Nowadays, desulfurization of liquid
fuels is inevitable because of strict environmental and industrial
regulations on liquid fuels specifications. Hydrodesulfurization (HDS)
technology has been used widely to produce fuels with ultralow sulfur
content (S ≤ 10 ppm). However, this method is not effective
enough for removing refractory sulfur compounds (e.g., benzothiophene,
dibenzothiophene, and their derivatives). Consequently, alternative
or supplementary desulfurization methods have been rapidly developed
in recent years. The oxidative desulfurization (ODS) process is a
promising method with high selectivity, low cost, mild reaction conditions,
and high efficiency. In the past few decades, the ODS process of fuels
by polyoxometalates (POMs) as catalysts have attracted considerable
attention, resulting in different works have been published due to
their strong acidity, fast and reversible multielectron redox properties,
tunable redox properties, as well as thermal, hydrolytic, and oxidative
stability. In this review, the removal of S-compounds from fuel oils
is investigated via the ODS process using homogeneous and heterogeneous
polyoxometalate catalysts. Moreover, the advantages and problems of
each system are discussed. Various techniques for reducing their noticeable
drawbacks are also presented. Finally, the regeneration of POM catalysts,
as an important step in industrial applications, is examined.
The development of adsorbents for
gas desulfurization is highly
essential to control sulfur dioxide emissions. In this article, CuO-modified
SBA-15 and MOR-SBA-15 composite adsorbents were prepared by impregnation
and post-grafting methods. As-prepared adsorbents were characterized
by X-ray diffraction, scanning electron microscopy, energy dispersive
spectroscopy, Fourier transform infrared spectroscopy, transmission
electron microscopy, and N2 adsorption–desorption
methods. Furthermore, the adsorption desulfurization efficiency was
investigated. The results proved that the impregnation method exhibited
a remarkable dominance compared to the grafting method. The 8.7% CuO/MOR-SBA-15-imp
adsorbent showed superior performance compared with other adsorbents
in removing SO2 from the flue gas. Moreover, the 8.7%CuO/MOR-SBA-15-imp
adsorbent illustrated an excellent regeneration for five cycles. The
optimal condition for the flue gas desulfurization with the flow rate
of 13 NL/h was 400 °C and a 200 mg adsorbent. Kinetic model studies
showed that the model was pseudo-first order, and the amounts of activation
energy for the 8.7% CuO/SBA-15-imp and 8.7% CuO/MOR-SBA-15-imp samples
were 20.4 and 18.5 kJ/mol, respectively.
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