Abstract
Isomerization of xylose to xylulose was efficiently catalyzed by
large-pore zeolites in a two-step methanol–water process that
enhanced the product yield significantly. The reaction pathway
involves xylose isomerization to xylulose, which, in part, subsequently
reacts with methanol to form methyl xyluloside
(step 1) followed by hydrolysis after water addition to form additional
xylulose (step 2). NMR spectroscopy studies performed
with 13C-labeled xylose confirmed the proposed reaction pathway.
The most active catalyst examined was zeolite Y, which
proved more active than zeolite beta, ZSM-5, and mordenite.
The yield of xylulose obtained over H-USY (Si/Al=6) after 1 h
of reaction at 1008C was 39%. After water hydrolysis in the
second reaction step, the yield increased to 47%. Results obtained
from pyridine adsorption studies confirm that H-USY (6)
is a catalyst that combines Brønsted and Lewis acid sites, and
isomerizes xylose in alcohol media to form xylulose at low
temperature. The applied zeolites are commercially available;
do not contain any auxiliary tetravalent metals, for example,
tin, titanium, or zirconium; isomerize xylose efficiently; are
easy to regenerate; and are prone to recycling.
Original language | English |
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Journal | ChemSusChem (Print) |
Volume | 8 |
Issue number | 6 |
Pages (from-to) | 1088-1094 |
Number of pages | 7 |
ISSN | 1864-5631 |
DOIs | |
Publication status | Published - 2015 |
Keywords
- Alcohols
- Heterogeneous catalysis
- Isomerization
- NMR spectroscopy
- Zeolites