TY - JOUR
T1 - In situ transformation of geopolymer gels to self-supporting NaX zeolite monoliths with excellent compressive strength
AU - Wang, Hongquan
AU - Yan, Chunjie
AU - Li, Dan
AU - Zhou, Feng
AU - Liu, Yi
AU - Zhou, Chunyu
AU - Komarneni, Sridhar
N1 - Funding Information:
This study was supported by Shandong Geological exploration projects (2015, SDZS-2015-GTT01 ). The authors would also like to thank the Laboratory and equipment, China University of Geosciences (Wuhan).
Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - Geopolymers are a new class of green high-strength aluminosilicate materials, which generally maintain an amorphous structure due to the limitations related to their chemical compositions and reaction conditions but possess the ability to form molecular sieves. In this work, the in-situ transformation of geopolymers into self-supporting NaX zeolite monoliths of relatively large sizes was examined under hydrothermal conditions and various parameters of the synthesis process were optimized. The obtained results indicated that the optimal transformation conditions for geopolymers with a Si/Al ratio of 4.0 are as follows: precursors composed of metakaolin and modified industrial sodium silicate with a Na2O/SiO2 molar ratio of 1.0, H2O/Na2O molar ratio of 70, hydrothermal synthesis time of 18 h and a temperature of 90 °C. According to the obtained X-ray diffraction (XRD) data, the synthesized NaX Monoliths exhibited characteristic reflections consistent with those of standard NaX zeolites and possessed high degrees of crystallinity, while scanning electron microscopy revealed that the produced molecular sieves exhibited well-defined morphology. In addition, the zeolitic monoliths exhibited excellent compressive strength for potential practical applications.
AB - Geopolymers are a new class of green high-strength aluminosilicate materials, which generally maintain an amorphous structure due to the limitations related to their chemical compositions and reaction conditions but possess the ability to form molecular sieves. In this work, the in-situ transformation of geopolymers into self-supporting NaX zeolite monoliths of relatively large sizes was examined under hydrothermal conditions and various parameters of the synthesis process were optimized. The obtained results indicated that the optimal transformation conditions for geopolymers with a Si/Al ratio of 4.0 are as follows: precursors composed of metakaolin and modified industrial sodium silicate with a Na2O/SiO2 molar ratio of 1.0, H2O/Na2O molar ratio of 70, hydrothermal synthesis time of 18 h and a temperature of 90 °C. According to the obtained X-ray diffraction (XRD) data, the synthesized NaX Monoliths exhibited characteristic reflections consistent with those of standard NaX zeolites and possessed high degrees of crystallinity, while scanning electron microscopy revealed that the produced molecular sieves exhibited well-defined morphology. In addition, the zeolitic monoliths exhibited excellent compressive strength for potential practical applications.
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U2 - 10.1016/j.micromeso.2017.11.015
DO - 10.1016/j.micromeso.2017.11.015
M3 - Article
AN - SCOPUS:85033382424
SN - 1387-1811
VL - 261
SP - 164
EP - 169
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
ER -