microscopy to reveal the ordered mesostructure. The combination of bifunctionality in the silica nanoparticles enables two kinds of efficient enantioselective organic transformations with high yields and enantioselectivities, in which the asymmetric transfer hydrogenation of α‐haloketones followed by epoxidation provides various chiral aryloxiranes, and the amination of α‐haloketones with anilines followed by asymmetric transfer hydrogenation produces various β‐amino alcohols. Furthermore, the catalyst can be recovered and recycled for seven times without a loss of catalytic activity, which is an attractive feature for multistep organic transformations in a sustainable benign process.
To improve the center segregation of billet for 50CrMo structural alloy steel, a 3D numerical model of solidification and heat transfer process for continuous casting had been established. The influence law of continuous casting process parameters on the secondary dendrite arm spacing (SDAS) and equiaxed crystal ratio had been obtained. It was shown that reducing superheat and casting speed and increasing the secondary cooling intensity could decrease SDAS. Reducing any one of the three parameters could increase the equiaxed crystal ratio. Adjusting only secondary cooling intensity could not make the SDAS and equiaxed crystal ratio change in the desired direction, but regulating the other two parameters could supply this gap. After optimizing the continuous casting process parameters of 50CrMo billet, the defect of center segregation was solved basically.
In an enantioselective reaction, we expect to obtain two types of chiral products through a controllable strategy in asymmetric catalysis. Herein, we develop Ru‐catalysed asymmetric transfer hydrogenation of α‐ketoimides to realise an enantioselective construction of chiral α‐hydroxy imides or chiral α‐hydroxy esters. The transformation of α‐ketoimides catalysed by (S,S)‐[RuCl(η6‐mesitylene)diamine] can afford various chiral α‐hydroxy imides with high yields and enantioselectivities, whereas that catalysed by (S,S)‐[RuCl(η6‐hexamethylbenzene)diamine] gives the desirable chiral α‐hydroxy esters through a slight adjustment of the reaction conditions. The method described here is a controllable organic transformation with sodium formate as a hydrogen source under mild reaction conditions, and the benefit of this transformation is that various chiral α‐hydroxy imides or α‐hydroxy esters can be obtained selectively from α‐ketoimides.
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