1 research outputs found
Dehydration of Glycerol to Acrolein over Hierarchical ZSM‑5 Zeolites: Effects of Mesoporosity and Acidity
Selective dehydration of glycerol
to value-added acrolein is an
interesting catalytic process not only owing to the increasing coproduction
of glycerol in the biodiesel production but also due to the emerging
perspectives to provide a sustainable route for acrolein production.
The use of zeolites in glycerol dehydration is a very promising way
with high performance, but these microporous catalysts are often severely
constrained by the rapid catalyst deactivation due to coke formation.
Although the introduction of hierarchical structure in microporous
zeolite crystals is believed to be an effective approach to enhance
their activity and lifetime, the relationship between the mesoporosity
and catalytic performance is still controversial. In this paper, four
kinds of typical hierarchical ZSM-5 catalysts with diverse mesoporosity
and similar microporosity/acidity are prepared by the salt-aided seed-induced
route. By systematically studying their catalytic performances, the
effects of various mesopore types on the glycerol dehydration are
declared, including pore size, amount, distribution, and connectivity.
The sample with open and interconnected mesopore architecture display
the high activity, long lifetime, and improved selectivity, while
the worse behavior of closed and small mesopores is attributed to
the mass transfer limitations and/or the in-pore condensation of reactant
or its heavier derivatives. Moreover, the combined effect of acidity
and hierarchical structure was also explored by changing the framework
Si/Al ratio. The findings emphasize the necessity of reasonably designing
the zeolite catalysts with proper hierarchical structure and acidity
for maximal catalytic advantage