Olefin Epoxidations Using Supercritical Carbon Dioxide and Hydrogen Peroxide without Added Metallic Catalysts or Peroxy Acids

2002 ◽  
Vol 41 (3) ◽  
pp. 316-323 ◽  
Author(s):  
Shane A. Nolen ◽  
Jie Lu ◽  
James S. Brown ◽  
Pamela Pollet ◽  
Brandon C. Eason ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Olefin Epoxidations ◽  
Peroxy Acids ◽  
Supercritical Carbon

Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O2 pulps

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Roberta Pacheco Francisco ◽  
Jorge Luiz Colodette ◽  
Antonio Aprigio da Silva Curvelo
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Kraft Pulp ◽  
Poor Performance ◽  
Kappa Number ◽  
Elemental Chlorine ◽  
Chlorine Gas ◽  
Hexenuronic Acid ◽  
Supercritical Carbon

Abstract Kraft pulp is currently bleached largely by the elemental chlorine free (ECF) technology with oxygen, chlorine dioxide, and hydrogen as active agents. This technology brought about significant environmental improvements in relation to standard processes based on chlorine gas and hypochlorite, but there is still need for further improvements. This study presents a novel environmentally friendly bleaching stage – the so-called ‘hydrogen peroxide in supercritical carbon dioxide’, P(SC-CO2) – that can be adapted to current ECF bleaching processes, with preference in cases where hydrogen peroxide is already used. In this study, the P(SC-CO2) stage was evaluated as a replacement to the last peroxide stage of the D(EP)DP bleaching sequence and to the first peroxide stage of the D(EP)DP sequence, for an oxygen delignified eucalypt kraft-O2 pulp. The P(SC-CO2) stage was run with 0.5% hydrogen peroxide, at 15% consistency, 70°C, and 73 bar. The reaction time was 30 min. The performances of regular P stages and the new P(SC-CO2) stage were compared. Promising results were observed with the DEP(SC-CO2)DP sequence; the P(SC-CO2) decreased kappa number from 2.7 to 2.1, and the hexenuronic acid groups from 17.0 to 12.4 mmol kg-1. The P(SC-CO2) stage showed poor performance when applied in the D(EP)DP(SC-CO2) sequence. It is concluded that the process presents potential but requires further optimization to improve selectivity and efficiency.

Sterilisation of collagen materials using hydrogen peroxide doted supercritical carbon dioxide and its effects on the materials properties

2015 ◽  
Vol 102 ◽  
pp. 32-39 ◽  
Author(s):  
Michael Meyer ◽  
Ina Prade ◽  
Kathrin Leppchen-Fröhlich ◽  
Alexander Felix ◽  
Volker Herdegen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Supercritical Carbon Dioxide ◽  
Materials Properties ◽  
Supercritical Carbon

scholarly journals Effects of supercritical carbon dioxide on morphology of apocynum venetum fibers

2015 ◽  
Vol 19 (4) ◽  
pp. 1279-1282 ◽  
Author(s):  
Shi-Hui Gao ◽  
Chong-Wen Yu
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Hydrogen Peroxide ◽  
Scanning Electron Microscopy ◽  
Supercritical Carbon Dioxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Apocynum Venetum ◽  
Scanning Electron ◽  
Supercritical Carbon

This paper investigated the structures and compositions of apocynum venetum fibers treated with pectinase and mixture of sodium hydroxide and hydrogen peroxide in supercritical carbon dioxide fluid. The apocynum venetum fibers were analyzed by Fourier transform infrared spectrometry, X-ray diffraction, and scanning electron microscopy. Fourier transform infrared analysis indicated that pectinase could remove the pectin and hemicellulose and the mixture of sodium hydroxide and hydrogen peroxide could extract the lignin in supercritical carbon dioxide. Meanwhile, the results of X-ray diffraction showed that cellulose crystallinity index and crystallite sizes of treated fibers increased in comparison with that of untreated fibers. The studies of scanning electron microscopy also revealed a complete removal of non-cellulosic gummy material from surface of treated apocynum venetum fibers. Small gummy on the surface of apocynum venetum fibers would be removed by supercritical carbon dioxide, which can be verified by bubble dynamics.

Sign in / Sign up

Export Citation Format

Share Document