Tianliang Lu

Conversion of dihydroxyacetone to methyl lactate catalyzed by highly active hierarchical Sn-USY at room temperature

Hierarchical Sn-USY zeolites were prepared by the post-synthesis method via dealumination of H-USY zeolite with nitric acid and solid-state ion-exchange with SnCl4. High concentration of nitric acid was favorable for removal of framework Al and the following Sn incorporation. The physicochemical properties of Sn-USY zeolites were characterized by various techniques. Sn was incorporated into the framework site which created Lewis acid sites. Meanwhile, the abundant mesopores generated by acid treatment were preserved after Sn incorporation. The prepared hierarchical Sn-USY zeolites were used to catalyze the conversion of 1,3-dihydroxyacetone (DHA) to methyl lactate (MLA) in methanol. It is found that the hierarchical Sn-USY zeolites are highly active and selective for this reaction. At ambient temperature (25–40 °C), DHA was completely transformed with more than 95% MLA yield. Moreover, the hierarchical Sn-USY zeolites are recyclable and reusable at least five times without significant loss of activity and selectivity.

Fluoride-free and low concentration template synthesis of hierarchical Sn-Beta zeolites: efficient catalysts for conversion of glucose to alkyl lactate

Hierarchical Sn-Beta zeolite was prepared through a hydrothermal postsynthesis method, which employed no fluoride and only a small amount of tetraethyl ammonium hydroxide (TEAOH). The dual roles of TEAOH as a base and as a structure directing agent were discussed in detail, which were significantly affected by its concentration. At a TEAOH concentration of 0.2–0.4 mol L−1, hierarchical Sn-Beta zeolites with the most probable mesopore diameter of 7.8 nm were achieved. Other physicochemical properties of the hierarchical Sn-Beta including the content and state of Sn and the acidity were also characterized. The hierarchical Sn-Beta zeolite gave a higher yield of methyl lactate (58%) than the microporous Sn-Beta zeolite synthesized in fluoride medium (47%) due to the promoting effect of the hierarchical porosity on the conversion of glucose in methanol, which is an important and challenging process of a biorefinery. The hierarchical Sn-Beta zeolite is stable and can be recycled and reused five times without significant loss of activity and selectivity.

Sulfonic Acid Resin–Catalyzed Oxidation of Aldehydes to Carboxylic Acids by Hydrogen Peroxide

Abstract Oxidation of benzaldehyde to benzoic acid can be performed efficiently with 30% H2O2 as the oxidant and sulfonic acid resin Amberlyst 15 as the catalyst. The reactivities of benzaldehyde derivatives are determined by both hindrance effect and electron effect of substituents, and benzaldehyde derivatives with electron-withdrawing group at the meta- or para-position are highly active and almost quantitatively converted into their corresponding acids. In addition, this method also works well for the oxidation of aliphatic aldehydes. The key characteristic of the procedure is that the catalyst is recyclable. GRAPHICAL ABSTRACT

Promotion effect of nickel for Cu–Ni/γ-Al2O3 catalysts in the transfer dehydrogenation of primary aliphatic alcohols

Cu–Ni/γ-Al2O3 bimetallic catalysts were developed for anaerobic dehydrogenation of non-activated primary aliphatic alcohols to aldehydes. Systematic investigation about the promotion effect of nickel on the catalytic performance was carried out. Hydrogenation of C=C bond rather than C=O bond, was significantly improved over Cu–Ni/γ-Al2O3 catalyst by introducing nickel, which interprets the good conversion of primary aliphatic alcohols. This work would contribute to design new catalysts for dehydrogenation of primary aliphatic alcohols.