Effects of zirconia phase on the synthesis of higher alcohols over zirconia and modified zirconia

The catalytic performances of ZrO2-based catalysts were evaluated for the synthesis of higher alcohols from synthesis gas. The crystal phase structures were characterized by X-ray diffraction (XRD) and UV Raman. The results indicated that ZrO2 and Pd modified ZrO2 catalysts were effective catalysts in the synthesis of ethanol or isobutanol, and their selectivities basically depended on the crystal phase of ZrO2 surface. The ZrO2 with surface tetragonal crystal phase exhibited a high activity to form ethanol, while the ZrO2 with surface monoclinic crystal phase exhibited a high activity to form isobutanol. Temperature-programmed desorption (TPD) experiment indicated that the high activity of isobutanol formation from synthesis gas over monoclinic zirconia was due probably to the strong Lewis acidity of Zr4+ cations and the strong Lewis basicity of O2- anions of coordinative unsaturated Zr4+-O2- pairs on the surface of monoclinic ZrO2. (C) 2003 Elsevier B.V. All rights reserved.

Concise synthesis of novel practical sulfamide-amine alcohols for the enantioselective addition of diethylzinc to aldehydes

Novel sulfamide-amine alcohol ligands were designed using a grafting strategy and synthesized from readily available starting materials via a simple, efficient method. The key features of these ligands for the asymmetric addition of diethylzinc to aldehydes included stability, enhanced effectiveness without using Ti((OPr)-Pr-i)(4), suitability for a variety of aldehydes, the ability to operate at room temperature, and selectability to afford either absolute configuration products with enantiomeric excess up to >99%.

Novel catalysis of TiO2 for the catalytic alcohols synthesis from CO and H2O

Direct synthesis of alcohols from CO and H2O was investigated using TiO2 catalyst. MeOH (about 24 mg g(-1) h(-1)) and EtOH (about 8 mg g(-1) h(-1)) could be produced under the reaction conditions of T= 573 K, P= 0.5 MPa, CO flow rate of 30 ml min(-1) and CO/H2O = 3/2 during the period of 12 to 44 h time-on-stream. Compared with PbO, TiO2 could preserve stable catalytic activity during a long time of reaction. For the same catalyst TiO2, the reaction performance of alkali carbonates increased with their solubility (K2CO3>Na2CO3>Li2CO3). The corresponding catalytic activity was found to increase with the alkalescence of solvent. The formation mechanism of alcohols was proposed as well. (C) 2004 Elsevier B.V. All rights reserved.

Catalytic alcohols synthesis from CO and H2O on TiO2 catalysts calcined at various temperatures

The reaction performance for CO hydration on a TiO2 catalyst under different calcination temperatures was investigated. Under reaction conditions of T = 573 K, P = 0.5 MPa, CO flow rate of 30 ml min(-1), TOS = 12 h, and CO/H2O (g) = 3/2 (mol), the TiO2 catalyst with a futile content of 18% shows a maximum alcohols STY of 1.81 Mg m(-2) h(-1). In addition, the catalyst deactivation and regeneration were discussed.

Novel activity of TiO2 for catalytic conversion of CO and H2O to alcohols in the presence of K2CO3

In the presence of K2CO3, TiO2 shows good catalytic activity and stability for the alcohols synthesis from CO and H2O. CO conversion of 7.6% and the STY of MeOH (about 24 mg g(-1) h(-1)) and EtOH (about 8 mg g(-1) h(-1)) are obtained under reaction conditions of T = 573 K, P = 0.5 MPa, CO flow rate of 30 ml min(-1) and CO/H2O = 3/2 during the period of 12 h to 44 h time-on-stream.

Theoretical studies on the reaction mechanism of oxidation of primary alcohols by Zn/Cu(II)-phenoxyl radical catalyst

The catalytic mechanism for the oxidation of primary alcohols catalyzed by the two functional models of galactose oxidase (GOase), M-II L (M = Cu, Zn; L = N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)1-2-diiminoquinone)), has been studied by use of the density functional method B3LYP The catalytic cycle of Cu- and Zn-catalysts consists of two parts, namely, substrate oxidation (primary alcohol oxidation) and O-2 reduction (catalyst regeneration). The catalytic mechanisms have been studied for the two reaction pathways (route 1 and route 2). The calculations indicate that the hydrogen atom transfer within the substrate oxidation part is the rate-determining step for both catalysts, in agreement with the experimental observation.

An ionic liquid based on a cyclic guanidinium cation is an efficient medium for the selective oxidation of benzyl alcohols

A novel room temperature ionic liquid (RTIL) has been prepared containing a cyclic hexaalkylguanidinium cation. The selective oxidation of a series of substituted benzyl alcohols has been carried out in it, with sodium hypochlorite as the oxidant. The RTIL acts as both phase transfer catalyst (PTC) and solvent. The ionic liquid could be recycled after extraction of the benzaldehyde product with ether.