Table 1.
Literature review of hydrotalcite-based catalysts for the simultaneous removal of soot and NOx.
| Hydrotalcites Families | Catalysts | Preparation Method | Reaction Conditions | Ref. |
|---|---|---|---|---|
| Binary MgAlOx LDH | A series of K-supported MgAl with different amount of K doping (2, 5, 8 and 15 wt.% of K) | Co-precipitation; K addition by impregnation; calc. 600 °C | Cat/soot = 9/1; 9.97% O2 + He or 1050 ppm NO + He; total flow 100 mL/min; heating rate 5 or 10 °C/min | [22,23,24] |
| CuAlOx catalyst | Co-precipitation; calc. 800 °C | Cat/soot = 9/1; 0.25% NO + 5.0% O2 + He; total flow 20 cm3/min; heating rate 1.6 °C/min | [25] | |
| CoAlOx catalyst | Co-precipitation; calc. 500 °C e 800 °C | Cat/soot = 20/1; 0.25 vol.% NO + 5 vol.% O2 + He, total flow 80 cm3/min, heating rate 1.4 °C/min | [26] | |
| Ternary MgAlOx LDH | A series of Mn-doped MgAl with different amount of Mn doping (from 0.5 to 3) | Co-precipitation; calc. 800 °C | Cat/soot = 20/1; 750 ppm NO + 10 vol.% O2 + N2, total flow 240 cm3/min, heating rate 10 °C/min | [27] |
| A series of CuxMg3-xAl with different Cu contents (0.5, 1.0, 1.5, 2.0, 2.5, 3.0) | Co-precipitation; calc. 600 °C–700 °C–800 °C | Cat/soot = 20/1; 0.25 vol.% NO + 5 vol.% O2 + He; total flow 20 cm3/min, heating rate of 1.6 °C/min. | [28] | |
| Co2.5Mg0.5Al | Co-precipitation; calc. 500 °C, 600 °C, 700 °C or 800 °C |
Cat/soot = 20/1; 400 ppm NO + 10 vol.% O2 + N2; total flow 400 mL/min; heating rate of 10 °C/min. | [12,13] | |
| Quaternary MgAlOx LDH | A series of K-doped Co2.5MgAl with different amount of K doping (1.5, 4.5, 7.5, 10) | Co-precipitation; K addition by impregnation; calc. 600 °C | Cat/soot = 20/1; 400 ppm NO + 10% O2 + N2; total flow 20 mL/min | [13] |
| A series of K-doped Mn1.5MgAl with different amount of K doping (x = 1.5, 4.5, 7.5, 10, 15, 20) | Co-precipitation; K addition by impregnation; calc. 800 °C | Cat/soot = 20/1; 750 ppm NO + 10 vol.% O2 + N2, total flow 240 cm3/min, heating rate 10 °C/min | [29] |