(560hr) Development of Secondary Phase in Various Zeolites Framework

Development
of Secondary Phase in Various Zeolites Framework

Safa Gaber^†§, Dina Gaber^†,
Georgia Basina^*,†, Alyaa Alzaabi^†, Alya Alzaabi^†,
Aziza Alameeri^†, Fatima Abdullah^†, Meera Alqemzi^†,
and Yasser AlWahedi^*,†,§

^†Department of Chemical
Engineering, Khalifa University, Sas Al Nakhl campus, P.O. Box 2533, Abu Dhabi,
United Arab Emirates

^§Center for Catalysis
and Separation, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab
Emirates

Corresponding Author(s)

 * Georgia Basina,
e-mail address: georgia.basina@ku.ac.ae, Yasser AlWahedi,
e-mail address: yasser.alwahedi@ku.ac.ae

Abstract:

Hydrogen
sulfide is considered as one of the most common economic and environmental
problem in oil and gas industries [1]. Several techniques have been developed
to remove H₂S. Among these techniques, dry-adsorption based processes
are well-known class of methods which  has attracted attention due to it is use
of low cost, efficient and environmentally friendly adsorbents such as metal
oxide, carbon-based materials and zeolite [2].

Copper
oxide have demonstrated high adsorption capacity for H₂S as it
capable of reducing H₂S from thousand ppm to sub ppm levels, however
their efficiency is limited by the reduction of the adsorbent to copper metal/sulfate
upon cycling [3,4]. On the other hand, zeolite-based adsorbent has attracted
attention due to its higher adsorption capacity at low temperature. Zeolite
which are crystalline microporous aluminosilicate material with three-dimensional
network structure, are highly porous material that are easy to regenerate, have
high surface area and a large number of active sites [4,5]. All of these
features render them favorable adsorbent/adsorbent housing matrices.  Zeolite
modification by metal/metal oxide incorporation is a promising technique that
can improve H₂S adsorption capacity. Through our initial experiments
on copper liquid ion exchange on zeolite-Y, a mysterious secondary phase was
noticed. It was shown that the presence of this phase in zeolite matrix lead to
much higher adsorption capacity of H₂S when compared to the original
zeolite. hence, the main objective of this study is to investigate the
experimental factors that govern the formation of this mysterious phase and the
nature of the phase itself. Also, it aims to assess the extent of enhancement
due to their presence on the H₂S adsorption capacity. The factors
studied include: temperature, pH, zeolite type, zeolite amount, copper
concentration and sodium external addition. The resulting materials were
characterized by XRD and SEM, while their adsorption properties were determined
using a standard breakthrough system.  

Figure
1: SEM image of Zeolite
x a: before b: zeolite after liquid ion exchange with Copper obtained by
exchanging sodium ion in zeolite with Cu (NO₃)₂. 3 H₂O
solution 3 times at room temperature for 24 hours.

References:

1-  
Elsayed, Y., Seredych, M., Dallas, A., &
Bandosz, T. J. (2009). Desulfurization of air at high and low H2S
concentrations. Chemical Engineering Journal, 155(3),
594-602.

2-  
Shah, M. S., Tsapatsis, M., & Siepmann, J.
I. (2017). Hydrogen sulfide capture: from absorption in polar liquids to oxide,
zeolite, and metal–organic framework adsorbents and membranes. Chemical
reviews, 117(14), 9755-9803.

3-  
Xue, M., Chitrakar, R., Sakane, K., & Ooi,
K. (2003). Screening of adsorbents for removal of H 2 S at room
temperature. Green chemistry, 5(5), 529-534.

4-  
Kumar, P., Sung, C. Y., Muraza, O., Cococcioni,
M., Al Hashimi, S., McCormick, A., & Tsapatsis, M. (2011). H2S adsorption
by Ag and Cu ion exchanged faujasites. Microporous and Mesoporous
Materials, 146(1-3), 127-133.

5-  
Davis, M. E., & Lobo, R. F. (1992). Zeolite
and molecular sieve synthesis. Chemistry of Materials, 4(4),
756-768.