Gas permeation performance of cellulose hollow fiber membranes made from the cellulose/N-methylmorpholine-N-oxide/H2O system

Cellulose hollow fiber membranes (CHFM) were prepared using a spinning solution containing N-methylmorpholine-N-oxide as solvent and water as a nonsolvent additive. Water was also used as both the internal and external coagulant. It was demonstrated that the phase separation mechanism of this system was delayed demixing. The CHFM was revealed to be homogeneously dense structure after desiccation. The gas permeation properties of CO2, N-2, CH4, and H-2 through CHFM were investigated as a function of membrane water content and operation pressure. The water content of CHFM had crucial influence on gas permeation performance, and the permeation rates of all gases increased sharply with the increase of membrane water content. The permeation rate of CO2 increased with the increase of operation pressure, which has no significant effect on N-2, H-2, and CH4. At the end of this article a detailed comparison of gas permeation performance and mechanism between the CHFM and cellulose acetate flat membrane was given. (C) 2003 Wiley Periodicals, Inc.

Efficient reductive selenation of aromatic aldehydes to symmetrical diselenides with Se/CO/H2O under atmospheric pressure

An efficient method for the synthesis of symmetrical diselenides is described. Reductive selenation of aromatic and heterocyclic aromatic aldehydes (ArCHO) with Se/CO/H2O in DMF afforded diselenides (ArCH2SeSeCH2Ar) in yields up to 94% under atmospheric pressure without use of a base.

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.