11.08.2015   Biofuels Refining and Performance

Other Metal Oxide Catalysts

Cottonseed oil has been thermally decomposed at 450oC using 1% Na2CO3 as a catalyst [42]. Pyrolysis produced a yellowish-brown oil with 70OC yield. The fuel properties of original and pyrolyzed cottonseed oil are sum­marized in Table 8.7. Results of ASTM distillation compared to diesel are given in Table 8.8 showing a higher volatility for the conversion product.

Rapeseed oil was pyrolyzed in the presence of about 2% calcium oxide up to a temperature of 450OC [43]. An oil was obtained with a heating

TABLE 8.7 Fuel Properties of Original and Pyrolyzed Cottonseed Oil and No. 2 Diesel Fuel

Property

Diesel fuel

Pyrolyzed oil

Original oil

API gravity

35

35

21.5

Specific gravity (at 15.6OC)

0.8504

0.8500

0.9246

Kinetic viscosity (mm/s2) at 40OC

0.0213

0.0178

0.0357

Cetane index

33

28

20

Flash point, oC

96

53

268

Sulfur content, wt.%

0.04

Nil

0.02

Pour point, oC

0.0

>15

23

Sediment content, wt.%

Nil

0.04

5.0

Calorific value, kJ/g

45.57

45.57

41.80

Water content, vol.%

Nil

2.98

1.20

Ash content, wt.%

Nil

Nil

Nil

Carbon residue, wt.%

0.01

0.16

1.06

TABLE 8.8 Results of ASTM Distillation of No. 2 Diesel Oil and Pyrolyzed Cottonseed Oil as Volume Percent

Temperature °C

Parameter

Diesel oil

Pyrolyzed oil

Distillate, %

0

63

55

10

105

79

20

174

116

30

192

131

40

200

157

50

210

178

60

235

186

70

245

220

80

250

247

90

255

269

98

260

—

Recovery, %

98

90

Residue, %

1

9

Loss, %

1

1

value of 41.3 MJ/kg, a kinematic viscosity of 5.96 mm2/s, a cetane number of 53, and a flash point of 80°C. When tested on a diesel engine, the thermal efficiency (^th) and brake specific fuel consumption were improved. The concentration of nitrogen oxide in the exhaust gas was less than diesel. The absence of sulfur in the pyrolytic oil was seen as an advantage to avoid corrosion problems and the emission of polluting sulfur compounds from combustion.

Triolein, canola oil, trilaurin, and coconut oil were pyrolyzed over acti­vated alumina at 450°C and atmospheric pressure [44]. The products were characterized by IR spectrometry and decoupled 13C-NMR spec­troscopy. The hydrocarbon mixture contained both alkanes and alkenes. These results are significant for the pyrolysis of lipid fraction in sewage sludge as well as for wastes from food-processing industries [44].

Pyrolysis of rapeseeds, linseeds, and safflowers results in bio-oil con­taining oxygenated polar components. Hydropyrolysis at medium pres­sure in the presence of 1% ammonium dioxydithiomolybdenate (NH4)2MoO2S2 can remove two-thirds to nine-tenths of the oxygen pres­ent in the seeds to generate bio-oils in yields up to 75% [45]. In addi­tion, extraction with organic solvents including diesel oil gave yields up to 40%.

The potential of liquid fuels from Mesua ferrea seed oil [46], Euphorbia lathyris [47, 48], and underutilized tropical biomass [49] has been inves­tigated in the search for “energy farms” involving the purposeful culti­vation of selected plants to obtain renewable energy sources.