Production of renewable hydrocarbon fuels—Thermochemical behavior of fatty acid soap decarboxylation during microwave-assisted pyrolysis

Biodiesel(FAME) is poor in low temperature fluidity and antioxidation stability, it´s heat value is 9%-13% lower then petrodiesel. It is a promising route to derive renewable hydrocarbon fule from waste vegetable oil or animal oil via fatty acid decarboxylation. In present investigation, The sodium soap made from Swida wilsoniana fruit oil was used as the experimental material for preparing hydrocarbon fuel by microwave-assisted pyrolysis decarboxylation. The experimental results showed that: 1) Both of the yield of the liquid sodium soap pylolysis product and hydrocarbon content of the liquit product was usually above 70%, In addition, its´ dynamic viscosity and density is 2.09-2.85 mm²/s and 0.850~0.875 g/cm³, respectively, similar with prtrodiesel. The highest peak in the GC-MS profile of liquid product is fifteen carbon alkenes, which indicated that by using microwave heating technology, which may preferentially activate the polar partial of the soap molecular, leading to the high selectivity of decarboxylization, which is the most significant thermochemical reaction in present experiment. 2) The hydrocarbons content in the liquid product was increased with the microwave power input increased. 3) In addition with decarboxylation, carbon chain cleavage is very common in sodium soap microwave pyrolysis, C-C single bond is easier to be destroyed then C=C double bond, the later is mostly remained in the pyrolysis product. 4) Adding CaCO₃, FeCl₃, Kaolingite as catalyst respectively, have significant impact on both the yield of the liquid product and its´ hydrocarbons content and their alkenes, alkanes and aromatics composition.