TABLE 3.
Typical examples of adsorbents that have been tested for adsorptive denitrogenation.
| Adsorbent | Feedstock | Performance | References |
|---|---|---|---|
| General adsorbents | |||
| Fe(III) impregnated bentonite clay | Quinoline and methylene blue | Total adsorbed nitrogen (39 mg g−1) | Mambrini et al. (2013) |
| Activated carbon, MAXSORB-II | Straight run gas oil | 0.039 g N g adsorbent | Sano et al. (2004) |
| CuCl/activated carbon | Quinoline and indole in n-octane/p-xyene (75:25) | AC: quinoline (64 mg/g), indole (63 mg/g); CuCl/AC: quinoline (126 mg/g), indole (168 mg/g) | Ahmed and Jhung, (2015a) |
| Mesoporous silicas | Light gas oils | Up to 8.05 mg N per g adsorbent | Kwon et al. (2008) |
| Zeolites containing cuprous cations | Commercial diesel | Alkyl carbazoles completely removed | Hernández-Maldonado and Yang, (2004) |
| Yttrium ion-exchanged Y zeolite | Indole and quinoline in n-octane | Up to 12.37 mg per g adsorbent | Tian et al. (2020) |
| X-type zeolites | Quinoline in isooctane | Up to 17 mg N per g adsorbent | Ofoghi et al. (2021) |
| Hexagonal mesoporous silicas (molecular sieves) Ti−HMS | Pyridine, quinoline and indole in n-octane (N concentration 200 μg g−1) and diesel | Pyridine > quinoline > indole diesel (90% N removal) | Zhang et al. (2010) |
| Ion exchange resins | Shale-derived oils | Up to 0.072 g N/g resin | Marcelin et al. (1986) |
| Aluminosilicate mesostructures (MSU-S) and HPW and NiO-HPW modified MSU-S | Quinoline and carbazole in n-hexadecane/n-octane (50:50) | MSU-S (0.4 mmol/g), HPW-MSU-S (0.43 mmol/g) and NiO/HPW-MSU-S (0.44 mmol/g) | Rashidi et al. (2015) |
| ∼7% increase in nitrogen uptake in modified MSU-S | |||
| Tailored organic polymers | |||
| Styrene-divinylbenzene copolymer | Model fuel and crude oil | pyridine (99.9%), pyrrole (99.7%) | Awokoya et al. (2021) |
| Vinylpyridine based polymer | Indole in n-octane | Indole (31.80 mg g−1) | Cao et al. (2014) |
| Polybenzimidazole fibres | Model fuel and spiked diesel | pyrimidine (11.5 mg g−1), carbazole (11.8 mg g−1), quinoline (11.0 mg g−1) | Abdul-quadir et al. (2019) |
| Poly 4-vinyl aniline-co-divinylbenzene | Model fuel and Sasol diesel 500 | pyridine (30.2 mg g−1) | Mathidala and Ogunlaja, (2019) |
| Poly-2-(1H-imidazol-2-yl)-4-phenol microspheres | Model fuel and diesel | pyrimidine (10.56 mg g−1), carbazole (11.71 mg g−1), quinoline (10.84 mg g−1) | Abdul-Quadir et al. (2018a) |
| Poly 2-(1H-imidazol-2-yl)-4-phenol nanofibers | Model fuel and diesel | quinoline (11.7 mg g−1), pyrimidine (11.9 mg g−1), carbazole (11.3 mg g−1) | Abdul-Quadir et al. (2018b) |
| Fe3O4 nanoparticles equipped magnetic molecularly imprinted polymers | Model fuel | indole (37.58 mg g−1) | Niu et al. (2014) |
| Coordination polymers | |||
| MIL-101 (Cr) | Straight run gas oil (SRGO) and light cycle oil (LCO) | SRGO (9.0 mg N per g), LCO (19.6 mg N per g) | Nuzhdin et al. (2010) |
| Adsorption due to π-π stacking interactions with terephthalate bridges of MOF | |||
| MIL-100 (Al3+, Cr3+, Fe3+, V3+) | Indole and 1,2-dimethylindole in heptane | Indole (V>Cr>Fe>Al) | Van de Voorde et al. (2013a) |
| 1,2-Dimethylindole (V>Cr>Al>Fe) | |||
| MIL-100(V)vac has best performance due to CUSs | |||
| Indole>1,2-Dimethylindole | |||
| MIL-101 (Cr) | Pyridine | Pyridine (950 mg/g) pyridine adsorption via CUSs | Kim et al. (2011) |
| MIL-101 (Cr) | SRGO and LCO | MIL-101 (Cr) showed better adsorption than silica gel, Selexsorb® CD, Selexsorb® CDX and activated carbon (2.3 times higher adsorption capacity, two times rate of adsorption) | Laredo et al. (2016) |
| Adsorbent regenerated 280 times using acetone | |||
| MIL-100(Fe, Cr, Al), MIL-101(Cr), [Cu3(BTC)2], CPO-27(Ni), CPO-27(Co), MIL-47/MIL-43 | Indole, 2-methylindole, 1,2-dimethylindole in heptane or heptane/toluene (80:20) | No significant uptake (<1 wt%) in MOFs without open metal sites (MIL-47/MIL53) | Maes et al. (2011) |
| Reduced uptake when solvent was changed to heptane/toluene (80:20) | |||
| MIL-96(Al), MIL-53(Al) and MIL-101(Cr) | Pyridine, pyrrole, quinoline and indole in n-octane | Highest adsorption in MIL-101(Cr) due to CUSs | Wang et al. (2013) |
| Adsorption in MIL-96(Al) and MIL-53(Al) demonstrated importance of pore shape and size | |||
| MIL-53(Fe) | Indole and benzothiazole in heptane/isopropanol | Indole (22 wt%), benzothiazole (59 wt%) | Van de Voorde et al. (2013b) |
| Hydrogen bonding | |||
| UiO-66—SO3H | Indole in n-octane | Indole (37% improved uptake compared to pristine UiO-66) | Ahmed et al. (2015) |
| Hydrogen bonding with O in (-SO3H) | |||
| UiO-66 and UiO-66-NH2 | Pyridine | Improved adsorption capacity and kinetics in UiO-66-NH2 compared to pristine UiO-66 | Hasan et al. (2014) |
| UiO-66 and UiO-66-NH2 | Indole | UiO-66 (213 mg/g) > UiO-66-NH2(100) (312 mg/g) due to increased hydrogen bonding from amine group | Ahmed and Jhung, (2015b) |
| CuCl impregnated MIL-100(Cr) | Quinoline, indole in n-octane/p-xylene (75:25 v/v) | Quinoline (9%) and indole (15%) improved uptake comparedto pristine MIL-100(Cr) | Ahmed and Jhung, (2014) |
| Phosphotungstic acid impregnated MIL-101 | Quinoline, indole | 20% increase in quinoline uptake, no change for indole | Ahmed et al. (2013a) |
| Acidic MOFs good for the adsorption of hard bases | |||
| AlCl3 loaded MIL-100(Fe) | Quinoline and indole | 17% increase in uptake of quinoline, no change for indole | Ahmed et al. (2014) |
| AlCl3 is a Lewis acid salt | |||
| MIL-101(Cr) functionalized with -SO3Ag | Quinoline, indole in n-octane/toluene (85:15 v/v) | 50% increase in uptake, maintained uptake in presence of toluene | She et al. (2018) |
| Composite materials | |||
| Fe3O4@SiO2@PILs (magnetic polymeric ionic liquids) | Pyridine, quinoline, indole, carbazole in toluene/heptane (80:20) | Pyridine (80.28%), quinoline (84.45%), indole (32.48), carbazole (28.47) | Wang et al. (2019) |
| PILs were grafted on silica-coated Fe3O4 | |||
| Mesoporous Ti-HMS/KIL-2 composite | Pyridine and quinoline in n-octane | Pyridine(90%), quinoline (90%) | Song et al. (2017) |
| Increased surface area compared to precursor compounds | |||
| ZIF-67(x)@H2N-MIL-125 [Z67(x)@M125] | Indole, 1-metylindole, quinoline, pyrrole and pyridine in n-octane | Indole (680 mg/g) | Bhadra and Jhung, (2020) |
| Indole>1-methylindole>quinoline>pyrrole>pyridine | |||
| H-bonding, cation-π, acid-base and π-complexation | |||
| Graphene oxide (GnO)/MIL-101 (Cr) composite | Indole or quinoline in n-octane | GnO/MIL-101 indole (593 mg/g), quinoline (484 mg/g) > MIL-101 indole (416 mg/g), quinoline (446 mg/g) | Ahmed and Jhung, (2016b) |
| Graphite oxide/MIL-101(Cr) | Quinoline and indole in n-octane/p-xylene (75:25) | Improved uptake of quinoline (24%) and indole (30%) in GO/MIL-101 compared to pristine MIL-101 | Ahmed et al. (2013b) |