(582s) Fe and Zn Promoted Mo/ZSM-5 Catalyst for the Conversion of Ethane into Aromatic Products

Ethane can be extracted
from conventional natural gas and shale gas resources, then converted to
petrochemicals such as olefins and aromatic compounds by the non-oxidative
dehydro-aromatization reaction.  Benzene
and toluene are the targeted products in this study which can be further
processed into larger components for polymers, textiles, and plastics, thus
providing a stable market value for benzene and toluene.  The goal of this study is to investigate
catalytic performance and reaction mechanism over Mo/ZSM5 catalyst promoted
with Fe and/or Zn for the conversion of ethane into aromatic compounds.  The catalysts used in this study include  4%Mo-ZSM-5, 
4%Mo-0.3%Fe, 
4%Mo-0.3%Fe-0.3%Zn-ZSM-5,  0.3%Fe
–ZSM-5 and 0.3%Zn-ZSM-5 which were prepared by incipient wetness technique  and calcined at 550oC in the air.  The fresh and spent catalysts were
characterized by a number of analytical techniques including XRD, NH3-TPD,
pyridine-FTIR, TEM, SEM, and surface area micropore analysis. Elemental surface
composition was obtained from energy dispersive spectroscopic (EDS). The
reaction was carried out in a fixed bed reactor where gas chromatography
monitored the formation of ethylene, benzene and toluene.  Thermogravimetric Analysis (TGA) and Temperature
Programed Oxidation (TPO) coupled with mass spectroscopy analysis was performed
on the spent samples for coke characterization. The effects of Fe and Zn
promoters on the aromatics production and coke formation are elucidated. The
NH3-TPD profiles [Figure 1] of the fresh catalysts revealed the correlation
between promoters and surface acidity, further discussion will be made. The
influence of surface acidity, especially the ratio of Lewis/ Brønsted acid sites, on the catalytic activity and
deactivation behavior will also be discussed.

Figure 1: NH₃-TPD profiles of fresh catalyst